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Technical report for period October 1987 - March 1988.
Topic: STIFFENING.,BUCKLING.,BEAMS(STRUCTURAL).
Technical report for period October 1987 - March 1988.
Topics: STIFFENING., BUCKLING., BEAMS(STRUCTURAL).
The U.S. Army has identified a requirement to rotate 20 foot and 40 foot ISO containers during loading and unloading operations using the Army 250 ton crane P&H Model 6250 and 20 foot and 40 foot Line Fast Corp. Model 7127 spreader bars. To accomplish the mission a Bromma Model EH3 Rotator was installed. The rotator is suspended by the double hook blocks of the 250 ton crane. In its present operating configuration, the spreader bar is attached to the rotator by slings. the sling attachments...
Topics: DTIC Archive, LaChance, Robert A, VSE CORP ALEXANDRIA VA, *CRANES, *SLINGS, BEAMS(STRUCTURAL),...
The development and solution are presented of the differential equations of motion of a system of n-elastically connected parallel beams. Using the results developed for the general n-beam system, the particular case of a two beam system was analyzed in detail. The frequencies and associated mode shapes for various support conditions are presented explicitly. Vibration experiments were performed in order to ascertain the degree of applicability of the theory. It was found that at least up to...
Topics: DTIC Archive, Seelig, J M, RENSSELAER POLYTECHNIC INST TROY NY, *BEAMS(STRUCTURAL), MOTION,...
In progressive collapse events initiated by explosive threats, damage to some connections from blast loading of the structure is likely. In this paper, the results from ten tests of blast-damaged and undamaged beam-to-column connections are examined. An evaluation procedure leading to comparisons of performance based on rotational capacity of both blast damaged and undamaged capacity is presented.
Topics: DTIC Archive, PROTECTION ENGINEERING CONSULTANTS LLC SAN ANTONIO TX, *BLAST, BEAMS(STRUCTURAL),...
FAMSNUB is a digital computer program, written in single precision FORTRAN IV for the Philco-Ford/GE 265 time-sharing system, to determine the eigenfrequencies and eigenmodes of vibration in pure bending of loaded, piece-wise continuous single-span beams supported in any one of the ten possible combinations of the following end conditions: free, guided, hinged and clamped. Continuously variable beam properties may be accommodated by appropriate subdivision of the span. The distributed mass of...
Topics: DTIC Archive, McFarland, John L, ARMY TANK-AUTOMOTIVE COMMAND WARREN MI, *BEAMS(STRUCTURAL),...
Twelve-foot and 6-foot I-beams with webs of two different hardboard materials and plywood were subjected to constant loads in three different humidity environments. After 17,000 hours of test, the performance of the hardboard-webbed I-beams appears to be at least comparable to that of I-beams with plywood webs. Results of this study will be useful to researchers, designers, and building code officials for judging the acceptability of wood-base materials in structural components such as I-beams....
Topics: DTIC Archive, Superfesky,Michael J, FOREST PRODUCTS LAB MADISON WIS, *BEAMS(STRUCTURAL), *PLYWOOD,...
Further analytical investigations are made into the damping capability and determination of natural frequencies of laminated beams, consisting of elastic-viscoelastic-elastic layers, as a means for reducing the vibratory energy transmitted through machine foundation supports in naval vessels. An exact analytical solution is obtained for determining the natural frequencies of simply-supported sandwhich beams having no rivets at the ends. Three possible modes of vibration are shown to exist. The...
Topics: DTIC Archive, PENNSYLVANIA MILITARY COLL CHESTER, *BEAMS(STRUCTURAL), *SUPPORTS, SHIPS, LAMINATES,...
'Limit Design' guides the structural engineer towards an economic design of structures that are made of ductile materials and have to carry specified loads. From the mathematical point of view, the problem can be reduced to one in linear programming, but even simple structures may lead to linear programming problems of considerable size. A method of solution is discussed that was found efficient for structures of moderate complexity. A sketch of the historical development of limit analysis and...
Topics: DTIC Archive, RAND CORP SANTA MONICA CA, *LOADS(FORCES), *STRUCTURES, BEAMS(STRUCTURAL), DUCTILITY,...
An investigation was made of the hinging mechanism in under- reinforced concrete beams subjected to static or dynamic loads. Two test series on simply supported beams with a 6-foot span length were conducted. In one series, 11 beams were subjected to two concentrated loads symmetrically placed 18 inches apart; the primary variable was the magnitude of the step load pulse (1.0 to 1.4 times the static yield load). In the other series, 15 beams were subjected to a concentrated load at midspan; the...
Topics: DTIC Archive, NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA, *BEAMS(STRUCTURAL), *REINFORCED...
The amplitade of vibration of a member at resonance, as defined by its resonance amplification factor, is analyzed in relationship to the damping properties of materials. Data are presented on damping energy to indicate the effect of stress magnitude, stress history and temperature. Based on the mathematical relationship found to exist between damping and stress magnitude the resonance amplification factors ars determined for a variety of direct stress members and beams. It is shown that the...
Topics: DTIC Archive, LAZAN, B. J., MINNESOTA UNIV MINNEAPOLIS, *VIBRATION, *BEAMS(STRUCTURAL),...
This research addresses the possibility of controlling the dynamic response of telescoping beams with three or more segments by adjusting the position of the middle segment or segments independently of the total beam length. As part of this work, the idea of a beam configuration space is introduced, and the dependence of the response on the nature of the deployment and retraction process is discussed. Concepts for presentation of solution results in the form of nondimensional design charts are...
Topics: DTIC Archive, Andrusiv,Lubov P, United States Air Force Academy Air Force Academy United States,...
This report contains the results of a study aimed at exploring the sheltering potential for people remaining in high risk areas when such areas are subjected to a nuclear weapon attack. Basements of six conventional buildings are evaluated when subjected to direct effects of a large yield nuclear weapon. On the basis of this evaluation probabilities of survival for shelter occupants are assigned. The six basements are subsequently upgraded using expedient measures and reevaluated subject to the...
Topics: DTIC Archive, Longinow,A, IIT RESEARCH INST CHICAGO ILL, *SHELTERS, CIVIL DEFENSE,...
The Structural Analysis Code Kit (SACK) is a collective group of structural computer programs which solve typical problems encountered in analysis and design. The user is expected to be familiar with structural analyses typically found in textbooks or an engineering school curriculum. These programs are free from proprietary limitations and are smaller in scope than large commercial programs. The programs are very simple to use and understand. They will not become obsolete when new building...
Topics: DTIC Archive, Mack, K, NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA, *STRUCTURAL MECHANICS, TRUSSES,...
This report presents some new findings and revised data concerning the stability of a uniform free-free beam subjected to a constant thrust with and without directional control. An analysis is performed first showing that, other than the first branch of zero eigenvalues which correspond to rigid body translation modes, there can be only a set of discrete values of the thrust which admit zero eigenvalues. Then, stability data, revised from previous results with a numerical error eliminated, are...
Topics: DTIC Archive, Wu, J J, WATERVLIET ARSENAL NY, *BEAMS(STRUCTURAL), *GUIDED MISSILES, AERODYNAMICS,...
There are derived sufficient conditions for the positivity of Green's function of two-point boundary value problems of the fourth order. The results are gained by applying a theorem on inverse-monotonic operators in partially ordered spaces. In the case of an example (beam on elastic support), the derived conditions are also necessary.
Topics: DTIC Archive, BOEING SCIENTIFIC RESEARCH LABS SEATTLE WA, *GREENS FUNCTIONS, BEAMS(STRUCTURAL),...
A simple method is presented for estimating the combined influence of strain-hardening and strain-rate sensitivity on the permanent deformation of rigid-plastic structures loaded dynamically. A study is made of the particular case of a beam supported at the ends by immovable frictionless pins and loaded with a uniform impulse. The results of this work indicates that considering strain-hardening alone when appropriate or strain-rate sensitivity alone gives permanent deformations which are...
Topics: DTIC Archive, Jones, Norman, BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING, *BEAMS(STRUCTURAL),...
Free damped vibrations of linear elastic structures composed of uniform beam elements with a continuous distribution of mass are studied. Axial, torsional and flexural vibrations are considered. The amount of damping, which can be either internal or external viscous type, varies among the various beam elements of the structure resulting in many critical damping possibilities. A general method is developed, which, with the aid of dynamic stiffness influence coefficients defined for every...
Topics: DTIC Archive, Beskos,D E, NORTHWESTERN UNIV EVANSTON IL TECHNOLOGICAL INST, *BEAMS(STRUCTURAL),...
Topics: DTIC Archive, Youngquist,J A, FOREST PRODUCTS LAB MADISON WIS, *BEAMS(STRUCTURAL), *WOOD,...
Topics: DTIC Archive, LEE, GEORGE C, LEHIGH UNIV BETHLEHEM PA FRITZ ENGINEERING LAB,...
The basic concepts are discussed of limit analysis and limit de sign of reinforced concrete beams and frames. Many of these problems can be treated geometrically in terms of the safe domain in load space. The procedure is illustrated by a typical frame example. The method is adequate whenever the plastic deformation of the structure can be described in terms of 2 elementary mechanisms. When there are 3 elementary mechanisms, a 3-dimensional load space must be used.
Topics: DTIC Archive, Prager, William, BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS, *OVERLOAD,...
Topics: DTIC Archive, Jakubowicz, Antoni, LIBRARY OF CONGRESS WASHINGTON DC AEROSPACE TECHNOLOGY DIV,...
The analysis of the dynamic response of a vibrating structure in contact with a fluid medium can be interpreted as an added mass effect known as the Fluid Structure Interaction (FSI) problem. This effect is critical in the study of composites for marine applications since the densities of the composites and water are relatively close to one another. In this study, experimental testing was conducted to compare the free vibration response of composite beams in air with those in FSI immersed in...
Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *BEAMS(STRUCTURAL), *VIBRATION, COMPOSITE...
In this project, we studied the linear and nonlinear propagation of structured beams of ultrafast pulses. We have been taking advantage of the special characteristics of spatially-chirped beams, in which the frequency components cross each other at the focus of a lens. In this configuration, the pulse focuses temporally and spatially at the same time. We developed a theory for understanding the beam propagation, verified aspects of this theory experimentally, developed a suite of diagnostics to...
Topics: DTIC Archive, COLORADO SCHOOL OF MINES GOLDEN DEPT OF PHYSICS, *BEAMS(STRUCTURAL), *PROPAGATION,...
The results of a four-phase fatigue program for bending tests of 7075-T6 aluminum alloy box beams for positive loads only and for positive and negative loads for both constant-and variable-load amplitudes are presented. The relative damaging effect of four airplane flight-maneuver-loads spectra was determined, and the effects on fatigue life for variations in spectrum block size, stress level, stress direction, and load sequence were established and the results are discussed. When compared to...
Topics: DTIC Archive, Breyan, William, NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA AIR VEHICLE TECHNOLOGY...
The parametric stability of a slender, elastic simply supported beam subjected to the action of a concentrated mass moving at constant velocity along its axis is investigated. The Galerkin procedure is applied to reduce the partial differential equation of motion to an ordinary differential equation in time with periodic coefficients. A perturbation procedure is employed to solve this differential equation, and the boundary curves of the fundamental region of instability are determined. (Author)
Topics: DTIC Archive, Anderson,G L, WATERVLIET ARSENAL N Y, *BEAMS(STRUCTURAL), *DYNAMIC LOADS, STABILITY,...
The natural frequencies, nodal points and mode functions for transverse vibration of tapered beams are presented in this report. The beams considered have the cross-sectional area bounded by the curve \y/h\beta + \z/b\gamma =1 with the thickness h and width b varying along the beam according to the relations.
Topics: DTIC Archive, Wang, Han-chung, ILLINOIS UNIV AT URBANA, *BEAMS(STRUCTURAL), *NODES, *RESONANT...
The authors consider a system consisting of a rigid body to which a linear extensible shear beam is attached. For such a system the Energy-Casimir method can be used to investigate the stability of the equilibria. In this case, it can be shown that a test for (formal) stability reduces to checking the positive definiteness of two matrices which depend on the parameters of the system and the particular equilibrium about which the stability is to be ascertained. Keywords: Computations;...
Topics: DTIC Archive, Posbergh, Thomas A, MARYLAND UNIV COLLEGE PARK, *ATTACHMENT, *BEAMS(STRUCTURAL),...
This paper describes the results of theoretical studies on the effect of non-uniform stress fields limited to those encountered in prismatic beams under bending, upon the fracture of brittle materials. Derivations were carried out to determine the risk of rupture of bending specimens subjected to a symmetrical four-point load of arbitrary spacing, the symmetric three-point loading and pure bending forming limiting cases of this more general loading. The analysis was based on materials obeying...
Topics: DTIC Archive, Weil, N A, IIT RESEARCH INST CHICAGO IL, *FRACTURE(MECHANICS), BEAMS(STRUCTURAL),...
Topics: DTIC Archive, Bleich, Hans, DAVID TAYLOR MODEL BASIN WASHINGTON DC, *STRESS CONCENTRATION, LOAD...
Topics: DTIC Archive, Krefeld, William J., Anderson, George B., COLUMBIA UNIV NEW YORK, *PHYSICAL...
MS(STRUCTURAL), PRESSURE VESSELS, RIVETED JOINTS, FASTENERS*STRESSESThe analysis manual is issued to provide a general purpose structural analysis capability and to serve as a source of data. It represents a collection of techniques from a wide variety of industry sources, textbooks, periodicals, and government agencies. Attempts have been made where applicable to give appropriate recognition to each source. Based on the evaluation of the stress analysis and design techniques and procedures...
Topics: DTIC Archive, Maddux, Gene E, TECHNOLOGY INC DAYTON OH, *STRUCTURAL PROPERTIES, *HANDBOOKS,...
The minimum weight design problem for pressure-stabilized beams is formulated and solved in order to provide the designer some guidance in the use of the design analysis capability developed and reported previously. The weight is minimized subject to four inequality constraints to give the inflation pressure, cross-section radius and fabric density corresponding to the minimum weight. It is shown that high pressures, small radii, and low fabric density give minimum weight. In addition, it is...
Topics: DTIC Archive, Steeves, Earl C, ARMY NATICK RESEARCH AND DEVELOPMENT CENTER MA, *AIR PRESSURE,...
Nine coatings were evaluated for corrosion protection of carbon steel coupons and I-beams around Duluth Superior Harbor after 46 and 35 months, respectively. Coupons were intentionally scribed to metal before exposure. Part 1 of this article describes the coatings used and the locations of coupons and I-beams. Part 2, to be published in the October 2012 issue of MP, will discuss the results of the evaluation.
Topics: DTIC Archive, NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS OCEANOGRAPHY DIV,...
In this paper a new concept for a light weight, low cost, small packaging volume, unfurlable beam is presented. Two hardware models are constructed and deployment tests conducted. The first test involves the measuring of accelerations as the structure is horizontally deployed along a Teflon sheet. The second test involves strobed photography of a vertical deployment. From these tests the assumption of a constant deployment force is verified. The deployment force is then analytically solved for...
Topics: DTIC Archive, Goss, Jeffrey D., COLORADO UNIV AT BOULDER, *STRUCTURAL ANALYSIS, *BEAMS(STRUCTURAL),...
The objective of the proposed work is to study the fundamental mechanisms of active aeroelastic tailoring of high-aspect-ratio composite wings. The emphasis will be on actively exploring structural flexibility to enhance flight performance and reduce structural weight, while controlling aeroelastic instabilities. To investigate the effects of distributed anisotropic strain actuation and their synergism with the passive aeroelastic tailored composite structure, a suitable nonlinear active...
Topics: DTIC Archive, Cesnik, Carlos, MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND...
This annotated bibliographic review presents articles regarding optimization of structures (plates, shells, frames, beams, columns, panels, etc. ). A general problem in the theory of structures is to determine the configuration which has minimum weight from all those which can support the prescribed loads. Some progress has been made in the solution of this problem, and it was the purpose of the search to determine the present state of the theory. The literature contains great amounts of...
Topics: DTIC Archive, EVANS, G R, LOCKHEED MARTIN MISSILES AND SPACE CO SUNNYVALE CA, *BIBLIOGRAPHIES,...
The principle of dynamic equipollency is defined and applied to two areas of mechanical admittance/impedance testing: generation of experimental moment-rotational velocity admittances and impedances, and many-DOF (Degrees of Freedom) structures.
Topics: DTIC Archive, Bagley, Ronald L., MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB, *MECHANICAL...
A frequency domain transformation is the basis for a general approach to the identification of finite element modeling errors. The transformation provides information as to the location of modeling errors and provides the error matrices of stiffness, mass, and damping. The transformation is shown to have the unique property of directly revealing that the process of instrumenting an actual structure with a finite number of response transducers defines a reduced order system, with an attendant...
Topics: DTIC Archive, Gomes, Vincent C, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *FINITE ELEMENT ANALYSIS,...
Recently Hoa presented a finite element model to obtain the vibration frequencies of a rotating beam with tip mass. It was discovered later that there was a minus sign missing in the expression for d in Table 1 of reference 1: the correct expression should be d = -(R' + n). The correct expression for d gives faster convergence in teh finite element results and slightly smaller values than those report in reference 1.
Topics: DTIC Archive, Hoa, S V, ARMY RESEARCH AND TECHNOLOGY LABS MOFFETT FIELD CA AEROMECHANICS LAB,...
The deformation of boat hull bottom panels during the initial phase of slamming is studied analytically using a linear elastic Euler-Bemoulli beam as a representation of the cross section of a bottom panel. The slamming pressure is modeled as a high-intensity peak followed by a lower constant pressure, traveling at constant speed along the beam. The problem is solved using a Fourier sine integral transformation in space and a Laplace-Carson integral transformation in time. Deflection and...
Topics: DTIC Archive, LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS,...
A series of reinforced concrete beams were tested to study shear and diagonal tension in beams under dynamic load. The tests constitute the first phase of a study designed (1) to determine criteria for the minimum amount of web reinforcement required for developing the ultimate flexural resistance of beams and (2) to evaluate the difference between these criteria for static and dynamic loading. It was found that (1) the shear resistance at diagonal tension cracking and at first yielding of the...
Topics: DTIC Archive, NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA, *BEAMS(STRUCTURAL), *REINFORCED...
A rapid approximate method is presented for calculating the fundamental frequencies of flexural vibration of two-span beams and of particular arrangements of three-span beams which are continuous over non-deflecting supports and are elastically restrained against rotation at their end supports. The end restraints nisy be provided by actual coil springs or they may represent the effect of adjoining members, but in all cases the stiffnesses of these restraints are assumed to be positive. The mass...
Topics: DTIC Archive, Veletsos, A. S., Newmark, N. M., ILLINOIS UNIV AT URBANA-CHAMAPIGN, *VIBRATION,...
The displacement based finite element model of a general third-order beam theory is developed to study the quasi-static behavior of viscoelastic rectangular orthotropic beams. The mechanical properties are considered to be linear viscoelastic in nature with a scope to undergo von K rm n nonlinear geometric deformations. A differential constitutive law is developed for an orthotropic linear viscoelastic beam under the assumptions of plane-stress. The fully discretized finite element equations...
Topics: DTIC Archive, TEXAS A AND M UNIV COLLEGE STATION DEPT OF MECHANICAL ENGINEERING,...
Topics: DTIC Archive, Veletsos, A. S., Newmark, N. M., ILLINOIS UNIV AT URBANA ENGINEERING EXPERIMENT...
The report contains the results of a two-part Heavy Lift Helicopter (HLH) coupling development program. Part 1 was a stress analysis of photoelastic epoxy models of two HLH cargo load beam configurations. The 'L' shape proved to be more efficient than the 'C' shape in minimizing the weight of the coupling; and high-strength steel proved to be a more efficient material for this application than titanium. In Part 2, a complete load beam was instrumented and tested in order to evaluate stress...
Topics: DTIC Archive, Nutley, W, BOEING VERTOL CO PHILADELPHIA PA, *COUPLINGS, *HELICOPTER HOISTS,...
Topics: DTIC Archive, Lee, G C, LEHIGH UNIV BETHLEHEM PA FRITZ ENGINEERING LAB, *BEAMS(STRUCTURAL), LOAD...
A theory is derived for the flexural deformation of laminated beams subjected to initial stresses. Each layer is treated as a Timoshenko beam and 'smoothed' expressions for the kinetic and strain energies and the work done by external forces are derived. A SYSTEM OF THREE COUPLED PARTIAL DIFFERENTIAL EQUATIONS, INCLUDING THE EFFECT OF BENDING, EXTENSION, ROTATION, AND INITIAL AXIAL STRESS ARE OBTAINED FROM Hamilton's principle. Specific buckling and free vibration problems are solved exactly...
Topics: DTIC Archive, Anderson, Gary L, WATERVLIET ARSENAL NY, *VIBRATION, *BEAMS(STRUCTURAL),...
Large, simply supported beams of temperate lake ice were found, generally, to yield significantly higher flexural strengths than the same beams tested in the cantilever mode. Data support the view that a significant stress concentration may exist at the fixed corners of the cantilever beams. Maximum effects are experienced with beams of cold, brittle ice substantially free of structural imperfections; for this kind of ice the strength difference factor, here attributed to the effect of stress...
Topics: DTIC Archive, Gow,A J, COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER N H, *ICE, *FLEXURAL...
This report revises and extends an earlier report entitled 'Mechanical Four-Pole Parameters and their Application' (Journal of Sound and Vibration, 15, 307-323, 1971). Newly considered are so-called transmission matrices, which enable the transverse vibration response of beams with discontinuities to be analyzed readily. Further, the transmission matrices used in the report result in more concise beam analyses than the matrices generally employed in the literature. Additional examples that are...
Topics: DTIC Archive, Snowdon, J. C., PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB,...
