Papers by Oscar Barton Jr
Composite Structures, Feb 1, 2003
An analysis was performed to evaluate the bearing strength of pin-loaded composite joints. The an... more An analysis was performed to evaluate the bearing strength of pin-loaded composite joints. The analysis involved using the Chang-Scott-Springer characteristic curve model and a two-dimensional finite element analysis to evaluate the stress distribution around the fastener hole. Characteristic lengths in tension and compression were evaluated by applying the point stress failure criterion to a center notch plate subjected to tensile loading and a plate containing a circular inclusion subjected to compressive loading. The Yamada-Sun failure criterion was used to evaluate joint failure. The results were compared with available experimental data and good correlation observed.
Composite materials are widely becoming the material of choice for many structural and nonstructu... more Composite materials are widely becoming the material of choice for many structural and nonstructural applications. The aircraft industry for example, has used composites for wing skins and other control surfaces that provide savings in fuel consumption and weight. The marine industry incorporates thick single skin and sandwich composites for hulls, decks, risers and other primary structure, and the automotive industry uses composites to fabricate body panels, springs and drive shafts. The civil engineering community uses glass and carbon reinforced plastics in the repair of aging bridges, piers, columns and other structures vital to the nation's infrastructure and economy. Exposure to the mechanics of composite materials and structures is usually reserved for the graduate student. However, many undergraduate institutions find the need to provide their students with experience with these advanced materials and have crafted courses to do so. This describes the motivation at the United States Naval Academy (USNA). For the same reasons as other industries, the U. S. Navy is incorporating more composite material systems into its ships, aircraft and land vehicles. The paper describes a dual effort to expose midshipmen to composite materials and structures. Theory of composite materials is presented in a senior-elective course in the Mechanical Engineering Department. Here the midshipmen, using computational tools such as IDEAS, are taught the mechanics of composite materials including classical lamination theory(CLT). An elective course in the Naval Architecture and Ocean Engineering Department focuses on experimentation and fabrication. This senior-level course combines both theory and practice in the selection and planning of methods, materials, and equipment to fabricate, upgrade, and repair marine structures (ships and offshore structures) made of composites and traditional materials.
Buckling of rectangular symmetric laminated plates determined by eigensensitivity analysis
Closed-form approximate solutions for uniaxial and biaxial compressive buckling of rectangular sy... more Closed-form approximate solutions for uniaxial and biaxial compressive buckling of rectangular sy~nmetric angle-ply laminates are developed from eigensensitivity analysis. Boundary conditions, which consist of the various combinations of clamped and simply supported edges, are incorporated through appropriate edge condition parameters. Calculated results, presented for elastic moduli ratios up to 40, compare quite favorably with the corresponding buckling loads obtained from the Ritz method. Background
Vibration of Variable Thickness Orthotropic Plates Using Eigensensitivity Analysis
Journal of Thermoplastic Composite Materials, Mar 1, 1998
An approximate closed-form expression is presented which can be used to compute the fundamental f... more An approximate closed-form expression is presented which can be used to compute the fundamental frequency of orthotropic laminates of variable thickness. The quadratic expression is derived for a laminate with a general thickness variation in one direction, and explicit results are provided for a laminate with a linear thickness variation. The desired expression is determined by casting the governing differential equation into discrete form using the Ritz method and expanding the discrete equations in a Maclaurin series about the off-diagonal elements of both the stiffness and mass matrices. Simply supported and clamped boundary conditions are analyzed using both beam shape functions and orthogonal polynomials. Results are compared with those obtained numerically using the Rayleigh-Ritz approach for several laminate tapers $ and plate aspect ratios R.
Computers & Structures, Jul 1, 1997
closed-form expressions are developed to predict the vibration of rectangular angle-ply antisymme... more closed-form expressions are developed to predict the vibration of rectangular angle-ply antisymmetric laminated composite plates. The set of partial differential equations is first represented in abstract form and then converted into discrete form using an Ritz approach. Sensitivity derivatives are determined which are used to provide a Maclaurin series representation of the laminate's frequency. A comparison of numerical results calculated for various boundary conditions using both the derived formula and the Rayleigh-Ritz method validates the accuracy of the approximate formula.
Approximate Fundamental Frequency of Variable Thickness Composite Plates
Springer eBooks, 1995
A native of Fairfax, VA, he enrolled in the major in January 2015. In addition to the curriculum,... more A native of Fairfax, VA, he enrolled in the major in January 2015. In addition to the curriculum, he researches the mechanics of dynamic systems as a research assistant to the Department Chair, Oscar Barton, Jr., PhD, PE. In particular, his researches focuses on the computer modeling of vibrations in dynamic systems. Mr. Howe also provides academic support as a tutor for mathematics, science, and engineering in the Volgeneau School of Engineering, and is the Secretary of the George Mason University Chapter of the American Society of Mechanical Engineers.
Modal Analysis of a Thick Sandwich Plate: A Comparison Between Theory and Experiment
SPIE eBooks, 1997
Composite structures, beam, plates, and shells, are commonplace in many sectors of the automotive... more Composite structures, beam, plates, and shells, are commonplace in many sectors of the automotive and aircraft industries. Use of such structures is now being considered for off-shore and naval applications because of thepotential for improved strength to weight ratio and resistance to harsh environments. This paper considers the theoretical and experimental modal analysis of a thick sandwich plate, approximately 20 feet by six feet. This plate is a scale model of a new design for a ship's deck. In service, it is the fundamental mode that is normally most problematic for a ship's deck. Results are presented from an experimental modal analysis with the plate suspended on rubber bungee cords.
A simple method to model truss-beams as equivalent continua
A new method is presented for obtaining stiffness constants for structures modeled as three-dimen... more A new method is presented for obtaining stiffness constants for structures modeled as three-dimensional linear elastic beams. The three-dimensional lattice is comprised of multiple two-dimensional lattices. Matrix manipulation is used to determine the contribution of each two-dimensional substructure to the complete three dimensional lattice.
2016 ASEE Annual Conference & Exposition Proceedings
2014 as an Assistant Professor of Mechanical Engineering specializing in the area of thermal flui... more 2014 as an Assistant Professor of Mechanical Engineering specializing in the area of thermal fluid flows and sustainable energy. He is working to build the mechanical engineering program through teaching, research, and community outreach. Colin received his doctorate, master's, and bachelor's degrees from Virginia Tech in mechanical engineering (2007, 2009, 2012).
Thin-Walled Structures, 2010
Experimentally determined natural frequencies and modes shapes are presented for an elastically p... more Experimentally determined natural frequencies and modes shapes are presented for an elastically point-supported isotropic plate with attached masses under impulsive loading. These results are compared to frequencies and to modes shapes determined from the Rayleigh-Ritz method and a finite element analysis using COMSOL. Accelerometers mounted at three locations on the plate, provide input for ME'Scope Modal Analysis Software to identify frequency peaks and modes shapes. Orthogonal polynomials, which meet free-free plate boundary conditions, are selected as the basis functions used in the Rayleigh-Ritz method. A Mindlin plate theory, adjusted for negligible transverse shear effects, is used in COMSOL. Frequencies and mode shapes for four plate configurations are presented, compared using each method, and indicate good agreement between the numerical, analytical and experimental results.
ADVANCE: A Community College and University Partnership Model for Expanding and Diversifying the Talent Pipeline to the Jobs of Tomorrow
2019 CoNECD - The Collaborative Network for Engineering and Computing Diversity, Apr 14, 2019
Journal of Thermoplastic Composite Materials, 2009
In this paper, an approximate closed-form solution is presented to compute the thermal buckling r... more In this paper, an approximate closed-form solution is presented to compute the thermal buckling response of a symmetric angle-ply laminates that are clamped in one edge and free along the other edge. For this boundary condition, no exact solution is available and, in order to compute the critical buckling temperatures, numerical methods such as the Rayleigh—Ritz or finite element method must be used. Approximate closed-form solutions bridge the void between exact and approximate numerical solutions and can readily be employed in design optimization. The environment corresponds to a steady state condition providing a uniform temperature distribution for the laminate. The laminate consists of four layers [θ/-θ]s constructed of low, moderate, and high stiffness ratio materials. Comparative results using the Rayleigh—Ritz method provides a means of assessing the accuracy of the expression. For certain laminate architectures, several modes must be computed using the approximate quadratic...
2001 Annual Conference Proceedings
Eigensensitivity methods in composite structural analysis
Eigensensitivity analysis is used to develop approximate formulas to determine the frequencies an... more Eigensensitivity analysis is used to develop approximate formulas to determine the frequencies and buckling loads of rectangular angle-ply laminated plates. The approach converts a distributed parameter eigenvalue problem into a discrete form and then decomposes the representative stiffness and mass matrices into the sum of a diagonal matrix and a matrix containing zeros on its diagonal. By expanding the desired
Ocean Engineering, 2007
In this paper, an approximate closed-form solution is presented to compute the moisture-related b... more In this paper, an approximate closed-form solution is presented to compute the moisture-related buckling of symmetric angle-ply laminates. The environment corresponds to a steady state condition, which provides a uniform moisture distribution for the laminate. The laminate consists of four layers [y/Ày] s constructed of low, moderate and high stiffness ratio materials. Comparative results using the Rayleigh-Ritz method provides a means of assessing the accuracy of the expression. For certain laminate architectures, several modes must be computed to ascertain the lowest buckling mode, and once identified, provides an excellent approximation for the mode computed using the Rayleigh-Ritz method.
On the fundamental frequency of symmetric rectangular laminated plates - A new closed-form approximate solution
A new closed-form approximation for the fundamental frequency of symmetric rectangular laminates ... more A new closed-form approximation for the fundamental frequency of symmetric rectangular laminates subject to all combinations of hinged and clamped boundary conditions is presented. The distributed parameter eigenvalue equation is cast in an equivalent infinitely-dimensional discrete form. The stiffness and mass matrices are each decomposed into the sum of two matrices, one of which is diagonal while the other contains
Buckling of simply supported rectangular plates under combined bending and compression using eigensensitivity analysis
Thin-Walled Structures, 2008
In this paper, an approximate quadratic closed-form expression is presented for the critical buck... more In this paper, an approximate quadratic closed-form expression is presented for the critical buckling analysis of a plate subjected to combined bending and compression. The formula is developed by expanding the eigenvalue, the critical buckling load, for a plate under combined bending and compression in a Mauclaurin's series about a plate subjected only to compression. The general expression can be
Thin-Walled Structures, 2010
Normalized frequencies are computed for a rectangular, isotropic plate resting on elastic support... more Normalized frequencies are computed for a rectangular, isotropic plate resting on elastic supports. The normalized frequencies are determined using eigensensitivity analysis, which approximates the eigenparameters in a Mauclarin series, yielding an approximate closed-form expression. One benefit of the approximate closed-form expression is its computational efficiency and yet another is its application of re-analysis. Accuracy of the approximate expression is assessed by comparing results with the widely used Rayleigh-Ritz method using orthogonal polynomials and beam shape functions in both approaches. Consideration for a variety of edge conditions is given through a combination of simply supported, clamped and free boundary conditions. Results indicate that the accuracy of higher frequencies computed by the sensitivity approach is highly dependent upon choice of basis function.
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Papers by Oscar Barton Jr