Tolerance analysis of slider-crank mechanism for assembly functionality check

The purpose of functionality check is to analyse the stack-up of geometric deviation of part/feature whether it meets geometrical requirement and is it in the range of assembly tolerance. However, usual tolerance analysis model does not include assembly clearance. Aiming at this problem, we have done some research. Firstly, a nominal geometrical transfer model and a stackup model are established based on small displacement torsor (SDT) and homogeneous transformation matrix (HTM). Secondly, HTM expression of tolerance loop is constructed. Next, assembly tolerance matrix model is established and a new tolerance analysis method for assembling feasibility check is put forward. At last, taking a slider-crank mechanism as example, the contrastive study of tolerance analysis for functionality check is done. The results show that it is prone to lead to misjudge when analysing only dimension tolerance. And, it is more restrictively when considering dimension tolerance, geometric tolerance and assembly clearance.