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CivilComp Proceedings
ISSN 17593433 CCP: 88
PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis
Paper 36
Mesh Generation for Cavity Damage Identification in Piezoelectrics R. Palma^{1}, G. Rus^{1}, J.L. PérezAparicio^{2} and R. Gallego^{1}
^{1}Structural Mechanics & Hydraulic Engineering, University of Granada, Spain
, "Mesh Generation for Cavity Damage Identification in Piezoelectrics", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", CivilComp Press, Stirlingshire, UK, Paper 36, 2008. doi:10.4203/ccp.88.36
Keywords: piezoelectric, finite element method, inverse problem, genetic algorithms, medial axis, transfinite interpolation, stretching function.
Summary
The presence of defects in piezoelectric ceramics prevents the material from executing the function for which was designed. In this work, a modelbased inverse problem to find defects in a piezoelectric PZT4 quadrilateral plate has been developed combining the finite element method (FEM) and genetic algorithms. The modelbased inverse problem can be stated as a minimization problem where each solution is generated by computing a cost functional for which one forward problem is evaluated using the FEM. For this approach there are two problems: i) the genetic algorithm used to solve the optimization problem implies a large number of evaluations. However, the use of gradientbased algorithms is limited to local optimization, while the genetic algorithm permits a global optimization to be attained. On the other hand, ii) strong concentrations of the electric field and stresses around the defect arise for piezoelectric materials with a defect, as it has been reported in the literature. Note that, these concentrations are greater than for elastic materials without coupling.
Therefore, the main goal of this work is draw quality meshes to solve the forward problem using the FEM. To this end, a fully automatic algorithm has been developed to construct multiblock structured meshes in two dimensions that provide good results in a reduced CPU time. The algorithm follows three steps: i) to subdivide the domain into simple blocks, using the medial axis transform, ii) to mesh each block, by a simple transfinite interpolation, and iii) to concentrate elements next to the defect, using an special stretching function to determine strain, electrical and stress concentrations around the defect in piezoelectric ceramics. Finally, some results of the modelbased IP solution are shown, concluding that it is possible to characterize the defect with an error of less than 5 times the error in the measurements when a mechanical load transversal to the poling direction is applied. purchase the fulltext of this paper (price £20)
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