共查询到17条相似文献,搜索用时 218 毫秒
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聚氨酯泡沫铝动力学性能实验及本构模型研究 总被引:2,自引:0,他引:2
为了改进泡沫铝的动态吸能性能,将聚氨酯填充到开孔泡沫铝中制备成复合材料。通过霍普金森杆(SHPB)冲击实验,研究包含相对密度、应变、应变率和聚氨酯含量等影响因素的聚氨酯泡沫铝材料的动力学性能,并建立了动态本构模型。实验结果表明,聚氨酯泡沫铝的动态弹性模量与相对密度无关,屈服强度和流变应力与应变率和泡沫铝的相对密度成正比;聚氨酯泡沫铝的屈服强度与泡沫聚氨酯质量增加近似呈线性关系。所建立的动态本构模型在相对密度和应变率在一定的变化范围内与实验数据吻合较好。 相似文献
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基于相对即时密度的泡沫铝材料力学性能研究 总被引:6,自引:1,他引:6
通过对圆柱形泡沫铝试件进行静态压缩和冲击实验,考察了泡沫铝的初始密度、孔径和尺寸等因素对材料应力应变关系的影响,研究了基于相对即时密度的泡沫铝材料的塑性行为。实验所用泡沫铝试件包含四种尺寸,三种孔径及多种初始密度。实验结果表明,初始密度对泡沫铝的应力应变关系有着显著的影响,而其他因素,如孔径、试件尺寸等的影响较小。基于实验结果,提出了一种新的泡沫铝材料力学性能的描述方法,即用材料的相对即时密度与应力的关系来描述泡沫铝材料的塑性行为。该关系适用于静态和动态加载情况,只是两种情况下的参数不同。基于该方法,发现泡沫铝的塑性行为可以用单一的应力一相对即时密度关系描述,这一关系甚至不依赖于材料的初始密度,这将使泡沫铝材料塑性行为的描述大大简化。 相似文献
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不同应变率下泡沫铝的形变和力学性能 总被引:3,自引:0,他引:3
对低密度泡沫铝在不同变形率下的形变和力学性能进行了系统的试验研究。结果表明:(1)沿剪切方向骨架首先塌陷,即变形的局部化是低应变率下块体泡沫铝的主要变形特征;(2)在不同应变率下泡沫铝表现出体积应变基本上随工程应变呈线性变化,在低应变率下泊松比随轴向应变呈幂次关系增加,但在高应变率下泊松比随塑性应变增加,从一峰值降低并趋于稳定;(3)低应变率下泡沫铝材料塑性变形均匀,而高应变率下剪切变形较大;(4)泡沫铝材料的强度对应变率不很明显,但随塑性应变增加,它的率敏感性增加。 相似文献
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《实验力学》2018,(6)
泡沫金属在高速冲击下表现为变形局部化,采用传统的分离式Hopkinson杆技术进行动态实验测试可能存在问题。本文以动态、刚性-塑性硬化(D-R-PH)模型为理论基础,对闭孔泡沫铝开展Taylor-Hopkinson冲击实验,结合高速摄影技术和数字图像相关技术(DIC),获得了冲击速度的历史曲线。通过运用冲击波理论,提出了冲击速度与冲击时间的隐函数拟合方法,确定了动态初始压溃应力和应变硬化参数等两个动态材料参数。利用冲击端的应力历史曲线检验了结果的有效性,分析了动态材料参数对相对密度的敏感性,发现动态初始压溃应力和应变硬化参数均与相对密度近似呈幂函数关系。实验表明泡沫铝的应力-应变行为呈现明显的冲击速率敏感性。 相似文献
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通孔泡沫铝的动态压缩行为 总被引:4,自引:0,他引:4
在SHPB装置上对渗流法制备的通孔泡沫铝进行了动态压缩实验,研究了相对密度为0.341~0.419的通孔泡沫铝在10-3~2000 s-1应变率范围内的压缩响应特征和应变率相关性,并用扫描电镜(scanning electron microscope,SEM)分析了泡沫铝的压缩变形特征。实验结果表明,通孔泡沫铝有明显应变率效应,随应变率上升,泡沫铝流动应力提高。SEM观察结果揭示,在动态压缩下,通孔泡沫铝宏观上均匀变形,微观变形机制以泡孔横向伸展坍塌为主。 相似文献
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泡沫铝铜合金静态压缩力学行为和吸能性能的实验研究 总被引:1,自引:0,他引:1
通过静态压缩实验研究一种新型闭孔泡沫铝材料泡沫铝铜合金的静态压缩力学行为和吸能性能。对实验得到的一定密度范围内的材料的弹性模量E和平台应力pl关于相对密度进行曲线拟合,发现将Gibson等给出的开孔泡沫理论公式中的幂次常数修正为由实验确定的常数,可以给出一定密度范围的闭孔泡沫铝铜合金材料的弹性模量和平台应力与相对密度之间关系的一个较好的估计。采用比能-应力或比能-应变曲线,可以对不同密度的泡沫铝铜合金材料的吸能情况进行较为直观的比较和分析。该曲线对工程设计具有较好的指导意义。 相似文献
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采用旋转盘式杆-杆型动态拉伸试验机对TiCP颗粒增强钛基复合材料及其基体钛合金的动态拉伸性能进行了研究.同时为了比较,在MTS810试验机上做了两种材料的准静态试验.试验结果表明,复合材料及基体材料屈服后至材料的迅速失效,几乎没有应变硬化效应;复合材料的抗拉强度和屈服强度较基体明显提高,但延性明显下降;钛合金基体和复合材料均有明显的应变率强化效应,但复合材料的应变率强化效应明显高于基体;建立了复合材料率相关的本构关系.最后从位错等微观角度分析了复合材料的强化机理、复合材料的应变率敏感性以及复合材料应变率敏感性高于基体的原因. 相似文献
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数字图像相关方法在闭孔泡沫铝压缩试验中的应用 总被引:1,自引:0,他引:1
为了了解相对密度与胞孔结构对闭孔泡沫铝力学性能的影响,本文采用放大成像及数字图像相关技术对两种不同密度的泡沫纯铝试样进行了实验研究.利用数字图像相关方法对泡沫纯铝变形前后的图像进行相关计算,获得了弹性范围内静态压缩情况下闭孔泡沫铝材料表面的全场变形及局部孔结构的变形,同时根据试验结果计算了试件的名义弹性模量.实验结果表明泡沫铝整体孔结构的变形与泡沫金属材料相对密度有关,而单个孔结构的变形主要与孔壁面光滑程度和皱褶有关.实验结果还表明图像相关方法能够有效地应用于闭孔泡沫金属的力学性测量和评估的研究. 相似文献
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A modified version of the Kolsky thin-wafer technique is described. The method permits one to obtain the dynamic plastic properties of materials at strain rates as high as 105 sec?1. Data obtained from compression tests on high-purity aluminum are presented for strain rates ranging from 4000 to 120,000 sec?1 at room temperature. Specimen-size effects and the effect of lateral inertia are taken into account in analyzing the data. The results plotted as stress vs. strain rate at constant strains (5 to 20 percent) show that, at the highest strain rates, the stress rises very rapidly with strain rate suggesting that a limiting strain rate is being reached. At the lower strain rates (103 to 104 sec?1), the stress is linearly proportional to the strain rate indicating that the material is deforming in a viscous manner. 相似文献
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A. S. Yunoshev V. V. Sil'vestrov 《Journal of Applied Mechanics and Technical Physics》2001,42(3):558-564
A compression version of the split Hopkinson bar with pressure bars and a striker, which are made of Plexiglas (a material with low density and velocity of sound) is developed. The technique is designed to determine stress—strain diagrams under high strain rates of highly deformable materials with low density and strength, such as plastics, foams, and rubbers. Dynamic stress—strain curves in compression for spheroplastic, foam plastic, and rubber are presented, which were obtained using the technique developed. 相似文献
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A dynamic bulge testing technique is developed to perform biaxial tests on metals at high strain rates. The main component
of the dynamic testing device is a movable bulge cell which is directly mounted on the measuring end of the input bar of a
conventional split Hopkinson pressure bar system. The input bar is used to apply and measure the bulging pressure. The experimental
system is analyzed in detail and the measurement accuracy is discussed. It is found that bars made of low impedance materials
must be used to achieve a satisfactory pressure measurement accuracy. A series of dynamic experiments is performed on aluminum
6111-T4 sheets using viscoelastic nylon bars to demonstrate the capabilities of the proposed experimental technique. The parameters
of the rate-dependent Hollomon–Cowper–Symonds J2 plasticity model of the aluminum are determined using an inverse analysis
method in conjunction with finite element simulations. 相似文献
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Three-dimensional Voronoi models are developed to investigate the mechanical behavior of linearly elastic open cell foams. Dependence of the Young’s modulus, Poisson’s ratio and bulk modulus of the foams on the relative density is evaluated through finite element analysis. Obtained results show that in the low density regime the Young’s modulus and bulk modulus of random Voronoi foams can be well represented by those of Kelvin foams, and are sensitive to the geometric imperfections inherent in the microstructure of foams. In contrast, the compressive plateau stress of the foams is less sensitive to the imperfections. Failure surface of the foams subject to multi-axial compression is determined and is found to comply with the maximum compressive principal stress criterion, consistent with available experimental observations on polymer foams. Numerical results also show that elastic buckling of cell edges at microscopic level is the dominant mechanism responsible for the compressive failure of elastic open cell foams. 相似文献