Methodology for the Design and Optimization of Hybrid Structures in the Early Phase of Vehicle Development

Abstract

Hybrid structures hold a high potential of lightweight design which is important for the automotive industry. To find an appropriate design of those multi material parts is a key criterion for its application in a car body. In this paper a methodology is presented which allows the definition of an advantageous hybrid part design considering demands on structure stiffness, strength, local stability and weight. The analytical approach allows a rapid optimization of parameters, like the dimensions of a cross section, materials and boundary conditions. In order to improve understanding of the implementation and working method, an analogous model of a real car door sill is optimized. Two different concepts to reinforce the steel structure with CFRP are defined and investigated. A) CFRP reinforcement on each side of a rectangular crosssection leads to a weight saving of 31% compared to the reference structure with the same bending stiffness made of high-strength steel. At the same time the maximum transferable load causing first failure is increased by 54%. B) A second example, a beam reinforced on three sides results in a weight saving of 20% and an increase of load capacity of 16%.34