1.结论与讨论
应用泡沫金属子弹撞击加载的方式研究了泡沫铝夹芯梁和单层梁的抗冲击性能，分
别讨论了子弹冲量、面板厚度和芯层厚度对夹芯梁抗冲击性能的影响。得到了梁后面板
中心点的最终挠度与加载冲量的关系，并将实验结果与理论预测相比较，结论如下：（1）泡沫金属子弹撞击加载下，夹芯梁的变形主要集中在子弹作用的中心区域。前
面板主要表现为子弹作用区域的压缩变形，其失效模式分为压入失效和侵彻失效；芯层
的变形根据破坏程度的不同可分为加载中心区域的压缩变形和接近固支端的无压缩变形；后面板的变形为非弹性大变形，中心点挠度最大，与板不同的是未观察到明显的花
瓣形变形。
（2）参数研究结果表明，泡沫铝夹芯梁后面板中心点的最终挠度随着加载冲量的增
大而增大，且呈指数函数变化。研究范围内，最终挠度随着面板厚度的增加线性减少，
但也出现了面板厚度较大的夹芯梁的最终挠度大于面板厚度较小的夹芯梁的情况，这可
能是由于脱胶或泡沫材料的不均匀性造成的。芯层厚度与夹芯梁抗冲击性能密切相关，
增加芯层厚度能显著地提高夹芯梁的抗冲击能力。
（3）实验结果与理论预测比较后发现，冲量较大时吻合较好，实验挠度处于理论预
测的内、外屈服轨迹内；冲量较小时却存在一定的差异，这可能是泡沫材料的不均匀性
及理论预测中过高估计了弯曲和拉伸共同作用阶段的影响产生的。
（4）通过一定范围的冲量研究表明，与等质量的单层梁相比，泡沫铝夹芯梁具有较高的抗冲击能力和明显的结构优势。
Conclusion and discussion
The way of using foam metallic projectiles impact load studies the shock resistance of sandwich beams with core of aluminuim foam and单层梁,and respectively discusses the effects of projectile impulse, face sheets thickness and the thickness of core on the shock resistance of sandwich beams. The relationship between the final deflection of the central point of梁后面板and加载冲量is attained. The result of the experiment is compared with the theoretical prediction. The conclusions are:
（1）In the situation of foam metallic projectiles impact load, the deformation of sandwich beams mainly located in the central area where the projectiles are working. The front face sheet mainly shows the compression deformation of the area where the projectiles are working,and its failure modes can be divided into: indenting failure and pitting failure. According to the different damage degree of the芯层deformation, it can be divided into 加载中心区域的压缩变形and接近固支端的无压缩变形. The back face sheet shows large inelastic deformation and its deflection of the central point is the biggest. Obvious 花瓣形deformation isn’t observed, which is different from the sheet.
（2）The result of parameter study shows that the central point deflection of sandwich beams with core of aluminuim foam back face sheet increases with the increase in 加载冲量and it changes in exponential function. Within the study field,the final deflection decreases线性地with the increase in the thickness of the face sheets, but it also appears the situation that the final deflection of 面板厚度较大的夹芯梁is larger than面板厚度较小的夹芯梁. This is probably due to 脱胶或泡沫材料的不均匀性. The thickness of 芯层and the shock resistance of夹芯梁is closely related. Increasing the thickness of 芯层can notably improve the shock resistance of 夹芯梁.
（3）After the comparison of the result of the experiment and theoretical prediction, we find
that the larger the冲量is , the better the fitness is. The experimental deflection is located within内、外屈服轨迹of the theoretical prediction. When the 冲量is smaller, there’s certain difference. This is caused by 泡沫材料的不均匀性and overestimation the effect of 弯曲和拉伸共同作用阶段in theoretical prediction.
（4）Through the 冲量study in certain area, it shows that when compared with the same quality of 单层梁,sandwich beams with core of aluminuim foam have superior shock resistance and obvious structure advantages.
参考资料
泡沫金属子弹metallic foam projectile
6. Concluding remarks
The investigation on dynamic response of clamped sandwich beams with core of aluminuim foam and monolithic solid beams is achieved by using aluminuim foam projectile loading. And the effects of projectile impulse, face sheets thickness and the thickness of core on the response of structures are studied. The main conclusions are:
1. The deflection of sandwich beams loaded by foam metallic projectiles mainly located in the central area. The specimens show two types of localized compression failure of front face sheet, i.e. indenting failure and pitting failure; Core deformation/failure can be divided into two regions (the compressed section and uncompressed section). And the back face sheet shows large inelastic deformation.
摘要：冲击载荷下泡沫铝夹芯结构能产生较大的塑性变形，具有良好的能量吸收能力。为研究夹芯结构在冲击载荷下的结构响应，应用泡沫金属子弹撞击加载的方式，采用激光测速装置和位移传感器测量了泡沫子弹的撞击速度和后面板中心点的位移—时间历程曲线，分别研究了子弹冲量、面板厚度和芯层厚度对抗冲击性能的影响。实验研究给出了泡沫铝夹芯梁的变形与失效模式，结果表明结构响应对夹芯结构配置比较敏感，后面板中心点的永久变形与加载冲量、面板厚度分别成指数和线性关系。最后与等质量单层实体梁比较，结果表明，泡沫铝夹层梁具有更好的抗冲击能力。
The dynamic response of sandwich beams subjected to impact load
The institute of applied mechanics and biomedical engineering, Taiyuan University of Technology,
Taiyuan, Shanxi, 030024
Abstract: Based on the study of the deformation mechanism and failure mode of sandwich beam with core of aluminuim foam subjected to impact load, analytical solution of clamped sandwich beam is developed for dynamic response. According to this analytical model, the response of the sandwich structure can be split into three sequential stages: fluid-structure interaction phase, core compression phase, beam bending and stretching phase. The investigation on dynamic response of clamped sandwich beams with core of aluminuim foam is achieved by using aluminuim foam projectile loading. LDV device and Laser displacement transducer is applied to measure impact velocity of projectile and deflection-time history of the mid-point of back face of the beam, respectively. And then the effects of projectile impulse, face sheets thickness and the thickness of core on the response of structures are studied. Comparing with monolithic beams of the same mass, the result reveals that sandwich beams have a superior shock resistance.
Keywords: sandwich beam dynamic response impact load aluminuim foam
