Modeling and Simulation of the Dynamic Behavior of Multilayered Piezoelectric Fibers in Smart Structures

• Author / Creator

  Abdel-Gawad, Shadi

• The concept of using piezoelectric actuators and sensors to identify damages in advanced structural systems has drawn considerable interest among the research community due to its importance in preventing catastrophic failures. Recent progress in piezoelectric technologies and manufacturing has made it possible to manufacture smart multilayered multifunctional piezoelectric fibers. When these fibers are used in the health monitoring of smart structures, they are generally under dynamic loads. However, the modeling and simulation of these fibers is even more complicated by the fact that they are generally characterized by electromechanical coupling, anisotropy in the transverse plane, and the possible bonding imperfection between their layers. With this in mind, the current research program was undertaken to investigate the dynamic behavior of multiple multilayered piezoelectric fibers in smart structure applications. Four aspects of the work were accordingly examined. The first is the development of an analytical model of the anisotropic layer in the multilayered piezoelectric fiber, which is capable of predicting stress variations in the anisotropic layer, under dynamic loads. The model is necessary for determining the overall behavior of a layered anisotropic piezoelectric fiber. The analytical formulation is based on the use of Fourier expansion and the separation of variables to reduce the original problem to a set of linear equations in terms of Bessel functions. The resulting set of linear equations are normalized to reduce the numerical ill-conditioning then solved for different boundary conditions. The significance of this newly developed model is manifested by its versatility and application with different material combination, loading frequencies and geometry.The second is extending and applying the developed anisotropic layer model to analyze the performance of the electromechanical behavior of a multilayered piezoelectric fiber as an actuator or a sensor. The analytical formulation is based on the use of a newly developed piezoelectric layer model with a transfer matrix representation, which can represent multiple layers including imperfectly bonded layers. The third is concerned with the development of a general method for the interaction between multilayered piezoelectric fibers and other scatterers. The theoretical formulations are based upon the consistent use of the superposition procedure and cylindrical function coordinate transformations using Graf’s theorem. This reduces the original interaction problem to the solution of a set of a single multilayered piezoelectric fiber and embedded scatterer problems. By using this single multilayered piezoelectric fiber solution as the building block, this method provides a general approach to deal with interactions involving complex boundary/interfacial conditions. The fourth is concerned with the numerical simulation of applying the developed models for the identification of multiple damages using both global and local optimization algorithms. This problem is formulated as an inverse problem which uses optimization techniques to minimize the error between the observed voltage readings induced by damages from a numerical experiment and the calculated voltage predictions induced by trial damages from theoretical simulations on an array of sensors. The models and techniques developed previously are applied to determine the size and location of damages using a newly developed optimization algorithm. The algorithm converges faster than conventional algorithms for single and multiple damages with two types of damages investigated: a circular void and a curved crack.The methods proposed in this thesis can be used to understand the dynamic behavior of multiple multilayered piezoelectric fibers interacting with damages for the general design of smart structures and the applications of smart structural health monitoring.

• Subjects / Keywords

  • Inverse Dynamics
  • Piezoelectric Modeling
  • Smart Structures
  • Damage Identification
  • Structural Health Monitoring
  • Computational Solid Mechanics
  • Inverse Elastodynamics
  • Coupled Field
  • Elastic Waves

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R31C1TX7R

• License

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