This paper on "Optimization and Parametric Modelling" was presented at the 3rd International Conference on Quality Assurance and Standards in Finite Element Analysis - 10-12 September 1991, Stratford-upon-Avon, England.

Abstract

Applications of parametrically defined FEM-input are presented.
The HIFINEL3 element generator is based on macro-elements and the relationship between nodes and the surfaces they lie on. It is a part of a batch preprocessor requiring a very small input.
One example is a crank shaft for a large ship's Diesel engine and the main body of the paper consists of an overview of the system of programs we have developed for the analysis of this type of structure. The entire shaft may be built from one quarter of a throw by mirroring, translation and rotation. In spite of the fact that the system has several hundred thousands of degrees of freedom, forces on the system may be determined by relatively simple computations on a dynamic system which has been condensed to only four degrees of freedom in the middle of each bearing.
The stresses determining the dimensions occur in the fillet, the shape of which is optimized. In the example shown, which started with a well proven design, the constraints on the optimization put a severe limit on the improvement one could expect, but even a 15 percent reduction of the stresses makes life easier for the designer analysing torsional vibrations and may make room for uprating of the engine.
Finally we present a sample of the HIFINEL parametric input definition and some figures showing structures to which parametric design and in some cases also optimization have been applied.