Reliability analysis of structures containing defects carried out directly by practising engineers is quite complex and costly. Therefore. a simple and convenient reliability analysis method should be investigated and established. In this paper. the principle and building procedure of a reliabjlity analysis method are described and the feasibility of the method are also explicitly clarified. Based on the assumptions that: (1) the 1oad is a deterministic variable; (2) the yield strength and fracture toughness sarisfy normal distribution and their variational coecients are constant; (3) the initial crack length remains unchangeable, a set of probabilistic failure assessment diagrams (PFAD) called elementary reliability assessment method are established under the simplified option 1 curve of the 3rd version of CEGB R6. The investigation shows that the distribution of random safety factor and failure probability of a structure only depend on the Coordinates of the expectation of P (Lr, Kr) in the failure assessment diagram of the simplified option l curve and is not influenced by the other factors. The investigation further shows that the failure probability will decrease with the increase ofthe initial crack length if the expectation of P (Lr, Kr) keeps unchanged. A conservative result will be given when using the PFAD as an elementary reliability analysis method to assess the integrity of a structure and only a simple procedure is required Jike the deterministic assessment method given in CEGB R6. When the secondary stress exists. the conservativeness of the result assessed will increase with the increase of parameter P although the PFAD is only established based on considering primary stress.

Although it is recognised that biaxial or triaxial stressing can affect the fracture conditions and stress/strain field of a cracked body, insufficient attention has been paid to how biaxial or triaxial stresses affects the properties of the J-integral. In this paper, two-dimensional incremental and three-dimensional incremental theory elastic-plastic finite element programs have been adopted to analyse the effect of biaxial stressing on J-integral of a finite plate containing a through-thickness crack and subjected to biaxial stresses. Constitutive equations describing the material behaviour were chosen as: (i) the practical stress strain relation of 16MnR; (ii) modified yielding plateau stress strain relationship of 16MnR; and (iii) Ramberg-Osgood representation. The finite element analysis results show that the properties and values of J-integral under biaxial stressing can be significantly different from those under uniaxial stressing. Attention must, therefore, be paid to J-integral calculations when considering it as a fracture parameter to analyse multi-stressing situations. 2000 Elsevier Science Ltd. All rights reserved.

The design of nozzles by using RESS (Rapid Expansion of Supercritical Solution) was carried out in this paper. Based on the re-lated thermodynamics principles, two models to calculate the nozzle inner diameter were proposed which were based upon one-dimensional time-independent flow including adiabatic and convective heat transfer process. The obtained results indicated that one-dimensional time-independent isentropic and adiabatic flow model could satisfy the requirement of engineering design.

In this paper, the J-integral path-independence of a notch under incrementaltheory. the possibility of measurement of notch J. integral fracture toughness, and the equality in numerical values between the notch and the crack J-integrals. are investigated and demonstrated by means of elastic-plastic finite element analysis. Based on this. the authors deem that the J-integral may also play the role of a main parameter for notch elastic-plastic fracture analysis. Meanwhile. based on the notch J-integral numerical calculation. the authors further establish the notch failure assessment curve, and therefore investigate the dependence of the failure assessment curve on the dimension and geometry profile of the notch end and the feasibility of the R6 (third edition) failure assessment curve in the notch assessment. The method of the failure assessment diagram should be regarded as a simple and convenient engineering failure assessment approach for notch elastic-plastic fracture analysis, which can give the possible failure mode of the notch. The notch fracture toughness, JA, is no more a simple material constant. The engineering estimation method for the notch fracture toughness is expounded in this paper. which should lay the foundation of application of the notch failure assessment diagram.

应用增量理论弹塑性有限元方法以及弹塑性断裂力学J积分理论，深入研究和全面探讨了一种用于含裂纹结构完整性评定的工程方法--失效评定图，以及钝裂纹或缺口根部曲率半径、缺口长度、缺口端部椭圆离心率、试样形式和材料等对其的影响。提出了钝裂纹或缺口应力强度因子和极限载荷修正方法。通过这一方法建立的失效评定图可有效地消除缺口因素对失效评定图的影响，由此，可完全等效地将裂纹失效评定图用于含缺口结构的完整性评定。