Effect of structural parameters on design of variable-stiffness composite cylinders made by fiber steering

Stiffness tailoring of elliptical composite cylinders for axial buckling performance

“…The resulting curve, or hyper-surface in case of higher dimensions, is a low cost approximation for the costly high fidelity model that is used for function calls in MBDO process. Among several metamodeling techniques developed for engineering design optimization purposes [21,22], the radial basis functions (RBF) offer accurate and reliable predictions at a relatively low computational cost for buckling response of VS composite structures [7,8]. Therefore, RBF-based metamodels were used in this study to construct surrogate models relating the buckling load (F cr ) to the design variables (T i 's).…”

“…In this study, the number of test points is considered to be one tenth of the DOE training points (one tenth of the sample size). To reduce the errors associated with metamodeling, a multi-step design optimization method [23] was used in which the design domain is narrowed down in multiple steps of the optimization process so that a converged optimum design emerges with negligible error when the result is compared with the high fidelity FE model.…”

“…The resulting so-called variable stiffness (VS) composite laminate offers the designers more scope to use the directional properties of the material more efficiently to produce VS composite cylinders [5,6,7,8,9] with better structural performance compared with their traditional Constant Stiffness (CS) counterparts. However, this improvement is at the expense of adding more complexity to the design optimization process because of the increased number of design variables.…”

“…in bending. Therefore, extensive research works have been performed subsequently to improve the bending-induced buckling capacity of circular VS composite cylinders [5,7,8,9]. The inhomogeneity of the section load in the skin arising from overall bending gives designers suitable scope to vary the orientation angle of fibers from the compressive side to the tension side so that the section loads are redistributed more efficiently.…”

“…Afterwards, for VS design, the optimum fiber orientation angle distribution in the circumferential direction is calculated. For both cases, a multi-step surrogate based design optimization method [7,8,9] is used. Finally, the potential improvement of the buckling capacity for the VS design compared with its counterparts with constant stiffness (CS) and quasi-isotropic (QI) laminates is studied for different crosssectional aspect ratios.…”