Numerical and experimental study of energy ‎absorption amount of functionally graded honeycomb ‎with negative stiffness property under quasi- static ‎load

Functionally graded honeycomb with negative stiffness can be used extensively as an energy absorber because ‎of having two features of negative stiffness and being functionally graded. In this research, the effect of using ‎functionally graded honeycomb with negative stiffness in increasing energy absorption has been considered. In ‎functionally graded honeycomb the thicknesses of structure change gradually in each layer, as a result, each layer ‎has a different stiffness. Negative stiffness honeycomb is a type of energy absorber that absorb energy by ‎transition from one bucked shape to another and show snap through- like behavior .In this research, at first quasi-‎static tests have been carried out on negative stiffness honeycombs with constant thickness. Then finite element ‎model of negative stiffness honeycomb with constant thickness is simulated in ABAQUS software and the results of ‎simulation is compared with experimental results and a good agreement between numerical and experimental ‎results have been observed. Functionally graded honeycomb with negative stiffness then has been modeled ‎numerically. Energy absorption per unit mass of the functionally graded negative stiffness honeycomb has been ‎compared with conventional one. Based on the results, energy absorption per unit mass in functionally graded ‎honeycomb with negative stiffness increased by 1.57 times.‎‎