负泊松比蜂窝材料和功能梯度蜂窝材料的冲击动力学性能研究
发布时间：2019-04-26 02:28
【摘要】：由于质量轻、抗冲击和能量吸收性能良好,蜂窝和泡沫等多孔材料被广泛应用于国防、化工、能源、微电子、交通、生物医学、航空航天等多个领域中。随着对负泊松比材料研究的深入,具有负泊松比效应的蜂窝材料也相应出现,并且表现出更突出的力学和物理特性。与均匀蜂窝材料相比,功能梯度蜂窝材料的变形模式和动态响应会因梯度的存在而在局部发生变化,从而为提升结构的抗冲击性和能量吸收能力提供可能。本文借助非线性有限元程序LS-DYNA,研究了负泊松比蜂窝材料和功能梯度蜂窝材料的面内冲击动力学性能,主要进行了如下工作:(1)数值模拟了均匀正六边形蜂窝材料与具有内凹六边形单元的均匀负泊松比蜂窝材料在动态冲击荷载作用下的力学行为,研究了冲击速度和胞元内凹角度对负泊松比蜂窝材料变形模式、动态响应和吸能性能的影响。对比均匀负泊松比蜂窝材料与均匀正六边形蜂窝材料的面内冲击结果,揭示了负泊松比蜂窝材料动力学特性。(2)借鉴功能梯度材料的概念,改变蜂窝胞元角度,构建了具有密度梯度的蜂窝材料模型。研究了角度梯度型六边形和内凹六边形蜂窝材料在不同冲击速度下的变形模式、应力应变曲线和能量吸收效果,分别将它们与相应的均匀蜂窝材料进行对比,分析了角度梯度型蜂窝材料的动力学特性。(3)基于功能梯度材料的概念,改变蜂窝胞壁厚度,构造了具有密度梯度的蜂窝材料模型。对不同冲击速度下厚度梯度型正六边形和内凹六边形蜂窝材料的动力学行为进行了有限元仿真,对比了厚度梯度型蜂窝材料与相应的均匀蜂窝材料在变形模式、动态响应和能量吸收方面的异同。结果表明,负泊松比蜂窝材料比正六边形蜂窝材料的抗压强度更高,表现出的能量吸收能力更强。功能梯度蜂窝材料的动态响应和能量吸收能力受梯度、胞元角度和冲击速度的影响。因此,如果能适当选取各项参数,那么就能使材料在降低初始应力峰值的同时保持良好的能量吸收能力。综上,负泊松比蜂窝材料和功能梯度蜂窝材料在结构防护方面具有良好的应用前景。
[Abstract]:Porous materials, such as honeycomb and foam, are widely used in many fields such as national defense, chemical industry, energy, microelectronics, transportation, biomedicine, aerospace and so on because of their light weight, good impact resistance and good energy absorption. With the deepening of the study of negative Poisson ratio materials, honeycomb materials with negative Poisson ratio effect also appear, and show more outstanding mechanical and physical properties. Compared with homogeneous honeycomb materials, the deformation mode and dynamic response of functionally graded honeycomb materials will change locally due to the existence of gradient, which provides the possibility to improve the impact resistance and energy absorption capacity of the structure. In this paper, the in-plane impact dynamic properties of negative Poisson's ratio honeycomb materials and functionally graded honeycomb materials are studied by means of nonlinear finite element program LS-DYNA,. The main work is as follows: (1) the mechanical behaviors of homogeneous hexagonal honeycomb materials and uniformly negative Poisson ratio honeycomb materials with concave hexagonal elements under dynamic impact loads are numerically simulated. The effects of impact velocity and cell concave angle on the deformation mode, dynamic response and energy absorption performance of the honeycomb materials with negative Poisson's ratio were studied. The in-plane impact results of homogeneous negative Poisson ratio honeycomb materials and homogeneous hexagonal honeycomb materials are compared to reveal the dynamic characteristics of negative Poisson ratio honeycomb materials. (2) the concept of functionally gradient materials is used for reference to change the cellular angle of honeycomb. A honeycomb material model with density gradient was constructed. The deformation modes, stress-strain curves and energy absorption effects of angle gradient hexagonal and concave hexagonal honeycomb materials at different impact velocities are studied. The results are compared with the corresponding homogeneous honeycomb materials. The dynamic characteristics of angular gradient honeycomb materials are analyzed. (3) based on the concept of functionally gradient materials, a honeycomb material model with density gradient is constructed by changing the cell wall thickness of honeycomb. The dynamic behaviors of thickness gradient hexagonal and concave hexagonal honeycomb materials under different impact velocities are simulated by finite element method. The deformation modes of the thickness gradient honeycomb materials and the corresponding uniform honeycomb materials are compared. The similarities and differences of dynamic response and energy absorption. The results show that the compressive strength of negative Poisson honeycomb material is higher than that of hexagonal honeycomb material, and the energy absorption ability of negative Poisson honeycomb material is stronger than that of hexagonal honeycomb material. The dynamic response and energy absorption capacity of functionally graded honeycomb materials are affected by gradient, cell angle and impact velocity. Therefore, if the parameters can be properly selected, the material can reduce the initial stress peak while maintaining a good energy absorption capacity. In summary, negative Poisson ratio honeycomb material and functionally gradient honeycomb material have good application prospects in structural protection.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.4
本文编号：2465676
[Abstract]:Porous materials, such as honeycomb and foam, are widely used in many fields such as national defense, chemical industry, energy, microelectronics, transportation, biomedicine, aerospace and so on because of their light weight, good impact resistance and good energy absorption. With the deepening of the study of negative Poisson ratio materials, honeycomb materials with negative Poisson ratio effect also appear, and show more outstanding mechanical and physical properties. Compared with homogeneous honeycomb materials, the deformation mode and dynamic response of functionally graded honeycomb materials will change locally due to the existence of gradient, which provides the possibility to improve the impact resistance and energy absorption capacity of the structure. In this paper, the in-plane impact dynamic properties of negative Poisson's ratio honeycomb materials and functionally graded honeycomb materials are studied by means of nonlinear finite element program LS-DYNA,. The main work is as follows: (1) the mechanical behaviors of homogeneous hexagonal honeycomb materials and uniformly negative Poisson ratio honeycomb materials with concave hexagonal elements under dynamic impact loads are numerically simulated. The effects of impact velocity and cell concave angle on the deformation mode, dynamic response and energy absorption performance of the honeycomb materials with negative Poisson's ratio were studied. The in-plane impact results of homogeneous negative Poisson ratio honeycomb materials and homogeneous hexagonal honeycomb materials are compared to reveal the dynamic characteristics of negative Poisson ratio honeycomb materials. (2) the concept of functionally gradient materials is used for reference to change the cellular angle of honeycomb. A honeycomb material model with density gradient was constructed. The deformation modes, stress-strain curves and energy absorption effects of angle gradient hexagonal and concave hexagonal honeycomb materials at different impact velocities are studied. The results are compared with the corresponding homogeneous honeycomb materials. The dynamic characteristics of angular gradient honeycomb materials are analyzed. (3) based on the concept of functionally gradient materials, a honeycomb material model with density gradient is constructed by changing the cell wall thickness of honeycomb. The dynamic behaviors of thickness gradient hexagonal and concave hexagonal honeycomb materials under different impact velocities are simulated by finite element method. The deformation modes of the thickness gradient honeycomb materials and the corresponding uniform honeycomb materials are compared. The similarities and differences of dynamic response and energy absorption. The results show that the compressive strength of negative Poisson honeycomb material is higher than that of hexagonal honeycomb material, and the energy absorption ability of negative Poisson honeycomb material is stronger than that of hexagonal honeycomb material. The dynamic response and energy absorption capacity of functionally graded honeycomb materials are affected by gradient, cell angle and impact velocity. Therefore, if the parameters can be properly selected, the material can reduce the initial stress peak while maintaining a good energy absorption capacity. In summary, negative Poisson ratio honeycomb material and functionally gradient honeycomb material have good application prospects in structural protection.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.4
【参考文献】
相关期刊论文 前1条
1 卢天健;何德坪;陈常青;赵长颖;方岱宁;王晓林;;超轻多孔金属材料的多功能特性及应用[J];力学进展;2006年04期
，本文编号：2465676
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