Travail de fin d'études et stage[BR]- Travail de fin d'études : Reverse engineered modelling for structure stiffness analysis: application to automotive chassis[BR]- Stage d'insertion professionnelle

Abstract

Producing high quality secured vehicles starting from mass-produced ones involves a strong re-engineering of the initial product, for which only a 3D scan and a few additional data are available. Especially, this work intended to suggest structural stiffener elements to the front compartment of a car body through the analysis of a front left quarter part of the whole automotive body.

The geometrical modelling aimed at generating a suitable numerical model. Based on a particular reverse engineering process, it consisted in various operations on facets of the 3D scan. From this step results a geometric model approaching the physical chassis and composed of several connected parts consisting of sheet metals or massive parts, and made from various materials and/or thicknesses. It involved strong assumptions and simplifications since the 3D scan does only provides partial information about external surfaces.

The Finite Element Analysis, led through the two most important load cases that are bending and torsion ones, validated the mechanical consistency of the model with respect to the physical chassis. It concluded that the model is accurate and consistent enough for global structure stiffness analysis, especially when working with relative notions. What concerns absolute results, experimental testing is needed to provide a scaling between real and numerical results. Further improvements that are the addition of the subframe in the model and the investigation of load transfer through the suspension mechanism have been added.

Concrete applications about structural stiffness analysis of the built model have been suggested through three stiffening possibilities. It resulted that the piece resulting from the enterprise's know-how was quite effective even as a stand alone, while the combination of the strut tower's strapping with the flexural reinforcement part was the most effective with a limited additional deformation of the armoured vehicle compared to the classic unarmoured one.