SBIR Phase II: Direct Micromechanical Simulations for Damage Accumulation in Composite Materials

*穆勒9408572这个小型企业创新研究第二阶段项目解决了对一种技术的需求：一种广泛的分析工具，可以基于潜在的微结构缺陷和多轴载荷下微结构状态的演变来评估复合材料的变形、断裂、损伤累积和失效。第二阶段的工作将扩展MISTRA的现有能力，这是一种基于Windows的有限元分析代码，专门为微结构分析而设计，由Quest开发。Mstra允许用户轻松构建微观单胞几何结构，将材料属性分配给相，并对复合材料的标准力学测试进行有限元模拟，以评估宏观性能(如各向异性刚度和屈服)和微观特征(如残余应力)。在第一阶段，基于临界应变能释放率的断裂力学原理，通过允许裂纹在微观几何中扩展，引入了损伤和破坏的概念。此外，还开发了一种从显微照片生成非结构化网格的方法。在第二阶段，将进一步开发二维和三维模拟，以及图形用户界面，以允许用户快速构建微结构网格，执行微观机械模拟，并将结果可视化。这些细观力学模拟建立了微损伤累积的演化与块体复合材料承载能力丧失之间的关系。这种创新的方法将使设计工程师能够直接确定微观材料设计和加工对整个复合材料结构最终设计的影响。这种新的分析工具的潜在商业应用范围从关键的国防相关成分分析到地球科学的基础研究，再到娱乐用途的产品评估。预计该软件将作为一种工具向大学、企业和政府机构销售，以评估先进的复合材料，并在要求高刚度/重量比、低热膨胀、尺寸稳定性以及耐磨性和抗断性的关键部件应用中加快对新材料的接受。复合材料；损伤；有限元分析；非线性细观力学；陶瓷

*** Mueller 9408572 This Small Business Innovation Research Phase II project addresses the need for "bridging" a technology: a broad analytical tool to evaluate composite material deformation, fracture, damage accumulation, and failure based on the underlying microstructural defects and the evolution of the microstructural state under multiaxial loading. Phase II work will expand on the current capabilities of MISTRA, a Windows-based finite element analysis code designed specifically for microstructural analysis and developed at QUEST. MISTRA allows the user to easily construct a microscopic unit cell geometry, assign material properties to the phases, and conduct finite element simulations of standard mechanical tests of the composite material to evaluate macroscopic properties such as anisotropic stiffness and yielding and microscopic features such as residual stresses. In Phase I, the notion of damage and failure was introduced by allowing cracks to grow in the microscopic geometry based on the fracture mechanics principle of critical strain energy release rate. Also, a means to generate unstructured grids from photomicrographs was developed. During Phase II, further development of the simulations in both two and three dimensions will be developed, as will the graphical user interface to allow the user to quickly construct the microstructural grids, perform the micromechanical simulations, and visualize the results. These micromechanical simulations establish a relationship between the evolution of the microdamage accumulation and the loss of load-carrying capability of the bulk composite material. This innovative approach would allow the design engineer to directly ascertain the effects of the microscopic material design and processing on the ultimate design of the composite structure as a whole. Potential commercial applications of this new analysis tool range from critical defense-related component analysis to fundamental research in earth sciences to the evaluation of prod ucts for recreational use. It is expected that this software will be marketed to universities, corporations, and government agencies as a tool to evaluate advanced composite materials and to speed the acceptance of new materials in critical component applications require high stiffness/weight ratios, low thermal expansion, dimensional stability, and abrasion and fracture resistance. Keywords Composite materials, Damage, Finite element analysis, Nonlinear micromechanics, Ceramics ***