負泊松比蜂窩材料和功能梯度蜂窩材料的沖擊動力學(xué)性能研究
發(fā)布時間：2019-04-26 02:28
【摘要】：由于質(zhì)量輕、抗沖擊和能量吸收性能良好,蜂窩和泡沫等多孔材料被廣泛應(yīng)用于國防、化工、能源、微電子、交通、生物醫(yī)學(xué)、航空航天等多個領(lǐng)域中。隨著對負泊松比材料研究的深入,具有負泊松比效應(yīng)的蜂窩材料也相應(yīng)出現(xiàn),并且表現(xiàn)出更突出的力學(xué)和物理特性。與均勻蜂窩材料相比,功能梯度蜂窩材料的變形模式和動態(tài)響應(yīng)會因梯度的存在而在局部發(fā)生變化,從而為提升結(jié)構(gòu)的抗沖擊性和能量吸收能力提供可能。本文借助非線性有限元程序LS-DYNA,研究了負泊松比蜂窩材料和功能梯度蜂窩材料的面內(nèi)沖擊動力學(xué)性能,主要進行了如下工作:(1)數(shù)值模擬了均勻正六邊形蜂窩材料與具有內(nèi)凹六邊形單元的均勻負泊松比蜂窩材料在動態(tài)沖擊荷載作用下的力學(xué)行為,研究了沖擊速度和胞元內(nèi)凹角度對負泊松比蜂窩材料變形模式、動態(tài)響應(yīng)和吸能性能的影響。對比均勻負泊松比蜂窩材料與均勻正六邊形蜂窩材料的面內(nèi)沖擊結(jié)果,揭示了負泊松比蜂窩材料動力學(xué)特性。(2)借鑒功能梯度材料的概念,改變蜂窩胞元角度,構(gòu)建了具有密度梯度的蜂窩材料模型。研究了角度梯度型六邊形和內(nèi)凹六邊形蜂窩材料在不同沖擊速度下的變形模式、應(yīng)力應(yīng)變曲線和能量吸收效果,分別將它們與相應(yīng)的均勻蜂窩材料進行對比,分析了角度梯度型蜂窩材料的動力學(xué)特性。(3)基于功能梯度材料的概念,改變蜂窩胞壁厚度,構(gòu)造了具有密度梯度的蜂窩材料模型。對不同沖擊速度下厚度梯度型正六邊形和內(nèi)凹六邊形蜂窩材料的動力學(xué)行為進行了有限元仿真,對比了厚度梯度型蜂窩材料與相應(yīng)的均勻蜂窩材料在變形模式、動態(tài)響應(yīng)和能量吸收方面的異同。結(jié)果表明,負泊松比蜂窩材料比正六邊形蜂窩材料的抗壓強度更高,表現(xiàn)出的能量吸收能力更強。功能梯度蜂窩材料的動態(tài)響應(yīng)和能量吸收能力受梯度、胞元角度和沖擊速度的影響。因此,如果能適當選取各項參數(shù),那么就能使材料在降低初始應(yīng)力峰值的同時保持良好的能量吸收能力。綜上,負泊松比蜂窩材料和功能梯度蜂窩材料在結(jié)構(gòu)防護方面具有良好的應(yīng)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.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.4
本文編號：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.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.4
【參考文獻】
相關(guān)期刊論文 前1條
1 盧天健;何德坪;陳常青;趙長穎;方岱寧;王曉林;;超輕多孔金屬材料的多功能特性及應(yīng)用[J];力學(xué)進展;2006年04期
，本文編號：2465676
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