基于激光干涉测试技术的分离式Hopkinson压杆实验测试系统

分离式Hopkinson压杆（SHPB）实验的传统测试技术是基于应变片的电测技术，测试结果的可靠性强烈依赖于应变片与杆之间粘贴质量，受到人为因素的影响较大。本文中采用基于多普勒频移原理的双探头全光纤激光干涉测速技术，以粒子速度为监测目标，借助应力波传播理论，换算成试件的应变和应力，从而建立了SHPB实验的非接触光学测试系统。针对韧性和脆性两类材料，分别提出了激光正入射和激光斜入射两种测试技术。再以铝合金和PZT陶瓷为例，通过与传统的应变片测试结果以及DIC测量结果的对比分析，验证了两种测试技术的有效性。与传统的应变片测试技术相比，新的激光干涉测试技术具有免标定、抗干扰、可靠性高等许多优点，有助于实现SHPB实验测试系统标准化。

Measurement system for split Hopkinson pressure bar apparatus based on laser interferometry technique

Conventional measurements in SHPB are based on recording the strain profiles on the incident and transmitted bars with strain gauges, and require good adhesion between the strain gauge and bars, which strongly depends on the skill of an operator. In this paper, the all fiber laser interferometry technique with two fiber focusers based on the principle of Doppler frequency shift is used to establish a non-contact optical measurement system for SHPB. The monitoring objective of the new measurement system is the particle velocity that can be easily converted into strain and stress by means of stress wave propagation. For the ductile and brittle materials, two measurement methods by using of laser normal irradiation and laser obliqueirradiation were proposed, respectively. Taking aluminum alloy and PZT ceramics as examples, the validity of the two optical measurement systems was verified by comparing with the traditional SHPB measurement results and the DIC measurement results. The laser interferometry technique has several advantages over traditional strain gauge measurements. It is non-calibrating, high repeatable and high reliability, which is helpful to realize the standardization of SHPB measurement system.