Tolerance analysis of an assembly by considering part deformation

Part error will cause the assembly contact state between parts to deviate from the nominal state, resulting in error accumulation and propagation. Therefore, reasonable tolerance has to be applied to control the corresponding errors. Currently there are a number of tolerance analysis methods, however, most of them typically only consider dimensional and geometrical tolerances in the design phase. Analysis results without considering part deformation which was commonly observed in the realistic working conditions could lead to possible assembly failures. In this paper, both manufacturing and deformation errors are taken into account to establish a more comprehensive deviation calculation model based on Polytope-Skin Model Shape method. The total assembly error can be determined by calculating the Minkowski sum. The effectiveness of the proposed method is verified in a case study about an assembly of one-joint manipulator in which the external force is the cause of the change on part shape and size.