Papers by Keyword: Elastic-Plastic Behaviour

Abstract: The present work intends to evaluate, using simple, exemplary cases, the importance of a full elasto-plastic analysis in fatigue design. A strain cycling situation (-ε to ε) was modelled with ABAQUS considering two situations: firstly a linear σ vs. ε relationship was assumed, and secondly, the real cyclic σ vs. ε curve was used to model each cycle, which includes a small plastic deformation. The case of change of cross section in a steel shaft subjected to constant torsion and cyclic bending was analysed through finite element modelling using ABAQUS.

Abstract: Steam generator in a nuclear power plant is huge heat exchanger that transfers heat from reactor to make steam to drive turbine-generator. Failure of the steam generator tubes can result in the release of fission products to the secondary side. Therefore, accurate integrity assessment of the cracked steam generator tubes is of great importance for maintaining the safety of the nuclear power plant. This paper provides limit loads for circumferential through-wall cracks in steam generator tubes under combined internal pressure and bending loads. Such limit loads are developed on the basis of three dimensional finite element analyses assuming elastic-perfectly plastic material behavior. As for the crack location, both the top of the tubesheet and U-bend regions are considered. The analysis results can be directly applied to the practical integrity assessment of cracked steam generator tubes, because the comparison between experimental data and FE results shows a very good agreement.

Abstract: The mechanical properties of rock under high temperature and high geostress are the basic and important information to assess the safety of underground engineering. Based on the environmental conditions of the west route of south-to-north water transfer project in western China, experiments are conducted for a sandstone. The experiments are conducted in stress path of hydrostate, pure shear, and conventional triaxial compression at the temperature of 25°C, 50°C and 70°C. The change of strength and average moduli of the rock with temperatures are studied. By cycle loading and unloading tests, elastic and plastic deformation of the rock are decomposed, it is shown that the plastic deformations of the rock are clearly changed with temperature, while the elastic deformation of the rock seems to be unaffected by the temperature. Moreover, based on the associated plastic flow rule, a constitutive law considering temperature is proposed for the sandstone.

Abstract: The behavior of short fatigue cracks is a matter of importance not only because much of the fatigue lifetime is spent in propagating these cracks, but also because the boundary between propagation and non-propagation separates the safe from the potentially unsafe fatigue regimes. The method of analysis is based upon the following equation: