Research Publications (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215
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Item Optimal design of symmetrically laminated plates for maximum buckling temperature(Taylor & Francis, 1997) Walker, Mark; Reiss, Talmon; Adali, Sarp; Verijenko, Viktor E.The optimal designs of laminated plates subject to nonuniform temperature distributions are givenfor maximum bucklingtemperature. The method ofsolution involves the finite element method based on Mindlin plate theory and numerical optimization: A computational approach is developed that involves successive stages of solution for temperature distribution, buckling temperature, and optimalfiber angle. Three different temperature loadingsare consideredand various combinations of simply supported and clamped boundary conditionsare studied. The effectofplate aspectratioon the optimal fiber angle and the maximum buckling temperature is investigated. The influence of bending-twisting coupling on the optimum design is studied by considering plates with an increasing number of layers.Item Minimum weight design of composite hybrid shells via symbolic computation(Elsevier, 1997) Walker, Mark; Reiss, Talmon; Adali, SarpThe best layup for a hybrid laminated cylindrical shell subject to a buckling load constraint is determined. The objective of the optimisation is the minimum weight design of these structures. The ply angle is taken as the design variable. Various configurations of graphite and boron epoxy layers are considered in order to determine an optimal stacking sequence. The symbolic computational software package MATHEMATICA is used in the implementation and solution of the problem. This approach simplifies the computational procedure as well as the implementation of the analysisloptimisation routine. Results are given illustrating the dependence of the optimal layup on the cylinder length and radius. It is shown that a general purpose computer algebra system like MATHEMATICA is well suited to solve structural design problems involving composite materials.Item Optimal design of symmetrically laminated plates for minimum deflection and weight(Elsevier, 1997) Walker, Mark; Reiss, Talmon; Adali, SarpThe minimum deflection and weight designs of laminated composite plates are given. The finite element method using Mindlin plate theory is used in conjunction with optimisation routines in order to obtain the optimal designs. Various boundary conditions are considered and results are given for varying aspect ratios and for different loading types. Comparative results are presented for minimum weight priority design as an alternative to minimum deflection/minimum weight priority design to investigate the effect of priority on the deflection and weight.Item A procedure to select the best material combinations and optimally design hybrid composite plates for minimum weight and cost(Taylor & Francis, 1997) Walker, Mark; Reiss, Talmon; Adali, SarpThe optimal layup with least weight or cost for a symmetrically laminated plate subject to a buckling load is determined using a hybrid composite construction. A hybrid construction provides further tailoring capabilities and can meet the weight, cost and strength constraints while a non-hybrid construction may fail to satisfy the design requirements. The objective of the optimization is to minimize either the weight or cost of the plate using the ply angles, layer thicknesses and material combinations as design variables. As the optimization problem contains a large number of continuous (ply angles and thicknesses) and discrete (material combinations) design variables, a -sequential solution procedure is devised in which the optimal variables are computed in different stages. The proposed design method is illustrated using graphite, kevlar and glass epoxy combinations and the efficiencies of the hybrid designs over the non-hybrid ones are computed.