6061-T6铝合金薄板剪切试件设计及动态剪切力学特性分析

Shear Specimens and Dynamic Shear Mechanical Properties of 6061-T6 Aluminum Alloy Sheets

车身结构影响了整车的碰撞安全性,其中车身承载部件在碰撞过程中主要表现为剪切失效,因此需要对车身材料的动态剪切力学特性展开研究。为了描述6061-T6铝合金材料在复杂工况下的力学特性,进行了准静态和动态力学性能试验。基于不同应力状态和应变率下铝合金力学性能的测试数据,标定了材料的本构模型和断裂模型参数,并通过对比试验与仿真结果验证了材料参数的准确性。为了实现拉伸试验机开展铝合金薄板剪切试验,设计四种形状的薄板剪切试件,采用数值模拟对比所设计剪切试件的应力及应变分布,并分析不同剪切应变率对6061-T6铝合金材料剪切力学特性的影响规律。结果表明:圆形开口对称试件适用于研究塑性变形阶段的失效断裂,而圆形开口偏置试件适用于研究弹性变形阶段的应力应变关系。在低剪切应变率范围内,6061-T6铝合金无显著的应变率强化效应,然而随着应变率的增加敏感性有所提高。

The body structure is of great significance to the crashworthiness of automobiles,and the load-bearing parts mainly show shear failure during collision.Therefore,it is necessary to study dynamic shear properties of body materials.In order to study the mechanical properties of 6061-T6 aluminum alloy under complex working conditions,quasi-static and dynamic tests were carried out.The parameters of the constitutive and damage models of aluminum alloy were determined based on experiments.By comparing the experimental and numerical simulation result,the accuracy of the material parameters was verified.In order to carry out the shear test of aluminum alloy sheets using the universal tensile testing machine,four kinds of thin-sheet shear specimens were designed.Additionally,the finite element simulation was performed to compare the stress and strain distribution,followed by investigating the influence mechanism of shear strain rates on mechanical properties of 6061-T6 aluminum alloy.The results show that the symmetric circular notched shear specimen is suitable for testing shear fracture strain in plastic stage,while the offset circular notched shear specimen is suitable for testing shear modulus in elastic stage.Moreover,in the case of low shear strain rate,the 6061-T6 aluminum alloy has no significant strain rate effect;however,the sensitivity increases slightly with the increase of strain rate.