Assembly Tolerance Analysis with Nonrigid Parts, Masoud Pour, 2007

Abstract:

Due to error in manufacturing processes, all of the industrial parts aren't manufactured with specified dimensions. Therefore for each dimension of the desired part, dimensional variation is introduced. In order to create assemblies with proper performance, a limit of variation is prescribed for a specified po­int. The position of this point is functional and its variation depends on the tolerance stack-up of associated dimensions. If this point has limit of variation in two or more directions, the correlation between variations of the point in different directions also affects the limit of variation. To determine bivariate distribution of the point in assembly, the Direct Linearization Method (DLM) is used. In addition, the influence of loading on non-rigid part is taken into consideration. The proposed method is based on DLM and FEM which is written with MA TLAB and CALFEM toolbox. The bivariate distribution of the coupler point for four¬ bar and crank-slider mechanism are computed. The variation of normal-to¬ path error is analyzed during one cycle of the motion. The results are compared with Monte Carlo Simulation. For reliability of 95% the acceptance zones of DLM are determined. ­

Keywords:

Tolerance Analysis, Direct Linearization Method, Mont Carlo Simulation