Body In White

A preeminent factor in the geometrical quality of a compliant sheet metal assembly is the fixture layout that is utilized to perform the assembly procedure. Despite the presence of a great number of studies about the optimization of assembly fixture layouts, there is not a comprehensive algorithm to optimize all design parameters of fixture layouts for compliant sheet metal assemblies. These parameters are the location and type of hole and slot in each part, the slot orientation, and the number and location of additional clamps. This paper presents a novel optimization method that optimizes all these parameters simultaneously to maximize the geometrical quality of the assemblies. To attain this goal, compliant variation simulations of the assemblies are utilized along with evolutionary optimization algorithms. The assembly springback and contacts between parts are considered in the simulations. After determining the optimal design parameters, the optimal positions of locators are fine-tuned in another stage of optimization. Besides, a top-down design procedure is proposed for applying this method to multi-station compliant assemblies. The presented method is applied to two industrial sample cases from the automotive industry. The results evidence a significant improvement of geometrical quality by utilizing the determined fixture layout from the presented method compared with the original fixture layouts of the sample cases. Keywords Fixture layout optimization · Sheet metal assembly · Compliant variation simulations Abbreviations and nomenclature BIW Body in white KPC Key product characteristic SSM State-space modeling MIC Method of influence coefficients FEM Finite element method GA Genetic algorithm RMS Root mean square P The number of parts in the assembly Q p

The use of optical measurement equipment and software based on photogrammetry is becoming more affordable and is increasing their reliability in presenting results on surfaces topography as well as strain distribution. The question is, how feasible can their support be to the process/product development engineer in the choice of the right auto body-in-white (BIW) component design; how can they influence blank and tool geometries, process parameters and moreover the right material selection, in order to reduce the springback of such materials on drawing, reaching the required quality standards for the part. This paper describes some industrial cases on how these new techniques can be applied to lay out industrial deep drawing processes, accomplished by the use of optical measurement, improving design and process issues.

Finite element methods are well suited for the dynamic analysis of vehicles in the low frequency range (below 100 Hz). Similarly, SEA methods are well adapted to the higher part of the spectrum (above 500 Hz). A lot of research has gone over the past ten years in the development of methods dedicated to the mid-frequency range but none of them proved to be robust and flexible enough to be used in an engineering context. There is now a widespread agreement to consider that the mid-frequency range will be filled by : (1) enhancing finite element models to push their frequency limit up to, say, 200 Hz and (2) releasing some of the assumptions of SEA to make it a viable method from 200 Hz onward. We basically see three challenges hampering the fulfilment of the first task : • higher frequency means larger model and one must improve solver technologies to face the growing computational load ; • it makes little sense to predict the response of a body-in-white above 100 Hz and one must impr...