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高孔隙率闭孔泡沫铝的低应变率压缩行为

ISSN号：0459-1879
期刊名称：力学学报
时间：0
页码：1-14
语言：中文
分类：O39[理学—工程力学;理学—力学]
作者机构：[1]西安交通大学强度与振动教育部重点实验室,西安710049, [2]西安交通大学航天航空学院,西安710049
相关基金：国家重大基础研究计划（2011CB610305）; “国家111计划”引智计划项目（B06024）; 国家自然科学基金（10825210,11072188）资助项目
相关项目：物理波在超轻多孔材料和结构中的传播和吸收

关键词：泡沫铝, 低速冲击, 落锤实验, 碰撞解析模型, aluminum foam, low velocity impact, drop hammer experiment, analytical colliding model

中文摘要：

通过落锤冲击实验研究高孔隙率闭孔泡沫铝的动态压缩性能及抗低速冲击特性,同时通过高速摄影仪观察试件的动态压缩行为,并记录落锤冲击速度的衰减过程.结果表明,高孔隙率闭孔泡沫铝的抗冲击缓冲效果明显,且在低速冲击条件下其变形特征与准静态变形类似.采用有限元方法分析了落锤和泡沫中应力的分布特点以及表面摩擦系数对应力分布的影响.由于摩擦力阻碍了接触面处泡沫的横向位移,致使其压缩外形呈＂鼓形＂;在低速冲击时,应力在泡沫铝试件内部的传播周期远小于冲击的缓冲时间,应力波现象并不明显,应力的变化与准静态压缩时相似.在考虑接触面上摩擦力的基础上,通过第2类Lagrange方程建立了落锤-泡沫材料的碰撞解析模型,将预测的落锤冲击速度的衰减过程分别与实验和有限元结果进行比较,取得了较为一致的结论,并进一步讨论了不同冲击速度和材料参数对冲击过程的影响.

英文摘要：

Drop hammer experimental measurements are carried out to study the compressive behavior and energy absorption characteristics of high porosity closed-cell aluminum foam specimens subjected to low velocity impact loading.The dynamic deformation behavior of the specimen is observed by high speed camera and the velocity attenuation of the drop hammer is recorded.The results demonstrate that the aluminum foam has excellent energy absorption capabilities under low velocity impact loadings,with its dynamic compression behavior similar to that obtained under quasi-static loading conditions.Finite element method（FEM） is employed to obtain stress distributions in the drop hammer and foam specimen,with and without the effects of friction on contact surface considered.The presence of friction restrains the transverse displacement of the contact surface,causing the observed convex shape of the foam specimen.As the propagating period of stresses in the specimen is far less than the attenuation duration time,the variations of the stresses are similar to those under quasi-static loading conditions and no obvious stress wave effect is observed.With the effects of the friction on the contact surface accounted for,an analytical colliding model of the drop hammer-aluminum foam system is established.The predicted velocity attenuation is compared with both the experimental measurements and FEM simulation results,with overall good agreement achieved.The effects of different impact velocities and mechanical properties of foam material on the attenuation process are discussed.

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