基于弹性补偿有限元法的无梁岔管安全评价

引入承载比和广义屈服准则，提出基于弹性补偿有限元法的无梁岔管安全评价方法，该法根据塑性极限分析原理，先利用承载比改进采用无量纲内力表达的板壳单元广义屈服准则，扩展了广义屈服准则的适用范围，同时利用弹性补偿有限元法设置了单元弹性模量调整的广义应力阈值，改进了传统弹性补偿法的收敛问题，提高了板壳结构极限分析的精度。方法的可靠性通过3个算例得到验证。在此基础上，对某大型水电站的四通无梁岔管通过求解岔管的壳体安全系统和破坏模式进行安全评价。实际应用表明，弹性补偿有限元法可应用于结构极限分析，其收敛性、计算精度和稳定性均较好，可用于无梁岔管的安全评价。

Safety evaluation of shell type bifurcated pipes using elastic compensation finite element method

By, introducing the load-beating ratio and generalized yield criteria, a new safety evaluation method of shell type bifurcated pipes using elastic compensation FEM is suggested. According to the theory of plastic limit analysis, the generalized yield criteria of thin shell and plate expressed by dimensionless parameters is modified by load-beating ratio, which extends the applied range of generalized yield criteria. The elastic compensation finite element method is also used to set the threshold of generalized stress to overcome the problem of divergence and improve the accuracy of calculation. The validity of the proposed method is verified by 3 classical calculation examples. On this basis, the method is applied to evaluate the safety of a four-way shell type bifurcated pipe and predict its failure mode. The result verifies that this method has good accuracy, stability and convergence rate.