Application of Modal Analysis for Health Monitoring of Wind Turbine Blade

Articles in Press

Document Type : Article

Authors

1 Mechanical Engineering Department , Abadan Faculty. Petroleum University of Technology

2 Mechanical Engineering Department, Abadan Faculty, Petroleum University of Technology

3 Mechanical Engineering Department , Abadan Faculty, Petroleum University Technology

10.24200/j40.2025.67449.1745

Abstract

Health monitoring of rotating machinery is a critical engineering task that involves the measurement, recording, analysis, and evaluation of key parameters affecting machine behavior and performance over time. This process aims to assess the current condition and predict future behavior of mechanical systems to prevent sudden failures and optimize maintenance schedules. Among rotating components, the structural integrity of wind turbine blades is especially important, as damage can lead to costly downtimes or even catastrophic failures.

Since the modal or resonant properties of a mechanical structure are directly influenced by its physical characteristics—such as stiffness, mass, and boundary conditions—any alteration caused by damage, like a crack, can lead to detectable changes in modal parameters. Therefore, by continuously monitoring the system and analyzing changes in these parameters, it becomes possible to detect structural degradation at an early stage.

This study focuses on structural health monitoring (SHM) of a composite wind turbine blade using principles from fracture mechanics and vibration-based modal analysis. The numerical investigation is carried out by tracking the variations in natural frequencies as a crack initiates and propagates along the blade. Results indicate that the reduction in natural frequencies becomes more pronounced beyond a certain crack depth, enabling the identification of a critical threshold for maintenance intervention. Furthermore, it is observed that increasing the distance between the crack and the clamped root of the blade leads to a higher critical depth and more stable frequency behavior. For example, a crack located near the root with a depth of 250 mm results in about a 6% decrease in the first mode frequency, while a crack near the tip with a depth of 350 mm leads to over 20% reduction in the fourth mode, which is torsional and structurally critical.

If resonance occurs in specific modes, the approximate location of the crack can be estimated based on the observed frequency. These findings confirm the effectiveness of SHM techniques for real-time damage detection and localization in composite blade structures.

Keywords

Main Subjects

Sharif Journal of Mechanical Engineering

Articles in Press, Accepted Manuscript
Available Online from 04 October 2025

Files

Share

How to cite

Statistics