Numerical and Experimental Evaluation of Lamb Wave Dispersion curves in Composite Laminates

Edara, Satyavardhana Rao (2017) Numerical and Experimental Evaluation of Lamb Wave Dispersion curves in Composite Laminates. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Structural health monitoring (SHM) is an emerging research area with lot of application like a ssessment of structural integrity, real time inspection and residual life estimation in critical engineering s tructures. Among the different SHM approaches, the Lamb wave based approach has been used in this work to inspect composite laminates for damage q uantification. The first part of this work is to develop finite element models for study of Lamb wave propagation in isotropic metal and composite plates . Numerical finite element simulation was carried out using different approaches like explicit dynamic , implicit dynamic and co - simulation for understanding the fundamental Lamb wave propagation. Dispersion curves of composite laminate was constructed numerically for the fundamental modes using shell and brick elements. The s econd part of this work was to conduct Lamb wave experiments in composite plates to validate the finite element results. An eight layer quasi isotropic composite with stacki ng sequence of [45/90/ - 45/0]s was fabricated and thin piezoelectric active wafers were bonded to actuate and sense the fundamental Lamb wave modes in different directions. Dispersion curves of the quasi - isotropic laminates were constructed for the fundamental modes experimentally along different directions. Th is study is essential for understanding of the Lamb wave pr opagation in composite laminates and their interaction with defects.

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