芯轴导向结构对薄壁管轴向剪切加载的影响

Influence of mandrel guide structure on axial shear loading for thin-walled tubes

剪切实验过程中保持试件测试剪切面的稳定性是获得具有实用价值剪切实验数据的关键,管材轴向剪切实验中施加剪切力的半芯轴结构形式是管材试件能否处于最佳剪切状态的重要影响因素。针对外径为Φ50 mm、壁厚为1.2 mm的5052薄壁铝合金管材开展了轴向剪切加载研究,对比分析了有无导向结构的管材轴向剪切装置对剪切区应力状态的影响。采用数字视觉采集系统测量了剪切区的应变分布,结果显示轴向剪切试件在剪切区中心点的剪应变最小,并向剪切区两端逐渐增大。增加导向结构后,剪切区宽度减小,变形更集中地发生在预设剪切面,剪切区端部与中心点的差值减小,提高了剪应变分布的均匀性与剪切力学性能的测试精度。

During the shear test,maintaining the stability of the shear plane for specimen is the key to obtain the shear test data with practical value,and in the axial shear test of tubes,the semi-mandrel structure that applies shear force is an important factor affecting whether the tubes can be in the best shear state.Therefore,for thin-walled 5052 aluminum alloy tube with the outer diameter ofΦ50 mm and the wall thickness of 1.2 mm,the axial shear loading research was conducted,and the influences of the tube axial shear device with or without a guide structure on the stress state of shear zone were compared and analyzed.Furthermore,the strain distribution in the shear zone was measured by the digital image correlation system.The results show that the shear strain in the center of shear zone for the axial sheared specimen is the smallest,and gradually increases towards the two ends of shear zone.After adding the guide structure,the width of shear zone decreases,the deformation is more concentrated on the preset shear plane,and the difference between the end and center point of shear zone decreases,which improves the uniformity of shear strain distribution and the test accuracy of shear mechanical properties.