裂纹

Analyses Ⅲ crack creep fracture under the influence of the initial co_linear array of microcracks antiplane using macrocrack_microcrack inteaction model and the theory of stress intensity factors for creep fracture,and presents the relation between the concrete antiplane Ⅲ crack stress intensity factors for creep fracture and the initial stress intensity factors was obtained.

依据宏观裂纹—微裂纹相互作用模型和蠕变断裂应力强度因子理论，对具有初始等距共线微裂纹列影响的反平面Ⅲ型裂纹体的蠕变断裂问题进行了分析。

The branch crack problems in a finite-width strip were solved by using the complex potential of a branch crack of half-plane, in which the distributed dislocations were assumed along all the branches arid one boundary of the strip.

假设沿分叉裂纹各分支和板条边界有某位错分布，利用半平面内分叉裂纹问题的复势函数，将板条分叉裂纹问题转化为半平面内的多分叉裂纹问题处理。

Special solutions for the ring circular domain with crack surfaces acted on uniform compressive force, linear compressive force and linear shearing force are deduced in polar coordinate employed the eigenfunction expansion technique in the Hamiltonian system of elastic mechanics. Combined with the general solution for the above problems, the analytical solutions for crack tip fields with surfaces acted on the above three kinds of loads are obtained. These solutions offer theoretical basis to construct analytical elements for plastic analysis of crack.

从弹性力学哈密顿体系理论出发，利用平面弹性力学极坐标系下的本征向量展开求解，推导了环形圆形域裂纹边作用有均布压力、线性压力和均布剪切力情况下的特解，从而得到了裂纹表面作用有以上三种荷载情况下的裂纹尖端场的解析解，为进一步构造进行弹塑性裂纹分析的奇异解析元奠定了理论基础。

By applying contour integral method and high-order displacement functionsof MM,we obtain the accurate stress intensity factors of mixed-mode crack.Then,the open crack propagation of the mixed mode I and II is simulated by means oftheories of linear elastic fracture mechanics.This provides a simple and effectivenumerical way for crack evolvement studying.

接着，文中采用围线积分法和流形方法的高阶位移函数来计算得到比较准确的混合型裂纹尖端的应力强度因子，然后基于线弹性断裂力学的裂纹扩展准则，用流形方法实现了平面I-II混合型张裂纹扩展的数值模拟，为数值方法研究裂纹的演化行为提供了一条简单而有效的途径。

Quenching crack propagation characteristics of the organizations on both sides without decarburization phenomenon significant difference between crack and materials and forging cracks.

淬火裂纹的组织特征是裂纹两侧无脱碳现象，明显区别与锻造裂纹和材料裂纹。

Atfirst,stress and displacement at the end of collinear crucks are calculated by elasticity me-chanical method,then general solution of twist force at the end of collinear cracks is givenby rotation theory,single crack and double cracks are discussed emphatically.

本文计算并讨论了忽视旋转的传统理论所不能给出的裂纹端部场与场源的相互作用，首先利用弹性力学方法计算了共线裂纹组端部的应力场及位移场，然后应用旋转理论给出共线裂纹组端部的扭转力通解，对单裂纹和双裂纹情形做了重点讨论。

The influence of welding residual stresses on the fracture characteristics of thesteel weldments with short-crack s was evaluated,and an attempt has been made to improve the fracture characteristics of the steel weldments with short-crack s by the application of surface treatment.

本文探讨了焊接残余应力对带短裂纹焊件疲劳断裂性能（疲劳裂纹萌生寿命、疲劳短裂纹扩展速率及疲劳总寿命）的影响，并通过表面锤击、表面喷丸处理，使焊件短裂纹处的残余应力得到有利调整，从而改善和提高了带短裂纹焊件的断裂性能。

The crack and stress-strain of Chinese White Poplar were studied by the box counting method. The results showed that the cracks were obvious fractal and that the value of dimension D was determined to be between 1.2～1.5 by studying the crack propagation in the two dimensions. By comparing the crack propagation over a period of time, we found that the value of D increased as the crack increased.

运用数盒子法对裂纹发育带在二维平面内的分布进行了分形特征研究，发现木材裂纹具有明显的分形规律，分形维数为1.2～1.5；通过比较不同时间段的裂纹发育情况，发现裂纹的分形维数随着裂纹的扩展呈增加的趋势。

Calculations on the basis of the self-consistent approximation are used to study the effects of slit cracks, elliptical cracks and penny-shaped cracks. The influence of slit cracks on the elastic moduli under all kinds of loading conditions is discussed by Betti's reciprocal theorem and Irwin's relation describing the released energy rate of fracture to the stress intensity factors. The friction between the cracks' surfaces is taken into account for the closed cracks.

采用自恰方法研究了狭长型，椭圆型及硬币型裂纹在荷载作用下对弹性常数的影响；采用Betti的互易定理以及lrwin关于断裂能量释放率与应力强度因子的关系，分析了狭长型裂纹在各种应力状态下对弹性常数的影响；分析研究了裂纹闭合时，由于裂纹面上摩擦力的存在，闭合裂纹时弹性常数的影响。

The results of conversion show that the serious disc must be rejected because its reliable L-HCCF life is greatly less than an overhaul period. Finally, the load distribution of centrifugal and vibration force on labe is derived. Using two method, load on the crack labe gradually reducing and keeping constant with the crack propagation, a crack propagation analysis of fir-tree slot is carried out, and the calculating L-HCCF crack propagation life of slot on the unload method, which is nearly 3 times longer than that on constant method, is 20 times shorter than the pure low cycle life, and agree well with the experimental's.

最后，分析了离心力载荷和振动载荷在榫齿上的分布，进行了榫槽榫齿的有限元计算；提出了枞树型榫槽的卸载概念，并按带裂纹榫齿上的承载随裂纹增长而逐步减少和始终保持不变两种处理方法，进行了复合疲劳裂纹扩展及其寿命计算，由计算得出卸载下复合疲劳裂纹扩展寿命较单纯低周疲劳寿命下降二十多倍；按卸载处理的疲劳裂纹扩展寿命是按恒载处理的三倍多，前者与试验吻合，而后者则偏差较大。

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。