Spectral Feature Analysis and Wear Fault Characterization of Pressure Pulsation in Axial Piston Pumps

Axial piston pumps are critical power units in hydraulic systems, making reliable health management essential. While model-based diagnostic methods using pressure or vibration signals are widely recognized for their strong physical interpretability, their advancement is largely hindered by the inherent nonlinearity and ill-conditioning of high-fidelity models. To address this challenge, a spectral domain modeling framework is proposed to characterize pressure pulsation at the pump outport. By applying Fourier expansion to the pressure build-up equations, the original nonlinear dynamics are reformulated into an algebraic system of spectral coefficients, significantly improving computational efficiency. The model further incorporates wear-related parameters to represent faults in three key friction interfaces (piston/cylinder, slipper/swashplate, cylinder/valve plate). Experimental studies under different wear faults and varying working conditions validate the proposed framework and establish robust correlations between the fault modes and their spectral characteristics. Furthermore, a quantitative relationship between wear severity and rotational frequency amplitude is established, providing a physics-based diagnostic indicator. The proposed approach offers an interpretable and efficient framework for spectral feature analysis and fault characterization in axial piston pumps.