Andrew S. Bicos

Bio: Andrew S. Bicos is an academic researcher from Stanford University. The author has contributed to research in topics: Normal mode & Finite element method. The author has an hindex of 3, co-authored 3 publications receiving 106 citations.

Vibrational characteristics of composite panels with cutouts

Abstract: A method is presented for analyzing the free damped vibration characteristics of plates, cylinders, and cylindrical panels made of fiber reinforced, organic matrix composites. A computer code is described that can be used to calculate the natural frequencies, mode shapes, and damping factors of plates, cylinders, and cylindrical panels with free, clamped, or simply supported edges and with or without circular cutouts. Tests also were performed measuring the damping factors of Fiberite T300/934 graphite-epoxy unidirectional composite and the natural frequencies and mode shapes of rectangular plates made of this material. Plates with [Og], [(457 — 45h]s, and [(0/90>2]s layups were tested. Measurements were made with "solid" plates and with plates containing centrally located circular cutouts. The measured and calculated natural frequencies and damping factors were compared. The data and the numerical results were found to be in good agreement. As an illustrative example, the natural frequencies, damping factors, and mode shapes also were calculated for a semicircular cylindrical panel made of Fiberite T300/934 graphite-epoxy unidirectional tape.

Design of a Composite Boxbeam

Abstract: This paper presents an analysis for the preliminary design of boxbeams made of fiber-reinforced composites. The analysis provides deflections, bending and torsional stiffnesses, stresses, and the conditions for buckling and first-ply failure. Use of the analysis is illustrated through the example of a single cell, three bay, cantilevered box beam. This example demonstrates a design procedure for selecting the configuration which results in the required strength and stiffness at a minimum weight.

Formulation and evaluation of an analytical model for composite box-beams

Abstract: A direct method for determining the effective elastic stiffnesses and deformation behavior of composite box-beam (BB) structures is developed analytically, validated, and demonstrated. The BB walls are modeled as orthotropic-ply laminated plates, so that the elastic properties vary both through the thickness and around the BB contour; deformation is described in terms of extension, bending, twisting, shearing, and torsion-related out-of-plane warping. Numerical results for several BB configurations are presented in tables and graphs and compared with experimental data and FEM computations (Stemple and Lee, 1989): good general agreement is obtained for cross-ply, antisymmetric, and symmetric layups, except for symmetric layups with ply orientation angles theta greater than 30 deg. Both out-of-plane warping and transverse shear coupling are found to have significant effects on BB elastic response.

Flexural and shear moduli of full-section fiber reinforced plastic (FRP) pultruded beams

Abstract: An experimental methodology is presented for the simutaneous determination of the section flexural modulus and the section shear modulus of thin-walled fiber reinforced polyester and vinylester pultruded beams. A pilot test program, involving four different fiber reinforced plastic (FRP) beams, is described and results are discussed. A slenderness ratio is introduced to characterize the shape of the thin-walled beam, and recommended values of this ratio are suggested for design purposes. With available values of the section moduli the designer has the option of using the Timoshenko beam theory instead of the Euler-Bernoulli beam theory.