Dynamic Testing And Properties Analyzing Of Energy-absorbing Structures Under Large Deformations

Energy absorption behavior of packaging or protection materials andstructures is important for people and instruments under the impact loading.Therefore, the research on the impact energy absorption is significant in theautomotive, aerospace, nuclear power, precision instruments and other areas.Cellular materials and structures are widely used in engineering structuresbecause of their excellent properties in both physics and mechanics. Thus,research on the mechanical properties has become an increasingly importantissue. In this thesis, aluminium honeycomb structures and aluminium foamshave been investigated by combining the experimental test, theoreticalanalysis and FEM simulation. The research work can be summarized as thefollowing aspects:A pendulum impact testing system was built which contained apendulum-impacting unit, a three-dimensional shape measurement system anda kinematics measurement unit.The dynamic compression performance and low-velocity impact energyabsorption characteristics of the aluminium honeycomb structures werestudied with the pendulum impact tests. The results show that the aluminiumhoneycomb structure has good absorbing energy characteristics under impactloading, and their deformation behavior is similar to that of the quasi-staticdeformation under the low-velocity impact with a spherical shaped pendulum.A high-speed camera and an acceleration sensor were used to record themovements and acceleration changes of the pendulum during the experiments.A projection profile system was employed to obtain in situ thethree-dimensional topography of the aluminium honeycomb structures underimpact deformation. Finally, the internal damages which couldn’t be observedin the experiments were further analyzed using the finite element method, and the effects on the energy absorption by various structural parameters of thecellular structure were also discussed. The results show that the deformedvolume and the energy-absorbed value have a nearly linear relationship, andthe energy dissipation by the plastic deformation is the major factor of energyabsorption. The skin of the honeycomb structure can increase the energyabsorption capacity of the honeycomb plate.The dynamic compression performance and low-velocity impact energyabsorption characteristics of the aluminum foam were also studied with thesame testing system. The results show that the aluminum foam has goodimpact energy absorbing characteristics. Different with the aluminiumhoneycomb structure, the aluminum foam is isotropic, and thus differentlayers of aluminum foam panels were tested, as well as the relationshipbetween the energy absorption and the deformation volume was discussed.Finally, the effects on the energy absorption by various structure parametersand different placement of the order of the form plates were simulated and thesuggestions were proposed to improve the capacity of the energy absorbingstructures.