Study of a seat in composite material: Fem modelling and solver influence

For many centuries road transport had been ensured by horse-drawn carriages. Only around 1830, with the appearance of the first steam engines, the idea of a motor vehicle as we see it today was born. However, it has been many years before the subject of security was introduced. In fact, up to the 1960s, crashes and casualties were considered mainly the consequence of human behaviour and vehicles were considered as safe as manufacturers could make them. For this reason during the first half the 20th century the common understanding was that safety countermeasures should be mainly focused on education and training of drivers, stricter rule-enforcements and better road conditions. Significant improvements were introduced in the automobiles of that period: headlamps, turn signals, dual windshield wipers, tire less prone to blowout, all-steel body structure. Thanks to these and other design enhancements together with a better road quality the fatality rate decreased drastically. But like any other engineering progress, the improvement of vehicle safety had to be objectively assessed, to understand whether a modification on the vehicle structure was effective to reduce the risk of injury of the occupants. For example the measurement can be done through experiments that replicate at best the road accidents. At the beginning of 1970s, reliable testing method, crash facilities, instrumentations and dummies became available enabling car manufacturers to rely on effective tools for vehicle crashworthiness development. In the last decades regulators and safety experts have focused their effort to create safety standards that shall be observed by all the car makers. Today, motor vehicles are among the most comprehensively regulated global products, covering almost all aspects of its performances. A subset of the vehicle that is very important from the point of view of passive safety is the seat. It has the task of keeping the passengers in the correct position, in order to reduce as much as possible the effects of the "second collision" (the impact of the passenger with the interior of the vehicle) and to protect them in case of a side impact with other vehicles or obstacles. The goal of this thesis is to develop a seat of a motor vehicle in innovative material, submitting it to some of the tests required by the homologation regulations currently in force in order to test its structural properties. The results will be then compared with those obtained with the same seat model, but with an already tested composite material whose characteristics are known and which will be used as a reference point. This type of analysis will be conducted with the two most used solvers for FEM analysis in automotive field: Radioss and LS-Dyna, to investigate the possible differences between the results of the two solvers.