Advanced High Performance Optimization tools support car and other industrial product design

Sankt Augustin, 13 November 98 Industrial design engineers basically face two challenges. Due to the extremely short time frame in which the concept design has to take place, they are forced to make essential decisions with regard to both the final product performance and manufacturing costs, already in the early stages of a product design. Second, the consumer's demand for lightweight structures compels them to avoid overdesign in order to save material and time in the design-build-test scenario. To tackle these complex issues, the Esprit funded HIPOP (High Performance Optimization) project has been set up CAOSS, an optimization software programme developed by FE-Design in Karlsruhe, for complete integration into MSC/NASTRAN, which is used as the analysis engine. This software is marketed under the new name of MSC/CONSTRUCT by the Los Angeles based MacNeal-Schwendler Corporation (MSC) in its world-wide distributor network.

The fast and user-friendly HIPOP conceptional design tool has been based on a number of innovative options consisting of two optimization codes, MSC/CONSTRUCT TOPOLOGY and SHAPE; the shape optimization module SOL200 provided by MSC/NASTRAN; and the parallel version of the Finite Element Method (FEM) programme MSC/NASTRAN (PMN), which is able to run in a distributed High Performance Computing and Networking (HPCN) environment.

In topology optimization, the surface nodes are not moved but the industrial component's volume is being changed instead. The material is distributed within a design space envelope based on the optimum load paths. The proposed design gives the engineer an idea about the optimal strain energy distribution according to the loads applied. From this point, the trial concept can be applied for an initial Computer Aided Design (CAD) representation.

In shape optimization, the surface node locations are modified according to the calculated stress levels. In order to cost-effectively calculate the models, the amount of design variables may not be too high. In MSC/CONSTRUCT SHAPE, the control algorithms are no longer dependent from the number and selection of design variables, which allows the engineers to calculate and optimize real world 3D structures. The software provides optimality criteria procedures to create new shapes without having to use shape basis vectors.

The optimality criteria methods however show difficulties dealing with arbitrary object functions and constraints definitions. They therefore may be combined with mathematical optimization procedures and automatic shape generation with the SOL200 module. In addition, the performant FEM code MSC/NASTRAN has been ported to several parallel hardware platforms equipped with distributed memory features. In this way, the time for pre- and postprocessing in industrial design can be reduced to an acceptable and affordable proportion.

The MSC/CONSTRUCT programme operates in optimization cycles in which each single cycle comprises one MSC/NASTRAN and one MSC/CONSTRUCT run. The initial MSC/NASTRAN analysis generates a first trial design model after which MSC/CONSTRUCT optimizes the design according to the data of the selected load-stress hypothesis. The modifications are introduced for a new MSC/NASTRAN analysis until the optimization process has reached a final convergence.

The HIPOP solution has already been successfully evaluated by renowned companies in the automative industry, such as BMW, Pininfarina, IABG, and INA. For this type of CAD designers, the MSC/CONSTRUCT software constitutes an fully integrated tool to advance the design process in a much more efficient way than the most sophisticated Computer Aided Engineering (CAE) packages which operate in a non-integrated fashion. The companies tested the new software against a previously non-optimized version. For design of a fender, the computing time was reduced with 68%. For a pump lid, the computing time was even reduced with 73%. A reduction is shown consistently independent of the type of HPCN equipment used. Examples were run for instance on SGI, HP and IBM high-performance equipment. For more information on this project, please, check out the HIPOP home page.

Leslie Versweyveld