The Dynamic Behavior Of Sandwich Structure With Layered Graded Cellular Metallic Cores

Sandwich cellular structure, associated with more excellent mechanicalproperties and physical characteristic, such as, panel ductility and high corecompressibility, is widely used in aerospace, transportation, militaryequipment and civil infrastructure. The mechanical properties of sandwichcellular metal structure both under quasi-static and impact load has became ahot spot in academic research. The common sandwich core selections aremetal and polyester foam, lattice and gird structure, as well as thin-shellstructure (ring and pipe). As research progressed, functional gradient sandwichresearch gradually highlights, due to its high utilization of cores, low totalweight and excellent structure mechanical properties. However, few papers onthe behavior study of functional gradient sandwich either under blast or impactare available in present.This article presents the results of numerical, experimental and analytical investigation into the failure mode and dynamic plastic response of gradientsandwich structures (sphere and cylindrical shell, honeycomb sandwich) toair-blast loading, compares the structure impact resistance between un-gradientsandwich and gradient sandwich. The author mainly discusses how the corearrangements (different core density) affect the structure s deformationbehavior, energy absorption and impact resistance. When subjected to blastload, the gradient sandwich structure gradually compress beginning from thefront face sheet, with interaction of each core. Then after compression,structure vibrates lightly, final remaining at rest. It s pointed out that thedensity-decreased core arrangement sandwich has the best impact resistance,through comparing the back face deflections.A four-cable ballistic pendulum system has been employed to investigatethe dynamic response of gradient sandwich under blast loading. Analyzedstructure s final deformations and failure modes, something has been foundbelow: impulse imparted on the sandwich is decided not only by explosivecharge also the core arrangements; three typical failure modes can be observed,that is, local deformation, global bending and penetration failure; comparedwith un-gradient sandwich, the gradient has more excellent impact resistant,especially when the thickness or the load impulse is larger. However,un-gradient sandwich exhibits better function under small impact load.Based on the1-D wave propagation equation, proposes an analyticalgradient foam model and analysis the wave propagation rules and the velocity attenuation of rigid block when a foam rod strike by a rigid mass. Then avalidation in numerical calculation has been conducted, the result meet theanalytical result well. The research results are of worth to the theoretical andtechnical support for the wave propagation prediction and core arrangementoptimization.