Travail de fin d'études et stage[BR]- Travail de fin d'études : Optimal Design and Finite Element Analysis of a Speed Bump Made of Recycled Composite Material[BR]- Stage d'insertion professionnelle : GDTech

Abstract

Nowadays, the environmental and cost aspects dictate each choice that is made in the industry. The manufacturing of speed bumps is no exception to the rule. The target is to manufacture a traffic calming device strong enough to resist the loads to which it is subjected during its lifespan while reducing the production costs and the pollution. The aim of this Master's thesis is to make an optimal design of a speed bump made of recycled composite material able to withstand the passage of heavy vehicles and study its failure behaviour.

In order to create a speed bump design able to sustain various loads during its lifespan by minimising at the same time the amount of material needed for its manufacturing, the topology optimisation method can be used. In the first place, the speed bump is modelled by assigning material properties obtained experimentally corresponding to a mix of fibres and polypropylene and by developing a methodology to define a set of load cases representing the contact pressure of the wheels on the device. Then, the topology optimisation process begins. After determining the topology parameters leading to the best results, different auxiliary parameters are defined in order to approximate as best as possible the physical problem. A symmetry assumption is then made on the model and load cases are applied on the entire surface of the speed bump to consider a more generic case. Afterwards, four fixing points are designed close to the top flat part with integrated reflectors, corresponding to the most optimal configuration. Through a last topology optimisation, the final design of the speed bump is obtained, including the desired cable passage. This allows to obtain a 27% mass reduction.

To study the failure behaviour of the speed bump, the rupture material model available in the software is chosen. Numerous assumptions are made to use this model due to the lack of information regarding the material properties. To be able to calibrate and validate this rupture material model, a model of the coupon is created in order to verify that the numerical results correctly approximate the experimental ones. Some adjustments are then made regarding the experimental force-displacement curves to discard the part corresponding to the establishment of the experiment and some corrections are made regarding the values of the Young's modulus and of the stress limit in compression obtained in the compression tests. To validate the model developed, a statistical approach is adopted on the coupon, followed by a second one on the speed bump to determine the maximum pressure it can withstand as well as the probability of immediate failure of the device. A brief introduction to the fatigue phenomenon is finally provided.

A non-exhaustive list of recommendations and possible improvements for future research on the subject at hand is also provided.