Analysis for propagation characteristics of longitudinal mode and torsional mode guided waves in rod
Regarding the application of guided waves in one-dimensional structure, the propagation characteristics of the longitudinal guided wave and torsional guided wave are investigated. The dispersion equations of guided wave in the longitudinal and torsional modes in one-dimensional component are derived. Through programming numerical calculation in MATLAB, the frequency dispersion curves of the two modes are obtained, which imply that the engineering application of guided waves in detection of rod needs to choose an appropriate frequency and the corresponding propagation characteristics of the waves should be combined to get reliable results. The dispersion characteristics analysis results in different radius of rods show that it is feasible for detecting the defects in rod using L(0,1) mode of ultrasonic guided waves.
Application of Ultrasonic Guided Waves in Pipe′s NDT
The recent research advances in the application of ultrasonic guided waves for pipe′s nondestruvtice detection are briefly reviewed. Emphasis is given to the ultrasonic guided wave technology and modal acoustic emission technology, including the propagation characteristic of guided waves, the method of experiment and numerical simulation etc.
Robust solutions of inverse problems in electromagnetic non-destructive evaluation
Non-destructive testing (NDT) is the application of physical measurement technology based on energy interaction with the material and its nonconformities. The material's response is sensed by transducers and sensors which?in most cases?scan the component and document the results in inspection images. However, NDT measures a physically defined quantity or even an intrinsic property. The difference between non-destructive evaluation (NDE) and NDT is in the interpretation of the inspection data. NDE has to discuss the inspection results in terms of quality elements and characteristics which are relevant to describe the fitness of the material for use. In the case of macroscopic defects these are the kind of defect (cracklike, globular) and its size and orientation to the main stress directions; in the case of material property determination the parameters are mainly mechanical properties. Therefore, in NDE one has to solve inverse problems. The solution of inverse problems based on mathematical procedures such as integral equations is a strong developing discipline and most of the articles prepared for this special issue of the journal have the objective of discussing the latest state of the art in that field. However, practical NDE needs robust and quick solutions which are to be applied mainly online. Therefore, we present here inversion procedures based on multiple linear regression algorithms applied to inspection data. We describe the calibration procedure to fit the free parameters of the model functions and give examples of practical applications in industry.