Creep Life Estimation of Thick Tube Subjected to Elastic-Plastic-Creep Damage using Uniaxial Strain Energy Density and Multiaxiality Parameter

摘要

Engineers are often challenged to meet the ever-increasing demands Of designing and assessing lifespan of equipment operating in the creep regime. These demands range from achieving excellence in performance to satisfying stringent requirements and eventually to economic ramifications of a component failure. The present paper demonstrates the application of a previously developed creep life prediction model by authors to predict the failure time of a component made of 0.5%Cr-0.5%Mo-0.25%V low alloy steel when the material is subjected to elastic-plastic-creep damages. Elastic-creep analysis as well as elastic-plastic-creep analysis was employed to predict the creep lifetime of thick-walled cylindrical pressure vessel and a comparison was made of results to the experimental life. Creep life of the component was also calculated using the reference stress method and Robinson's fraction rule to compare the results with new method as well as with the experimental results. This paper addresses gross creep deformation/rupture and studies the problem from the macroscopic (engineering) point of view and not from the microscopic (material science) point of view. The pressure vessel was analysed first with an open end and end traction to simulate the test condition, and then with an end cap as it was tested in the experiment. The paper shows that the proposed model can predict the elastic-plastic-creep life of the vessel with an error of less than 3%.