温度、应变率对航空PMMA压缩力学性能的影响研究

本文利用INSTRON试验机和分离式Hopkinson压杆测试了航空有机玻璃在试验温度为299K～373K之间,两种准静态应变率(10-3,10-1 1/s)和一种动态应变率(550 1/s)下的压缩力学行为.试验结果表明:在准静态载荷下,随着温度的升高,材料的弹性模量和流动应力减小,在应变率为10-1 1/s时表现出明显的应变软化行为;在高应变率(550 1/s)下,随着温度的升高,材料的流动应力逐渐减小而破坏应变增大,当温度超过333K时也有应变软化现象发生;在相同温度下,随着应变率的升高,材料的流动应力增大,但破坏应变减小.通过观察变形后试样的形貌,可以认为试样内部的微裂纹是应变软化的主要原因.最后,ZWT粘弹性本构模型被用来对试验数据进行拟合,结果表明该模型能够较好地预测这种材料在应变8%以内的力学行为.

Study on Temperature and Strain Rate Effects on Mechanical Behavior of Aeronautical PMMA

In this paper,the mechanical behavior of a PMMA used as the windshield of aircraft was tested.The experiments were finished under two quasi-static strain rates by using an Instron servo hydraulic axial testing machine and a high strain rate by using compression Hopkinson bar with the testing temperature from 299K to 373K.The results show that the mechanical properties of this PMMA depend strongly on the testing temperature.The Young's modulus and flow stress were found to decrease with increasing temperature at low strain rate.At the strain rate of 10~(-1) 1/s,strain soften was observed under all experiment temperatures.At high strain rate,with the temperature increase,the flow stress deceases remarkably while the failure strain increases,and the strain softening was also observed at the temperature above 333K.Compared the experiments results at same temperature,it was found the flow stress increases with the rising strain rate.The predictions of the mechanical behavior using ZWT model have a good agreement with experimental results in the strain range of 8%.