Newsletter January 2014

DUT Racing Formula Student Team Delft Design Presentation Special Newsletter

January

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

dear reader, Things have been exciting these past weeks, cumulating in the Design Presentation on the tenth of January. In this issue, we will make sure to update you on all the work we have been doing, and give you a complete recap of the design of the DUT 14: lightweight!

We will start this issue with a brief update on what the team has been doing, then jump right into it: the centrefold will be a full coverage of the DUT14 design. Lastly, we will cover the period that is coming up: production! Though officially, production only starts on the second of February, we already received some significant parts. We hope you enjoy reading this latest newsletter of our team!

Regards, The DUT14 team

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

team update It has been a while since you have heard of us, and it would be our pleasure to bring you back up to speed with what we have got coming up in the following months! Since the start of the preliminary design phase in November, the team has worked hard to prepare the design for production. On the 10th of January the team proudly presented the design of the latest car, the DUT14, at the Design Presentation. About 400 guests and sponsors attended the presentation which made it a huge success. The presentation was also streamed live on the internet and had about 500 viewers. Right now, the team is finalizing the design, “dotting the i’s and barring the t’s”.

Also production drawings are made to be well prepared for the next phase: Production! On Friday the 31st of January all the engineers will attend our production kick‑off. At this kick-off our Technical Manager, Olaf Teichert, and Chief Engineer, Marinus van der Meijs, will present in detail how we will tackle the production phase and the global production planning. If the team can keep up with this planning the car will hopefully be finished in the end of April. But history learned us that there are a lot of uncertainties in this phase which will challenge every single one of our engineers and the planning they have to follow.

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

introducing the DUT14 After a second place at Formula Student Austria 2013, three consecutive wins of Formula Student Germany and setting a world record for fastest accelerating electric car, the expectations for the 2013-2014 season are up to the roof. An experienced core team and 80 enthusiastic engineering students accepted the challenge. The last couple of months, our engineers designed daring concepts,

innovative assemblies and lightweight structures to make the car even lighter and more reliable than previous years. After heavy brainstorming sessions, long nights and head aching problems, the team is proud to present: the DUT14. You can discover all the nice features of this magnificent car on the next pages.

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

top level concept

Formula Student Germany (FSG) clearly showed a key ingredient for success: four-wheel drive. The top three cars of FSG 2012-2013 all had four-wheel drive, making the decision for a four-wheel driven car almost mandatory. A four-wheel driven electric race car makes the design incredibly more complex than a two-wheel driven car. Nevertheless, the team accepted the challenge. This makes DUT14 the third four-wheel driven electric car in DUT history.

A common statement in the Formula Student community used to be: “Wings don’t work.”

Ironically, almost 40% of contestants at FSG had aerodynamic devices on their car. With the experience of last year, a new aerodynamics package was designed, creating more downforce and better handling for only a small increase in drag.

Yet the key-element in the history of DUT’s greatest achievements lies in the “Delft Concept”: lightweight construction. Every single element of the car is engineered as light as it can be. This has been the signature of DUT Racing since the DUT03. With larger wings and therefore higher forces on the structure, it is a challenge to keep on decreasing the weight of the car. Nevertheless, the team has achieved a theoretical mass of 155 kg! This is even more impressive when compared to last year’s weight which was 173 kg: a car that was built with the same philosophy and had less loads on the structure due to aerodynamic forces.

Some clever designs will be highlighted in this article, illustrating that 155 kg is incredible, yet not impossible.

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

chassis

The chassis consists of carbon fibre plies with an aluminium-honeycomb core forming a sandwich structure. This aluminium-honeycomb core increases the stiffness without drastically increasing the mass.

This is common practice for monocoque design, however this is the first time the team is using this type of core material. This core has better properties with respect to mass, compared to foam, which is a common more core and has been used for several years by our team. The catch is that a honeycomb structure is difficult to handle in round corners. In order to make the chassis producible, the shape of the monocoque consists of sharper corners. With this new material, the monocoque weighs in at 14 kg, 3 kg lighter than the foam core counterpart!

centerless concept

Most Formula Student tires have an outside diameter of 18 inch since this is the smallest available tire diameter on the market. However with the help of Apollo Tyres our engineers got the freedom to make a concept that is independent of the available tire sizes on the market. This results in the revolutionary centerless concept: the size of the tire is decreased to 14.5 inch! Decreasing the tire size opened up several great options and illustrate the “Delft Concept”.

Simplicity is key. A smaller tire, weighs less.

Because of this smaller tire a smaller gear ratio is needed which allows us to go back to a single stage planetary gearbox (see figure above this paragraph), again lowering the weight. The ring gear (gear on the outside) is directly attached to the wheel making it an integrated design which eliminates the need for spokes. By additionally integrating a pull-rod assembly in the suspension, the team saved over 2 kg per wheel in total!

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

“aerodymamics�

This is the second year for DUT Racing to design an aerodynamic package. When designing the package, a continuous trade‑off between downforce and drag is made. The DUT14 design is a successful balance that allows maximum downforce with minimum drag while keeping the aerodynamic forces in the middle of the car.

The advantage of a front wing on any car is that the airflow is undisturbed and only little extra drag is created as the wheels already create drag, adding a front wing will not increase the drag as drastically as a rear wing. Therefore, the frontal surface can be used maximally for creating downforce without compromising the low drag design. The front wing consist of three wing-elements. The first element spans across the entire front section, and the second and third wing element span until the monocoque. However, the front wing

blocks undisturbed air fom being used for cooling or the diffuser. A smart design solves this problem by increasing the height of the nose which creates a slot of undisturbed air flowing through the cooling elements and underneath the car to the diffuser.

A disadvantage of a rear wing is that it causes tremendous amount of drag. More drag means more energy is needed to accelerate, so more energy is needed which causes heavier accumulators. To maintain the Delft Concept, the rear wing needs to be low drag, while the resulting aerodynamic forces need to be in the centre of the car, in order to make sure the car handles as it should. This strategy resulted in a two-element rear wing that produces just enough downforce (and corresponding drag) so that the resulting aerodynamic forces are in the centre of the car.

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

electronics The electronics department has a great impact on the reliability of the car. This year, the team decided to redesign all electronics with two key elements in mind: lightweight (of course) and simplicity. What is remarkable is that in fact these two elements are closely related. By placing the components that need to communicate close to each other and by using a smart design the amount of wires required is drastically reduced. Reducing the amount of wires causes less interference problems, less possible production errors and of course entails a lower mass. An example of this philosophy is our self-designed Battery Management System (BMS), which reduces the amount of wires for the battery package from 40 wires per battery package of last year, to an impressive two wires per accumulator. Simplicity also means thinking

outside the box. Another good example is the sensor node design. The previous cars had a unique sensor node for every part of the car.

Now, one sensor node is used that can be used anywhere. This increases data reliability, decreases production time and decreases troubleshooting time.

The accumulator consists of lithium polymer cells. Although companies always give a specification sheet, the sheet given by the factory does not represent the data the team needs, since the cells will continuously charge and discharge. In order to get the maximum potential of a cell, they need to be tested.

Therefore by using a programmable power supply from Delta Elektronika and using heat-sensing camera from FLIR (featured in our next newsletter), we could test each cell extensively.

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

conclusion This will be the car that will compete with the top electric cars of the world in three competitions: Formula Student United Kingdom, Formula Student Germany and Formula Student Austria. The team is looking forward to see the designs of all the other

teams and exchanging ideas. The next few months the team will work hard to realise this 155 kg four-wheel driven electric vehicle.

Like us on facebook to follow the production and assembly phase of the team.

Author – Sietse van Schouwenburg

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

jeveka excursion In December, the DUT14 team left for Amsterdam, destination: Jeveka. Jeveka is a well-known dutch company, supplier of fasteners and tools. Once we arrived at their headquarters in Amsterdam, we were warmly received by Adriaan and Stephanie Veltkamp, senior directors of Jeveka. They had prepared a first college on fasteners: which ones to use, what their respective uses and advantages were. It is impressive to see how much these people know about the thousands of different fasteners and tools that seem to exist, we are happy to have them as partners!

After the presentation we got a short workshop on the new Kato inserts Jeveka now supplies, following this presentation was a tour in their facilities and their showroom of inserts and tooling. After some group pictures around the 75th anniversary lightblocks, it was time for us to head home. Before leaving, Jeveka had one last surprise for us though: they gave us some quite creative goodies, a chessboard with pieces that you could assemble out of the fasteners they supply! The chessboards are now proudly shining at our office and homes, a fun way to end the day!

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

monocoque plugs to make our moulds We already got our first big parts for production! The plugs to make our monoque moulds. The monocoque is a critical part because everything needs to be attached to it, therefore it needs to be finished first. It also defines the aesthetics of the car which makes the arrival of the plugs exciting since they gave the first impression of the shape of the car.

About the monocoque: The monocoque will be produced using aluminum honeycomb, a new material to the team. This choice followed from our lightweight design philosophy. In total, it will weigh no more than a full crate of beer!

About the production of the monocoque: the production of the monocoque happens in several phases. At first, positive moulds, also known as plugs, are milled from MDF at Model- en Matrijzenmakerij Twente. With this positive mould, we produce a negative mould from carbon fiber. This second mould will be used to produce the actual monocoque.

The reason for making these carbon fiber negative moulds is because then the thermal expansion coefficient of the mould and prepreg lay-up is completely the same. This ensures that our monocoque shape is true to its designed form.

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

Faculties: Mechanical, Maritime and Materials Industrial Design Applied Sciences Technology, Policy and Management Aerospace Engineering

Formula Student Team Delft Newsletter January 2014 Design Presentation Special

a d va n c e d

lightweight engineering