PE100管的室温单轴应变循环行为与棘轮效应
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摘要
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.
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.
引文
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[2]康国政,李友国.中碳贝氏体钢的室温单轴循环变形行为研究[J].工程力学,2007,24(4):173-177.
[3]李钊,刘宇杰,康国政.退火和调质42CrMo合金钢单轴循环塑性行为的实验研究[J].固体力学学报,2007,28(1):77-82.
[4]蔡立勋,刘宇杰,叶裕明,等.T225NG钛合金的单轴棘轮行为研究[J].金属学报,2004,40(11):1155-1164.
[5]高庆,康国政,杨显杰.304不锈钢室温单轴循环棘轮行为的粘塑性本构描述[J].固体力学学报,2002,23(2):167-171.
[6]XU Wen-juan,GAO Hong,GAO Li-lan,et al.Tensile ratcheting behaviors of bronze powder filled polytetrafluoroethylene[J].Front Chem Sci Eng,2013,7(1):103-109.
[7]张喆.聚四氟乙烯室温下单轴和多轴循环变形实验研究[D].天津:天津大学,2007.
[8]DROZDOV A D,CHRISTIANSEN J C.Cyclic viscoplasticity of high-density polyethylene:Experiments and modeling[J].Computational Materials Science,2007,39:465-480.
[9]BERGSTR J S,KURTZ S M,RIMNAC C M,et al.Constitutive modeling of ultra-high molecular weight polyethylene under largedeformation and cyclic loading conditions[J].Biomaterials,2002,23:2329-2343.
[10]LEMAITRE J,CHABOCHE J L.固体材料力学[M].余天庆,吴玉树译.北京:国防工业出版社,1997:28-32.
[11]高炳军.材料多轴棘轮效应本构描述及压力管道棘轮效应预测[D].天津:天津大学,2005:24-27.