Biomimetics_Movement actuation in low pressure pneumatic structures by Francesco M. Massetti

Emergent Technologies and Design

Movement actuation in low pressure pneumatic structures

Patricia Ojeada Francesco Massetti Krzesimir Poplawski Sebastian Lundberg

Emergent technologies and design

CONTENTS p. ABSTRACT 04 INTRODUCTION 05 BIOLOGICAL ANALYSIS 06 INTRODUCTION TO PNEUMATICS 09 EXPERIMENT DESIGN 10 FABRICATION 11 INITIAL MATERIAL TESTS

FOLDING SYSTEM 14 ACTUATION AND AN ORDER OF INFLATION

CROSS VEINS / SEPARATORS

PHYSICAL MODEL 21 PATTERNS 22 PATTERN TESTS SUMMARY

SYSTEM AGGREGATION 33 SYSTEM VARIATIONS 34 HEXAGONAL AGGREGATION 36 CONCLUSIONS 38

Reference list 39

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ABSTRACT

he aim of the project is to study and understand the logic behind the construction of the dragonfly wing, regarding its deployment and movement. As many studies on its structural properties and loadbearing capacities were conducted, from the initial research in this area our interest transferred onto the activity of deployment of the wing. The chronology of the actuation of each part of the wing became the main focus area. Through a lot of research about the dragonfly wing, and executing many physical experiments we set out to find new solutions for light weight deployable structures, using air pressure as an actuator and double layered polyethylene as the air compartments. Through manipulating the airflow and the form and patterns of the compartments, we could control the final geometries of a complex three dimensional structure which is deployed from a flat two dimensional system of components.

The following research was based on the mechanism of the dragonfly wing.

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INTRODUCTION

he dragonfly wing has former veins that create a network with cross veins and a membrane between them, that system stands mainly due to the pressure of the fluid running through them. That fluid, called the hemolymph, maintains the veins in tension from the last step of metamorphosis through their whole life. From that structure system and mechanism, the team was focused on the relationship between pressure and tension, an external dynamic input and an internal structure which relies on the former. Instead of using liquid input the experiment was developed using air pressure as an external actuator for controlling the stiffness and flexibility required in inflatable structures. The other aspect that was taken from the natural system studied is the deployment of a structure from an initial stage through a sequence to achieve its final stage. Having found the main abstract concepts of pressure, tension and deployment, the next step of the research process was aimed to explore materials and geometries. A primary approach to materials was experimenting with plastic due to its flexible capacity and defining single forms able to be inflated with low air pressure. The parameters studied were shape and sizes of the tubes, different thickness of plastic, different inflation methods, single elements versus sequences. The analysis is of a composite system which is built by a sequence of connected compartments of different sizes, that are filled with air for observing the different materialâ&#x20AC;&#x2122;s behaviors and their physical relations. Being aware of its abilities to do two actions, first to be able to control the deployment of the structure through the air actuator, and second to maintain the stiffness in the structure. The methods of analysis followed was first to understand the capacities and the constrains of the plastic material and its relation with low pressure. For that goal the tests were rationalized and created sequences of patterns embed into a component with the same dimensions for all of them. It was developed a series of patterned-sealing systems, creating different patterns for achiving different motions and observing how they behave. The inflation of those components where made in first attempts directly from the beginning of them. It appears the question of what would happen if a tube was introduced to fill the component from the previous compartment. After that experiments were made with holes into the tubes to control the points of inflation of the components. Natural System and Biomimetics Workshop

BIOLOGICAL ANALYSIS Three stages comprise the life-cycle of dragonflies. The egg converts into the larvae whose life evolves in underwater environments for approximately two years. For emerging as an adult, the larvae leaves the aquatic environment, and begins its metamorphosis. At this stage occurs the most interesting process of their entire life-cycle, the eclosion (wing expansion) is unchained by the contraction of the abdominal muscles forcing the hemolympth into the vein wings. Receiving that pressure of fluid, the wings acquire their functional tension. After attaining that stage, they remain in tension for their whole life-cycle.

Life cycle of a dragonfly.

Andre Butler, Univeristy of Bristol, 2005, http://palaeo.gly.bris.ac.uk/palaeofiles/fossilgroups/Odonata/Charac.html

Initial circulation pattern of hemolymph in the veins. redrawn from www.robertmroz.deviantart.com

Initial circulation pattern of hemolymph in the veins. Redrawn from “The circulatory organs of insect wings: Prime examples for the origin of evolutionary novelties”, Pass, Togel, Krenn, Paululat, 2014, modified after Arnold 1964,

The circulatory system is critical not only for the deployment of the wing, but also in order to maintain tension in the wing, which is needed for the dragonfly’s ability to fly.

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Forces originated in the thorax pumps the hemolympth into the veins. That positive pressure is based on the contraction of the diaphragm, and the negative pressure is through nano sized holes in the veins.

Main vein Cross vein Membrane Root

The most noticeable properties of the dragonfly wing in the abilities to do many different motion. The wing and its connection to an individual muscle allows the dragonfly to propel itself upwards, downwards and even rotate in the air. The wing is an extremely lightweight structure; its mass is only 2 percent of the whole body mass. When the dragonfly deploys its wing, it increases its volume by swallowing air to be able to contract its abdominal muscles, which forces fluid, hemolymph, through the torax into the network of veins in the wing.

Redrawn from “The Architecture of the Dragonfly Wing. A study of the Structural and Fluid Dynamic Capabilities of the Anisiothera’s forewing”, Maria Mingallon, Sakthivel Ramaswamy, http://www.slideshare.net/maria_mingallon/asme-thearchitecture-of-the-dragonfly-wing

Photograph (a) of a dragonfly Sympetrum vulgatum forewing with inset images (b t/mg) of the wings detailed structure captured by scanning electron microscopy (positions are approximated). Leading and trailing edge protuberances are believed to produce an increase in lift [43]. (b) Protuberances on leading edge. (c) The nodus of the wing. (d) The wing tip. (e) Vein crossing near the wing root. (f) Trailing edge with protuberances. (g) Wing surface near the wing tip

S.R. Jongerius, D. Lentink, Structural analysis of a dragonfly wing, Exp. Mech. 50 (2010) 1323–1334.

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Analysis of the stiffness in different parts of the wing.

redrawn from http://divisare.com/projects/17413-emergent-tom-wiscombe-dragonfly; copyright : Tom Wiscombe

Analysis of the bahaviour of the wing during a flight.

Analysis of the dragonfly wing show, that there is a clear relation between the flexibility of the wing and its structure. Parts responsible for a rigidity of a wing are reinforces with main veins and divided with bigger, thicker cells. Areas that function as a flexible membrane are constructed from smaller, thinner cells and fewer veins. This observation is later used in designing a division method for elements of a final system.

Thickness distribution of the membrane and the veins of the forewing of Sympetrum vulgatum.

“Structural Analysis of a Dragonfly Wing”, S.R. Jongerius & D. Lentink,2010

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INTRODUCTION TO PNEUMATICS

“Pneumatics - (Greek:“breath”) is a branch of physics applied to technology that makes use of gas or pressurized air. Pneumatic systems used extensively in industry are commonly powered by compressed air or compressed inert gases. A centrally located and electrically powered compressor powers cylinders, air motors, and other pneumatic devices. A pneumatic system controlled through manual or automatic solenoid valves is selected when it provides a lower cost, more flexible, or safer alternative to electric motors and actuators.” (via Wikipedia, “Pneumatics”)

Pneumatic structures are made by a soft envelope (membrane) whose internal volume is supplied with atmospheric air to provide stability and resistance to external loads. The envelope properties vary from fabrics coated with polymers including rubber or from reinforced films. Low pressure system are grouped in single and double membrane structures. In the first case one membrane defines a space in which the pressure is positive or negative, while in the second the internal space is defined by a a membrane whose component are made of two layers curved in opposite directions to each others. This permits not to have pressure differential between inside and outside. Double membrane structure are also called “cushion structures”.

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EXPERIMENT DESIGN In order to recreate the mechanism of wing deployment, a model basing on pneumatic mechanism, which would imitate the bahaviour of the wing, was designed. The structure would consist of elements recreating the roles of the excact same elements in the dragonfly wing. Main veins would be responsible for the general movement (raise) of the structure, and keeping it rigid in the required position. The cross veins would seperate the main veins, engage the geometry positioning and stiffen the structure. The actuation point has the same role as the root of the wing, being both the source of the air pressure and a joint enabling the movement. The membrane, like the cells, keep the veins together, creating tension between them and disallowing from falling to far from the planned position. The whole structure would be attached to the vertical surface in one point (the root).

Root / Actuation point

Main veins / inflated pipe system

Cross veins / inflated pipe system

Membrane

step 01.

step 02.

step 03.

step 04.

step 05. Deployment sequence, ver.01

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FABRICATION

he fabrication process was a rather difficult part of the project. In order to create pneumatic compartments, we needed to be able to perfectly seal the polyethylene. Initially a 200μ thick polyethylene was used, but after a few experiments we realized that using a thickness of 100μ was more appropriate to the scale we were working in. To seal the plastic we started by using a hand held constant heat roller, but we found out that it was easier to simply use a soldering iron. It’s important to make sure that the two layers of PE that you want to seal to each other have no air space in between. The top layer of PE would then burn quickly and ruin the whole component. To avoid this, and to also make sure we seal the correct areas, we lasercut molds out of MDF which we then held against the layers of PE while sealing. This method worked for the scale, but this sealing technique and this material would never be able to contain high pressure. The most difficult part was to create an air tight valve. We used 4mm silicon tubes. The point where the silicon tube was connected to the polyethylene compartment was always the weakest area and would almost always leak. We developed a techinque for attaching the tube to the compartment with as little air leak as possible. Since the PE was very difficult to seal to the silicon, we first rolled polyethylene a few turns very tightly around the tube, and were able to seal them together by applying heat. We could then easier connect the valve to the compartment as it now

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INITIAL MATERIAL TESTS As a first stage of experiments, different materials were taken into consideration. Basing on knowledge which was gathered during a reaserach into pneumatics, the material chosen for testing was a PE (Polyethylene). In order to observe and understand its properties and behaviour, several models of different shapes and sizes were crafted. Samples included â&#x20AC;&#x2DC;naturalâ&#x20AC;&#x2122;, irregular shapes, as well as orthogonal ones. Moreover, samples were created from PE of different thicknesses (0.1mm / 0.2mm / 0.4mm).

materials: 0.2mm PE test: simple tube inflation

materials: 0.2mm PE test: simple tube inflation, with a compartment dividing seal in the middle materials: 0.1mm PE test: achieving bending of the tube by welding on the sides

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materials: 0.2mm PE test: inflation of a curved pipe

materials: 0.2mm PE test: inflation of a straight ,two-branched structure

materials: 0.1mm PE test: inflation of a straight, multibranched structure

After the series of experiments was conducted, certain shapes were excluded from further investigations. The â&#x20AC;&#x2DC;naturalâ&#x20AC;&#x2122; shapes were difficult to control, as no mathematical formula could have been prepared for them. Moreover, the fabrication of curves caused more problems and gave had more flaws, than the one of straight edges. Multibranched shapes were also crossed out. Instead, the systems of multiple, identical elements was instroduced.

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FOLDING SYSYTEM The following stage of research focused on opening and closing the structure. Deploying the system from an initial ‘0 position’ to a fully opened structure was based on a folding system. 6 models were created, presenting various structures and folding techniques. All modeles were crafted with 0.1mm PE. The aim of the experiments, was to explore the abilities and reactions of each system, and determine which folding approach is the most efficient. The test consisted of three stages: opening the system, staying in a position, and folding back to the ‘0 position’.

test: the 1/4” vinyl pipe was insterted into a PE bag in order to see if the structure is capable of lifting heavier objects

test: a metal wire was attached to the right and left side of the PE bag, and broken in the middle. The model was then folded in half. The metal wire created a trajectory for a deployment

test: a metal wire was attached to the right and left side of the PE bag, and broken into 4 parts. The model was then folded.

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test: a similar concept, with 4 pieces of meatl wire on each side of the bag, but this time instead of folding, the model was rolled.

test: A bigger model was perpared, this time using the irregular, branch- shaped object. The model was

test: Double branch- shaped model. In addition, air distribution between more than one object was tested. Using a latex component with two pipes was connecting the low pressure source and the vents of the models. The model reacted as planned.

CONCLUSIONS Each model reacted differently, but the overall opening performance was satisfying. However, none of the structures returned to the initial ‘0 position’ when deflated. The most promising models, with metal wires on the sides, performed differently with every taken test, but never as demanded. At this stage, the return to the initial position was excluded from the research. As a side conclusion, knowing the performance capacities of each model, sample from test XX was chosen as a ‘main vein’ element. To continue the experiment, tests would have to include: external mechanical elements directing the movement in each joint and using the source of low pressure of higher capacity (especially in an suction mode).

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ACTUATION AND AN ORDER OF INFLATION

ollowing the observation of hemolymph movment during the deployment of the dragonfly wing and the chronology of veins fill up, the next step of experiments dealt with the actuation of multiple elements, and the control of its order. During this stage, several samples connected with a pipe in various configurations were created. The aim of the test was to determine, whether it is possible to control and schedule the actuation of multiple elements. Elements determining the changes in the behaviour of presented systems included: - different sizes of the bags; - variuos connections between the compartments; - number of openings in air transporting tubes; - location of the openings. Tampering with these settings gave a basic understanding and a control over the hierarchy of actions.

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test: 3 bags of the same size, connected with a separated pieces of a PVC tubes aims: defining the order of inflation observations: the bags were inflated in an consecutive order, according to the air transmission; the first bag to inflate was the closest to the actuation point, then the next one, etc. The actuation order was 1 - 2 - 3.

acuation order test: 3 bags of the same size, connected with a continuous pieces of a PVC tube, with additional irregular opening pattern in it aims: controling the order of inflation observations: the bags were inflated according to the size and number of the openings in the tube; the first bag to inflate had a biggest initial air inflow (in this case it was the bag with the pipe ending - the air found the quickest and straightest way to get out), next bags were inflated due to the number of openings in them. In this particular test, the actuation order was 3 - 1 - 2.

acuation order

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test: 2 bags of different sizes, connected with PVC tube; in test 01 the tube has 2 additional openings to let air inside the first bag, at a minimal rate; in test 02 there are 12 additional openings in the first bag aims: defining the order of inflation

observations: as anticipated, in test 01 the actuation begun in the second bag with the air outlet (the air filled the second bag and then slowly begun inflation of the first bag); in test 02 the inflation started in the bag with 12 openings, as the overall area of openings exceeded the area of the air outlet in the second bag.

acuation order test: 5 folded bags of the same size, connected with individual PVC tubes; the bags were separated with MDF strips attached to the metal ring. aims: testing the possibility of cooperation between inflated elements to engage the reaction of a simple mechanism. observations: the bagsâ&#x20AC;&#x2122; connection derrived from an observation from test 01. Bags inflated in the predicted order, causing a chain reaction of modules. The system did not work perfectly, due to fabrication flaws, but in general proved the possibility of agregating the elements into one, functioning system.

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CROSS VEINS / SEPARATORS Defying the rules for scheduling the inflation and the influence of different joining types for the process, the next step was to examine the possibilities of separating the elements from each other. The biggest challange was to include the separator into a inflation process, instead of crafting it as a fixed element.

test: ‘Veins system’ consisting of 3 bags of the same size, connected to the same source of pressure, separated at the end with a rubber bag. Each rubber bag is connecting two ‘vein’ elements, and transports air between them. obserations: Main veins inflated, but rubber bags required more pressure to efficently separate the elements than we could provide.

test: ‘Veins system’ consisting of 2 bags of the same size, connected to the same source of pressure, separated at the end with a single PE bag. The bag was loaded with a metal element to add weight, and force the direction of the closing movement. obserations: All elements were inflated. The separating element worked in one direciton, but was prone to twisting, and losing its position, withholding the element from functioning every time. test: ‘Veins system’ consisting of 4 bags of the same size, connected to the same source of pressure, separated at the end with a continuous PE bag. The separating bag didn’t have any additional elements, and was left to act naturaly. obserations: The whole structure inflated as planned, and the system opened in the demanded directio ns.

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After series of experiments, series of modifications had to be introduced to the concept model. Vinyl tubes were added to the main veins, as the reinforcement and an air transmission canal. The tubes were encircled with a metal wire to prevent them from bending. Membrane was excluded from the model and left for a separate research. The separators took over its function as a structure binder.

step 01.

step 02.

step 03.

step 04.

step 05. Deployment sequence, ver. 02

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PHYSICAL MODEL

step 01.

step 02.

step 04.

step 03.

step 05. Deployment sequence, ver. 03 / physical model

CONCLUSIONS The modelâ&#x20AC;&#x2122;s performance was a semi- success. The model reacted to the actuation, and each element was inflated in a scheduled order. However, the structure was still imperfect, as it required external help to achieve its final state. Structure consisted of a set of individual elements, thatt were supposed to act togethe. However, failure of one element affected others, which led to general disorder. The manual fabricaton had its flaws, as many air leas were found, especially in areas where two or more elements were connected. The dimensions and proportion ratio requires further exploration. Natural System and Biomimetics Workshop

PATTERNS

or the next stage of research, a new aproach was introduced. Instead of creating systems consisting of multiple, individual elements, it was proposed to engage the movement within the structure of a single elemet itself. In order to achieve that, pattern divisions were implemented. Following the cell structure in the dragonfly wing, one can notice, that parts, that are working as a rigid areas, apart from having more veins, have also different cell distribution. They also differ in size and shape from the ones in more flexible areas. Using that knowledge, multilple samples were created, with different distribution of compartments, that were working as cells in a dragonfly wing. Apart from focusing only on a size of cells, tests included differiation in shapes as well. In order to actuate the models, low pressure was used once more. At the beginning, the tube transporting air was plugged to the vent. In the process, it was noticed, that an additional stiffness of the structure can be achieved by leading the tube inside the model. In this case, every model was tested on these two variations. Some of the models reacted accorrding to the pattern and gained additional stiffness, others became to rigid to perform.

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NUMBER / LOCATION OF SUPPORTS During the inflation, supports are needed for establishing the main direction of expansion of the compartments and to define how it behaves. Taking into account the sizes of the seals along it, it appears reasonable to set supports in the form of line. Supports are designed according to the degrees of freedom requested for a certain performance, meaning that fixing more lines will oblige the component to a limited level of inflation. The simplest configuration presents the first line, the one in which the air is injected, fixed onto the ground, and the end (or the ends if the support is central) of the component free to move. In most of the cases this will result in a contraction of the component towards the support. Adding more supports will split the component in different areas in which is possible to notice different behaviours. The segment between the support and the end will behave as previously described, while the segment between the supports will be limited in expansion, achieving a different level of curvature.

THICKNESS OF SEALS Seals are an important part of the general beahviour of the components and with themselves of the overall system. It has been noticed through experimentation that in regards of the external seals, the ones that constraint the geometry of the component, their thickness is able to slightly change the flexibility of the cells during the movement. In particular, thicker seals tend to block the potential rotation along the lines between cells due to the higher amount of material that maintain the cells connected. In any case, due to the fabrication processes, it has been recognized as more reliable to use overage thickness of 1 cm, that permitts a good control over possible air leackages. The internal seals follow the same logic and adds a second factor: thicker seals mean that the cells are less closer to each others and being able to control this parameter permits to set the intensity of attachment between inflated cells, allowing to control the stiffness of the element.

NUMBER OF HOLES IN THE SEALS The most intuitive performance achieved by changing the number of holes is connected to the velocity of inflation. It is clear how more holes correspond to more air through the element in the same amount of time.

LENGTH OF HOLES IN THE SEALS The amount of air let through the consecutive compartments regulate the bahaviour of the model. Compared to the number of holes in the seals, the length of the holes might also influence the velocity of inflation. However, this change in the structure of the element has no effect on the movement .

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TUBE PATH The embedment of a silicon tube within the element gives control to several parameters. First of all, it permits to direct the air flux towards a certain cell and from there to all the others. This is a usefull feature when it is needed to start the inflation from a point that does not correspond to the air input. In addition, the tube acts as a spine along the element and, according to the path followed, it gives the chance to change its reaction during the inflation. A straigth path in the center will assign more rigidity along the longitudinal axe line and, even if reducing the flexibility, will achieve a more uniform deinflation, since it will always maintain free space for the air to be sucked. A straigth path along one side of the element will block the contraction along that axis and, since the tube is flexible, it will make the element curve in the opposite direction. An alternating path will act similar to the straigth one but will generate a higher stiffness also reducing the flexibility of the element.

TUBE POINTS LOCATION / AMOUNT Holes are created along the tube to achieve different orders and different intensities of inflation of the cells. Since the tube starts from the air input and ends in the last cell, it woul dnot be possible to inflate intermidiate cells. Applying holes where needed permitts to select what cell has to be inflated before the next one and at what rate. The latter parameter is related with the amount of holes and, as expected, more holes mean faster inflation due to the higher amount of air that diverges from the main flow. Theorically, it is possible, even using the holes, to achieve syncronization between inflation of different cells.

DIMENSIONS / NUMBER OF CELLS Mimicing the difference in cell dimensions in the dragonflyâ&#x20AC;&#x2122;s wing, similar variety was introduced during a research. Various sizes of the cellâ&#x20AC;&#x2122;s provoke different reactions of the model. The smaller the cells are, the bigger curl of the structure is achieved. This enables to create the movement of the structure in a vertical direction.

SEALING PATTERN - TYPES OF COMPARTMENTS Following the logic of different movement possibilities achieved by various dimensions of the cells, the irregular division of compartments is also explored. In contrast to the orthogonal distribution of the compartments, irregular divisions should perform in a new way. The aim of tests on this shapes is to find a way of bending / rotating the element in other than vertical directions. The possible movements include bending to the sides parallely to the ground or rotating the module around its X axis.

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test A / B. test: Experiment was based on an equal division of subcompartments in a module. The air distribution canal was lead through the middle of the module. observations: Test without the tube proved, that, when inflated, the compartments contract, turning the element into an arch. However, equal deflation failed, as the first compartment do deflate was sucked and blocked the air canal for the further parts. Test with the tube did not bend, as the was too stiff. Deflation on the other hand run smoothly. The tube only one point of air outlet (at the end of the tube).

A /// 4 cells

/// 1 channel /// thin seals /// without tube

B /// 4 cells

/// 1 channel /// thin seals /// with tube (middle) test C / D. test: experiment was based on an equal division of subcompartments in a module. This time, the air canals are lead on the sides of the modules. observations: to the surprise, both elements bended to the side, although the expected reaction, was a bend similar to test A and B. The bend was stronger in test D

C /// 4 cells

/// 1 channel /// wide seals /// without tube

D /// 4 cells

/// 2 channel /// thin seals /// without tube (side) Natural System and Biomimetics Workshop

test E / F test: Compartments were created through tilted seals, with an equal degree. The air distribution canal was lead on the side. observations: Both samples showed the tendency to twist, but in differet directions, depending on the presence of the tube.

E /// 5 cells

/// 1 channel /// thin seals /// without tube

F /// 5 cells

/// 1 channel /// thin seals /// with tube (side) test G / H. test: Compartments were created through tilted seals, with an increasing angle degrees. The air distribution canal was lead on the side. observations: Both elements reacted differently, depending on a tube positioning inside . The sample without the tube, having no rigid element inside, twisted a little bit along its seals. The second sample, with the tube, having a restrain from the tube, didnâ&#x20AC;&#x2122;t twist. Instead, it bended slighthly, initiating the twist move.

G/// 5 cells

/// 1 channel /// thin seals /// without tube

H /// 5 cells

/// 1 channel /// thin seals /// with tube (side)

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test I / J. test: Experiment was based on an equal division of subcompartments in a module. The air distribution canal was lead through the middle of the module. observations: Test without the tube proved, that, when inflated, the compartments contract, turning the element into an arch. However, equal deflation failed, as the first compartment do deflate was sucked and blocked the air canal for the further parts. Test with the tube did not bend, as the was too stiff. Deflation on the other hand run smoothly. The tube only one point of air outlet (at the end of the tube).

I /// 8 cells

/// 1 channel /// thin seals /// with tube (middle)

J /// 9 cells

/// 1 channel /// thin seals /// without tube test M / N. test: The experiment was testing the reaction of the sample to the size-decreasing compartments. observations: First test presented the curled up along the decrease of the compartment size. As a next step, the same pattern was applied to the longer object. The longer the sample was, the more it curled, untill the point when it performed a full, 180 degrees bend.

M/// 19 cells

/// mutliple channel /// thin seals /// without tube

N /// 16 cells

/// 1 channel /// thin seals /// with tube (middle) Natural System and Biomimetics Workshop

test O / P. test: The sample was divided into triangles, sealing parts outside the main compartment. observations: Both samples performed the similar motion, desregarding the presence of the pipe inside.

O /// 4 cells

/// 1 channel /// wide seals /// witout tube

P /// 4 cells

/// 1 channel /// wide seals /// with tube (side) test Q / R. test: in this experiment the sample model was extended to see the influence of the proportions ratio (length to width) for the modelâ&#x20AC;&#x2122;s behaviour. The compartment sizes were unified. Test was perfrormed with and without the air transmiting tube. observations: The model without the tube (test Q) bended verticaly. Inserting the tube reduced the movement completely, as the tube was to stiff. The alternating leading of the tube added the overall rigidity to the structure.

Q/// 7 cells

/// 2 channel /// thin seals /// without tube

/// 7 cells /// 2 channel /// thin seals /// with tube (alternating)

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test M

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PATTERN TESTS SUMMARY

test A

test B

test C

test D

test E

test F

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test G

test H

test I

test J

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test K

test L

test Nâ&#x20AC;&#x2122;

test Nâ&#x20AC;?

test O

test P

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SYSTEM AGGREGATION Following the previous experiments, a test now had to be made on how the different components act when they are connected to each other. The three components that showed the most extreme results(A, M and O), where chosen for this experiment. Using the same material and fabrication techniques as in the earlier experiments, the sealing patterns were welded in to the polyethylene, but now with a combination of pattern M to pattern A that then divides itself up into two mirrored O patterns. The aim was to see if by combining sealing patterns in the flat compartment, a more complex three dimensional outcome could be controlled. The result showed that the different components behaved the same way connected as the do individually. They could then easily be used to in combination with each other calculate the outcome of a pneumatically actuated three dimensional structure which starts from one flat compartment.

pattern M

pattern A

pattern O

aggregation physical model

aggregation technical drawing

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SYSTEM VARIATIONS After several physical experiments, the project was transfered into digital modeling in order to explore possible systems variations and actual fields of usage. In contrast to the previous experiments, where the structure was composed of different types of components, this test explored possibile aggregation of the same component, their relations and mutual infuences. Concepts varied in scale, from small, responsive wall systems, canopies, up to a scale of a skyscrapper. Physical experiments were executed. As an initial test, the cooperation of two, same elements was explored. However, no successfull result were achieved. The components were attached to each other in different places, and were supposed to create an dynamic, opening system. The experiments were carried out with a low pressure, which turned out to be not enough. For further exploration, change to the high pressure is adviced.

differrent typologies of the structures

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test: Single elements, which after actuation could create a bridge-like bend, were chosen. Connecting two elements of the same pattern in a mirrored configuration, was supposed to result with an opening

opening sequence of the componentâ&#x20AC;&#x2122;s aggregation

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HEXAGONAL AGGREGATION

test XX

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test XX. Hexagonal aggregation test: Prototype of a hexagonal system, using the information gathered during the research. 6 triangles of different paterns, connected with a continuous tube. observations: After testing patterns on rectangular samples, they were transffered onto different geometries, in order to test their bahaviour in new conditions. Several tests were taken, proving that although the reactions of elements were in general the same, yet the proportions had to be adjusted depending on a geometry they were implemented on.

material layering

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CONCLUSIONS

rom the inspiration of the dragonfly wings inflation process our research on inflated structures allows us to set parameters for controlling the steps of inflation, types of motions and relations between global and local geometries. Although the experiments were done using low air pressure and mainly plastic components, the information achieved was highly valuable for possible further exploration. One of the main objectives was to understand the possibilities that can be achieved from the application of different sealing patterns into the components. After attaining a diversity of motions, one of the difficulties that we encountered was the ability to raise the structure. The results were discrete movements of the systemâ&#x20AC;&#x2122;s components without achieving a significant global effect. The greatest challenges in the project were found within the fabrication process. In order to create pneumatic compartments, we needed to be able to perfectly seal the polyethylene compontents. Regardless, our method worked for this scale this sealing technique and this material would never be able to contain high pressure. As a consequense of that, the project remained in a small scale. Using a low pressure system in our experiment provided us with the information needed to analyse our work, however, changes would have to be made in terms of material and fabrication techniques in order to scale up the project.

Emergent technologies and design

Reference list

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Natural System and Biomimetics Workshop