[en] This volume contains 81 papers divided into three almost equal parts: Constitutive equations, combined loadings; damage, creep crack growth, creep rupture; structures, analytical and numerical methods, optimal design. (orig.)

[en] The concepts underlying slip theories of polycrystalline materials are implemented for the determination of constitutive equation for composite materials. The creep deformation and an influence of damages are described on the local planes. The area length density of cracks serves as an indicator for the extent of deterioration of the material and may be estimated by the use of stereological methods. (orig.)

[en] A new incremental creep theory of isotropic materials based on the three invariants of stress tensor is proposed. In order to evaluate the constants in the constitutive equations the basic experiments are formulated. Special creep relations that contain less constants and invariants are derived. The approach has been applied to the problem of creep of anisotropic materials with different behaviour in tension and compression. (orig.)

[en] A plane strain cell model is used to analyse the development of intergranular creep fracture in polycrystalline metals at elevated temperatures. Continuous nucleation of cavities and diffusive cavity growth are accounted for in the model, and also the effect of freely sliding grain boundaries is incorporated, while the grains undergo power law creep. The numerical analyses are here mainly employed to focus on the final part of the creep rupture process, when microcracks form and start to link up. (orig.)

[en] The incapacity of global fracture criteria (like K or G) to describe correctly a crack evolution for highly dissipative materials implies the use of local fracture criteria. One of these may be a classical damage law, but a new difficulty appears named 'strain localization' characteristic of strain softening materials. To avoid this problem, it will be necessary to develop a non local damage law introducing a new material intrinsic parameter in the modelization. All these aspects are developed in this paper and illustrated with some significant examples. (orig.)

[en] The effect of compressive stresses upon the creep failure of structures has been analysed in the paper. A combined theory of that by D.R. Hayhurst and J. Lemaitre was used to describe damage evolution, whereas a non-stationary creep theory coupled with damage described the structure deformation. Isochronous limit curves in plane stress state were build, and the clamped and simply supported plates were analysed to demonstrate the influence of compressive stresses. (orig.)

[en] New relation of mechanical constitutive equation for non-linear creep is represented. This one describes non-linear flow and ideal plasticity simultaneously. It is shown that this new relation permits more adequate description of experimental data. There are some examples of using this relation for particular problems of creep in structures. (orig.)

[en] In this paper emphasis is made on the concept of rheonomic nature of inelastic deformation of any type. It is shown that the both processes (creep and plasticity) can get a common description without any inconsistency by the structural model employing (Masing, Besseling and others). Some experimental data concerning the problem are discussed. (orig.)

[en] Kinematic equations of creep theory have been proposed by Yu.N. Rabotnov. Attempts of many researches to state constitutive equations for structural parameters caused discrepancy between theoretical and experimental results in the case of variable step load. We propose to use experimental reload data to define the structural parameters. (orig./MM)

[en] This paper shows the capabilities of the micromechanical approach concerning the description of initial and subsequent yield surfaces of metals. This type of simulation produces significant information concerning the microstructural level giving rise to the hardening: It is shown that kinematic type hardening may come from intergranular or transgranular level, but that the macroscopic properties are different in the two cases. Isotropic hardening has to be modelled on a microscale, by slip interactions. (orig.)