On tolerance modeling of plane featuer based on Small Displacement Torsor

The mathematical model of tolerance is the foundation of the assembly tolerance analysis. In order to study the mathematical model of the plane tolerance, at first, the SDTI (Small Displacement Torsor with Interval) model of plane tolerance and the constraints of screw parameters were investigated, based on SDT (Small Displacement Torsor) model and interval arithmetic. And then, a new simulated method was presented to solve the problem that the traditional simulated process of feature does not take into account the constraints of screw parameters. This new method used fraction defective of the constraint equation to establish the distribution of the parameters. At the last, an example of plane feature was introduced to validate the new method. The results indicated that the new method was proposed in this paper improve the accuracy of simulation.