焊接金属空心球单轴压缩实验研究

Experimental Study of Welding Metallic Hollow Sphere Uniaxial Compression

球基轻质多孔材料的单球基元有多种构建形式,四点焊接金属空心球(Metal HollowSphere,MHS)是其中一种特殊类型。对四点焊接的金属空心球进行了单轴压缩实验。由于其中某些空心球在焊接时出现了孔洞,故分别做了完整和焊接出现孔洞的两种情况下的多组实验,得出了焊缝与水平面夹角θ成不同角度时压缩的名义应力-应变曲线。对比了各种夹角θ情况下的弹性模量、屈曲应力。根据实验结果,得出了θ=45度时其首次屈曲应力最大的结论。通过简化模型给出了其原因,并定性地分析了二次屈曲的问题。另外,结合实验现象分析了金属空心球在压缩时的屈服和屈曲过程。同时,对焊接完整和焊接出现孔洞两种情况进行了对比,发现有孔洞时其首次屈曲应力更低。以上结果对球基多孔材料的研究具有参考价值。

Single sphere element of lightweight cellular material has many structure types. Four point welded thin-walled metallic hollow sphere （MHS） composed by two hemisphere shells is a sort of them. Uniaxial compression experiment for thin-walled MHS was carried out. Multiple experiments include whole sphere and sphere with cracks due to some spheres have a few cracks in the shell equatorial plane after welding. Then, the nominal compression stress-strain curves corresponding to different included angles θ between horizontal plane and welding line were plotted. Elastic modulus and the first buckling stress corresponding different angles θ were compared. It is concluded that the first buckling stress is the maximum when angle θ equals 45° based on experimental results. The interpretation of above conclusion and the second buckling process are qualitatively analyzed in this paper. Yield and buckling in compression process were analyzed combining with experimental phenomena. In addition, the comparison of first buckling stress between the whole MHS and MHS with some cracks was carried out. It is found that the first buckling stress of spheres with cracks is lower. These results have valuable reference for lightweight cellular material study.