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| THE DEPENDENCE OF ENERGY ABSORPTION BEHAVIOR OF CELLULAR MATERIALS ON RELATIVE DENSITY AND IMPACT VELOCITY |
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Abstract Cellular materials have been extensively used as core materials of impact energy absorbers and anti-blast sacrificial claddings for their lightweight and superior energy absorption capability. However, the dependence of energy absorption behavior of cellular materials on relative density and impact velocity is still unclear due to the diversity of its deformation modes and the inaccessibility of its dynamic stress-strain curve. In this paper, the dynamic energy absorption behavior of cellular materials is investigated by using the wave propagation technique, of which the main advantage is that no pre-assumed constitutive relationship is required. In the virtual Taylor impact test, the particle velocity history curves of the whole field in cellular materials are obtained, and thus the local stress and strain history profiles of cellular materials are determined based on the Lagrangian analysis method. The dynamic energy absorption behavior can be investigated by integrating local stress-strain history curves. The results show that the energy absorption behavior of cellular materials can be divided into three stages according to the deformation modes. In the stage of shock mode, the specific energy absorption of cellular materials increases linearly with the relative density since the inertia effect is dominant at this stage; in the stage of transition mode, the inertia is relatively weak, and the increase rate of the specific energy absorption decreases gradually with the increasing of relative density; in the stage of quasi-static mode, the energy absorption capacity is very weak, and it should be distinguished from the quasi-static energy absorption behavior under constant speed loading. Finally, the dynamic stress-strain state curve of cellular materials is obtained and its dependency on the relative density is further investigated. The results transpire that, with the increasing of the relative density, the dynamic densification strain under the same stress level decreases and the dynamic plastic platform stress increases.
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Received: 10 April 2018
Published: 28 December 2018
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2018, Vol. 39 
