Transient Flow–Thermal–Structural Response and Candidate High-Risk Region Identification of an Axial Piston Pump Slipper Pair Under Variable Loading

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In axial piston pumps under variable loading, the system-level excitation and local tribological responses of the slipper pair can become temporally and spatially decoupled. The scientific contribution of this paper is a phase-consistent chain that achieves three things: it resolves the central-pocket pressure boundary with a dual-orifice and dual-control-volume model instead of directly imposing piston chamber pressure, propagates this boundary through posture-dependent clearance to three-dimensional flow–thermal and single-slipper structural responses within the same local cycle, and screens candidate high-risk regions from the spatial proximity and phase relationship of multi-field cycle envelopes rather than from a single peak. The results show that the central pocket pressure exhibits peak attenuation, peak-time difference, and pressure-rate weakening relative to the piston chamber pressure. The steady peak attenuation ratio is 2.83–3.33%, while pressure-rate weakening under variable loading is 6.29–7.14%; the high-to-low unloading case gives the largest attenuation of 4.81%. Increasing steady load reduces the tilt amplitude and raises the minimum film thickness from about 13.024 to 13.452μm, but the maximum temperature rise increases from 34.12 to 65.01K. A 10% cycle-envelope projection shows no common overlap among the film-thinning, oil-film temperature-rise, and structural-stress core high-response regions with pairwise overlap ratios of 0–3.27%. This traceable chain supports comparative lubrication-safety screening; the identified zones remain numerical candidates rather than experimentally confirmed wear or failure regions.