Yves Ravalard

Application of kinematic models to compression and bending in simplified crash calculations

Abstract The growing complexity of transport vehicles requires huge finite element models to simulate their crash behaviour. The structure cannot be effectively optimized by means of these models which require long calculation times, and which should only be used as a final verifying tool. Distinct kinematic models have been developed in order to determine analytically the resistance to collapse of thin-walled structures of simple geometry subjected to compression or bending loading. Using an example of an “S” frame undergoing a collision against a rigid block, four modelling tools were tested. After comparison between the experimental test results and the numerical calculations, the “compression-bending” kinematic model appears to be a promising tool for rapid estimates of crash behaviour of simple structures.

Application of the generalized mixing kinematic model to the calculation of crushing response of complex prismatic sections

Abstract Impact behaviour of vehicles can be conveniently studied by means of hybrid numerical models using equivalent elements such as bars and non-linear springs. Wierzbicki and Abramowicz proposed a kinematic model for calculating the average and instantaneous crushing force for these macro elements. An equally simple model for the pre-collapse phase was developed by Huang and Wierzbicki. Our obective in the present paper is to determine the entire crushing characteristic of prismatic members consisting of plates with different wall thickness. Several examples are worked out in which comparisons with FE calculations and experimental results are made.

Un élément multi-matériaux pour l’étude du comportement en crash des structures stratifiées : synthèse et perspectives

Abstract.The materials used within the structures in the field of ground transportation are increasingly complex and it is usual to find numerous composite parts. New laminated materials are appeared, more particularly the multi-layered multi-materials (combining metals such as steel, aluminium… and composite materials such as resins, fibres…). We are to develop a finite element method permitting to study under impact these structures. The latter have been built into an explicit computation software. A synthesis of developments is presented and many perspectives are envisaged.