Experimental Study On Failure Mechanism Of Hierarchical Sandwich Structures With Second-order Triangular Core Under Compression Condition

The hierarchical sandwich structure has excellent mechanical properties,light weight and high strength,rich failure modes,and has the characteristics of "structural fuse" in the concept of disaster division design,which has attracted many researchers' attention.In this paper,the failure mechanism of hierarchical sandwich structures with second-order triangular core under compression load is studied by theoretical analysis,simulation and sample experiment.Combined with the existing theory,6 failure modes are classified and summarized according to panel yield failure and panel buckling failure.The failure mechanism diagram of hierarchical sandwich structures with second-order triangular core is adjusted by the dominant relationship of each failure mode.Select points on the failure mechanism diagram to design the structural samples.The samples are made by 3D printing with UV Curable Resin material.The compression experiment is carried out,and the Eigenvalue Buckling analysis of the sample model is carried out by ANSYS.The details are as follows:(1)Based on the theory of elastic thin plate and the stability theory of sandwich plate,the partial theoretical formula of failure mode of hierarchical sandwich structures with second-order triangular core is modified by different ways of stress decomposition,which improves the prediction accuracy of the failure load of the structure by the plate model.Through the dominant relationship between the failure modes,the failure mechanism diagram under the plate theory is adjusted.The proportion of each failure mode in the revised failure mechanism diagram is different.(2)Using the UV Curable Resin 9000 material to make on the Lite800 HD 3D printer,the sample making method of the complex structure of hierarchical sandwich structures with second-order triangular core is realized.The base metal experiment of UV Curable Resin was carried out and its mechanical properties were measured.(3)According to the properties of the base material,based on the beam theory and the modified plate theory,a total of 8 groups of hierarchical sandwich structures with second-order triangular core models were designed on the failure mechanism diagram.Three samples were produced by 3D printing for compression experiments in each group,and the Eigenvalue Buckling analysis of 8 models was performed by ANSYS.The experimental results and simulation results show that the modified plate theoretical prediction model is accurate in predicting the failure mode of the structure,and the prediction of the buckling load is also similar to the critical buckling load value obtained by simulation,with the relative error less than 9%.