Modal Analysis of Rotor System Using Line Body Elements in ANSYS Workbench

Abstract

Rotordynamics deals with the vibration and dynamic behavior of rotating structures and plays a crucial role in the design of high-speed rotating machinery such as turbines, compressors, pumps, and electric motors. Accurate prediction of rotor dynamic characteristics during the design stage is essential to avoid excessive vibration, resonance, and catastrophic failures. The Finite Element Method (FEM) has become one of the most reliable techniques for analyzing rotor-bearing systems. Traditionally, rotor dynamic analyses have been performed using specialized commercial software; however, the continuous advancement of general-purpose finite element software such as ANSYS Workbench has provided an efficient and user-friendly platform for such analyses. This study investigates the applicability of line body (beam) elements in ANSYS Workbench for the dynamic analysis of a rotor system. Unlike three-dimensional solid elements, line body elements significantly reduce computational effort while maintaining satisfactory accuracy for slender rotor shafts. A finite element model of the rotor system is developed using line body elements, and its dynamic characteristics are evaluated through modal, harmonic, and transient analyses. The numerical results are validated with experimental measurements to assess the accuracy and reliability of the proposed modeling approach. The study demonstrates that line body elements in ANSYS Workbench provide an efficient and computationally economical alternative for rotor dynamic analysis without compromising the accuracy of the predicted dynamic response.