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泡沫金属材料由于其较长的应力平台能吸收较多的能量,在结构耐撞性设计中有广泛的应用,然而实验研究表明当承受强冲击载荷时,泡沫金属材料中可能发生应力增强现象,从而对被保护物造成较严重的损伤.应用二维弹塑性质量-弹簧-连杆模型对这一现象进行了系统研究.给出了泡沫金属的本构关系及其加、卸载准则,建立了非线性动力平衡方程,采用显式积分算法对压缩冲击波在铝泡沫材料中的传播特征进行了模拟,并考察了铝泡沫材料非均匀性对冲击波传播特性的影响.结果表明,在较低的脉冲载荷下,铝泡沫材料通过其胞壁的渐进坍塌耗散大量的能量,从而减缓被保护物所受的冲击.当脉冲载荷达到一定强度时,在铝泡沫材料中应力传递可能会出现增强现象,特别是在局部非均匀泡沫材料中,会产生相当高的峰值应力.压缩冲击波在铝泡沫材料中的传播特征及其所产生的峰值应力的大小和位置与铝泡沫材料特性、脉冲载荷强度、载荷作用时间以及材料的不均匀程度等因素密切相关.本研究可为泡沫金属材料用于防护装置中的可靠性分析提供一定依据.
Due to its long stress, foam metal can absorb more energy and is widely used in structural crashworthiness design. However, experimental studies have shown that stress reinforcement may occur in foam metal when subjected to strong impact loads, Which will cause more serious damage to the object to be protected.This phenomenon is systematically studied by using two-dimensional elasto-plastic mass-spring-link model.The constitutive relations of foamed metal and its loading and unloading criteria are given, Nonlinear dynamic balance equation, the explicit integral algorithm is used to simulate the propagation characteristics of compressive shock wave in aluminum foam and the influence of aluminum foam nonuniformity on the propagation characteristics of shock wave is investigated. The results show that at lower pulse Under the load, the aluminum foam dissipates a large amount of energy through the progressive collapse of its cell wall, thereby reducing the impact on the protected object.When the pulse load reaches a certain strength, the stress transfer in the aluminum foam may be enhanced, Especially in the local non-uniform foam, will produce a very high peak stress Compressive shock wave propagation characteristics in aluminum foam and its The size and location of the peak stress generated are closely related to the properties of aluminum foam, the pulse load strength, the loading time and the material heterogeneity.In this study, we can provide certainty for the reliability analysis of foamed metal materials used in guards in accordance with.