聚甲基丙烯酸甲酯的冲击破碎扩散特性  

Deformation evolution and diffusion characteristics of polymethyl methacrylate under impact loading

作　　者：苗春贺 袁良柱 陆建华 王鹏飞[1] 徐松林[1,2] Miao Chun-He;Yuan Liang-Zhu;Lu Jian-Hua;Wang Peng-Fei;Xu Song-Lin(CAS Key Laboratory for Mechanical Behavior and Design of Materials,University of Science and Technology of China,Hefei 230027,China;United Laboratory of High-Pressure Physics and Earthquake Science,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国科学技术大学,中国科学院材料力学行为和设计重点实验室,合肥230027 [2]中国地震局地震预测研究所,高压物理与地震科技联合实验室,北京100036

出　　处：《物理学报》2022年第21期245-253,共9页Acta Physica Sinica

基　　金：高压物理与地震科技联合实验室室开放基金(批准号:2019HPPES01);国家自然科学基金(批准号:11672286,11872361,11602267)资助的课题。

摘　　要：应用霍普金森压杆(SHPB)实验装置,通过改变透射杆为钢杆和铝杆,对立方体聚甲基丙烯酸甲酯(PMMA)试样和两种梯台PMMA试样进行动态压缩实验.利用高速摄影记录试样的压缩过程,并结合力位移曲线分析试样的破碎过程,探讨了冲击载荷作用下PMMA试样变形和广义扩散阻力的演化.结果表明:试样的破坏模式主要为接触端局部产生失效阵面,然后失效阵面向试样内部扩展.立方体试样在低速冲击下,失效阵面优先在透射端产生;在高速冲击下,失效阵面在入射端先产生.通过改变试样形状和透射杆材质后,阵面的产生存在明显的弛豫现象,并且失效阵面仅在入射端产生.梯台试样破碎前的压缩变形是非均匀的,试样内部应力状态和变形状态随着截面增加逐渐变小,并且呈线性扩散分布.通过应变分布结合剪切激活扩散方程,得到失效阵面扩散过程中的广义扩散阻力分布情况;失效阵面前后广义扩散阻力先增加后减小,阻力的幅值与局部应变能的释放有关.Dynamic compression experiments on cubic polymethyl methacrylate(PMMA)specimens and two kinds of trapezoid PMMA specimens are carried by changing the transmission bars into steel bar and aluminum bar on the experimental device of split Hopkinson pressure bar(SHPB).The compression processes of PMMA specimens are recorded by high-speed photography,and the breakage processes of PMMA specimens are analyzed based on the force displacement curves and high-speed images.The evolutions of deformation and diffusion resistances of PMMA specimens under impact loading are discussed.The results show that the failure of the sample is caused mainly by the partial failure front at the contact end,and then the failure front propagates to the inside of the sample,leading the sample to break.The failure front of cubic sample is generated preferentially at the transmission end under low speed impact and at the incident end under the higher speed impact.After changing the shape of the specimen and the material of the transmission bar,the relaxation phenomenon is prominent,and the failure front occurs only at the incident end.The compressive deformation of the trapezoid sample before breakage is non-uniform,and the stress and strain in the sample gradually decrease with the increase of the cross section,and show a linear diffusion distribution.The strain distribution and shear activation diffusion equation are used to obtain the generalized diffusion resistance distribution of the failure front.The generalized diffusion resistance increases first in front of the failure front and decreases after the failure front,and the amplitude of the generalized diffusion resistance is related to the release of local strain energy.

关 键 词：冲击动力学 应力调整 聚甲基丙烯酸甲酯 应力扩散 

分 类 号：TQ317[化学工程—高聚物工业]