Reliability and Quality of Body Concept CAE Models for Design Direction Studies

There are two distinct classes of body CAE models (detailed and concept models) that can be used to support vehicle body design and development. A detailed finite element model achieves computational accuracy by precisely simulating component geometries and assembly interfaces. On the other hand, a concept model simulates stiffness behavior of joints and major load-carrying members (e.g., pillars, rails, rockers, etc.) in a body structure. The former is quite useful for conducting trade-off studies when detailed design drawings become available. The latter is valuable for up-front design direction studies prior to detailed design evolution. In concept models, major load-carrying members are universally represented by cross sectional properties (e.g., area, moments of inertia and torsion constant). The key difference between various kinds of concept models is the representation of body joints. This paper discusses generic characteristics of two typical joint representation methods: a mathematical representation and physical representation. A tri-spring joint representation with three physical joint stiffness constants is recommended over mathematical representation. The benefits of applying a body concept model of a project vehicle with the tri-spring joint representation to design direction studies are demonstrated in this paper.