A simplified computation method of plastic limit load for tee joint containing corner cracks

摘要

First, we introduce the iterative method of the modified elastic compensation method (KtECM) proposed by the authors for plastic limit load analysis of structures containing flaws. Then, plastic limit load of tee joint containing corner cracks under internal pressure is computed by using the KtECM and the elastic-plastic analysis method (EPAM). During computations, we adopt both 3-D tee joint geometry and a simplified plate model to consider through-wall cracks growing along the run pipe — a more dangerous crack growth mode. The errors between the results of the simplified plate models and those of the 3D tee joint models with different methods are within 10%, while the mean time consumed for the simplified plate models with the KtECM is about 20% of that for the 3-D unsimplified tee joint model with the EPAM. Finally, based on the results of the simplified plate model with the KtECM and those of the 3-D unsimplified tee joint model with the EPAM, we establish the empirical relationships between the crack length and the plastic limit load for the tee joint. These results illustrate that the simplified computation method of plastic limit load for tee joint is applicable and efficient for limit load analysis.