Papers by Keyword: Creep Analysis

Abstract: The effect of non-rigid motion on creep analysis for cylinders have been investigated. inner surface of the cylinder is exposed to a uniform heat flux and for cooling the outer surface of the cylinder an air steam is applied to it. The cylinder is subjected to a body force. That produced by rotating cylinder about its own axis. It is assumed the cylinder is not rigid. Therefore, using equations of equilibrium, stress–strain and kinematic equation, governed equation which includes redial displacement and creep strains, is obtained. The material creep constitutive model is defined by the Bailey-Norton time-dependent creep law. From a solution consisting of analytical solution and iteration method has been used to obtain history of stresses and deformations during creep evolution of rotating cylinders. Therefore, Prandtle-Ruess equation substituted in equilibrium equation in the rate form, the radial displacement rate is obtained for plane strain condition. To investigate the effect of non-rigidity, the non-rigidity parameter (ζ) is defined and its effect on the creep behavior of the structure is investigated. It was revealed that Considering the structure as rigid does neglect the amount of stresses and radial displacement. History of stresses and displacement during 20 years are studied and it is observed that the changes have not accrued in recent years. The effect of velocity is another parameter that is investigated its effect on structural behavior during the time. it was revealed that, velocity has significant effect on structural behavior which cause trend of variation behavior change from linear to polynomial curve.

Abstract: Creep is one of important properties of polymer matrix composites (PMC).It can be analysis by finite element method (FEM).But creep will be affected by a lot of factors and the creep material parameters are very difficult to be obtained. Shift factors method is one simple method which can be used to obtain the creep properties by fewer tests. Here the basic method analysis of the creep of PMC by FEM was studied. Focus on the analysis of how the material parameters of finite element creep analysis needed to get through the shift factors method. Finally the actual PMC pipe structure is calculated by this method.The error of FEM result and theory result around 2%, the results show that this method has certain rationality and reliability.

Abstract: This paper presents the development of a new boundary element formulation for analysis of fracture problems in creeping materials. For the creep crack analysis the Dual Boundary Element Method (DBEM), which contains two independent integral equations, was formulated. The implementation of creep strain in the formulation is achieved through domain integrals in both boundary integral equations. The domain, where the creep phenomena takes place, is discretized into quadratic quadrilateral continuous and discontinuous cells. The creep analysis is applied to metals with secondary creep behaviour. This is con…ned to standard power law creep equations. Constant applied loads are used to demonstrate time e¤ects. Numerical results are compared with solutions obtained from the Finite Element Method (FEM) and others reported in the literature.