裂纹区域

The sub-modeling technique of finite element analysis or FEA is studied as an alterative numerical method.

箱形结构中应力集中部位椭圆形表面裂纹区域的名义应力场分布不规则，无法使用现有的解析解和经验公式，有限元子模型法是求解此类问题的途径之一。

The analysis and test results show that the concentration of stresses at the end of fillet welds between the tensile anchor plate and the tensile anchor tube is obvious, and the maximum principal tensile stress occurs in the stress concentration region.

结果表明，锚拉板与锚拉筒之间的连接焊缝下端部应力集中明显，最大主拉应力出现在该区域；在设计疲劳荷载作用下，该结构关键构造细节处均未发现疲劳裂纹，结构疲劳性能满足设计要求。

The multiple cracks and multiple circular holes problem of the particular antiplane regions are studied in the paper by the complex variable function and integral equation method.

利用Fredholm积分方程和复函数方法对断裂力学中的一些特殊反平面区域内的多圆孔、多裂纹问题进行了计算。

The propagation of interface cracks, the chemical reaction and element diffusion at the interface zone has been studied.

研究了此种新型覆层材料硬质覆层和钢基体之间界面裂纹扩展的情况以及在界面区域的化学反应和元素的扩散。

The structure is complex at the joint root of welding pipelines, where exist cold solder joint and cracks.

管道焊缝根部区域结构复杂，是未焊透和裂纹的产生处，反射回波杂乱，是超声波检测的重点也是难点。

The corrosion fatigue crack growth and near-threshold characteristcsof high tensile steel HT60 were investigated by using the compact specimens underexposure to synthetic sea water. The da/dN vs △K_ relation in air may be conser-vetivel estimated for that in sea water. In the high △K region with high stressratio, owing to the acceleration of crack growth promoted by stress-induced dissol-ution, the crack opening stress intensity factor K_ represents only the result ofcrack surface in contact with corrosion products, so as to give an overestimation ofK_ at crack tip.

对高拉力钢HT60的腐蚀疲劳裂纹扩展特性和门槛值区域特性，采用紧凑拉伸试件在人工海水中进行了实验和研究，结果表明：在空气中的da/dN与ΔK_关系可以作为在海水中的da/dN与ΔK关系的一个偏保守的预测；在高应力比的高ΔK区域，由于应力诱起溶解促进了裂纹扩展的加速；该裂纹开口应力强度因子K_仅反映了裂纹表面同腐蚀生成物接触的结果，从而导致了K_在裂纹尖端的偏大的估计结果。

The microfracturing process of Jinping marble specimen in Sichuan province under uniaxial compression is recorded by using the testing scheme. Quantitatively investigated the propagation and coalescent of cracks at meso-scale with digital technology, the basic geometric information of rock microcracks such as area, angle, length, width, perimeter, are obtained from binary images after segmentation. The failure mechanism of specimen under uniaxial compression with the quantitative information is studied from macro/micro scopic perspective. The result shows that during the damage of the specimen the distribution of microcracks in the whole specimen are still subjected to exponential distribution with some microcracks concentrated in certain regions.

应用于四川锦屏大理岩预制裂纹试样中进行单轴压缩破坏全程的数字化试验，对微裂纹的萌生、生长及贯通过程进行数字化定量分析，得到试样在受荷过程中微裂纹的面积、方位角、长度、宽度和周长基本几何数据，从宏细观角度描述了岩石试样单轴压缩过程中的破坏机制，并分析得出试样单轴受压破坏过程中虽然微裂纹在某些区域集中，但在整个试样中微裂纹的统计分布依然是服从某一指数分布的这一结论。

A layer of strip steel was found abrasion-welded to the surface of the spalled fragment and a 0.06mm thin layer of untempered martensitic structure was observed on the surface of the roll just beneath the welded strip.

在剥落块的表面上粘结着带钢，在带钢下的轧辊表面上观察到一层厚度约0.06mm未经回火的马氏体组织，此层下面还有一个具有低硬度的回火马氏体区域，晶间显微裂纹就从此两区域之间发生，然后垂直地向里向外扩展。

The main research tasks and results are as follows:(1) Through comparing the stress intensity factor of compact tension specimen calculated by finite element software with the theoretical value, the feasibility of calculating fracture parameters of crack tip in ABAQUS software was verified.(2) The relationship between the elastic modulus of the material and research scale was studied based on deriving the cohesive stress theory and other relevant theories. And the elastic modulus of the material on meso-scale was determined.(3) Global model and sub-model of the finite element were built in th...e macro-scale, and stress-strain field nearby the crack tip was analyzed, and the results show that the detailed stress-strain in the crack tip could be obtained by using the sub-model technique.(4) In meso-scale, the crack growth model was also established by assuming the crack propagating along the grain boundary, and the detailed stress-strain field in the crack tip was obtained.(5) The effect of crack length on Von Mises stress, and maximum principal stress and strain was analyzed in meso-scale when equivalent KI equals 30MPa.m1/2. And the results show that except for crack tip area, the stress-strain distribution in whole specimen is not affected.

主要完成研究内容和取得成果如下：(1)利用有限元软件计算出紧凑拉伸试样的裂纹尖端应力强度因子KI值，其结果与理论值一致，从而验证了利用ABAQUS计算裂纹尖端相关断裂参量的可行性；(2)在研究内聚应力等相关理论的基础上，推导出了研究尺度与材料弹性模量的近似关系，并确定了介观尺度上的弹性模量；(3)在宏观尺度上建立了全局有限元计算模型和子模型，得到了裂纹尖端应力应变场分布，结果表明利用子模型技术获得比较准确的裂纹尖端应力应变场分布是可行的；(4)在介观尺度上利用平均晶粒尺度的方式建立了裂纹沿晶扩展模型，得到了裂纹尖端断裂过程区的微观应力应变场；(5)当应力强度因子为30MPa.m1/2时，分析了介观尺度上在裂纹沿晶扩展过程中裂纹长度对Mises应力、最大主应力和应变的影响，结果表明，裂纹扩展长度对试样整体应力应变分布影响不大，而对裂纹尖端区域有较大影响；(6)介。。。

The crack is modeled by distributed line spring ,the local compliance matrix of which is determined according to fracture mechanics.

管道的振动用Flügge方程来描述，通过将裂纹模拟为分布的线性弹簧，运用断裂力学理论，得到裂纹区域的局部柔度矩阵，从而建立外力作用处以及裂纹两侧区域的位移和内力的连续性条件对裂纹管道的功率流进行求解。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。