Sensitivity Analysis of Tolerances which Restrict ...

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International Symposium on Robust Design (ISoRD'14) Technical University of Denmark, DTU

Sensitivity Analysis of Tolerances which Restrict Multiple Similar Features
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Author:Philipp Ziegler (Chair of Engineering Design KTmfk, Friedrich-Alexander-University Erlangen-Nürnberg, Germany)
Sandro Wartzack (Chair of Engineering Design KTmfk, Friedrich-Alexander-University Erlangen-Nürnberg, Germany)
Date: 2014-08-15     Track: Main     Session: 10:30-12:00 Poster Session : Robust Design & Reliabilty Engineering
DOI:10.4122/dtu:2096

In tolerancing, the product functions and quality should be ensured in the presence of geometric variations of the product components. For this purpose, tolerances restrict these geometric variations. Usually, the products functions are transferred to so-called functional key characteristics (FKC), which mostly are geometric quantities of the product. The requirements on the products functions are transferred to requirements of the FKCs. Afterwards, geometric analyses of the FKC variations are performed based on tolerance simulations. These simulations have input parameters (geometric deviation parameters) and output parameters (FKC deviation parameters). The aim of tolerance simulations is to set the tolerance values in a way that the FKC fulfil its requirements. In this context, sensitivity measures can quantify the impact of single tolerances with respect to a FKC (Ziegler and Wartzack, 2014). A common sensitivity analysis method bases on the conditional variance of the simulation output, which can be calculated by a number of different algorithms (Saltelli, et al, 2008). Normally, a tolerance object is adopted on one geometry element. In some cases, tolerances can restrict multiple geometry elements. In this case, multiple sensitivity values for the geometry elements are calculated by standard sensitivity analysis. This is disadvantageous if the influence of the tolerance which restricts the geometry elements is of interest, because the sensitivity values cannot be simply added together. This paper discusses the case, when a position tolerance is adopted on multiple similar geometry elements. A statistical sampling method for the sensitivity analysis algorithms is introduced. The method is adopted to a hole pattern to show its practical use.