Investigation on manufacturing and low-velocity impact performance of all-composite sandwich structure with S-type foldcore

A novel all-composite sandwich structure with S-type composite foldcore was designed and fabricated using an improved hot-press molding. Low-velocity impact tests with varying impact locations named "Node-impact" and "Base-impact" on the sandwich structure were performed via an Instron CEAST 9350 impacting machine. Experimental results showed two peaks exhibited on the histories of impact loads, where the peak value for Node-impact was larger than that of Base-impact at equal impact energy. Impact position possesses a significant influence on the impact resistance and damage mode of the composite structure. The sandwich structure achieved better impact resistance at Node-impact than Base-impact due to the strengthening of S-type composite foldcore. A user defined three-dimensional progressive damage mode was developed to predict the constitution and damage evolution of glass/epoxy fabrics, including fiber damage, matrix damage and interlaminar delamination. The predicted dynamic response and failure behavior of composite sandwich specimen agreed with experimental results.