An Approximate Method of Determining the Load of Plastic Failure in Pressure Vessels with Nozzles

Resumo

An approximate approach for determining the load of plastic failure (burst load) in pressure vessels with nozzles through calculation of the maximum of the characteristic loading curve of the structure (where the load is the maximum intensity of plastic strain) constructed with the use of restrained nonlinear finite element analysis and the theory of approximation of curves is proposed. Two methods of approximation of the characteristic curve are considered: elliptic approximation and approximation with the use of a quadratic polynomial. Analytical formulas for determining the value of the burst load are obtained for both methods. Estimation of the burst pressure for an experimental model of a vessel with a radial nozzle is presented as an example. A comparative analysis of a calculation of the burst pressure using formulas obtained for different choices of base points for the approximation and different values of the burst pressure obtained from the full nonlinear finite-element analysis for the experimental model is performed. It is shown that an approximation of the burst pressure can be achieved with a sufficient degree of accuracy on the basis of a limited volume of computed results with moderate computational costs.