An ideal mating surface method used for tolerance analysis of mechanical system under loading

A method to substitute the actual mating surfaces into an ideal mating surfaces is proposed in this paper. A unit normal vector is used to express their position and orientation. To simulate the variation propagation in assemble process, an error accumulate model was built in the foundational coordinate system and can be solved by the homogeneous transformation matrix (HTM). Thus the accuracy prediction of mechanical system could be realized in the condition of rigid body. The ideal matting surfaces under loading could be calculated by finite element method. The parameters of the normal vectors would be varied due to the part deformation. By discretization of vector elements in tolerance zone, the actual element variation under loading can be calculated and the distribution and probability density function compared to the rigid body can be obtained. A grind dress was taken as an example to illustrate this method.