A Scalable Temperature Compensation Method for Guided Wave Based Structural Health Monitoring of Anisotropic CFRP Structures

Abstract

Minimising the change in guided wave caused by temperature variation rather than occurrence of damage is a key step to reliable damage diagnosis using guided wave based structural health monitoring. To account for the influence of temperature variation on guided wave signals in complex structures, a large amount of baseline measurements need to be collected over a required temperature range to serve as a library. The establishment of baseline library is repeated for each monitored structures, which, if not impossible, is highly impractical. This paper presents a data-driven temperature baseline reconstruction approach that is applicable for various structures made from the same material. The influence of temperature on the amplitude and phase of guided wave measurements are experimentally quantified as dimensionless compensation factors. The derived compensation factors are used for reconstructing baseline signals at various temperatures for guided wave signals. The proposed temperature compensation method is implemented in detecting and localising barely visible impact damage (BVID) in two anisotropic CFRP composite structures, a simple flat plate and a stiffened panel, under different temperature conditions. By compensating the influence of temperature, BVID is successfully detected and located for temperature difference between baseline and current signals up to 25 \(^\circ \)C and \(20\,^\circ \)C, respectively.