Fracture experiments on through wall cracked elbows under in-plane bending moment: Test results and theoretical/numerical analyses

Fracture assessment of pipe bends or elbows with postulated through wall crack is very essential for leak-before-break qualification of primary heat transport system piping of nuclear power plants. The methodology for fracture assessment of cracked elbows is still in developing stage. Any new development in theoretical aspect requires experimental validation. However, fracture test data on cracked elbows is not so abundant as straight pipes. The earlier experiments on cracked elbows were focused mainly on the determination of limit load. Other fracture parameters e.g. crack growth, crack initiation load or crack opening displacement were not reported in the open literature. Against this backdrop, a comprehensive experimental and theoretical program on component integrity has been initiated at Reactor Safety Division (RSD) of Bhabha Atomic Research Center (BARC), India. Under this program, a number of fracture tests have been carried out on elbows with through wall circumferential/axial cracks subjected to in-plane closing/opening bending moment. These test data are then thoroughly analysed numerically through non-linear finite element analyses, analytically through limit load comparison and also through comparison of crack initiation loads by finite element and R6 methods. These test data may be utilized in future for validation of new theoretical developments in the integrity assessment of through wall cracked elbows.     

Three dimensional virtual crack closure-integral method (VCCM) with skewed and non-symmetric mesh arrangement at the crack front

In this paper, an extension of virtual crack closure-integral method (VCCM) for three dimensional linear fracture mechanics analysis using hexahedron finite elements is presented. In conventional three dimensional VCCM, there are some inherent requirements on the finite element model. They are (i) the faces of finite elements across the crack front have the same areas and (ii) they must be arranged symmetrically across the crack front. In present study, we developed a three dimensional VCCM without such requirements by considering work required to open one element face area whose shape is arbitrary. Though we assume the use of an ordinary 20 node serendipity element, present approach can be applied to other types of hexahedron elements.     

Cracked Brazilian disc specimen subjected to mode II deformation

The centrally cracked Brazilian disc specimen has been used by many researchers to study mode I and mode II brittle fracture in different materials. However, the experimental results obtained in the past from this specimen indicate that the fracture toughness ratio (K_IIc/K_Ic) is always significantly higher than the theoretical predictions. It is shown in this paper that the increase in the ratio K_IIc/K_Ic can be predicted if a modified maximum tangential stress (MTS) criterion is used. The modified criterion takes into account the effect of T-stress in addition to the conventional singular stresses. The fracture toughness ratio K_IIc/K_Ic is calculated for two brittle materials using the modified criterion and is compared with the relevant published experimental results obtained from fracture tests on the cracked Brazilian disc specimen. A very good agreement is shown to exist between the theoretical predictions and the experimental results.     

中国上市公司总经理报酬影响因素的实证研究

总经理报酬是总经理激励机制的主要因素，如何决定总经理报酬是迫切需要研究的问题．通过对国外相关研究的综述和结合我国上市公司特点的分析，形成了关于企业绩效、企业规模和董事会控制强度与总经理报酬之间关系的假说，并以1999和2000年上市公司为样本，首次利用协方差结构模型对总经理报酬和其影响因素之间关系的假说进行了检验和分析．实证研究表明，两年里，企业业绩、企业规模和董事会控制强度3类因素对总经理报酬的总解释率分别为8．9％和30．7％．     

含内埋裂纹板条瞬态响应的有限元--线弹簧分析

将线弹簧模型与有限元软件ANSYS相结合，求解了冲击载荷作用下的含内埋裂纹的板条问题，所得的结果与已有的有限元解吻合良好，此方法可推广用于其它三维裂纹动态响应分析。并对内埋裂纹板条瞬态响应的影响因素做了分析。     

新型高压放电灯的开发和应用

近年来，从节能和环保的观点出发开发成功许多具有高光效、高显色性、长寿命的新型高压气体放电灯。这些新型灯包括有大功率金卤灯、低功率陶瓷管金卤灯、高压钠灯、超高压汞灯和无电极金卤灯等。已被广泛应用于室外、室内照明、汽车照明和背光照明。本文主要介绍新HID灯的种类、特性和应用。     

裂纹尖端的位错密度及其应用

本文为弹性断裂力学分析提供了一个新的变量：位错密度．并论证了这一变量在裂纹尖端具有1√r所阶的奇异性．分别给出了三类裂纹问题裂尖位错密度与应力强度因子的关系，对这一变量在数值计算中的应用进行了探讨．     

地震砂土液化可能性的非确定性灰色预测方法

地震作用下的饱水砂土体系是一内部信息部分已知、部分未知的灰色系统，反映其液化可能性的指标值实际上是一些灰数。取平均粒径、相对密度、标准贯人击数和上覆有效压力作为评价砂土液化可能性的指标，以它们在各级烈度下液化现场资料的统计均值作为参考数列，将已知烈度区内待预测砂土的指标实测值作为被比较数列，计算它们之间的关联度。若最大关联度值所对应的参考数列烈度大于待预测区，则判为液化；反之，则判为不液化；若相等     

相关集合：集合的相关强度与相似关系

从集合的相关性及相关强度出发，提出了一种新的集合，相关集合与集合的相似关系，相关集合是等价类的推广，是一种集合形式表示：而集合的相似关系则是一种模糊关系，它们可用于分析关系的性质、研究和知识系统的鸨民综合以及模式识别等领域，给出了在传统关系特性分析中的有关定理及在短评肤浅民加工过程中的应用示例。     

特殊吸附式隔板(SAS)的研制

叙述了特殊吸附式隔板（SAS）的设计思想、技术途径、原料特点、产品性能及结构。