Effect of boundary conditions on the low-velocity impact damage mechanism of fiber metal laminate

The boundary condition is a very important factor when characterizing the impact performance of a material or a structure. However, its effect on fiber metal laminate (FML) has been rarely mentioned. In the present investigation, three levels of low-velocity impact tests were conducted on the glass fiber reinforced aluminum laminate (Glare) under two different boundary conditions, one was that defined in ASTM D7136 and another one was self-designed that has the same constraint area but different constraint degree. One basis of the experiments, finite element analyses were performed to gain a deeper understanding of the different damage mechanisms. With which another three boundary conditions were investigated for further considering the effect of constraint areas on both the impact and non-impact sides, including that defined in another commonly used standard ASTM D5628 and two self-designed cases. It was indicated that the boundary conditions influenced less the force and energy responses of Glare laminate, regardless of the impact damage levels, and hardly on the damage behavior as well when perforation was encountered. However, influences were obtained under lower and intermediate damage levels, and it was the constraint area on the rear side and constraint degree that played the dominant roles, respectively. The results achieved can provide suggestions for reasonably evaluating the low-velocity impact performance of FML.Highlights Comparisons were made between the low-velocity impact behavior of Glare laminates under five different boundary conditions. Boundary conditions influenced hardly on maximum impact force and energy absorbed ratio, but evidently on damage behavior. Constraint area and constraint degree governed damage mechanism under lower and intermediate impact energies, respectively. Influence of boundary conditions on damage behavior disappeared when the impact energy was enough to perforate Glare laminate. Impact responses and damage degrees of Glare laminates under different boundary conditions. image