Zhao P D, Lu F Y, Chen R, Lin Y L, Li J L, Lu L, Sun G L
College of Science, National University of Defense Technology, 410073 Changsha, China.
Rev Sci Instrum. 2011 Mar;82(3):035110. doi: 10.1063/1.3557826.
It is critically important to study the dynamic response of materials under a combined compression-shear loading for developing constitutive laws more accurately and fully. We present a novel technique to achieve the combined compression and shear loadings at high strain rates. The main apparatus consists of a strike bar, an incident bar, and two transmission bars. The close-to-specimen end of the incident bar is wedge-shaped with 90°. In each experiment, there are two identical specimens, respectively, agglutinated between one side of the wedge and one of transmission bars. When a loading impulse travels to specimens along the incident bar, because of the special geometrical shape, the specimen-incident bar interface gets an axial and a transverse velocity. Specimens endure a combined compression-shear loading at high strain rates. The compression stress and strain of the specimens are deduced from signals recorded by strain gages mounted on the bars. The shear stress is measured by two piezoelectric transducers of quartz (Y-cut with rotation angle 17.7°) embedded at the close-to-specimen end of transmission bars; the shear strain is measured with a novel optical technique, which is based on the luminous flux method. An analytic model was proposed and validated by the numerical simulations. The simulation results yield good agreement with the analytic results. The proposed technique was then validated through experiments carried out on lead specimens, by comparing experimental results with that of the split Hopkinson pressure bar experiments.
为了更准确、全面地建立本构关系，研究材料在压缩 - 剪切复合载荷作用下的动态响应至关重要。我们提出了一种在高应变率下实现压缩和剪切复合加载的新技术。主要装置由一根撞击杆、一根入射杆和两根透射杆组成。入射杆靠近试样的一端为90°楔形。在每次实验中，有两个相同的试样，分别粘结在楔形的一侧和一根透射杆之间。当加载脉冲沿入射杆传播到试样时，由于特殊的几何形状，试样 - 入射杆界面会获得一个轴向速度和一个横向速度。试样在高应变率下承受压缩 - 剪切复合载荷。试样的压缩应力和应变由安装在杆上的应变片记录的信号推导得出。剪切应力由嵌入在透射杆靠近试样一端的两个石英压电传感器（Y切割，旋转角度17.7°）测量；剪切应变采用基于光通量法的新型光学技术测量。提出了一个解析模型，并通过数值模拟进行了验证。模拟结果与解析结果吻合良好。然后通过对铅试样进行实验，将实验结果与分离式霍普金森压杆实验结果进行比较，验证了所提出的技术。
