Experimental study and progressive failure analysis of stitched foam-core sandwich composites subjected to low-velocity impact

The effects of the impact energy and stitch density on low-velocity impact (LVI) damage in sandwich structures composed of a stitched foam core and woven face sheets have been investigated both experimentally and numerically. In the LVI experiment, force-time curves are recorded and analyzed to study the impact response of stitched foam core sandwich structures. In the numerical investigation, a progressive damage model for the composite structures is developed based on the continuum damage mechanics (CDM) approach in which the damage forms of the composites are predicted by the strain-based Hashin criteria. The damage evolution is simulated by the stiffness degradation procedure in exponential form. Interface elements are established between the panels and foam core to simulate the initiation and propagation of inter-laminar damage. The stitching region is simplified as glass fiber reinforced resin columns, and its mechanical parameters are estimated by a mixed series-parallel model. The numerical and experimental results are in good agreement, which demonstrates the validity of the progressive failure analysis method. The energy absorption is discussed using a numerical method, and the results help to characterize the damage mechanisms of LVI on stitch foam-core sandwich composites. POLYM. COMPOS., 39:624-635, 2018. (c) 2016 Society of Plastics Engineers