Application of synchro spline-kernelled chirplet transformation in nonlinear ultrasonic wave modulation: self-sensing method with temperature protection

Abstract

The purpose of this work is to investigate the synchro spline-kernelled chirplet extracting transformation (SSCET) method for defect detection in the nonlinear ultrasonic wave modulation (NUWM) method. To implement the NUWM method using only one piezoelectric transducer, the self-sensing method is used. Self-sensing has many advantages, but it is sensitive to temperature changes. To reduce the temperature effects, a novel circuit has been designed and implemented. A sandwich beam with bolt loosening and an aluminum beam with boundary loosening damages are used to test the results of the SSCET method on the signal received from the self-sensing circuit. First, an aluminum beam with a loosened boundary is modeled based on beam theory including self-sensing circuits with temperature effects. In this study, SSCET results are compared with those of other time–frequency methods for the detection of the loosened boundary. Based on the temperature effects, the theoretical results are compared with the experimental results of the circuit. To quantify defect detection, a damage index calculated based on instantaneous frequency is provided. Three piezoelectric configurations are also compared with the self-sensing method damage index results. SSCET is then used to check bolt loosening in a sandwich beam for further investigation. The proposed method is compared to a previous self-sensing temperature compensation method. Based on the SSCET method, the severity of the bolt loosening is determined.