Numerical Study Of Static And Dynamic Behavior Of Honeycomb Material-based Structures

Honeycomb material has been used extensively in many industries, such as aircraft, airspace, transportation, mechanics, energy and architecture due to its light weight, high stiffness and strength to weight ratios, excellent anti-impact and the ability of absorbing. But the honeycomb material is not used alone in the engineering applications. In fact, it is always used with the face panels and side panel. As a result, the effect of the face panels and the side panel on the mechanical behavior of honeycomb cores must be considered.Although many researchers have been derived the some models to predict of the equivalent in-plane moduli of the honeycomb materials, most of them neglected the effect of the face panels and the side panels. In this thesis, a 2D model of the honeycomb material has been established by using the Timoshenko beam element BEAM188 in the finite element software ANSYS. By applying the displacement constraints on the X and Y direction respectively, the equivalent in-plane elastic moduli of the pure honeycomb material are calculated. Then by using the BEAM188, a 2D finite element model including the side panels is established, which gives the equivalent in-plane elastic modulus under the effect of side panel. Further, the thickness effect of side panel on the equivalent in-plane moduli of honeycomb material is investigated. A 3D finite element model with face panels is established by SHELL181 and the equivalent in-plane moduli are then evaluated. The application limitation of the popular prediction models of honeycombs are evaluated based on the numerical results given by the 3D model.Secondly, the explicit dynamic software LS-DYNA is used to evaluate the impact energy-absorbing device composed of honeycomb core and panels. By changing the impact velocity of impactor and types of honeycomb materials, the energy absorption capability of honeycomb materials is obtained. The results show that all types of honeycomb materials present good capability of energy absorption, but the aluminum with higher yield stress is better in energy absorption. Thus the honeycomb materials with higher yield stress are more suitable as energy absorption materials in relative high velocity impact. A finite element model with the honeycomb material and side panels is built up, in which the effect of the thickness of side panel and the distance between the panels and the honeycomb core are also included. Further, the energy absorption characteristics are studied under different impact velocities and different honeycomb materials.The foamed aluminum is used to fill the honeycomb core to increase the energy absorbing capability. The solid element SOLID164 is adopted to model the equivalent mechanical properties of foamed aluminum. The simulated results indicate that the energy absorption rate is increased as the foam density increasing. Comparing with the device without filler material, the results show that the energy absorbing efficiency of the device with the honeycomb core filled with foamed aluminum is considerably higher under the impact velocities ranged from 15m/s to 25m/s.The results given this thesis provide some useful guideline for the design of the efficient impact energy-absorbing devices.