ANALYSIS OF WAVE PROPAGATION THROUGH 1-D CRACKED WAVE GUIDES

Abstract

The past decades have been marked by a significant increase in research interest in development of Structural Health Monitoring (SHM) techniques and its application. In this report, descriptions of the basic methodologies of SHM are discussed. Two broad areas of SHM, vibration based SHM and wave based SHM with various linear and non-linear approaches are focused. General introduction of the guided waves with their distinguishing features are included and their superiority over vibration based techniques are reviewed. Previous work extensively focusses on plate with waves travelling at comparatively higher frequencies. While in this report, another structural member, i.e. beam is being considered with waves travelling at lower frequencies. Experimental setup has been developed for lamb wave generation and acquisition. Contact type, Piezoelectric Wafer Transducer (PWT), have been used to generate lamb waves while non-contact sensor, Laser Doppler Vibrometer (LDV), is being used for reducing the error. More emphasis is given on numerical and experimental analysis of lamb waves in an intact beam and their behavior are studied. Thereafter, numerical and experimental study on a cracked beam are performed. The study is compared with validation with respect to data acquired. A detailed comparison is performed between cracked and pristine beams. Multiple modes and their reflection were also identified while analyzing the signal. Identification of loop holes of wave propagation techniques has been discussed at the end.