功能梯度多层金属板的冲击行为研究

发布时间：2018-02-28 20:06

本文关键词： 功能梯度多层金属板双剪切试验穿甲试验表面机械研磨 Hopkinson杆　出处：《西北工业大学》2015年博士论文　论文类型：学位论文

【摘要】：针对航空航天飞行器、高速列车和汽车发生撞击时,耐撞结构的抗坠撞或碰撞设计问题以及防弹衣的抗冲击性能等问题(例如,功能梯度多层金属材料应用于汽车防撞结构中遇到的冲击问题等),本文研究了由表面机械研磨处理方法得到的功能梯度多层金属板在动态双剪切和反向穿甲条件下的力学响应,旨在研究梯度材料在动态加载条件下的力学特性和抗穿甲能力。本文的主要研究内容包括以下几个方面:(1)功能梯度多层金属板的双剪切试验技术研究。首先,为了实现功能梯度多层金属板的动态双剪切力学性能的测试,系统地分析了大直径Hopkinson杆在实验测试中的误差问题及其解决途径,设计了可进行双剪切试验的试样和夹具。其次,采用表面机械研磨方法制备了功能梯度多层板的剪切试样,利用万能试验机和Hopkinson压杆进行了在准静态和动态加载下的双剪切试验,分析了平面剪切等效应变和等效应力的计算公式;最后,对双剪切动态和准静态的试验结果进行了对比分析。(2)双剪切试验的数值模拟。为了更加详细地描述双剪切试验过程和得到更为准确的试验数据,采用ABAQUS有限元软件,系统地研究了剪切区域内的应变和应力状态,分析了剪切区域长度对模拟结果的影响,得到了夹具装置对剪切区域的变形均匀性的影响规律。分析了大变形剪切时,有限元软件中对名义应变的定义。研究结果表明,在数值模拟中,可由累积欧拉应变法计算等效应变和由柯西应力法计算等效应力。(3)多层金属功能梯度材料中各层材料本构参数的研究。通过梯度不锈钢板的压痕试验,得到了试样沿厚度方向上的梯度分布规律。采用加权平均的方法,得到了每一个梯度层的弹塑性本构关系表达式。采用数值模拟的方法,构建了弹塑性延性破坏数值模型,得到了每一个梯度层的破坏应变。(4)功能梯度多层金属板抗穿甲特性的研究。制备了具有功能梯度的试样,设计了试验夹具,分别采用MTS810静态试验机和改进的Hopkinson压杆实验装置,对制备的试样进行了准静态和冲击载荷下的穿甲试验,并结合试验结果进行了穿甲的数值模拟。得到了两种加载条件下的穿甲位移和穿甲力曲线,通过穿甲模拟验证了该梯度材料中每一个梯度层的破坏应变。最后,分析了经过表面机械研磨处理的材料的应变率敏感性,对比研究了经过表面机械研磨处理的靶板和未经过表面机械研磨处理的靶板的抗穿甲能力。(5)材料梯度的优化设计。采用ABAQUS/Explicit数值模型,分别从梯度分布和铺层顺序两个方面对梯度靶板进行了优化设计,评估了梯度靶板的吸能效果和抗穿甲能力。
[Abstract]:For aerospace vehicles, high-speed trains and cars, the impact resistance of crash-resistant structures and the impact resistance of bulletproof jackets are discussed (for example, the impact resistance of bulletproof jackets). The impact problems encountered in the application of functionally graded multilayer metal materials to automotive anti-collision structures are discussed in this paper. The mechanical responses of functionally graded multilayer metal plates obtained by surface mechanical grinding under dynamic double shear and reverse armour-piercing conditions are studied in this paper. The purpose of this paper is to study the mechanical properties and armour-piercing ability of gradient materials under dynamic loading. The main contents of this paper include the following aspects: 1) double shear test of functionally graded multilayer metal plates. In order to test the dynamic double shear mechanical properties of functionally graded multilayer metal plates, the error problem of large diameter Hopkinson rod in experimental test and its solution are systematically analyzed, and the specimen and fixture that can be used for double shear test are designed. The shear specimens of functionally graded multilayer plates were prepared by surface mechanical grinding, and the double shear tests were carried out under quasi-static and dynamic loading by using universal testing machine and Hopkinson compression bar. The formulas of equivalent strain and equivalent stress of plane shear are analyzed. The dynamic and quasi-static test results of double shear are compared and analyzed. The numerical simulation of double shear test is carried out. In order to describe the process of double shear test in more detail and obtain more accurate test data, ABAQUS finite element software is used. The strain and stress states in the shear region are studied systematically, the influence of the length of the shear region on the simulation results is analyzed, and the influence of the fixture on the deformation uniformity of the shear region is obtained. The definition of nominal strain in finite element software. The equivalent strain can be calculated by accumulative Euler strain method and the constitutive parameters of each layer of multilayer metal functionally gradient materials can be calculated by Cauchy stress method. The gradient distribution of the specimen along the thickness direction is obtained. The elastoplastic constitutive relation expression of each gradient layer is obtained by using the weighted average method. The numerical model of elastoplastic ductility failure is constructed by numerical simulation. The anti-armour-piercing characteristics of each functionally graded multilayer metal plate were studied. The specimens with functional gradient were prepared, the test fixture was designed, and the MTS810 static test machine and the improved Hopkinson compression bar test device were used, respectively. The armour-piercing test was carried out under quasi-static and impact loading, and the numerical simulation of the armor-piercing was carried out in combination with the test results. The displacement and force curves of armor-piercing under two loading conditions were obtained. The failure strain of each gradient layer in the gradient material is verified by armour-piercing simulation. Finally, the strain rate sensitivity of the material treated by surface mechanical grinding is analyzed. The optimum design of material gradient of target plate after surface mechanical grinding and target plate without surface mechanical lapping is studied. ABAQUS/Explicit numerical model is used. The gradient target plate was optimized from two aspects of gradient distribution and layer sequence, and the energy absorption effect and anti-armour-piercing ability of gradient target plate were evaluated.
【学位授予单位】：西北工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB34

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