The effect of damage on wave propagation in plates with circular piezoelectric transducers

• Ano de defesa: 2023
• Autor(a) principal: Lopes, Kayc Wayhs
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Wave propagation; Structural health monitoring; Symmetric damage; Circular piezoelectric transducers; Optimal frequencies; Propagação de ondas; Monitoramento da integridade estrutural; Dano simétrico; Transdutores piezoelétricos circulares; Frequências ótimas
• Link de acesso: https://hdl.handle.net/11449/253116

Damage detection using Structural Health Monitoring (SHM) techniques is a challenge with increasing importance for the scientific community. SHM processes usually involve selecting actuators to excite the structure and sensors to measure outputs. The sensor outputs are post-processed to detect the damage. Usually, aspects such as the size and location of the actuators and sensors, and the choice of the excitation frequency are neglected in SHM campaigns, and they are very relevant to many damage detection algorithms. This thesis presents an approach to define the sensor's size in terms of its position in the structure considering the scattering of longitudinal and flexural waves in damaged plate-like structures. Modeling is developed to compute each wave packet of reflected and transmitted waves separately, which allows one to describe the wave scattering in thin plates with symmetric damage. Numerical simulations are carried out and the results show that the sensor size can be adjusted to improve the damage detection process. Results from experimental tests are presented to demonstrate the approach considering circular actuators. A damage index R is introduced and used to detect the damage. The modeling of circular piezoelectric transducers bonded to thin plates is also presented, and it demonstrates that there are optimal frequencies to create and measure these waves. In addition, new equations to compute the sensors' output voltages in terms of the actuator input voltage applied are presented and demonstrated from experimental tests. The findings contribute to SHM systems based on longitudinal and flexural wave propagation to detect damage in plate-like structures. They contribute to the current state of the art in wave propagation SHM by investigating the effects of different excitation frequencies and the influence of the damage parameters and sensor sizing on the resulting waves.