Abstract
Experimental prediction and evaluation of thermal fatigue is an uneconomical and time consuming procedure. Thermal fatigue has been one of the major causes in reducing life of thick walled pressure vessels working at high temperatures. To increase thermal fatigue resistance of materials, a Finite Element Model has been proposed which includes the effect of autofrettage on thermal fatigue resistance of AISI 4340 Stainless Steel thick walled cylinder. These simulations are verified using an analytical model selected from previous studies and by simulating a cracked specimen model. FEA model takes into account different boundary conditions and material parameters such as coefficient of thermal expansion, density, heat conductivity, elastic modulus and yield stress for thermal stress calculations. Simulations were performed in Abaqus 14. Cylinder model was pressurized internally with five different constant internal pressure values to cause plastic deformation on inner side of the wall. Effect of this pressure on hoop stresses and plasticity of the material was determined. Another cracked specimen model was simulated for validation of proposed autofrettaged model and to observe whether it is reliable for increasing thermal fatigue resistance of thick walled cylinders. These results were then compared to the analytical model and it was observed that both analytical and simulation results showed fair conformance. This model can, therefore, be used for future studies for predicting and evaluating how autofrettage can be used for increasing thermal fatigue resistance of thick walled cylinders for space applications at high temperatures.

M. Latif, F. Qayyum, M. Z. Khan, M. R. Shah. (2017) Demonstrating the Effects of Autofrettage on Thermal Fatigue Resistance of Thick Walled Cylinder Using Finite Element Simulations for Space Applications, Journal of Space Technology , Volume 7, Issue 1.
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