In this paper, the effect of temperature and out-of-plane dynamic moments on ratcheting behavior of pressurized elbows have been investigated. The combined hardening model (Chaboche kinematic hardening model with isotropic hardening rule) is used for the plastic analysis of materials. Piping elbow specimens had temperatures of 50, 100, 150 and 200 °C. By using of many tension–compression-stabilized tests of specimens under symmetric strain-controlled, constant parameters for materials are obtained. The results obtained by the FE method of specimens show that the deformations occurred mainly because of creep at high temperature and ratcheting strain by out-of-plane moments. Also, ratcheting rate increases by increasing moment bending and temperatures. Initial, strain accumulation rate is low, and it increases with the increasing temperatures, which express softening phenomenon due to thermal creep. The strain accumulation is highest along the hoop direction at flanks, similar to results from experimental data without considering temperature effects. The results show that the increase in ratcheting due to high temperature may lead to incontrollable damages to pipework structures. Of course, the prediction of strain accumulation is improved in the presence of isotropic hardening rule.

本文研究了温度和平面外动态力矩对加压弯头棘轮行为的影响。组合硬化模型（具有各向同性硬化规则的Chaboche运动硬化模型）用于材料的塑性分析。管道弯头样品的温度分别为50、100、150和200°C。通过在对称应变控制下使用许多拉伸-压缩稳定的试样测试，可以获得材料的恒定参数。样品的有限元方法获得的结果表明，变形的发生主要是由于高温蠕变和平面外力矩引起的棘轮应变。而且，棘轮速度通过增加弯矩和温度来增加。最初，应变累积率很低，并且随着温度的升高而增加，由于热蠕变而表现出软化现象。在侧面，沿箍圈方向的应变累积最高，与不考虑温度影响的实验数据相似。结果表明，由于高温导致棘齿的增加可能导致对管道结构的不可控制的破坏。当然，在各向同性硬化规则的存在下，应变累积的预测将得到改善。