Multiskalenbasierte thermomechanische Bruchanalyse polykristalliner Siliziumschalen in Photovoltaikmodulen durch einen kombinierten Phasenfeld – Kontinuumsschädigungsansatz.
Leichtbau, Textiltechnik
Zusammenfassung der Projektergebnisse
In this project, we discuss and develop an anisotropic extension of the well-established phasefield approach to simulate the orientation dependence of fracture toughness observed in silicon-based solar wafers. While the second-order model can be used for two-fold symmetric materials, cubic symmetric materials necessitates a fourth-order model. Features of the two models are brought about using several numerical studies. The C 1 continuity requirements of the phase-field variable in the higher-order model is addressed using the iso-geometric analysis framework. Experimental results from fracture tests on silicon are presented. Further, the lower-order model is extended to account for the polycrstalline microstructure of solar wafers. Given the typical thicknesses of silicon wafers, a Kirchoff-Love shell theory based phase-field model is discussed. Finally, the thermo-mechanical behavior of thin structures is studied taking thermal loading in to account. In the contribution, the influence of the residual stresses on the damage propagation of PSSCs is studied. A framework is developed for the calculation of the overall material properties of PSSCs by the numerical homogenization approach. The complex geometry of grains in the PSW was created by using Voronoi-tesselation method. The anisotropic nature of the PSW is also considered in the model. Results of numerical homogenization are presented. Stiffness degradation of PSSCs is also calculated by the framework for the crack propagation in PSW. Finally, overall effective material properties for different degrees of homogenization are calculated and are compared with the material properties of heterogeneous PSSCs.
