温度⁃应力耦合下聚四氟乙烯压缩蠕变行为及本构描述

CREEP BEHAVIOR AND CONSTITUTIVE DESCRIPTION OF POLYTETRAFLUOROETHYLENE UNDER TEMPERATURE-STRESS COUPLING

聚四氟乙烯(Polytetrafluoroethylene,PTFE)具有耐高低温、耐化学腐蚀和高热稳定性等优点,已成为工业领域中不可或缺的密封材料,其压缩性能对密封结构的安全服役至关重要。通过对PTFE开展压缩试验和压缩蠕变试验,研究PTFE在不同温度下的压缩性能,探究应力、温度对蠕变行为的耦合影响规律。研究结果表明,PTFE的压缩屈服强度和压缩模量随温度的升高而降低。压缩蠕变性能受到温度和应力的耦合影响,在相同温度下,随着应力的增加,PTFE的瞬时应变和蠕变速率增加。在相同应力下,随着温度的增加,压缩模量降低,分子能量和自由体积增大,从而PTFE的瞬时应变和蠕变量增大,总应变也增大。最后,采用Burgers模型、Findley模型和时间硬化模型对PTFE在不同加载工况下的蠕变行为进行了分析,发现Burgers模型和Findley模型可以较好地描述PTFE在不同温度下的蠕变行为。本研究可以为PTFE压缩蠕变性能的密封结构设计及工程应用提供理论指导和数据支撑。

Polytetrafluoroethylene(PTFE)has the advantages of high and low temperature resistance,chemical corrosion resistance and high thermal stability,and has become an indispensable sealing material in the industrial field.Its compression performance is crucial to the safe service of the sealing structure.By carrying out the compression experiments and compression creep experiments on PTFE,the compression properties of PTFE at different temperatures were studied,and the coupling effect of stress and temperature on creep behavior was explored.The results show that the compressive yield strength and compressive modulus of PTFE decrease with the increase of temperature.The compression creep performance is influenced by the coupling of temperature and stress.At the same temperature,the instantaneous strain and creep rate of PTFE increase with the increase of stress.Under the same stress,as the temperature increases,the compressive modulus decreases,the molecular energy and free volume increase,resulting in an increase in the instantaneous strain and creep of PTFE,and an increase in the total strain.Finally,the Burgers model,Findley model,and Time-Hardening model were used to analyze the creep behavior of PTFE under different loading conditions.It was found that the Burgers model and Findley model can better describe the creep behavior of PTFE at different temperatures.This study can provide theoretical guidance and data support for the design and engineering application of sealing structures that consider the compressive creep performance of PTFE.