Elastoplastic Load Distribution Modeling of Planetary Roller Screw Mechanisms Considering Machining Errors under Short-Term High Overload

Planetary roller screw mechanism (PRSM) are often subjected to extreme operating conditions involving high acceleration and short-term overloads. Under such conditions, the thread interfaces may transition from elastic to elastoplastic or plastic states, leading to surface degradation such as micro-cutting and plastic flow. Conventional purely elastic models are insufficient to capture these nonlinear behaviors. Therefore, this study develops a comprehensive load distribution model that incorporates machining errors and elastoplastic contact deformation to predict the critical axial load at the onset of yielding and to characterize thread-level deformation. To validate the proposed framework, static load-bearing experiments were conducted under high-overload conditions. The results show that the elastoplastic model improves agreement with experimental data, reducing the maximum relative error from 26.4% to 18.6%. In addition, the analysis indicates that machining errors increase load nonuniformity, which promotes earlier plastic deformation in thread teeth near the loaded end of the roller–screw interface. This work provides a useful analytical basis for evaluating load distribution and predicting failure limits in PRSM operating under high-load conditions.HighlightsProposed an elastoplastic load distribution model for PRSM under high overload.Revealed the nonuniform yielding sequence of thread teeth near the loaded end.Validated the theoretical failure limit via static high-overload experiments.