Failure analysis of auxiliary support bearing/shaft tribopair in seawater hydraulic axial piston pump

•Improper radius fitting clearance in auxiliary support bearing tribopair leads to damage of SHAPP.•A parameterized numerical model based on nonlinear dynamic theory to analyze dynamic characteristics.•Optimal radius fitting clearance for auxiliary support bearing is determined.•Nonlinear shaft centerline orbit of auxiliary support bearing in SHAPP operation is analyzed.