[en] The book presents the derivation of conservation laws and the associated distance independent integrals from the basic equations of continuum mechanics in a general form. Afterwards, the equations for special applications (e.g. linear theory of elasticity) are derived therefrom, by introducing the corresponding conditions. In this way, it is possible on the one hand to classify already tested integral fracture criteria (e.g. J-integral) in a superior frame, on the other hand it is possible at any time to check the applicability of formulas defined for special cases. (orig./MM)

[en] Among the topics discussed are: fracture analysis methods evaluation; instability prediction using the K sub R-curve approach; and the deformation failure assessment diagram. Consideration is also given to: instability prediction based on the modified J, J sub M-resistance curve approach; and stable crack growth and instability prediction on the V by means of the V sub R-curve method

[en] In pressure vessels with artifical surface cracks of various sizes failure at ambient temperature and -20⁰C was due to ductile fracture. The fracture surface is exhibiting dimples without cleavage. Onset of crack extension and instability occurred in the elastic plastic regime. Using the mean value bewtween the yield and tensile strength as flow stress the plastic collapse approaches will generally produce conservative results although the calculation was based on the original crack size and not on the crack size at failure. Realistic predictions may be obtained from the approaches by Ruiz, Harrison (Mises) and Kiefner with the latter's approach being suited particularly for crack depths of less than 80% of the wall thickness. (orig./DG)

[en] Short communication

[en] 7000 entries summarize the most important and frequently used terms in fracture mechanics: modes of fracture, concepts and criteria, cracks and crack growth, test methods, specimens etc. Some general terms that have a special meaning in the scope of this book are also included as are important abbreviations, acronyms, symbols and units. All entries are alphabetically ordered and, if appropriate, combined with groups of related words. Groups of word combinations are thought to be useful for the understanding of linguistic laws. Annotations in italics may be helpful in relating the entry to a special technical scope. Within the entries the source-language terms are bold-faced. In the German alphabet the mutated vowels ae, oe and ue are ordered as ae, oe and ue; ss is ordered as ss. (orig./HP)

[en] B139 - Continuum Damage Mechanics - Critical States

[en] Three conservation laws, expressed in terms of line and surface integrals, are derived for Reissner's transverse shear theory of plates. Mindlin's and Kirchhoff's (or classical) theories are included as particular cases. A physical interpretation of three plate transformations used to obtain the conservation laws is proposed. The path-domain independence property of the integrals, their connection to energy release rates due to cavity motions and their relationships with stress intensity factors are also discussed. (orig.)

[en] Definition and meaning of concepts like 'J integral' are given without any assumption about material behaviour. The key of the work is the field of 'defect forces' and 'defect couples' in a continuous media. These forces and couples, which can also be called 'material forces' and 'material couples' are related to the work done by a particle moving through a solid. It is shown that the resultant of all the defect forces included in a volume is the Jsub(k) integral computer on the surface surrounding this volume. A similar result is obtained about the moment resultant. Conventional form of the principle of virtual work is not applicable to fractures mechanics because equations of compatibility are not satisfied. A generalized form is given, which is valid when (virtual) crack propagation is considered. The virtual work of 'material' forces is included in the generalized form, and can be used as a new definition of J concept. As an illustration application, a simple procedure is described which allows to obtain the curve J-Δa (the so called J-R curve) from only one experimental test

[en] The paper presents the testing methodology on the CANDU pressure tube specimens (Zr-2.5% Nb alloy) to determinate the fracture mechanics parameters. The crack initiation and subsequent DHC propagation tests were performed on compact-tension (CT) specimens prepared from pressure tube off-cuts. Previously, the CT specimens were subjected to the specific method to increase the hydrogen concentration up to 50 ppm. This process consists of two stages: the first one is the electrolytic disposal of a uniform zirconium hydride layer and, the second one is to apply a homogenization thermal treatment causing the diffusion of hydrogen into the zirconium matrix from the hydride surface layer. The testing temperature was around 280oC, which is the temperature of interest for the pressure tubes operating in CANDU 6 reactor. (authors)

[en] The thermodynamical strength acting on a crack tip, when the unilateral contact between the lips of the cracks is considered, is deduced in this note from energetic formulations. The formula obtained is particularly well suited to numerical computation