• Steel and Composite Structures
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• v.21 no.3
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• pp.605-628
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• 2016

The energy absorption characteristics of diamond core sandwich cylindrical columns under axial crushing process depend greatly on the amount of material which participates in the plastic deformation. Both the single-objective and multi-objective optimizations are performed for columns under axial crushing load with core thickness and helix pitch of the honeycomb core as design variables. Models are optimized by multi-objective particle swarm optimization (MOPSO) algorithm to achieve maximum specific energy absorption (SEA) capacity and minimum peak crushing force (PCF). Results show that optimization improves the energy absorption characteristics with constrained and unconstrained peak crashing load. Also, it is concluded that the aluminum tube has a better energy absorption capability rather than steel tube at a certain peak crushing force. The results justify that the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. A ranking technique for order preference (TOPSIS) is then used to sort the non-dominated solutions by the preference of decision makers. That is, a multi-criteria decision which consists of MOPSO and TOPSIS is presented to find out a compromise solution for decision makers. Furthermore, local and global sensitivity analyses are performed to assess the effect of design variable values on the SEA and PCF functions in design domain. Based on the sensitivity analysis results, it is concluded that for both models, the helix pitch of the honeycomb core has greater effect on the sensitivity of SEA, while, the core thickness has greater effect on the sensitivity of PCF.

• Journal of the Korean Ceramic Society
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• v.39 no.11
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• pp.1048-1054
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• 2002

When forming the ceramic body with plastic mass, it is needed that a quantitative testing method for plasticity, not only to evaluate the plasticity of a body, but also to control it within limits. Although many testing instruments were introduced, but no handy testing instrument for the plasticity quantitatively has been developed. In this study, modified vicat needle was designed to handily evaluate the plasicity of extruding bodies for honeycomb. The plasticity of three plastic masses was tested with this equipment. Columned needle with 2 mm diameter was adopted to measure the resistance for deformation and spherical needle with 9.5 mm diameter was adopted to measure the amount of deformation before cracking. The plasticity of three tested bodies were clearly distinguished quantitatively each other and the testing results were helpful to evaluated the workability of theses bodies. Probably, it is possible to evaluate the plasticity of various ceramic bodies with this apparatus, if suitable diameters of columns and spheres are selected.