Concept modelling of an automotive body in white for early-stage design exploration and optimization.

For vehicle design optimization, automotive Original Equipment Manufacturers (OEMs) want the ability to have early stage assessment of vehicle performances and face potential design issues. This thesis work has been developed in collaboration with Siemens Digital Industries Software in order to develop a methodology for the concept design of beam-like structures and joints in a vehicle Finite Element (FE) model, with the aim of enabling accurate simulations of the Body in White (BiW) and overcoming current limitations on Computer Aided Engineering (CAE) models already in the initial phases of the car design process. The development and application of the vehicle advanced CAE tools in the automotive sector is a certified approach to predict the various functional performance attributes (crashworthiness, ride and handling, noise, vibration & harshness, etc.) and adapt the design based on the outcome of virtual simulations and their relation to targets and requirements. Alternatively, Body in White CAE models have reached a high level of detail and complexity, resulting in heavy simulation models and long computation times. As a result, the design of an automotive car body is a lengthy and iterative process where the vehicle performances for the different attributes can be evaluated and balanced only at an advanced design stage, when the detailed geometry and simulation model are available. The reduction of the time to market has been one of the main thrusts in the automotive industry in the last years, pushing researchers to find more efficient methods to solve design problems. In the conceptual stages of design, engineers need simplified models to extrapolate the structural and functional characteristics and apply custom modifications for achieving the best vehicle design in order to balance the different attributes. Unlike the detailed Finite Element (FE) model, the concept CAE model can be created without any need of the detailed computer-aided design (CAD) data. Therefore, engineers have the need of utilizing trade-off simplified models of Body in White (BiW), composed of only the basic structural elements (beams, joints and panels) while at the same time being able to capture the static and dynamic behaviour of the vehicle. The study described in this thesis consists of creating a BIW concept model that offers the advantages of geometric parameterization of the car body main structural members while retaining a reliable stiffness representation of them based on beam and joint libraries from existing car bodies. The created model consists of a network of stiffness elements (beams and joints) which can be assembled in a very short time, allowing for fast design space explorations and optimization.