Structure and matrix models for tolerance analysis from configuration to detail design

A substantial amount of all quality problems that arise during assembly can be referred back to the geometrical design, and especially the geometrical concept of the product, i.e. the way in which parts are designed and locat ed with each other. Special emphasis should thus be put on geometry design, especially during the early design phases, to try to find robust concepts and avoid solutions that may cause dawn-scream production problems. This paper presents a generic set of evaluation tools for robust geometry d esign encountering (i) potential tolerance chain detection in configuration design, (ii) assembly robustness evaluation in concept design, and (iii) t olerance sensitivity analysis in detail design. Special attention is given to the development of a new matrix-based evaluation tool for the configurat ion design part. The tool presented is based oil a new way of representing geometry variation constraints QI an enhanced function-means tree structure model. Different parts of the function-means tree that are of interest for analysis purposes are then extracted and converted to matrix representatio n. The reason for doing this is that the structure model is most suitable f or modeling, but becomes unsuitable for analysis as the model complexity in creases. For this latter purpose, the matrix representation is far better T he use of the different fools is demonstrated in the design of a new vehicl e front system for which the geometry a priori is unknown.