裂纹

It was the first time in this work to set up the subcritical crack growth model under monotonical loads by use of R—curve, starting with the fracture mechanics. The V—K curves under the static loads and dynamic loads were made by use of computer numerical method.

首次从断裂力学出发，利用R曲线，建立了单调载荷形式下亚临界裂纹扩展模型，并利用计算机数值计算获得材料在静载及动载下的V—K曲线。

The distribution of glacial-erosion traces on the roche moutonnee has fair regularity, that is to say the long-straight striations were often formed on the top of stoss side and the crescentic scars, crescentic wedges, chatter marks and shorted striations on the end of stoss side and striation of many groups on the flanks, which can show the condition of glacial division-flow.

迎冰面的顶部为长度大且平直的擦痕，尾部为新月型裂纹，新月型凿口，颤痕和较短的擦痕；侧部常有多组擦痕，它可指示冰川分流的情况。

The influences of mean stress, multiaxial stress and yield stress on the fatigue crack growth rate and the threshold value are analyzed.

分析了平均应力、多轴应力和材料屈服应力等对疲劳裂纹扩展速率和门槛值的影响。

The process of establishing neural network is as follows: two-layer neuronic network configuration is selected, S-type active function is used, input parameter of network are selected for thickness, preheat temperature, heat input and sampling point, output parameter of network is selected for fracture toughness property CTOD, learning algorithm of network is used for back-propagation algorithm.

本文选择了2层神经元的神经网络结构，采用S型激活函数，将板厚、预热温度、线能量、取样位置作为神经网络的输入，将环焊接头的裂纹尖端张开位移CTOD值作为网络的输出，通过BP算法的网络学习，采用VC语言建立了X70管线钢环焊接头CTOD与环焊工艺之间的神经网络。

But, the characteristics of its adhered-elastic fracture in high temperature and brittle fracture in low temperature were discovered during impact load test The impact fracture mechanism of the high-energy nitroamine propellant had been put forward by studying the fracture appearances of impact fracture surface, the expansion of secondary crack and the weakness or failing of mechanical structure combined with the analysis of impact fracture properties and dynamic adhered-elastic properties and structures.

通过研究冲击断裂表界面的断口形貌、二次裂纹的发展、材料的力学结构缺陷或弱点，并结合冲击断裂性能、动态粘弹性能及结构分析，提出了硝胺发射药的冲击断裂破坏机理。

The results showed that the orientations of the initiation and propagation for fatigue crack were mainly in the two maximum shear planes, and affected by the nonproportional degree under multiaxial proportional and nonproportional loading.

结果表明，多轴比例与非比例加载下，疲劳裂纹萌生的位向及扩展方向主要在两个最大剪切平面上，且受非比例加载程度的影响。

The 3D topography of fractured surfaces was reconstructed and quantified by the means of SEM stereo pairs, image processing and analysis, and computer vision. It was shown that measured 3D roughness indexes Rs, Rq and Rmax have good positive relations to the crack propagation part of absorbed impact energy. Although fractal behavior had been checked out on the fractured surfaces, the fractal dimension was found nonsensitive to the fracture mode and mechanical properties. The geometric characteristics of fractal fractured surfaces should be quantified in fractal dimension together with absolute parameters.

利用扫描电镜立体对技术、图像处理与分析和计算机视觉方法对示波冲击断口形貌进行了三维重建和定量分析结果表明，断口三维粗糙度指数Rs，Rq和Rmax与示波冲击裂纹扩展功有很好的对应关系，显示了它们良好的应用前景断面虽然表现出分形行为，但分形维数是一个对断裂模式和性能不敏感参量对分形断口的几何特征描述应将分维和绝对尺度结合起来

Results show that the alteration of parameters has a great influence on whether Fe3Al overlayer can be obtained or not. Cracking is the major flaw in this experiment.

研究表明，工艺参数的改变对能否获得F3Al合金堆焊层有较大的影响，裂纹是堆焊Fe3Al合金时出现的主要缺陷。

In this paper, the internal transverse cracks of continuous casting slabs of a niobium bearing peritectic grade of steel are investigated using electron probe microanalyser and optical microscope.

连铸坯厚度中心存在的内裂纹在后续的轧制过程中轧不合而对产品的质量带来重大的影响。

Sanidinite (some have transformed to perthite) and quartz inclusions with radial cracks are often seen in the garnet of eclogite. The geothermal gradient of ＜10℃/km is recorded in the early stage mineral assemblage of high-pressure metapelitic rocks with relict aragonite. these features imply a possibility that there may be ultra-high-pressure rocks existed in Altun.

根据榴辉岩中石榴石常见透长石和石英包体，并有放射状裂纹的特征，以及高压变泥质岩石早期矿物组合温压条件记录的地温梯度小于10℃/km和残存文石等特征，不排除区内有超高压变质岩石存在的可能性。

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。