在室温下对聚乙烯(PE100)管分别进行了单轴拉伸试验、扭转对称应变循环试验和单轴棘轮效应试验, 探讨了不同应变速率下PE管的应力-应变响应, 分析了循环应变幅、应变幅历史对应变循环特性的影响以及均值应力和幅值应力及其加载历史对PE100管棘轮变形的影响。结果表明: PE100是一种率相关循环软化材料, 无论应变循环特性还是单轴棘轮行为, 两者都强烈依赖于当前的载荷条件和既往加载历史; PE100管存在产生循环硬化的对称扭转应变幅阈值, 其值为5%, 当PE100管经历大于该阈值的循环后再经历后续小应变幅循环时会发生一定程度的硬化, 但静置后这种硬化现象又会消失, 表现出时效恢复特性。

The uniaxial tension test, cyclic strain test under symmetric torsion and uniaxial ratcheting test were carried out for Polyethylene 100 (PE100) pipe at room temperature. The stress-strain responses of the PE100 pipe under different strain rates were discussed. The effects of cyclic strain amplitude, mean stress, stress amplitude and their loading histories on strain cyclic characteristics and ratcheting deformations of PE100 pipe were studied. The results show that PE100 is a kind of rate-dependent and cyclic softening material. Both strain cyclic characteristic and uniaxial ratcheting behavior were all strongly dependent not only on the current load condition, but also on the prior loading history. There was a threshold value to induce cyclic hardening for PE100 under symmetric torsion, namely 5% torsion strain amplitude. The former cyclic load larger than the threshold value induced cyclic hardening of PE100 under the following smaller load conditions. However such kind of hardening would vanish after standing for some time, indicating recovery ageing effect of PE100.