# Dynamic Modeling and Analysis of Rotary Joints with Coupled Bearing Tilt-Misalignment Faults

## TL;DR

This paper develops a detailed model to study how tilt and misalignment faults in rotary joints affect their dynamic behavior and vibration patterns.

## Contribution

A high-fidelity nonlinear dynamic model for dual-support bearing–rotor systems with tilt-misalignment faults is proposed and validated experimentally.

## Key findings

- Tilt angles and misalignment magnitude significantly influence contact forces and vibration patterns.
- The model shows nonlinear increases in vibration amplitudes with higher misalignment.
- Fault characteristic frequencies and spectral modulation effects are effectively captured by the model.

## Abstract

This study systematically analyzes the dynamic behavior of bearing tilt-misalignment coupling faults in rotary joints and establishes a high-fidelity nonlinear dynamic model for a dual-support bearing–rotor system. By integrating Hertzian contact theory, the nonlinear contact forces induced by the tilt of the inner/outer rings and axial misalignment are considered, and expressions for bearing forces incorporating time-varying stiffness and radial clearance are derived. The system’s vibration response is solved using the Newmark-β numerical integration method. This study reveals the influence of tilt angle and misalignment magnitude on contact forces, vibration patterns, and fault characteristic frequencies, demonstrating that the system exhibits multi-frequency harmonic characteristics under misalignment conditions, with vibration amplitudes increasing nonlinearly with the degree of misalignment. Furthermore, dynamic models for single-point faults (inner/outer ring) and composite faults are constructed, and Gaussian filtering technology is employed to simulate defect surface roughness, analyzing the modulation effects of faults on spectral characteristics. Experimental validation confirms that the theoretical model effectively captures actual vibration features, providing a theoretical foundation for health monitoring and intelligent diagnosis of rotary joints.