University of Twente Student Theses


Haalbaarheidsonderzoek composiet bladveren voor de gCab

Hoek, Aafke Jeanine van der (2013) Haalbaarheidsonderzoek composiet bladveren voor de gCab.

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Abstract:The Mobility Lab Twente is involved in the development of the gCab. The gCab is a firm, small and fully electrical vehicle for both passenger and cargo transport. The leaf springs of the gCab are heavy metal parts of the vehicle. Because a road legal vehicle is bound to a maximum weight by European law, it's important that the weight of the spring leafs is kept low. If the weight of the leaf springs can be reduced, this weight reduction makes it possible to add doors to the gCab or to transport more people or cargo. One possible weight reduction technique is to switch to a new type of material, like composites. The aim of this bachelor assignment is to perform a feasibility study on composite leaf springs for the gCab. The goal hereby is to minimise the weight of the construction by using a composite material for the leaf springs and attachment points. First, the current design of the metal leaf spring has been analysed (4). On the basis of this analysis the requirements (5.1) and specifications (5.2) has been defined. The optimisation has been carried out in two phases: firstly the beam element and secondly the attachment points. The first phase resulted in a geometry needed for the desired spring properties. The second phase was a bit of a challenge since the attachment points were difficult to make out of composite materials. The client complicated this even further by posing the restriction that the suspension system might not be altered. After the choice for the final concept, it was produced in the lab of Production Techniques. The lab offered the opportunity to produce the product with the vacuum infusion technique. First, a mold was made with the correct shape for the production process. During this process the resin flowed to all the places of the product. However, during the toughening process in the oven, foam appeared. Further investigation is needed for this production process to prevent this. Attention should be paid for the quality of the vacuum and the amount of resin used in the infusion. The results at this moment indicate that this production process has a high potential, although further research is needed whether the technique can be applied or not. As mentioned earlier, the optimisation has been divided in two parts: the beam and the attachment points. The conclusion follows this division: BEAM-ELEMENT --- For the production of the beam (without the attachment points), composite materials proved to be a good alternative to metal. This part of the spring leaf resulted in a weight reduction of 78% compared to the metal equivalent. In order to realise this reduction a uni-directional fibreglass should be used. In the lab of the University of Twente it is possible to make the beam with vacuum infusion. However, when produced in large quantities it is preferable to use press technology, which is significantly faster. Unfortunately, the University of Twente cannot offer this technology, so it should be outsourced to an external company. ATTACHMENT POINTS --- Results in the lab show a promising technique to produce the attachment points in composite material as well. By means of the folding concept (see figuur 2), the production of the attachment points can be integrated in the production of the beam itself. In this concept, long strips of fabric of the correct shape are folded in a particular order, resulting in a weight reduction of 70% compared to the metal equivalent. The feasibility study shows that it is possible to construct the spring leafs of the gCab entirely from composites resulting in a significant weight reduction. Further research can improve the production process of the leaf spring. Furthermore, a cost estimate should be made by consulting external parties. As a conclusion we can state that a weight reduction of 70% can be reached and that in the future the gCab can be equipped with leaf springs made of composites.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:20 art studies
Programme:Industrial Design BSc (56955)
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