异面交错式铝芯吸能特性研究

发布时间：2018-03-11 13:04

本文选题：交错式铝芯　切入点：蜂窝　出处：《哈尔滨理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：多孔材料如铝蜂窝等具有优良的缓冲吸能性能,被广泛应用于交通车辆被动防护系统中,用来吸收车辆意外碰撞事故中的冲击能量。但因自身结构在空间内并不完全对称,使得铝蜂窝共面和异面承载性能存在很大的差异。本文在分析铝蜂窝结构特点和吸能特性关系的基础上,提出了一种新的多孔结构——交错式铝芯,并对其吸能特性进行了重点研究,具体工作如下:(1)基于能量守恒原则和_>塑性理论,对共面压缩下的“Z型交错式结构胞元”进行力学分析,建立了交错式铝芯共面初始峰值应力模型。(2)运用数值仿真模拟了交错式铝芯在准静态载荷下的吸能特性。首先,仿真结果表明,交错式铝芯共面压缩和异面压缩应力-应变曲线均可分为三个阶段:弹性变形阶段、稳态塑性变形阶段和密实化阶段。其次,仿真结果验证了交错式铝芯共面初始峰值应力模型的正确性。再者,还研究了胞元壁厚、边长对交错式铝芯异面吸能特性的影响,结果表明,其吸能能力随着胞元壁厚的增大而增强,随着胞元边长的增大而降低;并用MATLAB拟合出了交错式铝芯异面平均应力的经验计算公式。(3)在理论和仿真分析的基础上,通过准静态压缩实验研究了交错式铝芯与同规格蜂窝的吸能特性,验证了理论模型和仿真模型的正确性。其次,非轴向加载实验结果显示,在0°~45°偏移角内,交错式铝芯的吸能能力随着偏移角度的增大而增强,而蜂窝的体积比吸能随着偏移角度的增大急剧下降,这说明了交错式铝芯承受多向载荷的能力优于蜂窝。(4)此外,还对交错式铝芯动态吸能特性进行了实验研究,结果表明,交错式铝芯在冲击载荷下应力-应变曲线波动较大,力学特性不稳定,且试件呈现局部失效状况,可靠性有待提高。(5)针对交错式铝芯在冲击载荷下吸能可靠性不足的问题,提出了包覆型交错式铝芯的优化方案。通过实验研究了该方案垂向承载能力和轴向吸能能力,结果表明,相对于纯交错式铝芯,包覆型交错式铝芯吸能可靠性有明显提高,为后续交错式铝芯的实际应用提供了理论支持和实验依据。
[Abstract]:Porous materials, such as aluminum honeycomb, have been widely used in passive protection systems of traffic vehicles because of their excellent absorbency and energy absorption, which are used to absorb the impact energy in vehicle accidents. However, the structure of porous materials is not completely symmetrical in space. In this paper, based on the analysis of the characteristics of aluminum honeycomb structure and energy absorption characteristics, a new porous structure-staggered aluminum core is proposed. The specific work is as follows: (1) based on the principle of conservation of energy and the theory of _ > plasticity, the "Z type staggered structure cell" under coplanar compression is analyzed. The initial peak stress model of staggered aluminum coplanar is established. The numerical simulation is used to simulate the energy absorption characteristics of interleaved aluminum cores under quasi-static load. First, the simulation results show that, The stress-strain curves of staggered coplanar compression and cross-plane compression of aluminum cores can be divided into three stages: elastic deformation, steady plastic deformation and compaction. The simulation results verify the correctness of the initial peak stress model for staggered aluminum cores. Furthermore, the effects of cell wall thickness and side length on the energy absorption characteristics of interleaved aluminum cores are also studied. The energy absorption ability increases with the increase of cell wall thickness and decreases with the increase of cell side length, and the empirical calculation formula of cross-plane average stress of staggered aluminum core is fitted by MATLAB. The energy absorption characteristics of interlaced aluminum core and honeycomb of the same size are studied by quasi-static compression experiment, and the correctness of the theoretical model and the simulation model are verified. Secondly, the experimental results of non-axial loading show that the energy absorption characteristics of the interlaced aluminum core and the honeycomb of the same size are in the range of 0 掳or 45 掳offset angle. The energy absorption ability of the interleaved aluminum core increases with the increase of the offset angle, while the volume specific energy absorption of the honeycomb decreases sharply with the increase of the offset angle, which indicates that the interleaved aluminum core is superior to the honeycomb. The dynamic energy absorption characteristics of interleaved aluminum cores are also studied experimentally. The results show that the stress-strain curves fluctuate greatly under impact load, the mechanical properties are unstable, and the specimens show local failure. In order to solve the problem that the energy absorption reliability of interlaced aluminum core is insufficient under impact load, the optimization scheme of cladding staggered aluminum core is put forward. The vertical bearing capacity and axial energy absorption capacity of this scheme are studied by experiments. The results show that compared with the pure interlaced aluminum core, the energy absorption reliability of the cladding interlaced aluminum core is obviously improved, which provides theoretical support and experimental basis for the practical application of the subsequent interlaced aluminum core.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TB383.4

【相似文献】