Abstract
In this analysis results of Elastic-plastic stress distributions in a spherical pressure vessel with ThermoMechanical loads are discussed. Results of study are obtained with Finite element (FE) analysis. A quarter of pressure vessel is considered and modeled with all realistic details. In addition to presenting the stress distribution of the pressure vessel, in this work the effects thermo-Mechanical autofrettage on different limit strength for spherical pressure vessels are investigated. The effect of changing the load and various geometric parameters is investigated. Consequently, it can be observed that to be the significant differences between the present thermo-Mechanical autofrettage and earlier (Mechanical autofrettage and Thermal autofrettage) method of autofrettage for the predictions of Elastic-plastic stress distributions of spherical pressure vessels. Some realistic examples are considered and results are obtained for the whole vessel by applying thermal load and mechanical load. The actual material curve is used for loading, unloading and residual stress behavior of spherical pressure vessel. Kinematic hardening material is considered and effect of Bauschinger effect factors are studied with thermo-mechanical load. Equivalent Von -Mises yield criteria is used for yield criteria. Behavior of elastic-perfectly plastic is also studied and compared. Influence of Thermo-Mechanical autofrettage over stress distribution and load bearing capacity of spherical vessel is examined. The question of whether Thermo-mechanical autofrettage gives more favorable residual compressive stress distribution and therefore extension of pressure vessel life is investigated in this analysis.
Highlights
THEORETICAL CONCEPTThe elastic stresses for the combined loading problem are a superposition of the elastic stresses in the innersurface pressurization problem
There have been bountiful study on the analysis of residual stresses and deformation for thick-walled cylindrical and spherical vessel subjected to Autofrettage process[1-21]and Re- autofrettage process [22-24].Some researchers [25-30] further extended their work for Fatigue life of autofrettaged vessels
Thermal stress analysis of cylindrical vessels and spherical vessels for elastic range were discussed by several authors [31-33].It is observed that most of the previous work related to Autofrettage had been done based on the mechanical load
Summary
The elastic stresses for the combined loading problem are a superposition of the elastic stresses in the innersurface pressurization problem. If an internal pressure P is applied along with the thermal gradient, the stresses in the elastic sphere are expressed by the sum of Mechanical stress and thermal stress. Fig.[1] shows loading and unloading of a Kinematic hardening material. The radial and tangential stresses for sphere r and must satisfy the equilibrium equation, d r dr
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