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Dynamic Modeling of Macro-Fiber Composite Transducers integrated into Composite Structures[edit]

Author: ZhongZhe Dong

Disertační práce 2019

Composite structures have been already widely applied in engineering. Laminated composites using isotropic or anisotropic layers provide numerous options for designing lightweight structural components, that have high static stiffness and excellent impact resistance for automotive and aerospace products. However, lightweight structures can be susceptible to external disturbances due to the mass reduction and light damping in many cases. As a result, unwanted vibrations and noise can easily occur on these structures. Smart structures that use multifunctional materials as actuators/sensors spurred considerable research, aiming at reducing the noise and vibrations. Macro-fiber composite (MFC) piezoelectric transducers are an attractive choice in engineering because of their flexibility, reliability, and high-performance comparing to other types of transducers. Comprehensive design of composite structures with integrated MFC transducers is essential for appropriate deploying control systems in noise and vibrations control. Finite Element Modeling (FEM) methods are commonly used for modeling piezoelectric systems such kind of model always needs to be reduced for dynamic applications. For example, MFC transducers can be used in vibroacoustic systems for noise and vibrations control. Reducing the piezoelectric vibro-acoustic system model can be challenging because the controller design and real-time simulations require stable low-order models. Conventional model order reduction techniques, such as the Krylov subspace projection and the balanced truncation, project the system model into an equivalent vector space. Many important physical parameters are not preserved by the reduced-order model. As a result, it is also challenging to determine the optimal placement and piezoelectric fibrous orientation of MFC transducers on a host structure with the consideration of their mechanical influences. There is no practical approach yet for these purposes in the literature. In this dissertation, laminated composite plates with spatially distributed rectangular MFC transducers are studied. Equivalent Substructure Modeling (ESM) approach is developed to generate stable structure-preserving low-order system models of piezoelectric composite structures.We proposed equivalent forces as a new solution to characterize the inverse piezoelectric effect of the integrated transducer. The corresponding direct piezoelectric effect is also derived. The analytical piezoelectric couplings are introduced into an equivalent substructuring process for modeling piezoelectric systems. Experiments verified the validation of the ESM approach. Two kinds of study cases are given to demonstrate the odds of the ESM approach for evaluating the placement and piezoelectric fibrous orientation of a MFC transducer on a non-homogeneous composite plate. The vibro-acoustic study of composite plates with integrated MFC transducer is carried out. The ESM approach is used to generate a low-order stable model, and validated by experimental data. The piezoelectric reciprocal relations in a vibro-acoustic field are defined. The work enables MFC transducers to expand their application in vibro-acoustics.