IM20184EN by Innovatieve Materialen

Volume 4 2018

Glass-ceramic stands the heat Renovation of steel bridge decks with a GRP sandwich construction Self-Healing Al2O3 ceramics Acoustic metamaterials: Metamaterials for wave control and manipulation by exploring nonlinearity

I N T E R N A T I O N A L

E D I T I O N

CONTENT Innovatieve Materialen Aboutis een vaktijdschrift gericht op de civieltechnische Innovatieve Materialen sector en bouw. Het bericht over ontwik(Innovative Materials) is a digital, kelingen op het gebied van duurzame, inindependent magazine novatieve materialen en/of de about toepassing material the fields of daarvaninnovation in bijzondereinconstructies.

engineering, construction (buildings, infrastructure and industrial) and Innovatieveindustrial Materialendesign. is een uitgave van Civiele Techniek, onafhankelijk vaktijdschrift voor civieltechnisch ingenieurs werkzaam in de grond-, weg- en waterInnovatieve Materialen has bouw en verkeerstechniek.

News 1 3D-printed ceramic façade cools buildings 2 Freement: circular concrete 3 NAWA pavilion: arches of inflated steel 4 Glassomer: processing glass like a polymer

entered partnerships with several intermediate and De redactie staatorganisations open voor bijdragen universities, allUactive in the field of van vakgenoten. kunt daartoe contact materialmet innovation. opnemen de redactie. More information (in Dutch): www.innovatievematerialen.nl

8 The Longhouse

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18 Renovation of steel bridge decks with a GRP sandwich construction

4200 AW Gorinchem tel. (0183) 66 08 08 Publisher e-mail: info@innovatievematerialen.nl SJP Uitgevers www.innovatievematerialen.nl

Postbus 861 4200 AW Gorinchem Redactie: tel. +31 183 66 08 08 info@innovatievematerialen.nl Bureau Schoonebeek vof Hoofdredactie: Gerard van Nifterik

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Innovative Materials

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Dr. ir. Fred Veer, prof. Ir. Rob Nijsse (Glass & Transparency Research Zie ook: www.innovatievematerialen.nl Group, TU Delft), dr. Bert van Haastrecht (M2I), Niets uitWim deze Poelman, uitgave magdr.worden prof. Ton verveelvuldigd en of openbaar worden Hurkmans (MaterialDesign), door middel van herdruk, fotokopie, miprof.dr.ir. Jos Brouwers, crofilm of op welke wijze dan ook, zonder (Department of the Built voorafgaande schriftelijke toestemming Environment, Section van de uitgever.Building Physics and Services TU Eindhoven), prof.dr.ir. Jilt Sietsma, (4TU.HTM/ Mechanical, Maritime and Materials Engineering (3mE)

10 Eindhoven gets first 3D-concrete printing housing project 12 World’s first circular car is made of sugar 14 Wienerberger Brick Award 2018

20 Perfect shade

22 Glass-ceramic stands the heat

NEXTREMA glass-ceramic is a new, versatile material platform from SCHOTT. It’s well suited for extreme conditions and innovative designs with near-zero thermal expansion and high temperature resistance. The company created six different versions of glass-ceramics, differing in terms of color impression and technical characteristics.

26 Self-Healing Al2O3 ceramics: Selection and testing of novel healing particles

Scientist Linda Boatemaa (TU Delft) examined the self-healing recovery process of several ceramic materials. In particular, she looked at the behaviour of three new alumina-composites designed to self heal at high temperatures and she tested them under both laboratory conditions and turbine-like conditions. This resulted in the dissertation ‘Self-Healing Al2O3 ceramics: Selection and testing of novel healing particles’. In May this year she obtained the degree of doctor at Delft University of Technology.

30 Acoustic metamaterials: Metamaterials for wave control and manipulation by exploring nonlinearity

The development of metamaterials enables to engineer materials with extraordinary features, beyond the traditional limits. In the linear dynamic regime, metamaterials have already enabled a wide range of new functionalities, such as cloaking, super-lenses, and signal filtering. The consideration of nonlinearity has the potential to bring a myriad of new opportunities for metamaterials. Within the 4TU.High-Tech Materials research program, metamaterials were developed with nonlinear resonant inclusions. Results of this research show emergent dynamic features which may enable tunability, new mechanisms of sound and vibration attenuation, and the realization of a ‘mechanical diode’. Besides, efficient computational schemes are being developed for optimal analysis of the emergent metastructure design.

Cover: Tera cotta studio by Tropical Space; Wienerberger Brick Award, page 14

BERICHTEN RESEARCH NEWS

Photo: Mashrabiya mockup. A full-scale mockup of the façade was assembled from 140 individual 3D-printed ceramic units to display the gradient of assembly potentials. Contributed by International Masonry Institute

3D-printed ceramic façade cools buildings Earlier this year an Iowa State Univeraty architecture team won a award of the Joan B. Calambokidis Innovation in Masonry Competition for the use of masonry to cool buildings. The so-called JBC Competition challenges architects, engineers, students, and firms to imagine the future of masonry design and construction. Participants should rethink the innovative potential of masonry construction by exploring approaches to energy efficiency, resiliency, sustainability, and mass customization. Use of BIM, computational design, and emerging construction and manufacturing techniques is also encouraged. All designs must incorporate one or more of the following materials: brick, concrete block, tile, marble, terrazzo, stone, and plaster. Solutions should address both the aesthetic and structural nature of masonry assembly. The proposed project could be a building; exterior building element such as a wall, floor, or roof assembly; or

other concept construction. The competition invites creative freedom to allow designers to innovate without restraint. The Iowa team - Shelby Doyle, assistant professor and Daniel J. Huberty Faculty Fellow in Architecture; Leslie Forehand, lecturer; Nicholas Senske, assistant professor; and Erin Hunt, computation and construction lab associate - won in the young architects and engineers category.

saturates the ceramic disks, while air blowing through the façade ventilates and cools the building. The façade comes in three modules or shapes. Woven patterns on the screen wall create ‘micro-pores’ that help ventilate and cool the space as air passes through.

Their project, ‘Mashrabiya 2.0,’ is a 3D-printed ceramic façade that can be integrated into a building’s mechanical system to control light, airflow and privacy while offering evaporative cooling. The team was inspired by Arabic lace screens, replacing the traditional wood with 3D printed ceramics. The team created a mockup of 140 individual 3D printed ornamental disks made on a a Potterbot. The disks were eventually wrapped around pipes with tiny holes that are connected to a building’s water system. Water in the pipes

More at Iowa State University

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NEWS

Freement: circular concrete

During the Provada at the RAI in Amsterdam on 5 June Rutte Groep and New Horizon Urban Mining launched the Smart Liberator, an innovative proces installation that recycles concrete for 100 percent. The idea is that there is still 50% useful reactive cement in concrete rubble. Socalled SmartCrushers release this usable cement from concrete waste for reuse. In the Smart Liberator the lighter, used (hydrated) cement is broken and extracted. The unhydrated cement is ‘liberated’ from the rubble after which gravel sand and active cement are separated with an advanced sieve. All materials are reused, for instance for the production of new cement or it is reprocessed to get a binder or limestone improver. Based on this proces the parties involved developed Freement: a circular concrete that is obtained through a pioneering, innovative concrete processing with the ‘smart liberator’. During the Provada the first pocket of the circular cement was awarded to the Dutch astronaut André Kuipers. The production of concrete is accompanied by a huge CO2 emission. Especially the production of the necessary cement

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is very damaging to the environment. Worldwide, the emission of cement production is comparable to the emission of all logistical processes. According to the Freement website SmartCrushing will ensure there is 1 billion metric tons of CO2 per year less on a global scale.

The Smart Liberator installation has been extensively tested and will be used from the launch moment for all the concrete released on New Horizon projects during the dismantling of buildings. www.freement.nl

BERICHTEN NEWS

NAWA pavilion: arches of inflated steel

In August Material District paid attention to a striking construction in Poland: the NAWA pavilion, designed by Oskar Zięta, is an ultralight construction made with FiDU, a technology that inflates steel elements with compressed air. The 7.5 m x 10 m x 11 m pavilion is an ultralight, durable construction made up of 35 FiDU steel arches. Put together, they create an open portal that is easily accessible from all sides. FiDU is a technology invented by Zięta. It allows to distort the 2D shapes of steel elements welded together, turning them into 3D profiles by inflating them with compressed air. The metal forms become durable and stable, while remaining relatively light. The technique requires just one thousandth of the pressure needed for internal high-pressure forming. The sculpture was realised in 2017 on Daliowa island in the city of Wrocław, Poland. It was awarded the most innovative Polish architectural project of 2017 by Architektura-Murator magazine. Photos: Zieta Prozessdesign Studio Urbanext>

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NEWS

Glassomer: processing glass like a polymer Pure quartz glass is highly transparent and resistant to thermal, physical, and chemical impacts. These are optimum prerequisites for use in optics, data technology or medical engineering. For efficient, high-quality machining, how ever, adequate processes are lacking. Scientists of Karlsruhe Institute of Technology (KIT) have developed a forming technology to structure quartz glass like a polymer. This innovation is reported earlier this year in the journal Advanced Materials. A team lead by dr. Bastian E. Rapp, Head of the NeptunLab interdisciplinary research group of KIT’s Institute of Microstructure Technology (IMT), developed a new processes for industrial glass processing. Instead of heating glass up to 800 °C for forming or structuring parts of glass blocks by laser processing or etching, they mix glass particles of 40 nanometers in size with a liquid polymer, form the mix like a sponge cake, and harden it to a solid by heating or light exposure. The resulting solid consists of glass particles in a matrix at a ratio of 60 to 40 vol%. The polymers act like a bonding agent that retains the

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glass particles at the right locations and, hence, maintains the shape. This ‘Glassomer’ can be milled, turned, laser-machined or pro-cessed in CNC machines just like a conventional polymer. For fabricating high-performance lenses

that are used in smartphones among others, the scientists produce a Glassomer rod, from which the lenses are cut. For highly pure quartz glass, the polymers in the composite have to be removed. For doing so, the lenses are heated in a furnace at 500 to 600 °C and the polymer is burned fully to CO2. To close the resulting gaps in the material, the lenses are sintered at 1300 °C. During this process, the remaining glass particles are densified to pore-free glass. According to Rapp, the forming technology enables production of highly pure glass materials for any applications, for which only polymers have been suited so far. This opens up new opportunities for the glass processing industry as well as for the optical industry, microelectronics, biotechnology, and medical engineering. The process would be suited for mass production. Original publication: Glassomer - Processing Fused Silica Glass Like a Polymer F. Kotz, N. Schneider, A. Striegel, A. Wolfschläger, N. Keller, M. Worgull, W. Bauer, D. Schild, M. Milich, C. Greiner, D. Helmer, B. E. Rapp: ‘Glassomer: Processing Fused Silica Glass like a Polymer’

www.kit.org>

NEWS

ARCHITECT @WORK THE NETHERLANDS

TOTAALEVENEMENT MET FOCUS OP PRODUCTINNOVATIES VOOR ARCHITECTEN, INTERIEURARCHITECTEN EN VOORSCHRIJVERS

ARCHITECT MEETS INNOVATIONS Rotterdam Ahoy 12-13 september 2018 7Â° editie - 13:00-20:00

THEMA: ARCHITECTUUR & LICHT < EXHIBIT Lovely Light by MaterialDistrict < PROJECT WALL by world-architects.com < IMAGES by DAPh < The ART of Upcycling by OCEAN SOLE < SEMINARS - DONDERDAG 13 SEPTEMBER - 13:30 Landscape of the future / Artist and Innovator Daan Roosegaarde

treer s i g Re t code me 885 19

ORGANISATIE Beurzen Adviesbureau T 030 298 22 93 netherlands@architectatwork.com @ATW_INTL #ATWNL @architect_at_work WWW.ARCHITECTATWORK.NL

CANADA

TURKEY

NORWAY

SWEDEN

DENMARK

SPAIN

ITALY

SWITZERLAND

AUSTRIA

GERMANY

UNITED KINGDOM

FRANCE

LUXEMBOURG

THE NETHERLANDS

BELGIUM

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BERICHTEN RESEARCH NEWS

Concrete Canoe Race 2018 In the weekend from the 25th until the 27th of May, the concrete canoes race was held in Eindhoven. The BetonKanoRace (Concrete Canoe Race) is an annual competition between teams from different colleges and universities from various European countries. The goal is to design and build a concrete canoe and to compete on different categories. The lightest canoe was only 7.4 kilograms and was made by the TU Dresden. However, one day later it turned out that this canoe was not able to race the minimum required distance of 100 meter, and therefore the price for the lightest canoe was won by ‘Rosa Schweinchen auf Grüner Wiese’, also made

by the TU Dresden, with a weight of 23.6 kilograms. The heaviest canoe was the 3D printed canoe made by Utrecht University of Applied Science with a weight of over 400 kilograms. Besides these quantitively decided prizes, the judges also looked for the winners of the most innovative canoe, the BouwQ 360 Quality award, and the unluckiest canoe. The most innovative canoe was a floating foundation beam made by B-Invented. The judges appreciated the fact that the team did not use the standard shape of a canoe and tried to make it out of concrete, but took a structural element

and modified it to become a canoe itself. The BouwQ 360 Quality Award was won by the HTWK Leipzig with their canoe ‘Blackbeerd’. The judges appreciated the use of glassfibre in the walls of the canoe and carbon in the bottom. The quality of both the in- and outside was very high and two composite materials were applied. Lastly, the team from the University of Applied Sciences in Enschede won the price for the unluckiest canoe, since their first canoe broke on transport and their second canoe early in the races on Saturday, which excluded them from participating. More at betonkanorace.eu>

Video: Concrete Canoe Race 2018

Printing the canoe of Utrecht University of Applied Science at 3D printing pioneer company Vertico (Amersfoort)

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Video: The making of a 3D printed concrete canoe at Vertico

NEWS

Second life for hardwood sheet pile In the Dutch city of Koog a/d Zaan, a pilot project was carried out for a new sheet pile construction over a length of 30 meters. Old sheet pile sections are reused according to a new process. In this process, old azobĂŠ hardwood sheet pile sections are extended just under the waterline by means of a finger joint with softwood to the required length of the new sheet pile. Research has shown that the durability of the hardwood reprocessed and used in this way doesnâ&#x20AC;&#x2122;t differ from that of new hardwood. With this development, according to the parties involved, the wood is used both circular and Cradle to Cadle with a lifespan of at least 25 years. The new process is being applied by Van Swaay Duurzaam Hout (Harlingen, The Netherlands) which processes the combination of hardwood and softwood in the so-called H2H products. The pilot project was carried out by Benecke Aannemingsmaatschappij from Zaandam. http://www.vanswaay.nl/

Biobased bridge Monday 18 June, Schiphol Logistics Park officially opened the biobased bridge at the logistics business park in Rozenburg. Schiphol Logistics Park, FiberCore Europe and TU Delft joined forces to construct this special footbridge. Never before was a bridge constructed in a regular building process with materials as sustainable as the materials of this bridge. Because of the composition of its materials the bridge is a special innovation. For his thesis at the Bridge Design Group of TU Delft architect Rafail Gkaidatzis did research into a footbridge implementing the highest proportion of biobased materials possible. The result is a so-called bio-basalt balsa (B3) bridge of 15 meters long and 2 meters wide. The bridge spans the waterway between the Ringdijkpark and the Naritaweg at Schiphol Logistics Park and is publicly accessible. The composite bridge at Schiphol Logistics Park was made possible by Mafic S.A. as supplier of the basalt fibres, BALTEK VBC by Airex AG, a member of 3A Composites, as supplier of the balsa, Poly Base Produktie B.V. for the processing of the balsa and Royal Haskoning DHV. More at the website of Innovatieve Materialen (Dutch)>

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BERICHTEN NEWS

The Longhouse Recently, MIT Mass Timber Design, a design workshop at the Massachusetts Institute of Technology, has explored the design and engineering potential of new mass timber technologies and developed a mass timber-building prototype: The Longhouse.

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The idea is that conventional buildings are one of the largest consumers of global resources and all energy produced, and are primary contributors to greenhouse gases and solid wastes. Mass timber, a wood-based building design and construction technology, could be

an interesting, environmental friendly alternative. Whereas the production of concrete, used in most of the worldâ&#x20AC;&#x2122;s large buildings, involves large releases of greenhouse gases from the baking of limesto-

NEWS ne, construction using mass timber has the opposite effect. While concrete adds to the worldâ&#x20AC;&#x2122;s burden of greenhouse gases, timber actually lessens it. With the Longhouse prototype, MIT designed wants to demonstrate that even huge buildings can be built primarily with wood. The design will be presented this October at the Maine Mass Timber Conference, which is dedicated to exploring new uses of this material. A longhouse is a multifunctional building type common across the world and through history. The MIT version is designed to accommodate a range of event scenarios from co-working, exercise classes, social mixers, exhibitions, dinner gatherings and lectures. The structure uses massive beams made from layers of wood veneers laminated together, a process known as Laminated Veneer Lumber (LVL), made into panels 15 m long, 3 m wide, and more than 15 cm thick. These are cut to size and used to make a series of large arches, 12 m tall to the central peak and spanning 15 m across, made of sections with a triangular cross-section to add structural strength. A series of these arches is assembled to create a large enclosed space with no need for internal structural supports. The arches would be factory-built in sections, and then bolted together on site to make the complete building. The MIT Longhouse was developed by a cross-disciplinary team in Mass Timber Design, a design workshop in MIT Architecture that explores the future of sustainable buildings at the intersection of architecture and technology. Project credits: (Research Scientist) John Klein,

Video MIT

(Design-Engineering Team) John Fechtel, Paul Short, Demi Fang, Andrew Brose, Hyerin Lee, Alexandre Beaudouin-Mackay. MIT Mass Timber Design was generously supported by MITâ&#x20AC;&#x2122;s Depart-

ment of Architecture, BuroHappold Engineering and Nova Concepts. MIT News>

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NEWS

Eindhoven gets first 3D-concrete printing housing project Photo: An artist impression of the five 3D-printed concrete houses that will be realized in Eindhoven. Picture: Houben/Van Mierlo architects

In the city of Eindhoven the realization of the first of five planned 3D-printed concrete houses will start this year. The project, called Project Milestone, is a worldâ&#x20AC;&#x2122;s first, as the houses will all be occupied. The six parties involved showed the design today. The project will be realized in the Eindhoven city expansion area Meerhoven over the next five years. The first house, which will be a single-floor house, is expected to be ready for occupation in the

first half of 2019. The other four houses will be multi-storey houses. The municipality of Eindhoven, Eindhoven University of Technology, contractor Van Wijnen, real estate manager Vesteda, materials company Saint Gobain-Weber Beamix and engineering firm Witteveen+Bos are the project partners. The design of the houses is based on erratic blocks in a green landscape. The irregular shape of the buildings can be realized thanks to one of the key featu-

res of 3D-printing: the ability to construct almost any shape. The design aims at a high level of quality and sustainability. For instance, less concrete is needed and hence much less cement, which reduces the CO2 emissions originating from cement production.

Real time innovation

During the project, research on concrete printing will be done for new innovations. The five houses will be built consecutively, so every time these innovations and all lessons learnt can be applied in the next house. The building elements of the first house will all be printed by the concrete printer at the university. It is the intention to gradually shift the whole construction work to the construction site. The last house will be fully realized on site, including the print work. The design by Houben/Van Mierlo architects is inspired by boulder stones in a green landscape. With the 3D printer, simple forms can be carried out that are very labor intensive to produce with traditional concrete construction methods. www.3dprintedhouse.nl

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NEWS

Hét expertisecentrum voor materiaalkarakterisering. Integer, onafhankelijk, objectief onderzoek en advies. ISO 17025 geaccrediteerd. Wij helpen u graag verder met onderzoek en analyse van uw innovatieve materialen. Bel ons op 026 3845600 of mail info@tcki.nl www.tcki.nl

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09-05-17 13:19

2017 volume 3

INNOVATIVE MATERIALS

International edition Innovative Materials, the international version of the Dutch magazine Innovatieve Materialen, is now available in English. Innovative Materials is a digital, independent magazine about material innovation in the fields of engineering, construction (buildings, infrastructure and industrial) and industrial design.

3D-printing cellulose World’s first 3D-printed reinforced concrete bridge Materials 2017 Composites improve earthquake resistance in buildings

www. innovatievematerialen.nl info@innovatievematerialen.nl

Glass bridge Lina: world’s first bio-based car

I N T E R N A T I O N A L

E D I T I O N

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NEWS

Photos: tuecomotive.nl

World’s first circular car is made of sugar On Friday 6 July, Noah, the world’s first complete circular car, was unveiled at the Cosun Innovation Center in Dintel oord. The two-person car, the chassis of which is largely made of sugar and the bodywork of flax and bio resin, was developed by a team of 22 students from Eindhoven University of Technology. The car, Noah, is made entirely out of recyclable materials. It was developed by a team from TU/ecomotive and was sponsored by Suiker Unie. The chassis is made out of sugar and the body out of polylactic acid. The unveiling of Noah was also the start of a tour through several European cities. The TU/ecomotive team wants to introduce the general public to the car made of fully recyclable material. It is an objective of the students to contribute to a reduced climate load.

Next Lina

The 350-kilo light Noah is a two-seater city car with modular batteries and a 240-kilometer range. Powered by 15 kW the vehicle can reach a top speed of 100 km per hour. The team believes this suc-

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cessor to Lina has the capacity to become the world’s first circular car. Lina was developed and built by TU/ecomotive in 2016/2017 by a student team from the TUE (Innovative Materials 3 2017).

Lina was structurally built from bio‐composites, based on sugar beets and flax. NOAH’s components are vegetable-based as they were in Lina, but are now fully recyclable. In contrast to Lina, the

NEWS binding agent (this time round PLA) and the flax structure can be separated from one another when the car is withdrawn from use. Becoming the worldâ&#x20AC;&#x2122;s first circular car refers for instance to the scope for recycling Noahâ&#x20AC;&#x2122;s parts. Take the binding agent in the flax panels for example. Its components are vegetable-based as they were in Lina, but are now fully recyclable. In contrast to Lina, the binding agent (this time round PLA) and the flax structure can be separated from one another when the car is withdrawn from use.

Sugar

A special aspect of Noah is the use of a bioplastic which can be made from sugar. The chassis and the interior are made of particularly strong sandwich panels, made of this bioplastic and flax fiber. The body is made of flax mats that are injected with a bio-based resin. These biological and particularly light materials require up to six times less energy to produce than the usual lightweight car materials such as aluminum or carbon. Still, the students claim that they have the necessary strength, and it is also possible to create a crumple-zone-like structure. Flax is a widely used intermediate crop that is essential to soil enrichment, so its cultivation does not compete with food production.

Raw material

At the end of its useful life, the biocomposite can be ground and used as a raw material for other products, such as building blocks. The non-organic parts of the car can be included in the existing recycling chain. From a survey by the student team, there appears to be no other car on the road that has just as low an environmental impact over its entire life cycle, not even a prototype. tuecomotive.nl www.suikerunie.nl

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NEWS

Wienerberger Brick Award 2018

Westkaai Towers

On May 28 brick manufacturer Wienerberger presented the biennial Brick Award for the 8th. Nearly 600 projects from 44 countries were submitted for

this manual leading price for ceramic architecture. This year, two projects were awarded the Grand Prize. In the Category ‘Working together’ the Grand Prize went to the Westkaai Towers 5 & 6 in Antwerp, Belgium by Tony Fretton Architects, UK in collaboration with DE Architecten NV, BE. The towers are part of a larger residential project within a new developed mixed-used quarter. Thanks to the brickwork an overall monumental expression is combined with an individual façade.

Kunstmuseum Basel

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The second Grand Prize was awarded in the Category ‘Sharing public spaces’ for the Kunstmuseum Basel Extension by Christ & Gantenbein, Switzerland. The solitary grey brick structure is connected through an underground hall with the main building. LED lights are integrated into the relief-like grooves made of moulded bricks in the façade – informing passers-by about current exhibitions.

NEWS The Category winner in ‘Feeling at home’ is Atlas House by Monadnock, A private living space in Eindhoven (The Netherlands)organized on three floors on a small plot, it is a good answer to demonstrate how private quality housing can be built in small-scale. The brickworks both in- and outside are carefully detailed and perfectly fit to the house. Terra Cotta Studio by Tropical Space is the working and living place of a famous ceramic artist in Vietnam. The Category winner of ‘Working together’ is a brick cube at the foot of a river, bamboo shelves protect the artwork for occasional flooding. The unusual perforation of the façade already attracts attention at first glance and allows the wind to blow through and cool the workspace naturally. The building combines working production and domesticity.

Atlas house

Terra Cotta Studio

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NEWS

Värtan Bioenergy WKK-plant

San Bernardo-chapel

The Värtan Bioenergy CHP Plant in Stockholm by U.D. Urban Design & Gottlieb Paludan Architects could convince the jury the most and received the Award as Category winner ‘Building outside the box’. It includes the world’s largest urban biofueled cogeneration plant and makes a significant contribution to the reduction of the city’s CO2 footprint. The overground part of the plant has been clad in a curved façade of vertical ceramic elements.

and nature determine the atmosphere. The sunlight, together with two wooden poles shade a Christian cross on the wall in the east once a day.

This year the jury chose two Special Prize winners: In the Category ‘Sharing public spaces’ San Bernardo Chapel by Nicolás Campodonico Estudio is a small masterpiece. It is dedicated to the patron saint of a small community near where it was erected, in the Argentine Pampa. Neither running water nor electricity are available at the site itself. Only the light of the sun

Church of Vilanova de la Barca

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The revitalization of Old Church of Vilanova de la Barca by AleaOlea architecture & landscape was awarded the second Special Prize in the Category ‘Building outside the box’. Dating back to the 13th century, the church was destroyed during the Spanish Civil war. The renovation of it is an unusual approach to dealing with historical building fabric. This project shows the versatility and adaptability of brick and creates a unique dialog between the present and history. Text/photos: Wienerberger>

NEWS

The first PlasticRoad bike path will be located in Zwolle The PlasticRoad, a road made of recycled plastic, becomes a reality. June 2018, the municipality of Zwolle and the province of Overijssel have committed to the first PlasticRoad pilot project. In September the first PlasticRoad will be constructed in Zwolle and in another location in the province a few months later. The PlasticRoad concept was launched in 2015 by road construction company KWS (a subsidiary of Royal VolkerWessels). In 2016, KWS entered into a partnership with Wavin and Total for further development of the PlasticRoad. The province of Overijssel and the municipality of Zwolle see great potential in the PlasticRoad as a solution for the challenges of the future as it pertains to a circular economy.

The road to the PlasticRoad

The first two pilot projects will be realized in the form of 30 meter long bicycle paths made of hollow prefabricated elements enabling water drainage and laying down of cables and pipes, with the exact final locations still to be decided. The PlasticRoad concept consists of a prefabricated, modular and hollow road structure made from (recycled) plastic. The prefabricated production, the light weight and the modular design of the PlasticRoad make construction and maintenance faster, simpler and more efficient compared to traditional road structures.

extreme precipitation. The hollow space can also be used for the transit of cables and pipes, thus preventing excavation damages. And there are numerous other conceivable applications, including the installation of sensors or the electric charging of vehicles. According to the developpers the expected lifetime of the PlasticRoad is two to three times as long as that of traditional road paving. The expected construction time of a new road will be reduced by approximately 70%. The PlasticRoad is expected to be four times as light as a traditional road structure. Last but not least: the PlasticRoad is 100% circular and is made from recycled plastic as much as possible. More at www.plasticroad.eu

The concept

The PlasticRoad has a hollow space that can be used to (temporarily) store water, thus preventing flooding during

Video

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RESEARCH

Renovation of steel bridge decks with a GRP sandwich construction In 1997, during an inspection of the second Van Brienenoord bridge (Rotterdam), several fatigue cracks were discovered in the cover plate and trough-shaped cover plate stiffeners. This led to a lot of attention for fatigue problems (Photo: Rijkswaterstaat)

Since 1997, the problems of fatigue of orthotropic steel bridges became an important issue. As a result of an inspection of the second â&#x20AC;&#x2DC;Van Brienenoordâ&#x20AC;&#x2122; bascule bridge, it became clear that several fatigue cracks occurred in the steel deck plate and V-shaped deck plate stiffeners. To prevent frequent delays in traffic due to inspection and repair, cracks in orthotropic steel deck of all

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frequently loaded steel bridges should be prevented. Research by Robin Rook and Robbin Lassche, students Civil Engineering, Hogeschool Windesheim (HW), Lectorate Plastic Technology (LKT), now shows that renovation of steel bridge decks with a fiber reinforced sandwich construction can be an interesting alternative, espe-

cially for movable bridges. The research took place in collaboration with Peter Bosman, lecturer-researcher HW, commissioned by Aliancys, Fiberneering and Hogeschool Windesheim, LKT with a grant from Green PAC. The goal of their research was to investigate the feasibility of an alternative solution for the fatigue problems: sandwich structure consisting of foam core and glass fibre reinforced plastic (GRP) under-flange replacing the V-shaped deck plate stiffeners. In comparison with the current solution, a high strength concrete (HSC) overlay, the GRP sandwich underlay offers several advantages: lighter structure (particularly favourable for movable bridges), underlay under bridge deck (less traffic delay during renovation), and no raise of the abutments (less interface adjustments). Experiments show that a hybrid sandwich structure can be made that is sufficiently capable to absorb the prescribed impact of falling cargo in case no flow media/fibres are applied in the interface between deck plate and core. Furthermore steel deck plate denting occurs before delamination or core crushing appears. A structure can be obtained that is sufficiently capable to resist impact loads and gives external signals before internal damage occurs.

RESEARCH The results of an engineering case show that a GRP sandwich has to be able to resist all other failure modes. Furthermore, experiments show that with vacuum infusion above head (from the lower side) a complete wetting under the deck plate can be accomplished without using flow media/fibres. For vacuum infusion a brief implementation plan is made. With this a cost estimate is composed. Both the direct and indirect costs of a GRP sandwich structure can appear to be favourable for movable bridges compared to a HSC overlay. The GRP sandwich seems to be a technical feasible and economical favourable solution for movable steel bridge decks with fatigue problems. This article is based on the report â&#x20AC;&#x2DC;Renovatie stalen brugdekken met een VVK sandwichconstructieâ&#x20AC;&#x2122;, by Robin Rook and Robbin Lassche and teacher researcher ir. Peter Bosman, Hogeschool Windesheim, Civiele techniek, Lectoraat Kunststoftechnologie

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Perfect shade Designed on a computer and built with the help of robots: ETH (Zurich) students studying for the Master of Advanced Studies (MAS) in Architecture and Digital Fabrication have built a striking wooden pergola to turn the sun-baked terrace at the Istituto Svizzero in Rome into a pleasant, shady spot. Their project

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demonstrates the potential that digital fabrication holds for wooden buildings. What is striking about the almost four-metre-tall construction is how its short wooden elements are joined with nothing more than wooden dowels. According to Hannes Mayer, Programme Director of ETHâ&#x20AC;&#x2122;s MAS in Architecture

and Digital Fabrication, it would have been impossible to use traditional methods to define the positions of the 700 wooden elements and 2,700 beech dowels in such a way as to produce a dynamic and harmonious whole. To do that takes rules, which, when translated into algorithms, unite all the disparate

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elements into a powerful and graceful structure. The Istituto Svizzero offered a site on which to build the pavilion: the Travertin Terrace, an sunny, L-shaped space covering 250 square metres atop an annex of the Swiss cultural institute. This terrace is exposed to the relentless Roman sun throughout the day, which makes it almost unusable despite its beautiful location. The students designed, developed and built the pavilion in under ten weeks. Three of those weeks were spent manufacturing the elements in Zurich; it took one week to erect the pergola on the terrace. The pergolaâ&#x20AC;&#x2122;s development and construction followed a purely digital process chain in which the students created a digital model that integrated their initial design, the results of a sun-position simulation to work out where to place the wooden elements, the construction parameters and the manufacturing data. Depending on the position of the sun, the system of wooden elements expands and thickens so as always to provide perfect shade.

ceiling of the Institute of Technology in Architecture on ETHâ&#x20AC;&#x2122;s HĂśnggerberg campus, took their instructions from the digital model. The 11 arch-segments that the students erected on this Roman terrace are made up of 22 individual elements connected to give the impression of a seamless overall structure. An official opening ceremony took place at the end of June.

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All the elements making up the pergola were manufactured in the Robotic Fabrication Laboratory at ETH Zurich. Two robot arms, fitted to a gantry system suspended from the

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INNOVATIEVE MATERIALEN 4 2018 INNOVATIVE MATERIALS 4 2018

SCHOTT NEXTREMA glass-ceramic is well-suited for optimised infrared transmission. This opens up new applications for energy-efficient heating processes, such as heating exterior and interior areas (Photo: www.heatscope.com)

Glass-ceramic stands the heat NEXTREMA glass-ceramic is a new, versatile material platform from SCHOTT. It’s well suited for extreme conditions and innovative designs with near-zero thermal expansion and high temperature resistance. The company created six different versions of glass-ceramics, differing in terms of color impression and technical characteristics. NEXTREMA stands for ‘Next EXTREme MAterial,’ justifying the claim by combining the qualities of technical glass with high-temperature materials. The result is a list of material specifications earning the product platform a place across industries and applications. A smooth, non-porous surface, high heat and thermal shock resistance, high transmission in the infrared and visible light range and general mechanical strength are advantages. It consists of six different versions of glass-ceramics, differing in terms of color impression and technical characteristics. Each glass-ceramic has slightly varying

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properties to suit specific customer needs. Thicknesses range from 2-6 mm (>6 mm on request). The combination of these characteristics enables innovative product designs and functionalities in many different areas of application. The glass-ceramic distinguishes itself for its reliable technical performance when exposed to high temperatures and rapid temperature changes. Due to its excellent resistance to temperatures of up to 950 °C and thermal shocks, NEXTREMA glass-ceramic is a capable solution for high temperature applications where glass properties are beneficial. With applications spanning form industrial

furnaces to electric toasters, the material is carving out an innovative place in the high-tech material market. The glass-ceramic’s versatility comes from its pairing of innovative technology with functional design. In the construction of technical applications, a customer’s primary interests are physical and chemical parameters, robustness under extreme temperature loads and chemical resistance. SCHOTT has introduced with NEXTREMA glass-ceramic a hightech material with a variety of these features.

INNOVATIEVE MATERIALEN4 42018 2018 INNOVATIVE MATERIALS

Robustness and resistance

One of NEXTREMA glass-ceramic’s interesting properties is its temperature resistance, which stretches up to 950 °C. This range makes it an obvious contender for application in various industries, particularly where conditions would push the limits of more conventional forms of glass. Its reliability is highlighted by another striking property, a thermal expansion ratio near zero. Where increasing temperature usually forces a material to expand, SCHOTT’s process introduces tiny crystals which do the opposite, achieving a stable, nearly unchanged result. The glass maintains its strength, durability and quality even at high temperatures.

number of industries where robustness is critical to performance. Its acid resistance according to DIN 12116, alkaline resistance to ISO 695 and its hydrolytic class to DIN ISO 719 contributes to this.

Design flexibility

Colors and shapes are critical for design innovation and differentiation. This material offers engineers and designers a homogeneously colored material plat-

Differing slightly by material type, NEXTREMA glass-ceramic has a temperature shock resistance of up to 820 °C. This indicates that the glass-ceramic can utilize its heat resistance in more than just the laboratory. High shock resistance has lent itself to the material’s deployment in a wide range of applications, including as a hot bed for 3D printers, many of which require an undistorted workpiece despite motion and heat. The glass-ceramic also boasts surface resistance properties that qualify it for a

The SCHOTT NEXTREMA glass-ceramic material platform consists of various versions of glass-ceramics that differ in terms of their colour impression as well as their technical characteristics (Photo: SCHOTT)

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a transparent cover for grills, allowing users to keep an eye on the cooking process while the heat is concealed. It is used as the inner lining, setter and heater cover in high-temperature furnaces in display production for AMOLED (active-matrix organic light-emitting diode) technologies. This latter application means the innovative solution contributes to the production of end customer products such as smartphones or tablets. The glass-ceramic platform finds similar industrial use as a substrate for thin-film coatings. Electrical appliances brand Morphy Richards, for instance, employs the glass-ceramic in several of its innovative products, including toasters and irons. The company’s Redefine collection grants users the opportunity to peer into the inside of the toaster as it operates.

Material properties

In conjunction with transparent thin-film heating coatings, SCHOTT NEXTREMA glass-ceramic enables innovative designs for household appliances, such as this elegant toaster of the Morphy Richards Redefine Collection (Photo: Morphy Richards)

form that suits varied needs and a wide transmission spectrum in visible light and infrared range. No application of the glass-ceramic is exactly like another. SCHOTT supplies the form of glass-ceramic that corresponds to a customer’s requirements as precisely as possible. With six types of NEXTREMA and a wide range of potential shapes and appearances, the material finds itself able to suit diverse customer needs. Its design flexibility also tends to lend itself to a particularly unique final appearance as it accommodates design developments in customer solutions.

The material’s natural coloration also reduces the complexity of value chains for innovative design concepts, the glass-ceramic now being used in panels of high-quality electrical and household appliances. One striking example is as

All six types of NEXTREMA glass-ceramic have similar material benefits in common, however, slightly varying in its form from type to type. An operating temperature up to 950 °C (depending on the material type) means customers can use the glass for applications with very high ranges, opening possibilities for many industries that rely on glass solutions. Robustness at high temperatures means the material maintains its reliability where simultaneously high mechanical stability in relatively

Applications

This glass-ceramic has found its way into different applications across many industries, particularly where heat could have an adverse effect on the performance of more vulnerable materials. Its earliest use has been to optimize transmission in infrared radiators, opening new applications for energy-efficient processes in indoor and outdoor heating. Therefore, the element of glass adds a design quality to heating products, such as Heatscope IR heaters from MHS Munich Home Systems.

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Vapour iron from the Morphy Richards Redefine Collection including a SCHOTT NEXTREMA iron sole (Photo: Morphy Richards)

high heat is critical - also if large formats are required. Near zero thermal expansion is the result of an intelligent microstructure that enables the glass-ceramic to keep its shape in a high temperature environment. Thermal shock resistance up to 820 °C means the material handles quick changes in temperature. The glass-ceramic also enjoys a wide transmittance spectrum in visible light and IR range. The entire material platform extends its heat-related resilience to other strengths, featuring surface resistance and gas impermeability, besides the above mentioned acid and alkaline resistance. Critically, NEXTREMA glass-ceramic is also practically process inert. Potentially interfering process factors such as gas emissions from organic components have virtually no influence on the material, even under extreme conditions. This allows it to perform reliably in exposed environments.

Six types

In addition to their shared properties, each material type of the glass-ceramic has further specific properties to offer engineers and designers an alternative that suits the requirements of their application. NEXTREMA transparent has the highest thermal shock resistance of all the other types of up to 820 °C in combination with high transmission in the short-wave infrared range. NEXTREMA translucent white has the broadest overall infrared transmission window of all the other types below 2,800 nm as well as the highest level of chemical resistance against acids and alkali solutions according to DIN 12116 and ISO 695. It is used for visible light reduction in combination with high infrared transmission. NEXTREMA opaque white reaches the highest maximum temperature resistance, up to 950 °C. Its applications often also utilize the material’s visible light diffusing properties. NEXTREMA tinted has the highest bending strength of all other types, reaching up to 165 MPa. It is notable for its visible

light reduction in combination with high infrared transmission and thermal shock resistance of up to 800 °C, making it a versatile option. NEXTREMA translucent bluegrey also reaches the highest maximum temperature resistance of up to 950 °C, deploying a unique translucent design along with visible light reduction and high infrared transmission. NEXTREMA opaque grey is the third form to reach the highest maximum temperature resistance, while having the highest thermal insulation properties of all other types due to its lowest overall transmission in the infrared range. More at www.SCHOTT.com>

Video

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RESEARCH

Self-Healing Al2O3 ceramics: Selection and testing of novel healing particles Scientist Linda Boatemaa (TU Delft) examined the self-healing recovery process of several ceramic materials. In particular, she looked at the behaviour of three new aluminacomposites designed to self heal at high temperatures and she tested them under both laboratory conditions and turbine-like conditions. This resulted in the dissertation ‘SelfHealing Al2O3 ceramics: Selection and testing of novel healing particles’. In May this year she obtained the degree of doctor at Delft University of Technology.

Ceramic materials are attractive for many applications in a wide range of fields ranging from aerospace, automotive, chemical, mechanical to medical because of their desirable properties. For instance, zirconia and silicon carbide are used in crucial components for the automotive and aerospace industries because of their low thermal conductivity and high strength at high temperatures. Also alumina (Al2O3) is an attractive ceramic for engineering applications operating at elevated or high temperatures because of its good thermal and chemical resistance. It also maintains high strength and hardness at high temperatures. These desirable properties are due

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to the strong covalent and ionic bonds existing between its atoms. However, these same strong and directional bonds are the origins of its inherent brittleness. Over the last decade, material scientists have adopted self-healing as a means of restoring the load bearing capability of such materials after damage from micro-sized surface cracks. In this approach, the material is restored to a status comparable to the original one by the ‘healing’ of such surface cracks at high temperatures. Healing is achieved by the addition of ‘healing agents’ to the base ceramic material which upon the occurrence of a crack oxidise into a healing oxide which fills and seals the

crack. While the overall concept is clear and academically well understood, there are some important gaps in the build-up of the knowledge ladder of self-healing ceramics to an application ready level. Linda Boatemaa addresses some of the material design questions and tests the capability of newly identified healing particles under laboratory and application conditions.

Healing agent

Boatemaa presents an unbiased selection procedure to determine viable healing agents to efficiently heal surface cracks in alumina at high temperatures. The selection was made from a data-

RESEARCH base of transition metals, carbides and nitrides and proceeded according to six identified primary criteria. The healing oxide which eventually fills the crack was evaluated on the basis of its melting point, ability to adhere to alumina and thermal mismatch with alumina. The healing agent on the other hand was selected by its melting point, volume expansion upon oxidation and thermal mismatch with alumina. Application of all selection criteria resulted in identifying granular Ti, Cr, Zr, Nb, Hf, TiC, TiN, Cr3C2, Cr2N, ZrN, NbC and NbN as promising agents for the autonomous healing of alumina at high temperatures.

TiC and Ti powder

Boatemaa investigated the effect of the particle size on the oxidation kinetics of one of the candidate materials: TiC. Different sizes of TiC powder ranging from nanometer to sub-millimetre sizes were studied by thermal analysis. The kinetic triplet: EA, f (α) and A were derived for all the powders using the Kissinger, the master curve plotting and the Senum & Yang methods, respectively. The oxidation of TiC proceeds via the formation of oxycarbides, anatase and then rutile. Activation energy is found to be a strong function of the particle size between 50 nm and 11 μm and becomes constant at larger particle sizes. The temperature for efficient healing was between 400 and 1000 °C. Hence, extrinsic self-healing in oxidic ceramic matrices can be tailored to a specific temperature range by tuning the size of the healing particle. The dissertation describes the use of TiC particles as high temperature healing agents in alumina based composites. Fully dense alumina containing 15 and 30 volume% TiC composites was made by Spark Plasma Sintering. Strength recovery was studied between 400 and 800 ˚C after damage was introduced by indentation. Complete tensile strength recovery was attained in both composites by annealing at 800 ˚C for 1 hour in air. In addition, she investigated the self-healing behaviour of an alumina composite containing 10% by volume of metallic titanium particles as a function of temperature and time. The evolution of the crack filling process via the solid-state formation of TiO2 was also studied. The fracture strength of the composites was measured by 4-point bending and the optimum healing conditions for full

strength recovery is 800 °C for 1 h or 900 °C for 15 min. Crack filling was observed to proceed in three steps i.e., local bonding at the site of the intersected Ti particle, lateral spreading and global filling. It was discovered that although significant strength recovery was attained by local bonding of the intersected particles, full crack filling is required to prevent an unfilled crack region acting as a crack initiator. The results of Ti oxidation results were applied in a simple model for crack-gap filling and the experimental results observed were in good agreement with the model predictions.

MAX phase particles

Boatemaa has also researched the recovery of alumina composites containing 20 volume% Ti2AlC MAX particles. Ti2AlC MAX was selected because earlier research at the TU Delft had shown that the monolytic material has excellent self healing behaviour at high temperatures, but the use of MAX particles in an intert ceramic matrix material had not yet been studied. From the oxidation kinetics of the Ti2AlC particles, oxidation starts at 600 °C, but, the temperature for efficient healing is between 800 and 1000 °C. Crack healing was studied at 800, 900 and 1000 °C for 0.25, 1, 4 and

4-point bending strength of Al2O3-MAX phase composite as a function of the healing time

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RESEARCH pose upon long-term high-temperature exposure and remained potentially active in the non-oxygen permeable Al2O3 matrix until intersected by a crack.

From laboratory to real-life conditions

SEM micrographs of Al2O3/TiC composite (a) Cracks created by Vickers’ indentation; (b) Close-up showing crack-particle interaction; (c) Healed crack after exposure to combustion environment for 4 h; (d) Ti X-ray mapping showing the filling of the healed crack

16 hours and the strength recovery was measured by 4-point bending. The Ti2AlC material was found to be a suitable healing agent for alumina containing 20 volume% of 10 micron sized

Ti2AlC particles. The optimum healing conditions recorded was 900 °C for 1 h or 1000 °C for 15 min. Ti2AlC particles embedded in the matrix (more than 20 μm from the surface) did not decom-

a) Crack in an Al2O3 - 10% Ti composite; b) partially healing after 6 hours exposure to air at 700 °C

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Finally, Boatemaa describes the behavior of three self-healing ceramic variants (one Al2O3/TiC) and two MAX Phase ceramics (Ti2AlC and Cr2AlC) as they were tested in a real scale simulator for the combustion chamber of an aircraft turbine engine. Circular samples (20 mm in diameter and 5 mm thick) were sintered by spark plasma sintering and cracks were introduced by either, indentation, quenching and low perpendicular velocity impact method. The samples were exposed in the post-flame zone of a turbulent flame in a combustion chamber to heal at temperatures of approximately 1000 °C at low pO2 levels for four hours. All cracks in the Al2O3/TiC composite (width 1 μm and length 100 μm) were fully filled with TiO2. Large cracks in the Ti2AlC material were also fully filled with TiO2 and Al2O3. And in the Cr2AlC, cracks of up to 1.0 μm in width and more than 100 μm in length were completely filled with Al2O3. Oxidation of the healing agents and hence its healing ability was not affected by the very low pO2 levels in the dynamic combusting chamber as the results were similar to those of samples studied under static laboratory conditions. All tested materials showed full crackgap filling for 0.5 to more than 10 μm wide cracks of up to 20 mm length, after exposure to the high velocity exhaust gas mixture at approx. 1000 °C for 4 hours. Although the oxygen partial pressure in the combustion chamber is much lower than in the synthetic air (0.088 versus 0.2 atm) used in the earlier experiments under static laboratory conditions, the conditions are sufficient to realize full healing of crack damage. The high gas flow rate (16 m/s) and the additional thermomechanical load did not impair the healing process. This article is based on the dissertation ‘Self-Healing Al2O3 ceramics: Selection and testing of novel healing particles’, in collaboration with Prof. Sybrand van der Zwaag, Faculty of Aerospace Engineering/ Novel Aerospace Materials, TU Delft

5E EDITIE

11 oktober 2018 *techniekHuys Veldhoven

ALLES OVER LIJMEN ONDER ÉÉN DAK Al 5 jaar hét event rond lijmtechnologie Dit specifieke event, met inhoudelijk programma en expo, voorziet u van kennis en nieuwe (praktische) inzichten. Meerdere praktijksprekers nemen u mee in de do’s and don’ts van verlijmen. Deze lustrum-editie staat in het teken van uitdagende lijmvraagstukken. Denk hierbij aan: • het voorspellen hoe de verbinding zich houdt op de lange termijn; • hoe u uw ontwerp kunt optimaliseren voor lijmen in de productie; • moeilijk te verlijmen materialen; • de voorbehandeling en dosering.

Aanmelden kan via de website: www.lijm-event.nl

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RESEARCH

Acoustic metamaterials:

Metamaterials for wave control and manipulation by exploring nonlinearity The development of metamaterials enables to engineer materials with extraordinary features, beyond the traditional limits. In the linear dynamic regime, metamaterials have already enabled a wide range of new functionalities, such as cloaking, super-lenses, and signal filtering. The consideration of nonlinearity has the potential to bring a myriad of new opportunities for metamaterials. Within the 4TU.High-Tech Materials research program, metamaterials were developed with nonlinear resonant inclusions. Results of this research show emergent dynamic features which may enable tunability, new mechanisms of sound and vibration attenuation, and the realization of a ‘mechanical diode’. Besides, efficient computational schemes are being developed for optimal analysis of the emergent metastructure design. Would it be possible to manipulate acoustic and elastic waves in a rational manner, by providing tunable control of wave propagation and attenuation, and enabling new functionalities as, for example, logic and sequential operations or complex quantum computation? The answer is yes, and the recent developments on metamaterials prove this is possible. Metamaterials are engineered structures in which the design of a microscopic structure, or meta-atom, with specific behavior (for example dynamics) gives rise to superb, on-demand response of the effective medium, beyond that of its constituents, making it possible to manipulate waves. Indeed, wave manipulation is promoted by the

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unusual dispersion characteristics of metamaterials, that is (i.e.) the relation between frequency and wavenumber of free waves propagating in a medium, induced by ‘exotic’ effective properties, such as negative effective density and/or elastic moduli. In the dispersion diagram of metamaterials, these features may induce frequency zones in which waves cannot propagate, the so-called band gaps, and negative slopes, i.e. negative group velocity with positive phase velocity, enabling unusual reflection, transmission and absorption characteristics within the band gaps, and unique refraction characteristics within certain pass bands. In the early 90s, the success of photo-

nic crystals for electromagnetic wave manipulation motivated the development of phononic crystals, i.e. periodic structures with contrasting materials and/or geometries inducing band gaps by destructive wave interference, the so-called Bragg scattering phenomenon. The work by Liu et al. (1) was strikingly important, demonstrating that localized resonances can promote subwavelength band gaps, i.e. in the regime of wavelengths orders of magnitude larger than the unit cell dimensions. Indeed, Liu’s material was the first realization of the so-called locally resonant metamaterial exhibiting negative effective density. A scheme depicting the typical dispersion diagram and transmission plot for Liu’s

RESEARCH material considering 1D periodicity and longitudinal wave propagation only is shown in Figure 1. Acoustic metamaterials with negative effective elastic moduli have been realized a few years later using an array of Helmholtzâ&#x20AC;&#x2122;s resonators, thus opening the possibility of realizing negative refractive index elastoacoustic materials, used to design focusing acoustic lenses and cloaking devices. Besides, a wide range of functionalities has been proposed for acoustic metamaterials,

induce mode-conversion (4) and unusual reflection effects (5). Within the 4TU.High-Tech Materials research program, high-performance locally resonant metamaterials are being developed by exploring nonlinearities within the internal resonant microstructures. So far, few studies have investigated the effect of nonlinearity in resonant attachments periodically distributed in a host material. Moreover, conventio-

Figure 1: Basic features of metamaterials (1D periodicity and longitudinal wave propagation): (a) dispersion diagram based on the unit cell analysis, (b) corresponding transmissibility plot (Ď&#x2030;R is the local resonance frequency)

such as: filtering, phase manipulation, and absorption. All the above-mentioned studies and related functionalities have been designed considering linear dynamic regime only. What would happen if materials are pushed into a nonlinear regime? In the past, nonlinear static and dynamic regimes in mechanical structures were avoided by design due to the complex behaviors induced by nonlinearity. The advent of metamaterials is creating a new paradigm in which nonlinear phenomena are regarded as an opportunity for enabling new and extraordinary functionalities. For instance, snapthrough instability mechanism induced by buckling has been used to conceive soft actuators, which would respond with large outputs to small inputs (2). Bistable structures have been used to release energy in a controlled way, enabling one-way propagation of solitary transition waves over arbitrary long distances (3). Higher-order harmonics generation due to wave propagation in a nonlinear medium has been used to

nal strategies to simulate the dynamic behavior of such nonlinear metamaterials are either computationally expensive (for example transient direct numerical simulations) or restricted to simple models (for example method of multiple

scales, harmonic balance method). Thus, the aim of the 4TU.High-Tech Materials research project is two-fold: (i) unravel physical phenomena induced by nonlinearities within the microstructure of locally resonant metamaterials and (ii) develop efficient computational schemes for their analysis.

Emergent dynamic features

Hyperelastic and viscoelastic materials are widely used in structural connections functioning as elastic springs and/ or dash-pots. Since the first design of a locally resonant metamaterial, rubber coatings have been used to provide the compliance required to make the heavy inclusion resonate inside the host medium. However, in that work and in numerous works inspired by the emergent local resonance phenomenon using rubber as coupling microstructural element, the analysis has typically been restricted to the linear regime of small oscillations. Within the framework of the 4TU.High-Tech Materials research project, the focus is on the nonlinear dynamic regime of hyperelastic materials, characterized by their asymmetric tension-compression material behavior.

Tunability

Nonlinear material behavior of rubber-like materials is characterized by strain-dependent elastic modulus, for example described by neo-Hookean material model, illustrated in Figure 2. This induces an effective amplitude-dependent frequency shift of acoustic and optical wave modes, and consequently,

Figure 2: Linear and nonlinear (neo-Hookean) local interaction forces versus stretch in locally resonant metamaterials

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RESEARCH

Figure 3: One-dimensional model of metamaterial with nonlinear local resonators

of the band gap. This feature of nonlinear materials makes nonlinear phononic crystals and locally resonant metamaterials tunable since transmission/reflection features of these materials can be modified by changing the input amplitude. Numerical wave propagation analysis of a one-dimensional lo-

in tension and stiffening in compression, the stiffening effect is stronger and explains the feature of these elastomeric metamaterials.

Parametric attenuation

In the dynamic analysis of the metamaterial with nonlinear and asymmetric local interaction of neo-Hookean type, a second attenuation zone (or transmission deep) was observed for sufficiently high excitation amplitudes (see Figure 5). Semi-analytical analysis using the method of multiple scales has been performed and showed that the energy exchange between the primary propagating wave mode and a subharmonic

Figure 4: Amplitude-dependent transmission of a nonlinear locally resonant metamaterial: onset of tunability

cally resonant metamaterial (Figure 3) with local interaction given by an incompressible neo-Hookean material model shows a frequency shift of the local resonance band gap towards high frequencies with the increase of the input wave amplitude (see Figure 4). Although asymmetric, i.e. undergoing softening

Figure 6: Scheme of the mechanism responsible for the second attenuation zone depicting energy exchange due to autoparametric resonance

Figure 5: Transmission analysis of a nonlinear locally resonance metamaterial depicting a second attenuation zone

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evanescent mode might occur above a certain critical excitation amplitude. This explains the emergent phenomenon, which is due to the so-called autoparametric resonance at the microstructure level (6). Indeed, above a certain energy level, the primary propagating wave mode with frequency-wavenumber pair (Ω,μ) becomes unstable and energy is transferred to the evanescent wave mode at the one-half subharmonic of the primary input frequency (1⁄2)Ω (see Figure 6), inducing the oscillator response at its resonance frequency. The nature of this phenomenon suggests that similar attenuation zones

RESEARCH Transient analysis via computational homogenization

Besides the emergent features induced by nonlinearity in metamaterials, efficient ways to perform transient wave propagation analysis on finite size structures is needed. Homogenization methods, i.e. a class of multiscale methods based on averaging theorems, are powerful tools in the analysis of composite materials and can be applied to the locally resonant metamaterials design for two main reasons. Figure 7: Nonreciprocal behavior of a structural system composed of linear and nonlinear locally resonant metamaterials connected in series and excited with frequency Ω=ωR

Figure 8: Scheme of dynamic computational homogenization implemented to perform transient analysis of nonlinear metamaterial

are expected to be induced at specific conditions, not only for a 2:1 frequency ratio. This novel mechanism of inducing attenuation by the interplay between nonlinearity and local resonance is inherently tunable and offers new avenues for wave manipulation in the subwavelength regime.

Nonreciprocity

The incorporation of nonlinearities constitutes a way of designing materials through which wave transmission is direction dependent (nonreciprocal materials), offering novel possibilities for sound and vibration control. Within the framework of this 4TU.High-Tech Materials research project, a structure composed of two distinct metamate-

rial waveguides has been designed, as shown in Figure 7. A metamaterial with linear resonant inclusions (on the left) is coupled in series to a metamaterial with nonlinear resonant inclusions (on the right). The designed mechanical system works as a mechanical diode, providing a nonreciprocal response around a particular frequency Ω=ωR. If the excitation source is on the left, no wave is transmitted to the right end. On the contrary, if the source is on the right, a wave signal is propagated to the left, as a result of harmonic generation in the nonlinear metamaterial. This structural system could be used in solutions for signal processing, imaging, sensor technology, among others.

Firstly, the extraordinary features of metamaterials emerge from the effective properties of the composite material rather than its constituents. Secondly, the main feature of the locally resonant metamaterials is their subwavelength feature which makes them suitable for homogenization. Recently, both analytical and computational homogenization schemes have been extended to incorporate micro-inertia and allow complex transient interactions. When complex microstructures need to be modeled in detail, computational homogenization schemes can be used and are typically more efficient than the conventional direct numerical simulations. In 2013, Pham et al. (7) extended the classical computational homogenization scheme to incorporate micro-dynamics. However, the numerical implementation provided at that time was restricted to a linear elastic locally resonant metamaterial only. Within the framework of the 4TU.High-Tech Materials research program, the dynamic computational homogenization scheme incorporating microscopic nonlinearities, schematically shown in Figure 8, was implemented and transient numerical simulations were performed (8). For the validation, a one-dimensional version of Liu’s locally resonant metamaterial was chosen and the dynamics of the nonlinear metamaterial was assessed under free wave propagation and transient structural dynamic analysis of a finite structure (see Figure 9). The results showed to be accurate, while the simulation time is significantly smaller compared to the conventional direct numerical simulations.

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RESEARCH

Figure 9: 1D nonlinear metamaterial transient problem analyzed via computational homogenization and direct numerical simulations. Full problem, macro and micro scales are shown. A typical solution is depicted for two levels of the amount of homogenization parameter h in comparison with solution via the conventional direct numerical simulation (DNS), with good agreement observed (8)

Figure 10: Conceptual scheme of a device incorporating nonlinear metamaterial able to generate tunable wave field for vibration and acoustic control

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RESEARCH Towards an emergent metamaterial design

Design of a locally resonant metamaterial subwavelength wave manipulation exhibiting the novel features induced by local nonlinearities for a real application in vibration/acoustic signal filtering, as shown in Figure 10, is the ultimate goal of this 4TU.High-Tech Materials research project. To this end, the first mechanical prototype is being conceived (Figure 11) and will be numerically and experimentally tested. In this first prototype, the nonlinear effect responsible for parametric attenuation will be induced by geometrical nonlinearity within the local resonator. This will provide a proof of the concept and will allow the application of the computational homogenization scheme to a complex nonlinear metamaterial model. Priscilla B. Silvaa, Tim van Nulanda, Thijs S. van Loona, Valentina Zegaa, Michael J.

Figure 11: Mechanical prototype of a nonlinear metamaterial able to provide parametric attenuation

Leamyb, Marc G. D. Geersa and Varvara G. Kouznetsovaa a - Mechanics of Materials Group, Department of Mechanical Engineering Eindhoven University of Technology Eindhoven, The Netherlands b - George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta, GA, USA Email: p.brandao.silva@tue.nl

References: 1 - Zhengyou Liu et al., ‘Locally Resonant Sonic Materials,’ Science 289, no. 5485 (2000): 1734–36. 2 - Jordan R. Raney et al., ‘Stable Propagation of Mechanical Signals in Soft Media Using Stored Elastic Energy,’ Proceedings of the National Academy of Sciences 113, no. 35 (2016): 9722–27.

v.g.kouznetsova@tue.nl The project page can be found here: https://www.4tu.nl/htm/en/new- horizons/metamaterials/ Parts of this research have been performed within the framework of the 4TU. High-Tech Materials research program ‘New Horizons in designer materials’ (www.4tu.nl/htm).

5 - Xinxin Guo et al., ‘Manipulating Acoustic Wave Reflection by a Nonlinear Elastic Metasurface,’ Journal of Applied Physics 123, no. 12 (2018): 124901. 6 - Priscilla B. Silva et al., ‘Emergent Subharmonic Band Gaps in Nonlinear Locally Resonant Metamaterials,’ in submission, (2018).

3 - Neel Nadkarni et al., ‘Unidirectional Transition Waves in Bistable Lattices,’ Physical Review Letters 116, no. 24 (2016): 244501.

7 - K. Pham, V.G. Kouznetsova, and M.G.D. Geers, ‘Transient Computational Homogenization for Heterogeneous Materials under Dynamic Excitation,’ Journal of the Mechanics and Physics of Solids 61, no. 11 (2013): 2125–46.

4 - R. Ganesh and Stefano Gonella, ‘Experimental Evidence of Directivity-Enhancing Mechanisms in Nonlinear Lattices,’ Applied Physics Letters 110, no. 8 (2017): 84101.

8 - Tim van Nuland et al., ‘Transient Analysis of Nonlinear Locally Resonant Metamaterials via Computational Homogenization,’ submitted, (2018).

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Invitation: NWO Cross-over Call Workshops â&#x20AC;&#x2DC;Living in Smart citiesâ&#x20AC;&#x2122; The so-called Cross-over Call, a new program of NWO (The Netherlands Organisation for Scientific Research) provides the opportunity for a research program in which various disciplines collaborate to come up with useful solutions for societal challenges. We invite you to think along about a new initiative to achieve a more sustainable use of materials. With our program we intend to make an important contribution to the realization of the Dutch Climate Agreement. According to this agreement CO2 emissions for the production of materials in 2030 must be reduced by 8 Mton per year. It will require a considerable effort on the part of all those involved to realize this objective and there is no time to lose. In order to have a serious impact, we want to focus on the built environment. The materials concrete and steel require a lot of our attention because of their large CO2 footprint. New techniques for sensors and data processing offer opportunities to realize the required transformation. The maximum size of the program is 15 million euros, for which we can start a serious program with scientific research. The intention is to work in parallel on the application of the results. The required investment by industry and public institutions is limited so that there will be a serious multiplier of the money invested. The purpose of the workshop is to bring people from both industry and academia together to understand what topics of common interest coincide partially or wholly so that these can be further defined. Needs and wishes will therefore be thoroughly discussed and mapped out. The content of the program has yet to be determined and depends on the interest and contributions of the participating parties. The emphasis can be on design,

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production methods, the development of accelerated tests, sensor techniques, maintenance, lifetime extension and recycling. We are organising two sessions to map the interest of potential participating parties. In the workshops, we would like to find out what your interest is and what you intend to contribute to this program. You can register via the links below for one or both workshops.

We hope to see you there! On behalf of the organisation committee, Prof.dr. Daniel Bonn University of Amsterdam

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Brainstormsession 1 Sensors & electronic devices d.d. 17.9.2018 Delft, van der Burghweg 1, 2628 CS Delft

Brainstormsession 2 Buildings, (infra)structure & cultural heritage d.d.18.9.2018 Delft, van der Burghweg 1, 2628 CS Delft