中文摘要：

对建筑用PTFE（聚四氟乙烯）膜材进行了5种温度（23,40,50,60,70℃）下的单轴应力松弛试验,考虑了初始拉伸速度（2,5,10,20 N/s）对于膜材应力松弛性能的影响,分析得到了材料的松弛模量变化规律,采用几种常见的粘弹性本构关系模型对试验曲线进行了拟合对比分析.研究发现PTFE膜材表现出了明显的应力松弛特性,且受温度和初始拉伸速度影响较明显;随温度的增加,膜材的应力松弛速度越快,最终稳定应力值越大;随着初始拉伸速度的增加,最终稳定应力值越小,应力松弛速度基本相同;大部分粘弹性本构关系模型能够对PTFE膜材的应力松弛行为做出较好的预测,少量模型预测效果较差,这主要与本构关系模型的组成形式有关系.

英文摘要：

With the PTFE membranes as the research object,the uniaxial stress relaxation tests were carried out respectively under 5 temperatures（23,40,50,60,70 ℃） and at 4 initial tensile rates（2,5,10,20 N /s）,and the effects of these 2 kinds of factors on the stress relaxation properties of the membranes were investigated.The variations of the relaxation moduli were got and several existent viscoelastic constitutive models were used to fit the experimental data.The results show that,the PTFE membranes exhibit obvious stress relaxation behaviors.Both the temperature and the initial tensile rate have significant effects on the stress relaxation characteristics.The membrane stress relaxation rate decreases while the final steady stress increases with the temperature;on the other hand,the final steady stress decreases with the initial tensile rate while the stress relaxation rate keeps almost unaffected.Most of the existent viscoelastic models,esp.the fractional exponent one,make good predictions for the stress relaxation behaviors of the PTFE membranes,while some models work ill due to their poor compositions.