Modal Analysis of Rotor Disc

Abstract

Rotor discs are critical elements in rotating machinery, directly influencing both operational performance and structural reliability. During service, these components are subjected to dynamic loads, centrifugal forces, and gyroscopic effects, which make them highly prone to vibrations. If left unaddressed, such vibrations can lead to fatigue failure, increased noise levels, reduced efficiency, and even catastrophic breakdowns. Modal analysis serves as an essential tool in understanding the vibrational behaviour of rotor discs by determining their natural frequencies and associated mode shapes. By identifying these parameters, engineers can effectively design systems to avoid resonance conditions, thereby enhancing durability and ensuring safe operation. The present study aims to perform a comprehensive modal analysis of a rotor disc using simulation techniques to evaluate its dynamic response under rotating conditions. The inner edge of the disc is constrained to replicate realistic boundary conditions, and the impact of rotational speed is considered. The analysis focuses on calculating natural frequencies, studying mode shapes, and observing the total and directional deformations corresponding to various modes. Based on the findings, strategies are proposed to optimize the rotor design for improved vibration resistance and overall performance. This work highlights the importance of modal analysis in predictive maintenance, fault diagnosis, and the development of more robust rotating machinery systems.

Introduction

Rotor discs are critical components in rotating machinery such as turbines and generators, subject to complex stresses that can cause harmful vibrations leading to wear or failure. Understanding their dynamic behavior is essential for safe and efficient operation. This study performs a detailed modal analysis of a rotor disc using finite element methods in ANSYS Workbench.

The rotor disc is modeled with realistic geometry and material properties, meshed carefully, and boundary conditions simulate the fixed inner edge and rotational speed (100 RPM). Modal analysis extracts natural frequencies and mode shapes to identify critical vibration modes and deformation patterns.

Key calculations determine the disc’s physical properties and fundamental natural frequency. Results show various deformation modes, guiding design improvements to avoid resonance and enhance stability. The study supports development of reliable rotating machinery by providing insights into vibrational behavior under operational conditions.

Conclusion

A modal analysis of the rotor disc was successfully conducted using ANSYS Workbench. The disc, with its inner edge fixed and subjected to a rotational speed of 1000?RPM, exhibited distinct natural frequencies and corresponding mode shapes. Understanding these vibrational patterns is crucial for preventing resonance and ensuring the mechanical stability of the system. The analysis highlighted how rotational effects such as gyroscopic forces can slightly shift the natural frequencies, underlining the importance of considering operational speeds during the design phase. Total and directional deformation patterns identified critical zones that may require structural reinforcement for improved durability and lifespan. The comparison between stationary and rotating conditions emphasized that neglecting rotational effects could lead to inaccurate predictions of dynamic behavior and potential design failures. Overall, this study reinforces the necessity of conducting early-stage modal analysis to ensure the safe and efficient operation of rotor discs in high-speed machinery. In future work, the investigation can be extended to include the effects of damping, thermal stresses, and harmonic response analysis to provide an even more comprehensive understanding of rotor behavior under real-world conditions.Based on the results, conclusions are drawn regarding the safe operating frequency range for the rotor disc. Design recommendations are made to avoid resonance and improve the mechanical stability and performance of the rotor disc

References

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Copyright

Copyright © 2025 Rajkumar Bhagat, Geetesh Rajurkar, Piyush Shingankar, Nikita Surwase, Shrushti Wakchaure, Siddharth Shimilkar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.