Multi-Contact Load Transfer and Cyclic Wear Evolution of a Symmetric High-Repeatability Precision Locator Under Repeated Tightening

To address the strong contact nonlinearity associated with explicit thread modeling and the high computational cost of long-term wear simulations during the cyclic operation of symmetric high-repeatability precision locators, an experimentally calibrated equivalent axial displacement method is proposed. Material parameters and the evolution of clamping force were obtained through tensile tests of T8A carbon tool steel, ball-on-flat reciprocating wear tests, and a 2000-cycle clamping test. The measured clamping force under a reference tightening torque of 3.5 N·m was then used to calibrate the equivalent axial displacement in a thread-free finite element model. On this basis, the Archard wear model was incorporated to investigate load transfer and wear evolution across multiple contact interfaces. The results show that the equivalent model can satisfactorily reproduce the overall evolution trend of the experimentally measured clamping force while preserving the principal load-transfer paths. The wear distribution is jointly governed by local contact pressure and relative sliding, with the inner wall of the locator-body bore identified as the primary wear-sensitive region. Cyclic wear continuously modifies the contact geometry, contact stiffness, and load distribution, resulting in a stagewise evolution of the clamping force. This experimentally calibrated thread-free model connects calculated local wear evolution with the measured global clamping response under the tested condition, providing an engineering basis for evaluating wear-sensitive contacts in precision locators.