Multiscale thermo-mechanical fracture analysis of polycrystalline silicon shells in photovoltaic modules by a combined phasefield – continuum damage approach.

全球日益增长的能源需求、生态优势和经济效益是光伏组件应用的三大看点。占主导地位的光伏组件技术是基于多晶硅的。构成光伏组件的多晶硅晶片(PSWs)的脆性断裂严重降低了光伏组件的电效率。因此，设计稳健的光伏组件不可避免地需要对光伏组件中的损伤事件进行彻底的调查。本项目的目标是在光伏组件的局部尺度和全球尺度上开发一个高效而准确的热或机械载荷对光伏组件造成的损伤模型。为此，提出了一种由局域尺度上的相场模型和全局尺度上的连续损伤方法组成的组合方法。该项目的基本方面是：(I)开发一种考虑PSWs各向异性的新的脆性断裂相场模型，(Ii)开发一种计算程序来研究由生产过程(共烧、压平和焊接)引发的PSWs中的残余应力，(Iii)基于几何非线性理论开发用于各向异性相场模型的连续壳体单元，(4)开发由PSW和密封剂组成的PSW的结构单元(V)通过实验分析验证纯机械模型(Vi)在相场中实施热-机械耦合和连续介质损伤模型(Vii)通过文献中的基准问题进行验证。这些步骤将在ISD和IAM之间的密切合作下根据双方针对手头问题的专门知识和经验进行。

The increasing global energy demand, ecological advantages and the economical benefits are three major points for the application of photovoltaic(PV)-modules. The dominating PV-module technology is based on polycrystalline silicon. Brittle fracture of polycrystalline Siliconwafers (PSWs), making up the PV-module, significantly degrades the electrical efficiency. Design of robust PV-Modules, therefore, inevitably requires a thorough investigation of damage events in PSWs.The objective of the present project is the development of an efficient and accurate model of damage induced by thermal or mechanical loads on the PV-module, both at the local scale of the PSW and the global scale of the PV. For this purpose a combined approach consisting of phasefield models on the local scale and a continuum damage approach on the global scale are persued. Essential aspects of the project are: (i) development of a novel phase-field model for brittle fracture accounting for the anisotropy in PSWs, (ii) developing a computational procedure to investigate the residual stresses in PSWs initiated from the production processes (cofiring, flattening, and soldering), (iii) developing a continuum-shell-element for the anisotropic phase-field model based on the geometrically nonlinear theory, (iv) development of a structural element for a PSW comprising of the PSW and the encapsulant (v) validation of the purely mechanical model by experimental analysis (vi) implementation of the thermo-mechanical coupling in the phasefield and continuum damage models (vii) verification by benchmark problems from the literature.These steps will be conducted within a close collaboration between ISD and IAM based on the expertise and experience of each side for the problem at hand.