【作者】 卢静涵；

【导师】 赵隆茂；

【作者基本信息】 太原理工大学 ， 固体力学， 2004， 硕士

【摘要】 金属多孔材料由于其具有特殊的理化性能和力学性能，特别是可承受一基本恒定、低水平应力而产生大范围的变形。此材料特性对于许多包装、冲击／爆炸缓冲系统最为理想，已在汽车、航空航天、铁路运输、建筑、包装等行业得到了广泛的应用。目前，由于采用实验方法测试材料在高应变率下的应力应变行为的困难性，对于材料性能的研究多集中在准静态方面，该材料动态性能的研究结果有限。 通过分析已有的研究结果可知，由于金属多孔材料内部特殊的胞孔结构，实验方法的准确性对其动态性能的研究有一定的影响。为了实验确定金属多孔材料的初始动力坍塌强度和“平台”应力，研究应变率效应和速度效应，本文对该材料的实验方法进行了深入研究，分析了SHPB实验技术存在的问题及相关解决办法。在现有SHPB实验装置的基础上设计了一套直接撞击装置，利用反分析法中的反卷积技术，通过计算机模拟给出了该实验装置的传递函数h(t)，对实验装置进行了动态标定，完善了数据处理系统，为实验研究多孔材料的动态特性提供了一种有效的方法。 在原有Taylor实验的基础上扩展了Taylor理论的应用范围，使该理论从原有的估算不可压缩材料的动态屈服强度，发 太原理一l几大学硕十研究生学位论文展到对可压缩材料的研究，提出相对密度是压缩应变e的函数并符合p/p。二1+ae关系，以估算金属多孔材料的塑性流动应力，确定金属多孔材料的动态特性。 利用SHPB实验技术对不同孔隙率的铜合金多孔材料和铁合金多孔材料的动态压缩性能进行了测试。研究结果显示:文中所研究的两种金属多孔材料具有明显的应变率效应，具体表现为随着应变率的提高，材料的屈服应力明显提高。在动态压缩初期有较明显的弹性阶段;在应变率较低时，两种金属多孔材料的“平台”区表现较为明显，而当应变率提高时它们的屈服“平台”阶段并不明显，且随着应变的不断增大，应力也逐渐增加，屈服“平台”区和致密区没有明显的界线。而且，在应变率相近的情况下，在达到相同的应变时，孔隙率较低的金属多孔材料的应力值较高。更多还原

【Abstract】 The metallic porous materials possess many superiority properties. Particularly, the materials can suffer large region deformation under constant lower stress level. Because of these properties the materials can satisfy the requirement of some engineering fields, such as packing, impact/blast mitigation system. They have been widely used in automotive, aerospace, railway transport, building, package and so on. It is very difficulty to determine the dynamic properties of materials in high strain rates with test methods. The research mainly focuses on the quasi-static properties of metallic porous materials and investigation results of dynamic properties are very limited.According to analyze investigation results of dynamic properties of metallic porous materials, it is found that the accurate of experimental methods are important because of the special internal structures of the materials. In order to identify the initial dynamic collapse strength and plateau stress and to investigate the effect of strain rate and the effect of velocity by tests, existing test methods are compared, the shortage of SHPB test technique is analyzed and betterment methods are given in this paper. A directimpact device- also is designed based on the current SHPB. The transfer function h(t) is given using the deconvolution in inverse analysis with computer simulation. The direct impact device is dynamically calibrated. The data processing system is performed and an efficient method to investigate the dynamic behavior of metallic cellular materials is afforded.The original Taylor model is extended in order to provide a theoretical basis for testing ductile porous materials in this paper. The main difference between solids and porous materials is that porous materials are compressible and their density changes with the compressive strain. Calculations have been made for porous materials with a relative density that is a linear function of compression strain e, i.e., ρ /ρ0=1+ae. The method can be used to determine the dynamic yield stress.The dynamic compression experiments of the bronze alloy porous materials and iron alloy porous materials were carried out with the SHPB technique. It is found that the dynamic behavior of these two metallic porous materials is very sensitive to strain rate and speed effects that the materials’ yield stress is increased with the increase of the strain rates. There is an elastic phase in the initial compression stage. The two materials’ plateau stress is evidenced when the strain is low. However, the yield plateau is unclear while the strain rate is increasing. Company with the enhancement of the strain, the stress enhanced gradually and it is very difficult todistinguish the boundary between plateau region and densified region. Moreover, the stress of the porous mental with lower porosity is higher than that with higher porosity on the condition of the similar strain rates and same strain. While the deformation of the porous mental with lower porosity are smaller than that with higher porosity under the same impact force.更多还原