海管焊接接头全壁厚裂纹尖端张开位移试验

裂纹尖端张开位移(CTOD)试验是深海管线管的一个重要试验项目,试验通常使用矩形横截面试样,由于该试样是截取焊接接头的一部分,并不能很好地反映整个焊接接头的断裂韧度。根据BS 7448:Part2:1997的要求制备全壁厚试样并在-10℃下做低温CTOD试验,结果与矩形横截面试样的结果作比较,发现全壁厚试样的断裂韧度明显优于矩形横截面试样的断裂韧度,分析发现结果与焊缝的应力状态、化学成分和显微组织的影响有关。全壁厚试样能更真实地反映焊接接头的真实断裂韧度,更好地指导工程设计。     

行程受限COD规在裂纹尖端张开位移试验中的应用

分析了COD规在裂纹尖端张开位移(CTOD)试验中由于行程受到限制而随载荷的变化所产生的各种可能结果，提出了用EXCEL数据处理软件对采集到的COD规的张开位移进行处理的理想方法，得到了令人满意的P-V曲线，从而可较准确地从该曲线上求得停机点的载荷Ps和COD规张开位移的塑性分量Vo，为CTOD试验的顺利完成提供了保证。     

美国ASTM裂纹尖端张开位移（CTOD）试验方法新标准简介

介绍了美国ASTM E1290-89裂纹尖端张开位移试验方法的主要内容和特点,这对我国COD试验方法标准的修订是重要的参考。     

温度对结构钢材裂纹尖端张开位移(CTOD)的影响分析

裂纹尖端张开位移(CTOD)与钢材的弹性模量、屈服强度、几何条件和荷载大小等因素有关.结构钢材的相关力学指标随着温度发生变化,因此温度变化也会改变CTOD的数值.从含穿透缺口无限大受拉平板的Dugdale-Barrenblett模型(D-B模型)出发,推导出了温度对裂纹尖端张开位移影响规律的基本公式,并把分析进一步扩展到含跨中裂纹的三点弯曲试样.并对带跨中裂纹的三点弯曲试样进行了有限元分析和低温试验,其结果和公式进行了对比.结果表明,CTOD值随着温度降低而减小,温度对CTOD的影响程度与裂纹尖端的塑性发展程度有关.     

接近液氦温度的简易却贝冲击试验法

提出了在低于5K温度下检验材料冲击性能的简易试验方法。     

连铸10CrNi3MoV钢裂纹尖端张开位移(CTOD)试验研究

对电炉模铸及不同批转炉连铸 10CrNi3MoV钢进行了CTOD试验研究 ,并探讨了CTOD特征值与钢板中心偏析关系。结果表明 ,模铸钢板抵抗裂纹早期扩展的能力高于连铸板 ,但连铸板抵抗裂纹失稳扩展能力并不低于模铸板 ;钢板中心偏析使CTOD特征值降低 ;控制碳含量在较低水平 ,或碳含量达上限 (0 .11%C)时采取减轻偏析的有效措施 ,可使连铸 10CrNi3MoV钢具有较高的断裂韧性     

用示波落锤试验法评价14Mn VTiRe钢的韧脆断裂行为

采用示波落锤试验法对 5mm热连轧 1 4MnVTiRe钢的韧脆断裂行为进行了研究并对落锤撕裂试样的动态断裂特征进行了评价。结果表明 ,当裂纹扩展功远大于裂纹萌生功时 ,试样处于韧性断裂状态 ;当裂纹扩展功小于裂纹萌生功时 ,试样处于脆性断裂状态 ;当裂纹扩展功与裂纹萌生功相当时 ,试样处于混合断裂状态。该结果与按标准测定的剪切面积百分数有良好的对应关系 ,说明示波落锤试验法可作为一种评定材料韧脆断裂特征的实用方法     

基于示波法原理电子血压计（动态）测量值的分析与评定

本文按照JJG692-2010《无创自动测量血压计（动态）》检定规程和JJF1059.1-2012《测量不确定度评定与表示》的有关要求,使用血压模拟器标准装置,对采用示波法原理的电子血压计的动态部分的测量结果进行分析与不确定度的评定。     

钻屑法预测冲击地压的数值模拟研究

RFPA软件可实现对岩石破坏全过程的应力、应变的连续模拟显示,可对比分析不同位置煤岩的应力、位移特征。本文以耿村煤矿的具体地质条件为原形,通过RFPA数值模拟,研究向煤体打钻屑孔过程中应力和位移等变化规律,以预测冲击地压的危险性。     

两种钢夏比V型冲击试验裂纹形成能量与扩展能量之间的关系

采用仪器化冲击试验方法对两种承压设备用钢Q245R钢和13MnNiMoR钢进行系列温度下的夏比V型冲击试验,对比研究了两种钢裂纹形成能量W_i与裂纹扩展能量W_p之间的关系。结果表明:两种钢在韧脆转变K_(V2)-t曲线的上平台以及紧邻转变区的温度范围内,裂纹形成能量W_i不随温度变化而变化,基本恒定,但13MnNiMoR钢的值高于Q245R钢的;材料的韧脆转变,始于裂纹扩展能量W_p转变,其是主导材料由韧向脆的关键。     

Determination of the Fracture Toughness of a Low Alloy Steel by the Instrumented Charpy Impact Test

An attempt to establish a non-empirical relationship between the Charpy V-notch energy CVN and the fracture toughness K _Ic is presented. We focus our study on the lower shelf of fracture toughness and on the onset of the ductile-to-brittle transition of a A508 Cl.3 low alloy structural steel. The methodology employed is based on the `local approach'. Brittle cleavage fracture is modelled in terms of the Beremin (1983) model, whereas the ductile crack advance preceding cleavage in the transition region is accounted for with the GTN model (Gurson, 1977; Tvergaard, 1982; Tvergaard and Needleman, 1984. Mechanical testing at different strain rates and temperatures allowed the establishment of the constitutive equations of the material in a rate dependent formulation. Numerous fracture tests on different specimen geometries provided the large data set necessary for statistical evaluation. All specimen types were modelled with finite element analysis. Special consideration was taken in order to handle the dynamic effects in the Charpy impact test in an appropriate way. The fracture toughness could be predicted from Charpy impact test results, on the lower shelf, by applying the `local approach'. In the transition region the parameters of the Beremin model were found to deviate from those established on the lower shelf. Detailed fractographic investigations showed that the nature of `weak spots' inducing cleavage fracture changes with temperature. It is concluded that the Beremin model must be refined in order to be applicable in the ductile-to-brittle transition region.     

起落架落震试验飞机机轮三向冲击位移的动态测量

为了研究飞机起落架受冲击载荷时的功量吸收状况，须在起落架落震试验中，对飞机着陆瞬间起落架机轮在空间三个方向上冲击位移的动态变化量进行测量。为此，本文设计了四自由度空间定位装置，并使其与计算机连接，实现了落震试验过程中，起落架在高速冲击状态下机轮三向位移的有效测量与记录。     

炸药低速撞击试验的分析与讨论

研究了标准型撞击装置、12型撞击装置测试的多种炸药撞击感度数据。通过与低速条件下小药片撞击感度和苏珊大型模拟感度等试验结果的比较,研究、分析了各种典型撞击条件下的炸药撞击试验测试结果及测试数据的合理性,并从撞击装置、测试状态等方面讨论了影响炸药在低速撞击条件下感度测试结果的因素。     

Displacement Discontinuity or Complex Shape of Sample: Assessment of Accuracy and Adaptation of Local DIC Approach

In this paper, we study the impact of a complex shape of sample and the appearance of a displacement discontinuity on performances of measurement by local Digital Image Correlation (DIC). Both cases are modelled from synthetic images into two parts: one with a speckle field and another part without speckle or two parts with similar speckle fields but with different kinematics. The accuracy of displacement measurements assessed for DIC subsets crossing the boundary between the two parts is lower than the one obtained without discontinuity and justifies adapting DIC method. A new local DIC process is presented in detail. It is an alternative way able to take into account any shape of sample and several curved lines of discontinuity in the same subset. Two experimental examples are presented: displacement and strain fields obtained by DIC and adapted DIC are compared. We can conclude that it is possible to lead a mechanical analysis until the limits of the sample and even during the appearance and the propagation of a crack.     

Inverse Analysis of Impact Test Data: Experimental Study on Polymeric Materials Displaying Brittle Behaviour

This paper deals with the influence of the testing equipment on impact load measurements. A previously developed method of analysis and processing of the experimental data based on a refined analogical model of the impact event and inverse problem techniques is used. This method makes it possible to obtain the mechanical response of the material, notwithstanding the disturbance of the dynamic effects associated to the test. Results from tests carried out both on falling weight and swing pendulum instrumented testing machines are compared. It is shown that this method can give an accurate estimation of the actual bending force in impact testing independent of the testing equipment.     

浅谈涂装车间新车型投产项目管理

将涂装车间的新车型投产项目管理分为项目启动前、项目实施中、项目完成后三个阶段,分别简述在此三个阶段的项目管理的重点工作。     

大小试样冲击功比值变化规律的研究

通过夏比Ｖ型缺口冲击试验，研究了结构钢小尺寸试样的冲击功与标准试样冲击功的比值在系列温度冲击试验中的变化规律，并述评了用等效比值数确定小尺寸试样冲击功指标的问题。     

基于LS-DYNA的冲击试验机碰撞分析

基于显示动力学和接触碰撞分析的基本理论,采用有限元方法建立冲击试验机的碰撞模型,对接触面的冲击载荷进行仿真分析。根据仿真结果得出冲击试验中各碰撞部件的运动与受力状况,以及冲击力对碰撞速度等参数的变化规律,为后续的接触面状态测试奠定基础。