A Novel Static Model of Planetary Roller Screw Mechanisms Based on an Energy Method

A novel static model of planetary roller screw mechanisms (PRSMs) is proposed to obtain the load distribution over threads by an energy method. The energy method consists of the structural potential energy and an optimization problem. The potential energy is calculated by structural discretization. And the optimization problem, whose objective is the structural potential energy, is obtained by combining the principle of minimum potential energy with the forces balance constraints. The load distribution is the result of the optimization problem. A finite element model is established for validation. Compared with previous models, the proposed model has lower complexity and higher precision. To further verify the reliability and practicability of the proposed model, effects of the nut position, shaft diameter, and number of roller threads on the load distribution are analyzed based on the proposed model. The results show that the nut position has little influence on the load distribution. The shaft diameter and number of roller threads significantly impact the load distribution.