裂纹

Fracture criterion for mixed mode crack propagation will be discussed in the thesis of part two. In practical engineering structures, due to unsymmetry of load distributed, crack direction and anisotropic of material. Crack subjected to a complex case of stress state.

因而复合型裂纹扩展的断裂准则的研(来源：ABCb5b5b5论文网www.abclunwen.com)究有着重要的理论意义和实用价值，探讨各种类型结构和材料中裂纹扩展的真实原因和动力一直是广大学者研究的热门领域。

The calculation results show that, the predicted life of crack propagation is in good agreement with the experimental data, and the model is veracious and feasible.

采用边界元法建立了裂纹扩展分析模型，对FGH95粉末高温合金标准紧凑拉伸试样的裂纹扩展试验结果进行了数值模拟，计算结果与试验吻合很好，表明分析方法的准确性及可行性。

The direction of crack propagation is victual to the direction of maximum stress if the anisotropy of material is sufficiently weak. Universality of fractal dimension of fractured surface would be easy to appear in this case. On the contrary, the crack propagates along the plane with the lowest surface energy.

当材料结构的各向异性特别显著时，裂纹的扩展沿着比表面能最小的方向扩展，这时，断口分维与材料本身的结构有关，表现为断口分维的特殊性；反之，当材料结构的各向异性特别微弱时，裂纹的扩展垂直于最大应力方向，在这种情况下，材料的断口分维与普适性有关。

However, Elssner and Ruhle observed the atomistically sharp crack tip.

而 Elssner 发现当材料发生脆性破坏时，依然在原子尺度上存在尖裂纹，虽然当时已经有大量的位错出现，却并没有出现按照经典塑性理论预测的钝化裂纹。

In near-neutral pH solution, the cracking mode is transgranular with the feature of quasicleavage.The function of SCC factors are as follows:(1)The additional potential takes an important role in the SCC behavior of X70 pipeline steel: the susceptibility to SCC increased with decreasing cathodal potential,HIC is the dominant reason,the crackles on the surface are almost vertical to stress;On the country, at anodic potential,there is a critical potential,below which the dominant reason is anode-dissolving supported by hydrogen,and the crackles on the surface are not vertical to stress.

电位因素和环境因素的影响作用为：(1)在阴极极化电位区，SCC敏感性随电位的负移而增加，氢致开裂作用占主导，表面裂纹多与拉应力垂直；在阳极极化区间，存在阈值电位，低于阈值电位时，SCC为氢促进阳极溶解所致，表面裂纹多与主应力方向成一定角度。

And it can be turned into surface circumferential crack and surface axial crack.

可分解成表面周向裂纹和表面轴向裂纹问题。

One of the necessary conditions of the initial cracking due to thermal fatigue is that the material on high temperature side has been deformed compressively and plastically, which is different from the cracking due to common fatigue.

热疲劳裂纹张开的一个必要条件是高温侧材料在升温过程产生压缩塑性变形，这与普通疲劳裂纹不同。

When you use safety belts ,you should check brand and certification, inspect nylon whether it is crackless and with strong thread, whether it is no lack of metal pieces, cracks and corrosion, safety rope should be linked to the connection ring.

每次使用安全带时，应查看标牌及合格证，检查尼龙带有无裂纹，缝线处是否牢靠，金属件有无缺少、裂纹及锈蚀情况，安全绳应挂在连接环上使用。

Theoretical analyses are made for obtaining the intrinsic relation between cracking and non-linear deformational response in conjunction with the experimental observations.

为了定量地描述裂纹扩展和变形响应的关系，定性地观察裂纹的扩展情况是不够的，特别是在受压力载荷下，需要用

The experimental investigation and analysis are presented for exploring the intrinsic link betweencompressive deformational response and crack behavior of the mortar specimens.

1引言 微裂纹的萌生、演化和成核而引起受损固体的非线性力学响应对材料和工程的变形和破坏非常重要，对于以水泥为基材的脆性固体材料，裂纹常常是材料的非弹性变形和破坏的决定性因素，因而它已经成为一项重要的研究课题[1]。

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。