推进剂粘弹性泊松比测试的数字图像相关方法

Digital image correlation method for measuring viscoelastic Poisson's ratio of propellant

固体推进剂是典型的粘弹性材料,其泊松比是时间的函数,相关标准中基于接触式测量方法的结果将推进剂泊松比视为常数,影响了药柱结构完整性分析的精度。针对此问题,推导了粘弹性泊松比的松弛型定义,提出了一种基于数字图像相关方法的固体推进剂泊松比高精度测量方法,研制了相应的测试系统,并测量了某HTPB推进剂的粘弹性时变泊松比。评估试验显示该测试系统的应变测量精度可达20με,有效解决了推进剂泊松比千分位测不准的难题。结果表明,推进剂泊松比随松弛时间的增加而增加,具有明显的粘弹特性。所提方法可为粘弹性材料泊松比的高精度测量提供参考。

Solid propellant belongs to typical viscoelastic material,whose Poisson＇s ratio is the function of time. However,the occupation standards regard the propellant Poisson＇s ratio as a constant with the contact measurement,which have a bad influence on the accuracy of structural integrity analysis for grain. In this study,a relaxation definition of the viscoelastic Poisson＇s ratio was derived. A high precision measuring method for propellant Poisson ＇s ratio based on Digital Image Correlation（ DIC） method was proposed. Using this method,a measuring system for propellant Poisson ＇s ratio was developed,and the time-varying viscoelastic Poisson＇s ratio of a certain HTPB propellant was measured. Test results show that the strain measuring accuracy of the system attains20 με,which can solve the problem of milli-measuring inaccuracy for solid propellant Poisson ＇s ratio. The results show that the Poisson＇s ratio increases with the time increasing,which exhibits obviously viscoelastic property. The present method is available for the noncontact measurement of other viscoelastic materials.