Numerical and experimental investigation for assessing the high strain rate response of nickel based multi-layered honeycomb sandwiches

The mechanical behaviors of a multi-layered nickel based honeycomb sandwich at quasi-static and high strain rate ranging from 800/s-6500/s were determined by a universal Instron and uniaxial dynamic compression SHPB experiment respectively. The results of experiment showed strain rate sensitivity at low strain rate portion (0-800/s) while by increasing the strain rate (3400/s-6500/s); the samples no longer showed noticeable rate sensitivity. Dynamic strain-stress curves showed clearly initial peak strength, flat flow potion and totally compressed ascending part process while a littler peak was appeared during the flat flow portion. Different folding process can be found during dynamic compression for one and two layered honeycomb cells by high speed camera. A numerical model was developed using LS-DYNA software, for investigating the different deformation modes under various strain rates. A bi-linear elastic-plastic constitutive model was utilized to simulate plastic deformation and in-stability status of multi-layered nickel based honeycomb under dynamic compression. In this work, different finite element models were used to investigate dynamic crushing strength as a function of cell wall thickness and the number of sandwich layers.