Analysis and study of an automobile rear seat by FEM

Abstract

The aim of this work is to carry out the design of an automobile rear seat and the simulation by finite element method (FEM) on its performance using different standard tests. The design is intended for the rear seats of a four-seat vehicle: two front seats and two rear seats. The rear seat set comprises the right and the left seats. Each of these seats is individual and independent so that it can house only a person and is structurally independent of the other one. Two main parts of this work are: (1) design; and (2) analysis by FEM. We carry out the design of the rear seat of a generic automobile, using the CAD Catia V4 software [P. Carman and P. Tigwell, CATIA Reference Guide, OnWord Press, New York, 1998; F. Karam and C.D. Kleismit, Using CATIA, OnWord Press, New York, 2003]. The seat is composed of two very different parts: (a) framework which is the internal structure of the seat, supporting the weight of the occupants and the seat itself, in order to allow the different positions and to assure the durability and correct operation throughout the vehicle's useful life, and (b) foam rubber whose function is to distribute the load, to provide comfort and to give the most aesthetic possible finish to the seat. During the design we have kept in mind criteria such as resistance, safety, durability, aesthetic and lightness; this last property is necessary to achieve fuel economy and a lower inertia in the event of a collision. The standard rules demand that the automobile seats are able to overcome a series of tests, implying the security in the event of a road accident. In this study the tests were carried out by finite element simulations. The software used was Pam-Crash, a well-known non-linear explicit solver of finite elements. From the computer simulation of these tests, stresses and displacement data are obtained for the seat's framework in order to check the correct execution of the demands of the standard rules, carrying out, if necessary, changes in the design within the allowed limits. In this way the use of this tool makes possible to carry out an optimisation of the geometry, materials, etc. of the product before the construction of the prototype, minimising costs and manufacturers’ development time.

Keywords:

• finite element modelling
• numerical methods
• rear seat design
• motor-vehicle crash test
• impact dynamics

2000 AMS Subject Classification :

• 74S05
• 5A15
• 34K28
• 74M20

Acknowledgements

The authors express their deep gratitude to the Department of Mathematics and Construction Department at Oviedo University and the Department of Mechanical Engineering at Vigo University for its computational help and useful assistance. Helpful comments and discussion are gratefully acknowledged. Thanks are also due to ESI Group Software Technology Corporation for the use of Pam-Crash program.