Multiscale friction-impact dynamics in piezoelectric motors via SPH/FEM

Ultrasonic friction-driven piezoelectric motors are critically limited by impact fatigue and interface wear, stemming from complex, multicyclic interactions at the stator/slider contact. The underlying physics—transient high-frequency impacts coupled with nonlinear friction—remains inadequately captured by conventional simulation methods, obscuring pathways to reliability improvement. This study introduces a novel multiscale SPH/FEM framework that uniquely couples finite element modelling of global piezoelectric-structural dynamics with smoothed particle hydrodynamics for solving micromechanical contact evolution. The approach directly simulates interfacial plasticity, real-time redistribution of contact stress, and wear morphology over thousands of vibration cycles. Results demonstrate spatially heterogeneous plastic strain accumulation, which quantitatively correlates with the experimentally observed indentation patterns and reveals the root cause of non-uniform wear. By resolving transient impact dynamics and cumulative damage at the interface, this work provides the first-fidelity numerical tool capable of predicting wear-life and performance degradation in low-voltage piezoelectric motors. The framework establishes a new paradigm for durable motor design, shifting optimization from trial-and-error to physics-based predictive engineering. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.