In this past two years, Unistra students have been assigned to do a project aimed at determining the optimum way of constructing an environmental friendly vehicle. The project was started in 2012 when we, as a group of Mechatronics students decided to be a part of the Shell Eco Marathon competition. We have created a chassis with the purposes of studying real performances of a fuel cell to compare it with the simulation values obtained from Matlab.
Premier Châssis
Earlier this year,we've started to design a new type of chassis because the first chassis was too heavy and the center of gravity was not well adjusted thus rendering the vehicle unstable at certain velocity. After a lot of reading, we came up with an ingenious solution. To reduce the weight of the chassis, we must look into a structure called "honeycomb". This structure is used frequently in aviation industry. Using the information given by the aided computer simulation, we came with a conclusion that the honeycomb structure is the best structure for our chassis. This structure would be a lot lighter than the current one.We also found out that this structure have a good resistant to deformation.
Honeycomb Structure (Design)
Honeycomb Structure (Real)
Comparaison des déformations des différentes structures :
1) Aluminium bar :Maximum Deformation = 0.083 mm
2) Aluminium tube :Maximum Deformation = 0.1252 mm
3) Aluminium (Honeycomb structure) : Maximum Deformation = 0.009708 mm
En comparant ces trois structures, on constate que la structure en nid d'abeille est la plus rigide car sa déformation est minimal.
As we compare these three values, we conclude that honeycomb aluminium structure is the most rigid because its deformation value is the smallest.
As we compare these three values, we conclude that honeycomb aluminium structure is the most rigid because its deformation value is the smallest.
CONCEPTION DU CHÂSSIS
Maintenant, il nous reste à concevoir le nouveau châssis en utilisant la structure qu'on a choisi précédemment. Pour minimiser le coût, on va concevoir un châssis qui n'a pas de support de base. A la place de travailler avec le montage fait par les anciens étudiants, on va construire un châssis ressemblant à un canoë. Avec ce design, notre coque sera mis en haut de cette structure est du coup, on a pas besoin de concevoir la partie basse de la coque. Cela rend notre véhicule moins cher.
Now, we would like to design a new chassis using aluminum of honeycomb structure. To decrease the fabrication price of our vehicle, we will design our cockpit in a way that it didn't need any base support. Instead of working with aluminum panels which were used in the first
model, we are proposing a new design which looks like a "canoe". With
this design, our cockpit can be self-supporting and no downside base
support
will be needed. Unlike in the first model where we needed to create the
upper and downside of the cockpit, this new design will make sure that
we create just one part to cover the entire vehicle. This render our
structure to be cheaper.
Chassis Single Cockpit
L'épaisseur de ce châssis est de 15 mm et sa surface de 3 m². On a donc la valeur de sa masse par la surface qui est de 6.7 Kg/m². Cela nous donne la masse totale du chassis qui est de 20.10 Kg, ce qui est beaucoup moins lourd que le châssis construit précédemment.
The thickness of this chassis is 15 mm and its area is 3m². We then have its mass per area which is 6.7 Kg/m². This gives us the weight of the chassis which is 20,10Kg which is a lot lighter than the first one.
