تلخیص
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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