Fundamental Study on Application-Phase Numerical Prediction Method for Dynamic Fracture Propagation Paths

本课题主要开展以下基础性研究：(1)动态裂缝路径预测应用阶段模拟方法的开发；(2)动态分支裂缝路径预测方法的开发。这些研究是通过使用实验，理论和计算力学方法在统一的方式进行的。通过这些研究，获得了动态断裂现象的基本信息和数据。进一步阐明了动态断裂现象的一些机理。本项目主要研究成果如下：1.研究成果。实验研究：(1)阐明了动态分支断裂的控制条件(2)发展了跨声速界面断裂的焦散理论(3)发展了各种智能混合测量方法，自动检测和消除了实验测量误差(4)发展了最小相关系数搜索方法的全场测量图像相关方法(5)阐明了动态分支断裂与动态分支断裂之间的相关性动态裂纹尖端能量通量和断口表面粗糙度(6)裂纹尖端跨声速扩展的应力奇点场因子和奇点阶的测量2。理论研究(1)动态界面断裂统一渐近解的推导(2)动态分支裂纹路径无关动态J积分的切换方法的发展(3)压电材料动态J积分的推导(4)压电材料裂纹尖端渐近近场解的推导(5)建立了提取力学混合模应力强度因子和电场的分量分离方法位移强度因子。(6)推导了裂纹生长问题的变分原理。计算力学研究：(1)基于Delaunay自动网格生成的各种运动有限元方法的发展(2)动态分支断裂数值路径预测模拟的成功(3)恒定裂纹加速度下动态断裂现象的应用阶段模拟的成功(4)自然和动态扩展的裂纹前沿的动态J积分和应力强度因子的评估(5)非线性动力学的发展裂缝面接触跨声速界面裂缝模拟方法的发展三维动态裂缝前缘形成机制的阐明上述研究成果包含了许多重要内容，本课题的研究成果有望为动态断裂力学的发展做出贡献。鉴于目前及相关成就，现颁发以下奖项：(1) JSME材料与力学成就奖，(2)JSME最佳论文奖，(3)JSME计算力学成就奖，(4)JSME影响部成就奖，(5)SEM合天益奖

In this research project, fundamental studies were carried out mainly for the following items : (1) development of application-phase simulation methodology for dynamic fracture path prediction, and (2) development of dynamic branching fracture path prediction methodology. These studies were performed by using experimental, theoretical and computational mechanics approaches in a unified fashion. Through these investigations, fundamental information and data on dynamic fracture phenomena were acquired. Furthermore, some mechanisms of dynamic fracture phenomena were clarified. The major research results of this project are listed as follows :1. Experimental Studies :(1) Elucidation of the governing condition for dynamic branching fracture(2) Development of the theory of caustics for transonic interfacial fracture(3) Developments of various intelligent hybrid measurement methods automatically detecting and eliminating experimental measurement erros(4) Development of the minimum correlation … More coefficient searching method for full-field measurement image correlation method(5) elucidation of correlation between the dynamic crack-tip energy flux and fracture surface coarseness(6) Measurements of the stress singularity field factor and the singularity order for transonically propagating crack tips2. Theoretical Studies(1) Derivation of a unified asymptotic solution for dynamic interfacial fracture(2) Development of the switching method of the path independent dynamic J integral for dynamically branched cracks(3) Derivation of the dynamic J integral for piezoelectric materials(4) Derivation of the asymptotic crack tip near field solution for piezoelectric materials(5) Development of the component separation method for extracting mechanical mixed-mode stress intensity factors and the electric displacement intensity factor.(6) Derivation of the variational principle for carack growth problems3. Computational Mechanics Studies :(1) Developments of various moving finite element methods based on Delaunay automatic mesh generation(2) Success of numerical path perediction simulations of dynamnic branching fracture(3) Success of the application-phase simulations of dynamic fracture phenomena under constant crack acceleration(4) Evaluation of the dynamic J integrals and the stress intensity factors for naturally and dynamically propagating crack fronts(5) Development of nonlinear dynamic fracture simulation methodology(6) Development of simulation methodology for transonic interfacial fracture with crack-face contact(7) Elucidation of the formation mechanism of three-dimensional dynamic fracture frontSince the above research results include many important items, the outcomes of this research project can be expected to contribute to the advancement of dynamic fracture mechanics.For the present and related achievements, the following awards have been offered.(1) JSME Materials and Mechanics Achievement Award,(2) The JSME Award for Best Paper,(3) JSME Computational Mechanics Achievement Award,(4) JSMS Impact Division Achievement Award,(5) SEM Hetenyi Award Less