滑轨导向式静/动态双轴拉伸实验技术

基于液压伺服高速加载系统，发展了一种材料双轴拉伸力学性能测试技术。利用锥面接触导向驱动方法，把加载锤竖直方向的驱动力转化为水平方向的双轴驱动力，从而实现对十字形试样平面双轴加载。借助有限元数值模拟手段优化了锥面接触角和十字形试样尺寸。当接触锥角为45°时，既有较好的水平驱动转化效率，同时又保持较小的接触力，确保水平驱动加载各组件在弹性变形范围内，可多次重复使用。确定了加载臂狭缝个数、狭缝与减薄区边缘长度和标距段厚度等试样设计关键参数，在十字形试样测试标距段内实现了均匀变形。设计了测力夹持一体化导杆和非接触光学全场应变测试系统，准确获得了试样的应力和应变。利用此平面双轴拉伸加载装置，开展2024-T351铝合金板单轴拉伸实验和激光探测同步性验证实验，验证装置设计的可行性；开展铝合金板材在不同加载速率下的双轴拉伸实验，得到在双轴加载下铝合金板材应力应变曲线，并与单轴加载下实验结果进行了对比分析。

Raft-guided static/dynamic biaxial tensile test technique

Based on the Zwick HTM-5020 hydraulic servo high-speed loading system, a planar biaxial tensile test technique was developed. The biaxial tensile loading device is mainly composed of a cross-shaped cone hammer head, a loading force arm, a cross guide slide rail, and a sample clamping guide rod. The driving force in the vertical direction of the loading hammer is transformed into the horizontal driving force by using the cone contact method, so as to realize the plane biaxial loading of the cruciform specimen. The contact angle of the cone surface and the cruciform specimen geometry was optimized using an Abaqus FEM code. The simulation results show that: (1) when the contact cone angle is 45 °, the horizontal driving conversion efficiency is better and the contact force is smaller than those of others, so that the components loaded by the horizontal driving within the elastic deformation range can be used repeatedly; (2) the key parameters of the cruciform specimen, such as the number of the slits in the loading arm, the length of the slit edge and thinning area, and the thickness of the gauge section, are obtained, so as to realize the uniform deformation of the cruciform specimen in the gauge section. A guide rod integrated measuring force-clamping specimen and a noncontact digital image correlation technique for the measurement of strain were employed in the planar biaxial tensile test device. By using the planar biaxial tensile loading device, the uniaxial tensile test and laser detection synchronicity verification experiment of aluminum alloy plate were carried out to verify the feasibility of the device design. The biaxial tensile tests of the aluminum alloy plates under different strain rates were performed, and the stress-strain curves of the 2024-T351 aluminum alloy sheet under biaxial loading were obtained, which were compared with the results under uniaxial tensile loading.