Ultrasonic guided wave damage imaging using the time difference coefficient between direct and scattered waves

Area of Science:

• Materials Science
• Mechanical Engineering
• Non-destructive Testing

Background:

• Damage imaging using ultrasonic guided waves (UGW) faces challenges due to wave speed uncertainty and dispersion.
• Accurate detection and localization of damage are critical for structural health monitoring (SHM).

Purpose of the Study:

• To propose and validate a novel UGW damage imaging method based on the time difference coefficient (TDC).
• To enhance damage imaging by integrating amplitude and instantaneous phase information.
• To assess the performance of the TDC method against existing techniques under various damage scenarios.

Main Methods:

• Developed a TDC method that analyzes an amplitude-phase product signal derived from UGW data.
• Determined wave arrival-time differences using the slope change of peak values in the product signal, independent of wave speed.
• Integrated the TDC with the reconstruction algorithm for probabilistic inspection of damage (RAPID) for imaging.
• Conducted numerical simulations and experimental tests on aluminum plates with through-hole damages.

Main Results:

• The TDC method achieved a localization error of less than 3.54 mm.
• Outperformed conventional methods like signal difference coefficient (SDC), energy damage index (EDI), and root mean square error (RMSE) in accuracy.
• Demonstrated improved tolerance to moderate dispersion and boundary reflections.

Conclusions:

• The proposed TDC method offers superior damage localization accuracy for UGW-based SHM.
• The method provides a practical and robust tool for detecting and imaging damage in structures.
• It effectively addresses challenges posed by wave speed uncertainty and signal dispersion.