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The concept of smart structures, such as piezoelectric laminates, has received a great deal of attention recently as an alternative to conventional techniques. These advanced structures can be designed to actively react to disturbance forces in order to maintain structural integrity while maintaining, or even improving, the level of performance. Great potential can be found in advanced aerospace structural applications. However, the introduction of smart devices inevitably perturb the local values of the field variables and nucleate damage such as debonding and delamination at the interface of piezoelectric devices and the host structure due to stress concentration. The layerwise characteristics of the laminates make the determination of stress and strain distribution a challenging problem. Conventionally, classical lamination theory has been extended to smart laminated structures which ignores transverse shear effects'3. A higher order theory was proposed and applied by Chattopadhyay et al.4'5 in the analysis oflaminated structures to address transverse shear effects without shear correction factors. The theory proved to be successful in global analysis for thick structures and smart structures. However, it fails to provide continuous distribution of transverse shear stresses. This implies that the theory is not sufficient in predicting local information regarding stress and strain distributions which is critical in the analysis of structural failure. The multifield characteristics of piezoelectric structures make the analysis even more complex, particularly in the presence of thermal effects as dictated by specific missions. A typical environment is represented by a solar flux of 1350W/m2 as vehicles move from shadow to sunlight. Some research in the field of smart structural modeling in the presence of thermal effects has been reported610. However, oneway coupling that only considers the effect of a known field on another field is used in these works. The bi-way coupling between piezoelectric and mechanical fields was included in the hybrid plate theory developed by Mitchell and Reddy3. A coupled thermal-piezoelectric-mechanical (t-p-m) model was developed by Chattopadhyay et al.1113 to address the bi-way coupling issues associated with smart composites under thermal loads. Their work indicates that the effects of bi-way coupling on structural deformation increase with the thickness of piezoelectric device. However, an equivalent single layer approach is used, and therefore the localized interlaminar characteristics cannot be addressed accurately by this theory. The present paper aims at the investigation of interlaminar stress distribution in laminated shell structures using coupled thermal-piezoelectric-mechanical model. The goal is to develop a theory that is capable of providing sufficient accuracy while guaranteeing computational efficiency compared to other layerwise theories. To maintain local accuracy of stress and strain distributions, the trial displacement field is assumed using zigzag functions and C0 continuity through the entire laminate thickness accommodating zigzag in-plane warping and interlaminar transverse shear stress continuity. The continuity conditions of inplane displacement and transverse shear stress fields as well as traction free boundary conditions are applied to reduce the number of primary structural variables. The temperature and electrical fields are assumed using higher order functions. These descriptions can satisfy surface boundary conditions of heat flux and electrical potential. The mathematical model is implemented using finite element technique. The case of cylindrical bending and spherical composite shell structures with piezoelectric patches are investigated. The analysis of stress distributions under electrical and thermoelectrical loading is performed and numerical results are presented.
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