Statistical Tolerance Analysis of a Mechanism with Gaps based on System Reliability Methods

One of the aim of statistical tolerance analysis is to evaluate a predicted quality level in the design stage. A method consists in computing the defect probability P expressed in parts per million (ppm). It represents the probability that a functional requirement D will not be satisfied in mass production. This paper focuses on the statistical tolerance analysis of over-constrained mechanism with gaps. In this case, the values of the functional characteristics depend on the gap situations, and are not explicitly formulated as a function of part deviations. To compute P, two different methodologies will be presented and confronted. The first one is based on D an optimization algorithm and Monte Carlo simulations. The second methodology uses system reliability methods. The whole approach is illustrated on a basic academic problem inspired by industrial interests.