Dynamic modelling of swashplate with local defects in axial piston pump and coupled vibration analysis

Local defects in a swashplate usually occur on the contact surfaces between the slipper and swashplate in an axial piston pump. An in-depth analysis of vibrations of a defective swashplate can be useful for the progress of defect detection approaches for the pump. An improved time-varying displacement excitation model considering the effects of defect sizes and bias angle is proposed to study a swashplate with a local defect based on coupling of a piecewise function. The effects of defect sizes and defect bias angle on the vibrations of a swashplate are analysed. A test rig is constructed to validate the dynamic model. The dynamic model can accurately predict the acceleration pulse waveform caused by the swashplate for parallel and bias defect cases with an error of only 0.98% in the frequency domain. The fault characteristic frequency of the swashplate is seven times the rotational frequency. The excitation peak and duration of the pulse waveform excited by the swashplate are related to the defect size and bias angle. The defect width has a significant effect on the acceleration peaks. This study provides a new method for dynamic simulation of a swashplate with a localised defect in an axial piston pump.