样品粗糙度对材料SHPB动态压缩性能的影响

有效消减样品端面摩擦力是保证分离式霍普金森压杆（split Hopkinson pressure bar, SHPB）实验结果有效性和准确性的必要条件。为了研究样品粗糙度和润滑效果对端面摩擦力和最终实验结果的影响，以应变率效应不敏感且性能稳定的紫铜为研究对象，通过机械加工配合酸蚀的方法制备了3种典型表面粗糙度的紫铜样品，分别在二硫化钼（MoS₂）充分润滑和完全不润滑的条件下各自开展高精度的SHPB重复动态压缩实验研究。结果表明，通常认为能够有效消减金属样品端面摩擦力的MoS₂仅能够在样品粗糙度不大于0.8 μm的情况下起到较好的润滑效果，随着紫铜样品粗糙度的增加，MoS₂的润滑效果不断降低，端面摩擦力不断增大，实验结果的分散性也显著增加。样品端面粗糙度为1.6 μm时，MoS₂已不能有效消减端面摩擦力；样品端面粗糙度达到3.2 μm时，MoS₂的润滑效果几乎为零。SHPB实验中使用MoS₂润滑金属样品时，压杆和样品实验端面的粗糙度需达到0.8 μm；腐蚀液处理后的金属样品外表面粗糙度难以达到0.8 μm，实验过程中需对样品端面进行比MoS₂润滑效果更好的润滑处理，或对实验结果进行扣除端面摩擦力的修正才能够保证实验结果的有效性和准确性。

Effects of roughness on dynamic compression propertiesof metallic materials by SHPB technique

Effective reduction of end surface friction is necessary to ensure the validity and accuracy of the split Hopkinson pressure bar (SHPB) experimental results. In order to study the effects of sample roughness and lubrication efficiency on the end surface friction and the final experimental results, copper was selected as a research material due to its steady mechanical properties and strain rate insensitivity of constitutive relation. In order to minimize the effects of end friction, all pressure bars with the diameter of 10 mm had a surface roughnesses of 0.8 μm. Copper samples of three typical surface roughnesses were prepared by mechanical processing and corrosion, then high precision repeat dynamic compression experiments by the SHPB were carried out under the conditions of full lubrication with MoS2 and complete non-lubrication, respectively. The results show that MoS2 can only play a good lubrication when the end roughness of the copper samples does not exceed 0.8 μm, then the lubricating efficiency of MoS2 decreases rapidly with increasing the end roughness of the copper samples, which results in a significant increase in the friction force and the dispersion of experimental data. MoS2 could not effectively reduce the friction force when the roughness of samples is 1.6 μm, and the lubricating efficiency was almost zero when the roughness is 3.2 μm, although the MoS2 has been believed to be an effective lubrication used in dynamic compression experiments by the SHPB for a long time. The end roughness of the pressure bars and samples should reach 0.8 μm when MoS2 is used as lubrication for the SHPB experiments, however, the end roughness of the samples treated by a corrosive solution is difficult to reach 0.8 μm. Therefore, it is necessary to lubricate the end of the samples better than MoS2, or to modify the experimental data by deducting the friction force to ensure the validity and accuracy of the SHPB experimental results.