玻璃纤维增强塑料低温收缩率的测量

以二级G-M制冷机为冷源建立了15~293K温区的应变测量系统.采用应变片法测量了材料低温收缩率,分析并修正了低温下卡玛箔应变片电阻和灵敏系数变化对测量结果的影响.通过测量304不锈钢收缩率并与标准值比较,验证了系统测量的准确性且得出灵敏系数的修正系数随温度的变化关系.随后测量Al6061-T6的收缩率并与标准值对比,两者最大偏差为-4.8%,验证了修正系数的合理性.最后测量了玻璃纤维质量分数为70%的玻璃纤维增强塑料(GFRP)横向和纵向的收缩率.结果表明:同一温度范围内GFRP横向应变值为纵向应变值的1.12倍.

Thermal Contraction Measurement of GFRP at Low Temperature

Abstract： An experimental system based on a two stage G M cryocooler was built to measure the thermal contraction from 15K to 293 K. The thermal contraction of the material at low temperature was measured by using the strain gauge method. The effects of variation of the resistance and gage factor (Ks) of karma foil strain gauge at low temperature on the measurement were analyzed and eliminated. The experimental thermal contraction of 304 stainless steel was first measured and compared with standard data to verify the reliability of the measurement and to obtain the correction coefficient (η′) of Ks at different temperatures. Then, the thermal contraction of Al6061 T6 was measured and compared with standard data, and the maximum deviation is -4.8%, which proved that η′ was reasonable. Finally, the transversal and longitudinal thermal contraction of GFRP (glass fiber weight content of 70%) was measured at different temperatures. The experimental results show that the transversal thermal contraction of GFRP is approximately 1.12 times of the longitudinal thermal contraction in the same temperature range.