Effect of Defect on the Compressive Response of Sandwich Structures with Carbon Fiber Pyramidal Truss Cores

In the present study, the defect was introduced in the form of missing strut for the individual cell. The effect of defect on the compressive response of carbon-fiber pyramidal truss cores sandwich panel was investigated through experimental and theoretical methods. A series of sandwich panel sample with or without defect was fabricated, and compressive tests were performed at ambient temperature. Scanning electron microscopy (SEM) was conducted on the samples to evaluate the carbon-fiber distribution and failure mode. A revised theoretical model was proposed to predict the effect of defect considering the strut bending and shear behavior. Our results revealed that the compressive moduli of sandwich panel decrease linearly with the fraction of missing struts. Comparing with open-cell foams and honeycombs, the pyramidal truss has better defect tolerance. The theoretical result calculated by the proposed model was in general agreement with experimental result.