Yazarlar
- Topal, U.(5)
- Uzman, Ü.(5)
- Topal, Umut(3)
- Uzman, Ümit(1)
Yayınlar
- MakaleYalnız künye2009Thermal buckling load optimization of angle-ply laminated cylindrical shells
Topal, U.; Uzman, Ü.
In this study, thermal buckling load optimization of symmetrically laminated cylindrical shells subjected to uniformly distributed temperature load is investigated. The objective function is to maximize the critical temperature capacity of laminated shells and the fibre orientation is considered as design variable. The first-order shear deformation theory is used to study thermal buckling response of the laminates. The modified feasible direction method is used as optimization routine. For this purpose, a program based on FORTRAN is used for the optimization of shells. Finally, the effects of number of layers, length-to-radius ratio and boundary conditions on the optimum results are investigated.
- MakaleYalnız künye2009Multiobjective optimization of laminated composite cylindrical shells for maximum frequency and buckling load
Topal, Umut
This paper deals with multiobjective optimization of laminated cylindrical shells to maximize a weighted sum of the frequency and buckling load under external load. The layer fibre orientation is used as the design variable and the multiobjective optimization is formulated as the weighted combinations of the frequency and buckling under external load. The first order shear deformation theory is used for the finite element formulation of the laminated shells. Five shell configurations with eight layers are considered as candidate designs. The modified feasible direction method (MFD) is used as optimization routine. For this purpose, a program based on FORTRAN is used for the optimization of the laminated shells. Finally, the effect of different weighting ratios, shell aspect ratio, shell thickness-to-radius ratios and boundary conditions on the optimal designs is investigated and the results are compared.
- MakaleYalnız künye2009Frequency optimization of laminated skew plates
Topal, U.; Uzman, Ü.
In this study, the frequency optimization of laminated skew plates is investigated. The objective function is to maximize the fundamental frequency of the laminated skew plates and the fiber orientation is considered as design variable. The mathematical formulation is based on the first-order shear deformation theory (FSDT) for the frequency analysis of the laminated skew plates. The modified feasible direction (MFD) method is combined with the finite element solution of laminated skew plates for optimal designs. Therefore, a program based on FORTRAN is used. Finally, the effect of skew angles, boundary conditions, aspect ratios and functionally graded materials on the optimal results is investigated and the results are compared.
- MakaleYalnız künye2009Frequency optimization of laminated general quadrilateral and trapezoidal thin plates
Topal, Umut
This paper deals with frequency optimization of symmetrically laminated angle-ply general quadrilateral and trapezoidal thin plates. The objective function is to maximize the fundamental frequency of the quadrilateral and trapezoidal laminated plates and the fibre orientation is considered as design variable. The mathematical formulation is based on the classical laminated plate theory (CLPT) for the frequency analysis. The modified feasible direction (MFD) method is used as the optimization routine. Therefore, a program based on FORTRAN is used. Finally, the significant effects of aspect ratios, boundary conditions, taper ratios and unsymmetric trapezoidal plates on the optimal results are investigated and the results are compared.
- MakaleYalnız künye2009Effects of nonuniform boundary conditions on the buckling load optimization of laminated composite plates
Topal, Umut; Uzman, Ümit
This paper deals with buckling load optimization of symmetrically laminated composite thin plates under the uniaxial and biaxial compressive loads with discontinuities along the boundaries. The objective of the design problem is to maximize the buckling load of the laminated plates and the fibre orientation is taken as design variable. The classical laminate plate theory is used for the mathematical formulations of the laminates. The modified feasible direction method is used as optimization routine. Therefore a program based on FORTRAN is used. Finally, the effect of nonuniform boundary conditions, aspect ratios and load ratios on the optimum results is illustrated.
- MakaleYalnız künye2009Thermal buckling load optimization of laminated skew plates
Topal, U.; Uzman, Ü.
In this study thermal buckling load optimization of laminated skew plates subjected to uniformly distributed temperature load is investigated. All of the laminates considered are assumed to have fully clamped boundary conditions, though the general boundary conditions may also be studied without any difficulty. The objective function is to maximize the critical temperature capacity of the laminated skew plates and the fibre orientation is considered as design variable. The first-order shear deformation theory is used in the mathematical formulation. Nine-node Lagrangian rectangular plate element is used for the finite element solution of the skew laminates. The temperature field is assumed to be uniform over the plate surface and varies in the thickness direction only. Modified feasible direction method (MFD) is used for the optimization routine. A program based on FORTRAN is used for the optimization problem. Finally, the effect of number of layers, skew angles, aspect ratios, width-to-thickness ratios and antisymmetric lay-up on the optimal designs is investigated and the results are compared.
- MakaleYalnız künye2009Frequency optimization of laminated folded composite plates
Topal, U.; Uzman, Ü.
In this study, frequency optimization of symmetrically laminated folded composite plates is presented. The folded plates are modelled as a composite structure that consists of flat plates. The fundamental frequencies of one- and two-fold folded plates are maximized with respect to fibre orientations. The first-order shear deformation theory (FSDT) is used for vibration analysis of laminated folded plates. The modified feasible direction (MFD) method is used for the optimization routine. Therefore a program based on FORTRAN is used. Finally, the significant effects of length-to-thickness ratios, crank angles, different plate lengths and boundary conditions on the optimum results are demonstrated.
- MakaleYalnız künye2008Frequency optimization of laminated composite angle-ply plates with circular hole
Topal, U.; Uzman, Ü.
The fundamental frequencies of simply supported symmetrically laminated composite angle-ply plates with central circular holes with a given material system are maximized with respect to fibre orientations. The first-order shear deformation (FSDT) theory is used for finite element analysis. Modified feasible direction (MFD) method is used for the optimization routine. Also, the optimum fibre orientations are obtained using golden section (GS) method to compare with MFD method. Finally, the significant effects of different number of layers, boundary conditions, plate aspect ratios, hole diameter-to-width ratio, material anisotropy and antisymmetric lay-up on the results are demonstrated.