Experimental and numerical analysis of low-velocity impact on composite sandwich panels with grid stiffened core

Composite sandwich panels with grid stiffened core, are composed of composite face sheets and kagome type lattice core. These structures can be used as alternative to the structures reinforced with stringer, sandwich panels with honeycomb core and aluminum grid structures. In this study, experimental tests and finite element analysis using ABAQUS software are applied for low-velocity impact on grid stiffened sandwich panels. In the experimental method, two sandwich panels with grid stiffened core are manufactured and undergo drop weight impact with a hemispherical steel impactor. Also, in the numerical method, the results are compared with the three-dimensional elements and progressive damage model is applied by employing user defined material subroutines in finite element method using ABAQUS software. Making comparison between the present numerical results with experimental results, shows that the finite element method is an efficient way to reduce the time and cost for understanding the behavior of this type of structure against impact loads. The energy absorption occurs in the structures mainly due to the induced damage in the impact region of the structure. This damage may affect the top face sheets or the ribs within the core of the sandwich panel and the rigidity of the impact position, reduces the visible damaged area in the structure. Also, the impact on the points such as the ribs’ intersections, which are more rigid than the space between the ribs, causes the contact time to be decreased and the maximum contact force to be increased.