| Reengineering and Fast Manufacturing for Impact-Induced Fatigue and Fracture Problems in Aging Aircrafts |
31 JAN 2006 |
40 pages |
| Authors:
Kuang-Hua Chang; Zahed Siddique; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
 | In this research, a systematic reverse engineering, re-engineering, and fast manufacturing (RRF) process has been developed and validated. Commercial off-the-shelf (COTS) software tools and equipment that support the RRF process have been identified, evaluated, and tested. An integration framework has also been developed and employed to create an RRF testbed. This testbed constructed using COTS software and equipment supports three major engineering tasks: the reverse engineering that supports recovering of ... |
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| Fatigue and Fracture Characterization of Aircraft Aluminum Alloys Damaged by Prior Corrosion |
19 MAR 2002 |
58 pages |
| Authors:
J. D. Baldwin; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| At the time of the initiation of this project, there was no comprehensive data describing corrosion's effect on the fatigue and fracture behavior of aluminum alloys typically found in aging aircraft. One of the primary objectives of this project was to perform experimental and analytic characterizations of these materials response for three aluminum alloys (2024- T3, 7075-T6 and 7178-T6, all widely used in order aircraft) in the presence of prior ... |
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| Rheological Properties of Fiber Suspensions: A Statistical Approach Using Discrete Fibers |
93 |
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| Authors:
S. Akbar; B. N. Rao; M. C. Altan; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
 | An analytical-statistical technique for the representation of rheological properties of fiber suspensions is presented. the statistical orientation distribution function generated from the orientation of discrete fibers can be used to calculate the orientation tensor components. jeffery's equation is considered as the governing equation for the motion of individual fibers. solution of jeffery's equation for a large number of fibers is used to generate the statistical orientation distribution function. increasing the ... |
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| Critical Speed Analysis of Laminated Composite, Hollow Drive Shafts |
93 |
|
| Authors:
Chun-Do Kim; Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| A theoretical analysis is presented for determining the critical speeds of a rotating circular cylindrical hollow shaft with layers of arbitrary laminated composite materials by means of the thin- and thick-shell theories. the theory used is the dynamic analog of the sanders best first approximation shell theory. by means of tracers, the analysis can be reduced to that of various simpler shell theories, i.e. love's first approximation, loo's, morley's and ... |
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| Influence of Structural and Aerodynamic Modeling on Flutter Analysis and Structural Optimization |
JUN 91 |
77 pages |
| Authors:
Alfred G. Striz; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| The influences of structural and aerodynamic modeling on the flutter analysis and multidisciplinary optimization of fully built-up finite element wing models in an aeroelastic environment are not yet well understood. Therefore, the dynamic aeroelastic and optimization capabilities in the Automated STRuctural Optimization System (ASTROS) were used to evaluate the flutter behavior and the behavior of structural optimization with flutter constraints of various representative fully built-up finite element wing models in ... |
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| Plate Wave Propagation in Transversely Isotropic Materials, |
MAY 1989 |
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| Authors:
R. A. Kline; M. M. Doroudian; C. P. Hsiao; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| The modes of plate wave propagation in a fiber reinforced composite (assumed to be transversely isotropic) were investigated. The waves were modeled as harmonic plane waves propagating in the plane of an infinite plate whose bounding surfaces were assumed to be stress free. A numerical analysis procedure was developed to calculate the dispersion relationships for plate waves propagating in arbitrary directions in the plate. Particle displacements and stress distributions were ... |
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| Transverse Tensile Strength of Unidirectionally Reinforced Metal-Matrix Composites |
87 |
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| Authors:
Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| First, a literature review is presented on the strength of unidirectionally reinforced composites subject to uniaxial tension normal to the fibers. Emphasis is placed on composites with metal matrices, and it is demonstrated that the ductility under the subject loading is very small. However, it is shown that present procedures for prediction of TTS (transverse tensile strength) are inadequate. A new framework for evaluation of TTS is presented and the ... |
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| Optimization of Tip Store Modeling |
MAR 85 |
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| Authors:
Alfred G. Striz; Sun-Kuk Jang; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Due to the high cost of performing detailed three-dimensional flutter analyses for aircraft which are carrying large numbers and types of external stores, it is often not economically feasible to include sophisticated store aerodynamics especially when they will not cause significant changes to the flutter results. Thus, the stores are presently often modeled as simple flat plates. This tends to decrease the accuracy of the computed pressure distributions as the ... |
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| Normal and Shear Stress Gages and Rosettes for Orthotropic Composites |
85 |
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| Authors:
C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Stress gages, plane-shear gages, and three-elemental strain rosettes have long been used in experimental-mechanics investigations on isotropic materials. This paper generalizes these concepts for applications to fiber- reinforced composite materials. Also included for the first time are data- reduction equations which explicitly incorporate strain-gage transverse sensitivity. (Author) |
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| Turbulent Boundary Layers Over Rough Surfaces Hypersonic Flow |
30 JUN 1984 |
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| Authors:
J. M. Russell; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| A method for predicting the downstream development of momentum thickness, skin friction, and heat transfer in a supersonic turbulent boundary layer over a rough flat plate based on ideas of Van Driest, Rotta, and Bradshaw is derived and discussed. Admissible thermal boundary conditions include the case of prescribed wall temperature and the case of an adiabatic wall. The velocity profiles for compressible nonadiabatic flow are expressed as transformations of the ... |
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| Nonlinear Analysis of Laminated, Bimodular Composite Material Structures |
NOV 1983 |
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| Authors:
C. W. Bert; J. N. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Geometrically nonlinear analyses of BCM structures; experimental investigations of BCMs and structures; analyses of structures made of nonlinear composite materials, and new structural analyses. The research program was reported in a series of thirty-seven technical reports (including the present one) and sixty-eight conference papers and journal articles, all of which are listed herein. (Author) |
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| A Critical Evaluation of New Plate Theories Applied to Laminated Composites |
AUG 1983 |
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| Authors:
C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| The plate theory recently developed by Levinson is extended to laminates. Closed-form solutions of this theory, as well as those of Reissnet- Mindlin plate theory with appropriate shear correction, Seide's discrete-layer plate theory, and Lo, Christensen, and Wu's higher-order theory are all compared with Pagano's elasticity-theory solution for the cases of cylindrical bending of a single orthotropic layer and a symmetric cross-ply (0 deg/90 deg/0 deg) laminate consisting of three ... |
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| New Theory for Thick, Composite-Material Rings |
AUG 1983 |
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| Authors:
C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A new theory for the in-plane elastic behavior of shear-deformable ring-type structures, i.e., curved beams and complete rings, is presented. This theory falls between Bresse-Timoshenko-type ring theory, in which the shear deformation is assumed to be distributed uniformly through the thickness and corrected by a shear correction factor determined in an ad hoc fashion, and two- or three-dimensional elasticity theory. As an example, the theory is applied to the problem ... |
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| Forced Vibration of Timoshenko Beams Made of Multimodular Materials |
JUN 1983 |
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| Authors:
F. Gordaninejad; C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| This paper presents a transfer-matrix analysis for determining the sinusoidal vibration response of thick, rectangular-cross-section beams made of multimodular materials (i.e., materials which have different elastic behavior in tension and compression, with nonlinear stress-strain curves approximated as piecewise linear). An experimentally determined stress-strain curve for aramid- cord rubber is approximated by four straight-line segments (two segments in tension and two segments in compression). To validate the transfer-matrix results, a closed-form ... |
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| Analysis of Containment Rings for Flywheel Burst Protection, |
MAY 1983 |
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| Authors:
Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| This paper is concerned with the analysis of Hertzian impact of a band-supported, thick-rim flywheel against an elastic containment ring. The following topics are addressed: consideration of probable failure mode of the flywheel, estimation of impact velocity, prediction of maximum conditions at contact, prediction of the maximum bending stress in the impulsively loaded containment ring, and sample calculation for a proposed containment ring. |
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| Transverse Shear Effects in Bimodular Composite Laminates |
APR 1983 |
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| Authors:
C. W. Bert; F. Gordaninejad; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A closed-form solution for the Timoshenko-type shear correction coefficient (K2) governing the deflection of bimodular composite laminates in cylindrical bending is presented. The bending-stress distribution for a laminate constructed of bimodular materials (which have different elastic moduli in tension and compression) is used in the two-dimensional equilibrium equation to obtain the transverse shear-stress distribution. This shear-stress distribution is used to obtain expressions for the shear correction coefficient (based on equivalent ... |
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| Mechanics of Bimodular Composite Structures |
JUL 1982 |
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| Authors:
C. W. Bert; J. N. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This report is a survey of the mechanics of beam and plate structures laminated of fiber-reinforced composite materials having different elastic and thermoelastic properties in tension and compression. Examples of such materials include tire cord-rubber, wire-reinforced solid propellants, and soft biological materials. Specific topics covered include: mathematical models of fiber- reinforced bimodular materials and their experimental verification; static and dynamic analysis of laminated and sandwich beams; plane elasticity; analysis of ... |
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| Analyses of Beams Constructed of Nonlinear Materials Having Different Behavior in Tension and Compression |
JUL 1982 |
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| Authors:
C. W. Bert; F. Gordaninejad; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This report consists of two parts. In part 1, a transfer-matrix analysis is presented for determining the static behavior of thick beams of 'multimodular materials' (i.e., materials which have different elastic behavior in tension and compression, with nonlinear stress-strain curves approximated as piece-wise linear, with four or more segments). To validate the transfer-matrix method results, a closed-form solution is also presented for cases in which the neutral-surface location is constant ... |
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| Analytical and Experimental Investigations of Bimodular Composite Beams |
JUL 1982 |
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| Authors:
Charles W. Bert; Clarence A. Rebello; C. J. Rebello; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This study deals with both analytical and experimental investigations of sandwich beams with cores of polyurethane foam and facings of unidirectional cord-rubber, which is bimodular (i.e., having drastically different behavoir in compression as compared to tension). This work is believed to be the first devoted to vibration of bimodular mateials in a sandwich configuration. Two different analyses are presented: one is a sandwich version of the well-known Timoshenko beam theory, ... |
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| Research on Dynamics of Composite and Sandwich Plates, 1979-1981 |
JUL 1982 |
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| Authors:
C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This report presents a survey of the literature concerning dynamics of plate-type structural elements of either composite material or sandwich construction. Papers from mid-1979 through early 1982 are reviewed, as are a few 1978 and early 1979 references unavoidably omitted in 1979 (Technical Report No. 5); there is a total of 167 references. Particular attention is given to experimental research and to linear and nonlinear analysis. Configurations include rectangularly orthotropic, ... |
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| Experimental Investigation of the Mechanical Behavior of Cord-Rubber Materials |
JUL 1981 |
|
| Authors:
OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This report covers the experimental determination of the complete stress-strain behavior, in both fiber tension and compression, for three cord- reinforced, soft-matrix composites. These were unidirectional cord-rubber with cords of aramid, polyester, and steel. Ordinary metallic-foil strain gages could not be used because of their high stiffness relative to the matrix stiffness and because of the large strains encountered. Thus, liquid-mercury strain gages were used, and their fabrication, calibration, and ... |
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| Static and Dynamic Analyses of Thick Beams of Bimodular Materials |
JUL 1981 |
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| Authors:
Charles W. Bert; A. D. Tran; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| The literature on bending of beams made of bimodulus materials (which have one value of the elastic modulus in tension and another in compression) is limited. All of the works known to the present investigators are restricted to beams with natural boundary conditions and subjected to specific distributions of normal pressure only. In the present work, the transfer-matrix approach is used to determine the small-deflection static behavior of bimodulus beams, ... |
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| Aerodynamics of Supersonic Lifting Bodies |
FEB 1981 |
417 pages |
| Authors:
M. C. Jischke; M. L. Rasmussen; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This report describes a combined theoretical and experimental program of research in the aerodynamics of supersonic lifting bodies. Analytical perturbation techniques are used to study the supersonic flow past slightly elliptical cones, cones whose cross-sections deviate slightly but arbitrarily from that of a right circular cone, cones of small longitudinal curvature, and right circular cones undergoing small harmonic pitching and/or plunging motions. These studies all involve perturbations of the well-known ... |
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| Thermoelasticity of Circular Cylindrical Shells Laminated of Bimodulus Composite Materials. |
JUL 1980 |
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| Authors:
Y. S. Hsu; J. N. Reddy; C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Closed-form and finite-element solutions are presented for the thermoelastic behavior of laminated composite shells. The material of each layer is assumed to be thermoelastically orthotropic and bimodular, i.e., having different properties depending upon whether the fiber-direction normal strain is tensile or compressive. The formulations are based on the thermoelastic generalization of Dong and Tso's laminated shell theory, which includes thickness shear deformations. The finite element used here has five degrees ... |
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| Thermal Bending of Thick Rectangular Plates of Bimodulus Composite Material. |
JUN 1980 |
|
| Authors:
J. N. Reddy; C. W. Bert; Y. S. Hsu; V. S. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Closed-form and finite-element solutions are presented for thermal bending and stretching of laminated composite plates. The material of each layer is assumed to be elastically and thermoelastically orthotropic and bimodular, i.e., having different properties depending upon whether the fiber-direction normal strain is tensile or compressive. The formulations are based on the thermoelastic version of the Whitney-Pagano laminated plate theory, which includes thickness shear deformations. Numerical results are obtained for deflections ... |
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| Vibration of Thick Rectangular Plates of Bimodulus Composite Material. |
MAY 1980 |
|
| Authors:
C. W. Bert; J. N. Reddy; W. C. Chao; V. S. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A finite-element analysis is carried out for small-amplitude free vibration of laminated, anisotropic, rectangular plates having arbitrary boundary conditions, finite thickness-shear moduli, rotatory inertia, and bimodulus action (different elastic properties depending upon whether the fiber-direction strain is tensile or compressive). The element has five degrees of freedom, three displacements and two slope functions, per node. An exact closed-form solution is also presented for the special case of freely supported single-layer ... |
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| Large Deflection and Large-Amplitude Free Vibrations of Laminated Composite-Material Plates. |
APR 1980 |
|
| Authors:
J. N. Reddy; W. C. Chao; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Finite-element analysis of the large-deflection theory (in von Karman's sense), including transverse shear, governing moderately thick, laminated anisotropic composite plates is presented. Linear and quadratic rectangular elements with five degrees of freedom (three displacements, and two shear rotations) per node are employed to analyze rectangular plates subjected to various loadings and edge conditions. Numerical results for bending deflections, stresses, and natural frequencies are presented showing the parametric effects of plate ... |
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| Vibration of Composite Structures. |
MAR 1980 |
|
| Authors:
Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| The purpose of this paper is to review some of the recent contributions to the field of vibration of composite structures. The topics of fatigue and fracture, while quite important in the overall dynamic performance of composite structures, are not considered in this survey. The survey treats these topics: dynamic stiffness and damping of composite materials, beams and curved bars and rings, flat panels, and cylindrically curved panels and shells. ... |
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| Cylindrical Shells of Bimodulus Composite Material. |
FEB 1980 |
|
| Authors:
Charles W. Bert; V. Sudhakar Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Certain fiber-reinforced materials, especially those with slightly curved fibers in very soft matrices, exhibit considerably smaller stiffnesses when loaded in compression than when loaded in tension. Examples are tire cord-rubber, wire-reinforced solid propellants, and certain soft biological tissues. For purposes of analysis and design, such materials can be modeled as a bimodulus material, i.e., one having one set of stiffnesses when the fiber-direction strain is tensile and another set when ... |
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| Analysis of Thick Rectangular Plates Laminated of Bimodulus Composite Materials. |
JAN 1980 |
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| Authors:
C. W. Bert; J. N. Reddy; V. Sudhakar Reddy; W. C. Chao; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A mixed finite-element analysis is presented for static behavior of rectangular plates having finite transverse shear moduli and different elastic properties depending upon whether or not the fiber-direction strains are tensile or compressive. As a benchmark to evaluate the validity and accuracy of the finite-element analysis, a closed-form solution is presented for the particular case of an unsymmetric-cross-ply plate having freely supported edges and subjected to a sinusoidally distributed normal-pressure ... |
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| Analyses of Cross-Ply Rectangular Plates of Bimodulus Composite Material. |
JAN 1980 |
|
| Authors:
V. Sudhakar Reddy; Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A differential-equation formulation is presented for the equations governing the small-deflection elastic behavior of thick plates laminated of anisotropic bimodulus materials (which have different elastic stiffnesses depending upon the sign of the fiber-direction strains). This study is concerned with the problems of bending due to pressure loading, free vibrations, and thermal expansion of thick plates having finite transverse shear moduli. Large static deflections of thin plates are also analyzed by ... |
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| Effects of Shear Deformation and Anisotropy on the Thermal Bending of Layered Composite Plates. |
DEC 1979 |
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| Authors:
J. N. Reddy; Y. S. Hsu; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A finite-element formulation of equations governing layered anisotropic composite plates subjected to thermal and mechanical loadings is presented. An exact closed-form solution is also presented for simply supported rectangular cross-ply laminated plates under sinusoidal loading to validate the finite element solutions obtained. The finite element results are in good agreement with the closed-form solutions and with the results of others. (Author) |
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| A Comparison of Closed-Form and Finite-Element Solutions of Thick, Laminated, Anisotropic Rectangular Plates. |
DEC 1979 |
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| Authors:
J. N. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| In this study the effects of reduced integration, mesh size, and element type (i.e. linear or quadratic) on the accuracy of a penalty finite element based on the theory governing thick, laminated, anisotropic composite plates, are investigated. In order to assess the accuracy of the present element, exact closed-form solutions are developed for cross-ply and antisymmetric angle-ply rectangular plates simply supported and subjected to sinusoidally distributed mechanical and/or thermal loadings, ... |
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| A Penalty Plate-Bending Element for the Analysis of Laminated Anisotropic Composite Plates. |
AUG 1979 |
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| Authors:
J. N. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A C degrees (penalty) finite element is developed for the equations governing the heterogeneous laminated plate theory of Yang, Norris and Stavsky. The YNS theory is a generalization of Mindlin's theory for homogeneous, isotropic plates to arbitrarily laminated anisotropic plates and includes shear deformation and rotary inertia effects. The present element can also be used in the analysis of thin plates by appropriately specifying the penalty parameter. A variety of ... |
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| Finite-Element Analysis of Laminated Bimodulus Composite-Material Plates. |
AUG 1979 |
|
| Authors:
J. N. Reddy; W. C. Chao; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Finite-element analysis of the equations governing the small-deflection elastic behavior of thin plates laminated of anisotropic bimodulus materials (which have different elastic stiffnesses depending upon the sign of the fiber-direction strain) is presented. Single-layer and two-layer cross-ply, simply-supported rectangular plates subjected to sinusoidally distributed normal pressure and uniformly distributed normal pressure are analyzed. For the sinusoidally loaded case, the finite-element solutions are gratifyingly close to the exact closed-form solutions. (Author) ... |
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| Classical Analyses of Laminated Bimodulus Composite-Material Plates. |
AUG 1979 |
|
| Authors:
Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A differential-equation formulation is presented for the equations governing the small-deflection elastic behavior of thin plates laminated of anisotropic bimodulus materials (which have different elastic stiffnesses depending upon the sign of the fiber-direction strains). As a basis for comparative evaluation of a finite-element formulation presented in Technical Report No. 3 of the contract, exact closed-form solutions are presented for two cross-ply-laminated plate problems: (1) a freely supported rectangular plate subjected ... |
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| A Penalty Plate-Bending Element for the Analysis of Laminated Anisotropic Composite Plates, |
AUG 1979 |
|
| Authors:
J. N. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A C deg. (penalty) finite element is developed for the equations governing the heterogeneous laminated plate theory of Yang, Norris and Stavsky. The YNS theory is a generalization of Mindlin's theory for homogeneous, isotropic plates to arbitrarily laminated anisotropic plates and includes shear deformation and rotary inertia effects. The present element can also be used in the analysis of thin plates by appropriately specifying the penalty parameter. A variety of ... |
|
| Recent Research in Composite and Sandwich Plate Dynamics. |
JUL 1979 |
|
| Authors:
Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This paper is a survey of literature concerning dynamics of plate-type structural elements of either composite material or sandwich construction. Papers which appeared from late 1976 through early 1979 are reviewed. Special attention is given to anisotropic plates, laminated plates, thick and sandwich plates, and nonlinearities. Free vibration and various kinds of forced vibration are treated, as well as classical and finite-element methods of analysis. (Author) |
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| Recent Research in Composite and Sandwich Plate Dynamics, |
JUL 1979 |
|
| Authors:
C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| This paper is a survey of literature concerning dynamics of plate-type structural elements of either composite material or sandwich construction. Papers which appeared from late 1976 through early 1979 are reviewed. Special attention is given to anisotropic plates, laminate plates, thick and sandwich plates, and nonlinearities. Free vibration and various kinds of forced vibration are treated, as well as classical and finite-element methods of analysis. (Author, modified). |
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| Classical Analyses of Laminated Bimodulus Composite-Material Plates, |
JUL 1979 |
|
| Authors:
C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A differential-equation formulation is presented for the equations governing the small-deflection elastic behavior of thin plates laminated of anisotropic bimodulus materials (which have different elastic stiffnesses depending upon the sign of the fiber-direction strains). As a basis for comparative evaluation of a finite-element formulation presented in Technical Report No. 3 of the contract, exact closed-form solutions are presented for two cross-ply-laminated plate problems: (1)a freely supported rectangular plate subjected to ... |
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| Finite-Element Analysis of Laminated Composite-Material Plates. |
JUN 1979 |
|
| Authors:
J. N. Reddy; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| A finite-element formulation of the equations governing the laminated anisotropic plate theory of Yang, Norris and Stavsky, is presented. The theory is a generalization of Mindlin's theory for isotropic plates to laminated anisotropic plates and includes shear deformation and rotary inertia effects. Finite-element solutions are presented for rectangular plates of antisymmetric angle-ply laminates having material properties that are typical of a highly anisotropic composite material. Two sets of material properties ... |
|
| Mathematical Modeling and Micromechanics of Fiber-Reinforced Bimodulus Composite Materials. |
JUN 1979 |
|
| Authors:
Charles W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| In Part I of this report are described and evaluated various mathematical constitutive equations proposed to model the mechanical behavior of fiber-reinforced composite materials having different compliances in tension and compression. Five different constitutive equations are described in detail and evaluated in the light of three criteria. In Part II of the report two entirely different micromechanistic approaches are developed to explain these observed differences in tension/compression behavior: the mean-fiber-angle ... |
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| Analyses of Plates Constructed of Fiber-Reinforced Bimodulus Composite Materials. |
JUN 1979 |
|
| Authors:
J. N. Reddy; C. W. Bert; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| To implement the structural application of the recently introduced fiber-governed symmetric compliance model for bimodulus compostie materials, both classical closed-form and finite-element solutions are being developed. This paper summarizes the results obtained for deflection of single-layer orthotropic and two-layer, cross-ply plates of the following configurations and loadings: (1) Thin elliptic plates clamped on the boundary and subjected to uniform pressure. (2) Moderately thick rectangular plate freely supported on the boundary ... |
|
| flaw detection in rails |
DEC 78 |
|
| Authors:
a. k. gurvich; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| the physical principles and techniques of magnetic and ultrasonic flaw detection in rails are given. the intended use, working principles and layout of various rail flaw detector systems and the procedure for working with them are described. the methodology of rail inspection, both in the field and at railwelding facilities is also described. the repair of flaw detection equipment on the railroads is examined. the book has been approved the ... |
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| Lifting Bodies Derived from Supersonic Flows Past Inclined Circular and Elliptic Cones |
DEC 1978 |
86 pages |
| Authors:
Maurice L. Rasmussen; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
|
| Lifting-body configurations are constructed from stream surfaces generated by means of supersonic flows past inclined circular and elliptic cones. By such means waverider shapes are devised with curved surfaces and known pressure fields and shock-layer structures. The conical flow fields stem from perturbations of the basic axisymmetric cone flow arising from small angle of attack and small cross-section eccentricity. The approximate results are analytic and in the form of hypersonic ... |
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| Hypersonic Flow Past a Slender Elliptic Cone. |
NOV 1978 |
|
| Authors:
Hsiung Ming Lee; Maurice L. Rasmussen; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| An approximate analytical solution is obtained for hypersonic flow past a slender elliptic cone at small angle of attack. The analysis is based on perturbations of hypersonic flow past a circular cone aligned with the free stream, the perturbations stemming from the linear combination of small angle of attack and small cross-section eccentricity. By means of previously obtained hypersonic approximations for the basic-cone problem, closed-form approximate solutions for the perturbation ... |
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| Whirling Response and Stability of Flexibly Mounted, Ring-Type Flywheel Systems, |
NOV 1978 |
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| Authors:
T. L. C. Chen ; C. W. Bert ; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| Free whirling, stability, and forced whirling responses were examined for rim-type composite flywheel systems. Numerical results most directly applicable to the Sandia single-rim systems currently under development are presented. The present analyses can be extended to other flywheel designs within the broad category of the rim type. (Author, modified). |
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| Supersonic Flow Past Conical Bodies with Nearly Circular Cross-Sections. |
OCT 1978 |
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| Authors:
Martin C. Jischke; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| Inviscid, supersonic conical flows past bodies whose cross-section deviates slightly from that of a right circular cone are studied by means of a perturbation technique. The effects of small angles of attack and yaw are included. Using the hypersonic small disturbances theory approximations, we have developed explicity results for the flow field velocity components, pressure, entropy, and shock shape for cases n, m = 1, 2, 3, 4. Comparisons of ... |
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| Assessment of New Technologies for General Aviation Aircraft. |
SEP 1978 |
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| Authors:
Karl H. Bergey; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| This report assesses the use of new technologies in general aviation aircraft. It also investigates the potential for a technology demonstration program aimed specifically at the needs of general aviation. It concludes that at least 46 new or under-used technologies could be incorporated in general aviation aircraft with benefit to safety, performance and cost. The rate at which these new technologies might be integrated into the fleet will depend on ... |
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| nondestructive measurement of longitudinal rail stresses - application of the acoustoelastic effect to rail stress measurement |
JAN 78 |
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| Authors:
d. m. egle; d. e. bray; OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR ENGINEERING
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| an ultrasonic probe has been designed, evaluated and shown capable of measuring longitudinal stress changes in railroad rails. the probe utilizes the effect of applied stress on wave velocity (acoustoelastic effect) to determine the stress change. both laboratory and field evaluation has shown that the probe is capable of measuring stress changes with an accuracy of plus or minus 6.9 mn/ m squared (plus or minus 1 ksi). (author) ... |
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