Investigation impact behavior of composite core sandwich plates with variable geometry

The aim of this study is to experimentally and numerically investigate the impact and compression behaviors and damage mechanisms of sandwich structures consisting of full fiber reinforced composites with different cell and core geometries. For this purpose, firstly, triangular, square and rectangular cell cores, egg-box and lattice core sandwich structures were manufactured. Low-velocity impact tests were conducted using hemispherical-ended strikers on these sandwich structures. In the study, the effects of cell and core type, cell height and core density on impact strength were determined. In addition, compression tests of egg-box, lattice and square core sandwich structures were performed and their damage behaviors were examined. When 30 J impact energy is applied to the specimen with triangular, square and rectangular cell cores of the same height, the absorption energy of the rectangular cell specimen is 2.64% higher than the square and 0.9% more than the triangular specimen. Although the maximum contact force of the square structure is smaller than the triangular and rectangular cell sandwiches, the specific contact force is 15.52% higher than the triangle and 16.29% higher than the rectangular cell sandwich. In square, egg-box and lattice core sandwich structures under compression test, the specific maximum load occurring in the square is 33.2% higher than the egg-box structure and 78.1% higher than the lattice structure. Progressive damage analysis was also performed with the finite element method. In doing so, we utilized the MAT-162 material model, which facilitates three-dimensional progressive damage analysis of composite materials and applies the Hashin damage criteria for use in the LS-DYNA program. The numerical results that were obtained had a minimum rate of compatibility of 81 % with the experimental data.