Abstract
This paper presents a combined finite element and model Lamb waves propagation parameters method as a tool for structural health monitoring in composite materials. Modal analysis allows identifying the mode conversions induced by the defects. A simulation combining a lossless finite element approach and Lamb wave propagation parameter for finding natural frequencies and mode shapes of the structures in undamaged and damaged condition is proposed. This analysis is performed on two carbon-fiber-reinforced plastic bars in both undamaged and damaged state, where the two damaged states are (1) having a cut partway through the bar, perpendicular to the long axis of the bar and (2) having a circular hole. The lamb wave propagation parameters are calibrated using the ultrasonic pulse generator test setup. The natural frequencies for the theoretical, finite element and experimental results are compared and close agreement is found between the frequencies obtained experimentally and computationally.
Highlights
Identification of change in natural frequencies and mode shapes of a freely vibrating damaged plate with respect to its undamaged state has traditionally been a popular method for damage identification
Most studies so far have used acoustic emission (AE) descriptors such as counts, amplitude, and energy to characterize the development of damage mechanisms
The basic material property Young’s modulus which is of interest in many manufacturing and research applications can be determined quickly and through computations based on Lamb wave velocities [15–18]
Summary
Identification of change in natural frequencies and mode shapes of a freely vibrating damaged plate with respect to its undamaged state has traditionally been a popular method for damage identification. This method can be very much useful when a combined finite element and acoustic emission (AE) method is used. Descriptor-based AE techniques are relatively easy to perform, they ignore AE waveforms, which carry useful information. Another group of studies were dedicated to the more difficult task of waveform processing of AE signals
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