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# Elastic-plastic analysis of pressure vessels

Updated: Aug 22, 2021

Solving the problems of pressure vessels is followed by two approaches:

1) Elastic approach

2) Elastic-plastic approach which is also called elastic-plastic approach, sometimes also called plastic approach.

In this article, we intend to get acquainted with Elastic-plastic approach. Pressure vessels analysis by plastic method is more accurate than elastic method and in this method, the actual strain stress behavior of the part is used for analysis. The only negative point in the method of elastic-plastic analysis of pressure vessels. There is a fact that this method is more time consuming and more difficult to analyze. In the elastic-plastic analysis, which must be solved using finite element techniques, the following must be considered: a) Hardening must be considered to increase the accuracy of solving the behavior of the material, but to simplify the problem, the behavior can be assumed to be complete plastic. B) The strain-time relationship must be of the Large Deformation type. C) In suitable places such as the junction of the nozzle to the shell and used appropriate mesh.

### Steps for Elastic-plastic analysis of pressure vessels

1) Modeling the part and defining the type and intensity of loading 2) Applying Boundary Conditions 3) Selecting the actual stress-strain model of the material based on the hardening property. 4) The problem should be considered on Large Deformation. 5) Consider loading the time function. 6) The last step in the elastic-plastic analysis of pressure vessels is to solve the problem in a CAE simulator software such as Abacus software.Ismodeled. The resulting stress should be less than the final stress of the material and prevent the material from entering the damaged area. In the next scenario, it is possible that after simulating and analyzing the elastic-plastic analysis of pressure vessels, the resulting stress was greater than the final stress, so in this open case we have to redesign the pressure vessel and increase the thickness of the tank shell step 1 Follow up to 6 again so that the stress created in the tank is less than the final stress of the material.

### Investigation of a practical example of elastic-plastic analysis of pressure vessels

Assuming that there is a pressure vessel and want to check if the existing stress is less than the final limit, the material stress or not?

According to the concepts of material strength, it is not possible to obtain the amount of stress in the area under discussion and proceed with the analysis. Therefore, it is here that you have to decide on the accuracy of the design of the pressure vessel using finite element techniques and validation of the results obtained from the analysis . The correct design, which here we mean the minimum thickness used in the tank, is based on the fact that the answers you get from the finite element analysis are convergent, in other words, the stresses in the tank with a significant safety factor (Safety Factor) of The final stresses of the material should be less to prevent the phenomenon of failure in pressurized tank.

***The content of this article is taken from web open source. The blogs are intended only to give technical knowledge to young engineers. Any engineering calculators, technical equations and write ups are only for reference and educational purpose.*