裂纹

When crack propagation meet with mass with great strength, the direction of crack propagation will deviate from the particle with high strength.

即当裂纹扩展时遇到较强的介质时，裂纹的扩展方向会发生偏转，并绕过强介质继续扩展；较弱的介质和已贯通的裂纹组对其它组裂纹的贯通有屏蔽作用。

In the same way failure area is not single andis more complex with decrease of scale of specimens. And failure shape ismore close to quasi-brittle failure. It varies with homogeneousness that thescale of specimens at which failure shape changes.(3) The failure shape of homogeneous specimens with crack is controlledby crack. But that of heterogeneous specimens with crack is controlled bycrack and heterogeneousness.(4) Acoustic emission doesnt appear until homogeneous specimens fail.

但对于不同均质度，试件破坏形态发生变化的尺度也不同；(3)对于均质度较高的含裂纹试件，试件的破坏形态主要受裂纹控制，而对于均质度较差的含裂纹试件，试件的破坏形态由试件材料的非均匀性和裂纹共同控制；(4)均质度较高的试件，破坏前，试件内不出现声发射，破坏瞬间，声发射在某些部位同时出现，且随尺度增大，试件声发射能量增大，声发射区趋于集中。

According to the stress-strain complete process curve, the total volumetric strains and crack induced 1 volumetric strains is adopted as damage parameters for analyzing the five phases during the crack growth (crack closure , linear elastic, stable crack growth, unstable crack growth and post failure).

通过压缩试验获得的脆性岩石的全应力应变曲线，利用体积变量和裂纹体积变量等损伤变量分析得出裂纹发展的五个阶段即：压密、弹性、微裂纹稳定扩展、裂纹非稳定扩展和峰后失稳等。

Interface crack propagation problems under the influence of the central zone of the crack subjected to homogenous loads, the edges of the crack subjected to homogenous loads, the edges of the crack subjected to moving concentrated variable loads Px/ t and the origin of the coordinates subjected to point loads are studied separately, and analytical solutions of dislocation distribution functioncan also be attained.

对裂纹中心区受均布载荷、裂纹表面受均布载荷、裂纹表面受到运动集中变载荷、坐标原点受集中载荷作用下界面裂纹的扩展问题分别进行了研究，也获得了位错分布函数的解析解。

The detailed algorithm on analyzing cracks exploration inside blocks is: enriched approximations which describe singular crack tips fields and discontinuous crack faces are employed under the Partition of Unity theory; the enriched nodes surrounding crack tips or faces are respectively mapped with corresponding enriched degrees of freedom, and the solution of all these degrees of freedom is uniformly proceeded by the implicit iteration algorithm of DDA, then fracture and breakage of DDA blocks can be analyzed. The numeric examples show this algorithm is rational and efficient.

为此建立的无网格法裂纹扩展分析算法，采用满足单位分解条件的特殊增强型函数表达裂纹周围应力场的非连续、奇异特性，将对应的扩展自由度动态映射到裂纹周围的节点上，统一按DDA法隐式迭代方式求解，实现块体裂纹扩展和强度分析，相关算例结果显示该算法是合理有效的。

With the analysis of stress intensity factor near the crack tip of the cracked metallic panel,the influence of residual thermal stress on repairing cracked metallic panel with composite patch bonded is investigated.

本文建立了复合材料胶接修理金属裂纹板的三板有限元模型；采用分析金属裂纹板裂纹尖端应力强度因子的方法，分析了残余热应力对复合材料修理金属裂纹板修理效果的影响。

It is found that the wing crack extend along a curved path and gradually approximate to the line which passes the middle point of the main crack and is parallel to the direction of maximum principal stress.

采用数值和试验的方法对翼型裂纹的扩展路径进行分析，发现单轴下张开型裂纹的翼型裂纹的扩展路径逼近于过原主裂纹中心点、平行于最大主应力的一条直线。

An engineering procedure for estimating crack growth behavior and fatigue lives of semielliptical surface cracks at weld toe s in complex stress fields was proposed based on a database of stress intensity factors and the elementary modes method developed by author.

以作者建立的焊趾半椭圆表面裂纹应力强度因子数据库以及复杂应力场中焊趾半椭圆表面裂纹前缘应力强度因子分布计算的基本模式法为基础，给出了复杂应力场中焊趾表面裂纹在疲劳扩展过程中形态变化规律及寿命的工程分析方法；并用这个方法计算了一些典型焊接接头在一些典型的外加应力场和残余应力场中的裂纹形态发展曲线。

Employed the Hamiltonian system theories of elastic mechanics, a series of crack singular analytical elements satisfying different boundary conditions along crack surfaces in the vicinity of crack tip are constructed. These hyper-elements can describe the crack tip fields accurately for different simplified fracture models.

应用弹性力学哈密顿体系理论，在裂纹尖端构造出满足不同裂纹表面边界条件的一类裂纹奇异解析元，该类超级单元能够准确描述不同简化模型下的裂纹尖端场。

In Chapter Four, the surface fracture was studied for a functionally graded plate with a semi-elliptical surface crack under state thermal loading, and studied the influence of crack sizes, aspect ratios and material property on the stress intensity factors along a crack-front under two types thermal loading: calefactive state thermal loading and descent state thermal loading.

第四章研究了含有半椭圆表面裂纹的功能梯度材料板条在稳态温度热载荷作用下的裂纹问题分析，着重考虑了升温载荷及降温载荷作用下应力强度因子在裂纹前沿的分布及材料梯度及裂纹与板的几何尺寸对应力强度因子的影响。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。