【作者】 田杰；

【导师】 胡时胜；

【作者基本信息】 中国科学技术大学 ， 工程力学， 2006， 博士

【摘要】 泡沫金属是一种新型工程材料，由于其独特的物理、化学性能，其应用范围越来越广泛。低阻抗的泡沫金属材料通常具有优秀的冲击能量吸收能力，许多领域已采用泡沫金属达到冲击防护目的，尤其是降低材料重量方面有明显的优势。因此，其动态力学行为和吸能特征成为近几年来力学及材料科学等领域的研究热点之一。 本文首先研究了孔径参数和基体性能对泡沫铝的力学性能的影响。孔径对于泡沫铝的性能的影响取决于泡沫铝的基体性能。对于泡沫纯铝，孔径对屈服强度及塑性硬化模量基本没有影响。韧性泡沫金属的屈服段应力随着应变的增加而缓慢增加；脆性泡沫金属有比较长而平缓的屈服平台区。脆性泡沫的吸能效果总体优于韧性泡沫。 在爆炸载荷下泡沫铝中冲击波强度随着传播距离的增加呈指数衰减的形式。对泡沫铝在抗爆结构上的应用进行了试验研究，并对不同材料的防护结构进行了试验对比。试验结果表明：无论是把泡沫铝作为底板材料还是夹心材料都能减小次生冲击波的超压。 泡沫铝受到爆炸载荷作用时发生塑性变形，这种变形是不可恢复的，而高聚物泡沫在爆炸载荷作用时尽管也变形，但变形一部分是可以恢复的，因此相对延长了超压波的作用时间，超压冲量衰减的相对没有泡沫铝结构那么多。 利用大型工程数值软件LS-DYNA数值模拟了爆炸载荷下泡沫铝的冲击波衰减特性。泡沫铝的波阻抗比较低，泡沫铝在爆炸载荷作用下从上到下发生压缩变形。这与其在准静态和动态情况下泡沫铝均匀的变形模式不同。 对不同泡沫铝结构的抗爆性能模拟的结果表明，采用泡沫铝作为底板材料，能大大降低底板的质点速度，从而减小次生冲击波的超压。如果把泡沫铝作为夹心结构，则能减轻结构的重量，充分发挥泡沫铝的吸能作用，减小结构的整体弯曲变形，降低底板的质点速度，有效地衰减次生冲击波的峰值和冲量。 对不同密度、不同基体性能的泡沫铝中冲击波的衰减规律的数值模拟，结果表明高密度的泡沫铝的冲击波哀减系数比低密度泡沫铝的大。脆性泡沫相对韧性泡沫能更好的衰减冲击波的峰值、降低结构后的次生冲击波的强度、改变冲击波的形状、大大降低冲击波的峰值应力。更多还原

【Abstract】 Open cell metallic foams are relatively new materials that are being used increasingly in a range of applications due to their attractive combinations of physical, chemical, mechanical and optical properties. Highly metal foams with low impedance generally have an excellent shock attenuating capacity. They have found applications in a number of fields as an excellent impact protection material. For these reasons, the dynamic compressive behavior and the energy absorption characteristics of aluminum foams have become one of the most attractive topics in mechanics and materials sciences.Firstly the influence of cell size and matrix on aluminum foams is investigated. The effect of cell size depends on the matrix of aluminum foam. As for pure aluminum foam, there is neglected effect of cell size on the strength and plastic modulus. The stress rises slowly with the increase of strain in the collapse region of ductile metal foams. The collapse region of brittle metal foams is wide and even. The energy absorption of brittle metal foams is better than ductile metal foams.The shock wave attenuate rapidly as it propagates in the aluminum foam and the peak stress follows an exponential attenuation relation with the thickness of the foams under explosion. The different materials including aluminum foams applied on the protective structure is investigated. The results show that aluminum foams can attenuate the shock waves effectively. Aluminum foams can reduce the velocity of the structure and attenuate the peak of shock waves if it is placed at bottom or as sandwich.The deformation of aluminum foams under explosion load can not be resumed while the polymer foams deforms with some resumed strain, so the latter foams prolong the duration of over pressure, attenuate less over pressure impulse.The shock wave attenuation in the aluminum foams is simulated by LS-DYNA. The aluminum foams deform from the top to the bottom under explosion load, which is different with the uniform deformation under quasi static loading and dynamic loading. The simulation results show that aluminum foams can attenuate the over更多还原