Damage detection in composite materials using Lamb wave methods

TLDR

Cost‑effective and reliable damage detection is critical for composite materials, and Lamb wave methods—capable of long‑distance travel with low‑power piezoelectric actuators and sensors—are promising for structural health monitoring. This paper presents part of an experimental and analytical survey of candidate methods for in situ damage detection of composite materials. The study performed linear Lamb wave scans on narrow laminated specimens and sandwich beams with various cores, monitoring transmitted waves with piezoceramic sensors, and optimized actuator/sensor configurations and driving signals through experimentation. Experimental results on quasi‑isotropic graphite/epoxy specimens with delamination, transverse ply cracks, and through‑holes show that Lamb wave techniques provide more information about damage presence and severity than frequency‑response methods, enable accurate time‑of‑flight determination, and allow damage location estimation due to their local response.

Abstract

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasi-isotropic graphite/epoxy test specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Linear wave scans were performed on narrow laminated specimens and sandwich beams with various cores by monitoring the transmitted waves with piezoceramic sensors. Optimal actuator and sensor configurations were devised through experimentation, and various types of driving signal were explored. These experiments provided a procedure capable of easily and accurately determining the time of flight of a Lamb wave pulse between an actuator and sensor. Lamb wave techniques provide more information about damage presence and severity than previously tested methods (frequency response techniques), and provide the possibility of determining damage location due to their local response nature. These methods may prove suitable for structural health monitoring applications since they travel long distances and can be applied with conformable piezoelectric actuators and sensors that require little power.