Buckling failure mode and ultimate load of composite sandwich beam

In order to investigate the buckling, postbuckling characteristics and load capacity of composite sandwich beam under the effect of axial compression, test investigation and finite element simulation were carried out. Firstly, a series of buckling characteristic tests of composite sandwich beams were conducted. The effects of ply ratio angle, length of beam, face layer thickness and core layer thickness on buckling, postbuckling failure modes and ultimate load were discussed. Then, based on the nonlinear buckling theory, 3D cohesive interface elements were used to simulate the debond between skin and core, and initial predeformation as well as material damage criteria were also introduced to simulate and investigate the buckling characteristics and ultimate load of composite sandwich beam under axial compression. The results show that interface debond is the important mode of buckling failure. Comparing the ultimate load calculated by simulation with the test results, the errors are controlled within 10%. The conclusions obtained prove that the method can predict the postbuckling path, failure mode and ultimate load accurately.