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Simplified load path models (SLMs) of the body in white (BIW) are an important tool in the body structure design process providing a highly flexible, idealized concept model to explore the design space through load path evaluation, material selection, and section optimization with rapid turnaround. In partnership with Altair Engineering, the C123 process was used to create and optimize SLMs for BIW models at FCA US LLC. These models help structures engineers to develop efficient load paths, sections, and joints for improved NVH as ultra-high-strength steels enable thinner gauges throughout the body structure. A few key differences in the SLM modeling method are contrasted to previous simplified BIW modeling methods. One such example is the parameterization of cross sections through response surface models rather than using contemporary finite element descriptions of arbitrary cross sections.

The use of structural optimization in the design of automotive structures is increasingly common. However, it is often challenging to apply these methods simultaneously for different requirements or model configurations. Multi-model optimization (MMO) aims to simplify the iterative design process associated with optimizing multiple parts or configurations with common design variables especially when conflicting requirements exist. In this paper, the use of MMO is demonstrated to evaluate the feasibility of an automotive door concept using an alternative material.

The development of a structural magnesium instrument panel (IP) beam is presented in this paper. This magnesium IP was designed to be a structural load bearing member in a crash event. Unlike many IPs in production today, this IP helps mid-engine vehicles achieve certain FMVSS 208, US NCAP, IIHS and OEM standards for occupant crash protection. In typical front engine vehicles, the front-end structure absorbs the crash energy with the sandwiched engine acting as rigid body to resist the crash loads and intrusion into passenger compartment. However, in mid engine vehicles, the front-end structure is inadequate to fully absorb the crash energy and at the same time resist intrusion. Without a structural IP beam to resist crash loads, it is unlikely that mid engine vehicles can successfully meet the FMVSS 208, US NCAP, IIHS and OEM standards for occupant crash protection. With that in mind, this magnesium IP was designed as a structural load-bearing member.

The use of structural optimization in the design of automotive structures has become more and more common in recent years. However, manufacturing considerations have always been an obstacle to the effective use of these techniques. Recently, the use of die-direction constraints in topology optimization has been implemented in Altair OptiStruct [1]. This document describes a practical application of the die-direction constraints and shows how they were effectively used to improve the design of an automotive lower control arm.