聚氨酯泡沫材料的高温蠕变特性

摘要

在不同温度、应力条件下对聚氨酯泡沫进行蠕变实验研究,用Modified Time Harding模型对获得的蠕变-时间关系曲线拟合,得到高温条件下聚氨酯泡沫的蠕变本构方程.将拟合的模型及实验测得的稳态阶段的蠕变速率进行比较,发现聚氨酯高分子材料的蠕变特性与温度、应力水平有着重要的联系.随着温度的升高,应力水平的提高,材料的蠕变行为更加显著.高温蠕变曲线分为两个阶段:第一阶段,蠕变速率较大,且随着时间的增长,蠕变速率逐渐下降;第二个阶段,蠕变速率较小,且基本保持恒定.Modified Time Harding模型能够较好地预测聚氨酯材料在高温条件下的蠕变速率.%Under different temperature and different stress conditions,the creep experiment of polyurethane foam was carried out,and the creep constitutive equation of polyurethane foam under high temperature was obtained by fitting the obtained creep-time curve with Modified Time Harding model.Comparing the steady state creep rate fitted by model with the steady state creep rate measured by experiment,it is found that the creep property of polyurethane polymer has an important relationship with temperature and stress level.As the temperature and the stress level increases,the creep behavior of the material is more pronounced.The creep curve at high temperature is divided into two phases.In the first phase,the creep rate is larger and the creep rate gradually decreases with time.In the second phase,the creep rate is small and remains basically constant.Modified Time Harding model can better predict the creep rate of polyurethane materials under high temperature conditions.