Dynamic Analysis of Cracked Rotor Systems

The dynamic analysis of cracked rotor systems addresses the complex interplay between rotating shafts and fatigue‐induced defects that may compromise safety and performance in power plants, aerospace engines and industrial machinery. Central to this field is the modelling of breathing cracks — transverse faults that open and close as the shaft rotates — which give rise to nonlinear stiffness variations and characteristic vibration signatures. Investigations over recent decades have combined analytical models, numerical simulations and laboratory experiments to capture phenomena such as subcritical and superharmonic resonances, nodal diameter shifts in whirl orbits and energy exchanges between bending and torsional modes. Advanced signal‐processing techniques, including Fourier, wavelet and Hilbert–Huang transforms, have been employed to isolate crack‐induced sidebands and harmonic components under variable speed and load conditions. Numerical methods based on finite element analysis and surrogate modelling have enabled parameter studies of crack depth, location and orientation, while adaptive filtering and parameter estimation algorithms have supported real‐time condition monitoring. The integration of machine learning and data‐driven classifier schemes now offers enhanced fault discrimination between cracks, unbalance and misalignment. Collectively, these approaches underpin robust health‐management strategies in the context of Industry 4.0, facilitating predictive maintenance, minimisation of unscheduled downtime and extension of component lifetimes.

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Dynamic Analysis of Cracked Rotor Systems publication trend

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Technical terms

Breathing crack: A transverse crack whose opening and closing during shaft rotation induces time‐varying stiffness and nonlinear vibration responses.

Whirl orbit: The orbital trajectory traced by the shaft’s centre or a rotor disc in the transverse plane under dynamic excitation.

Subharmonic resonance: A resonant condition occurring at a fractional multiple (e.g. 1/2, 1/3) of the rotor’s natural frequency, often amplified by crack‐induced nonlinearity.

Torsional stiffness: The resistance of a shaft to twisting deformation, which decreases in the presence of a propagating crack.

Finite element analysis: A computational technique that divides the rotor structure into discrete elements to approximate stress, deformation and dynamic behaviour under operational loads.

References

1. On modeling and damage detection methodologies in rotor systems. Nonlinear Dynamics (2024).
2. Crack Monitoring in Rotating Shaft Using Rotational Speed Sensor-Based Torsional Stiffness Estimation with Adaptive Extended Kalman Filters. Sensors (2023).
3. Experimental Dynamic Analysis of a Breathing Cracked Rotor. Chinese Journal of Mechanical Engineering (2017).