Research Projects

Applications of smart materials in day to day life motivate the scientist and engineers to work in the direction of enhancing the life and reliability of the smart structures/equipment. One of the reasons for failure of these materials may be due to the presence of voids/holes/cracks which may occur at the time of fabrication of these structures. Therefore, fracture analysis of these materials is essential to know about the exact reasons for these failures. In piezoelectric/MEE materials, nonlinear fracture models such as PS/EMPS and DB/EMDB models were proposed as the studies presented on the basis of linear fracture mechanics theory were not found in agreement with the experimental findings subject to the applied electrical loadings. A new fracture parameter, local energy release rate, was defined in these models whose behaviour with respect to the applied loadings is found in agreement with the experimental results. In literature, most of the problems based on nonlinear fracture models (PS/EMPS, DB/EMDB) were discussed on infinite domains. But in practical situations, the cracks are of the order of the dimensions of the geometry. Therefore, the study of cracks on a finite domain is required and for it one has to apply a numerical technique. Considering the significant computational advantage of XFEM over the other existing numerical techniques, it is proposed here to study the cracks problems in these materials based on the PS/EMPS model. XFEM is a fast developing numerical technique for studying various kinds of engineering/fracture mechanics problems and is now available in many of the software packages. But the fracture analysis of smart materials using XFEM is still not available in these packages. Additionally, few papers are available on the semipermeable cracks problems in piezoelectric/MEE materials using XFEM. It is mainly due to the complexity of evaluation of crack-face electric displacement or/and electric induction conditions and their implementation in the framework of XFEM. The approach of applying the crack-face conditions reported in these papers is mathematically incorrect as they applied these conditions on the split nodes and not on the actual crack-surfaces. Further, their approach could not be able to provide the correct solution for an arbitrary inclined crack as in that case the split nodes are not symmetrically placed above and below the crack. In this work, the PI has proposed the implementation of the crack-face conditions using 1-D dummy elements along the crack path for evaluating the line integral present in the variational formulation of the problem. With modified enrichment strategy for the PS/EMPS models in XFEM and the above proposed approach for implementing the crack-face conditions, the nonlinear fracture models (PS/EMPS) in piezoelectric/MEE materials can be studied using XFEM.