Asynchronous partial contact motion due to internal resonance in multiple degree-of-freedom rotordynamics

Area of Science:

• Mechanical Engineering
• Vibrational Dynamics
• Nonlinear Dynamics

Background:

• Rotor-stator contact in rotational machines can cause sudden, damaging chattering or whirling motion.
• Understanding the onset and behavior of partial contact is crucial for industrial applications.

Purpose of the Study:

• To investigate the role of internal resonance in initiating bouncing-type partial contact motion.
• To analyze the characteristics of these partial contact limit cycles in multi-degree-of-freedom systems.

Main Methods:

• Development of a synchronization formula to predict drivespeeds for mode-locked bouncing orbits.
• Brute-force bifurcation analysis to numerically confirm the existence of bouncing orbits.
• Investigation of the influence of stator stiffness and damping on solution behavior.

Main Results:

• Internal resonance can lead to bouncing-type partial contact motion away from primary resonances.
• A synchronization condition predicts multiple drivespeeds for different mode-locked bouncing orbits.
• Low damping facilitates the existence of these orbits, leading to multi-stability and potential chaos through secondary bifurcations.
• Stator stiffness and damping significantly impact the number and nature of partial contact solutions.

Conclusions:

• Internal resonance is a key mechanism for initiating damaging rotor-stator contact.
• The system exhibits complex multi-stability and sensitivity to parameters like stator stiffness and damping.
• Findings provide insights into predicting and mitigating chaotic vibrations in rotating machinery.