Critical joints in large composite aircraft structure

A program was conducted at Douglas Aircraft Company to develop the technology for critical structural joints of composite wing structure that meets design requirements for a 1990 commercial transport aircraft. The prime objective of the program was to demonstrate the ability to reliably predict the strength of large bolted composite joints. Ancillary testing of 180 specimens generated data on strength and load-deflection characteristics which provided input to the joint analysis. Load-sharing between fasteners in multirow bolted joints was computed by the nonlinear analysis program A4EJ. This program was used to predict strengths of 20 additional large subcomponents representing strips from a wing root chordwise splice. In most cases, the predictions were accurate to within a few percent of the test results. In some cases, the observed mode of failure was different than anticipated. The highlight of the subcomponent testing was the consistent ability to achieve gross-section failure strains close to 0.005. That represents a considerable improvement over the state of the art

A CAD/CAM/CNC Curriculum for High School Students

The need for CAD/CAM/CNC curriculum for Washington State was researched. Based on research a resource workbook for CAD/CAM/CNC was in demand. In order to meet the demand for CAD/CAM/CNC curriculum and bridge the gap between the state standards, drafting frameworks, STEM curriculum, increased focus on implementation within multiple disciplines, providing a starting point for teachers who want to use CNC machinery in their program, and prepare students for quality jobs and careers related to CAD/CAM/CNC, a workbook was created. The workbook includes 27 hands-on lessons and projects, student handouts, applied STEM problems and activities, tutorials, drafting standards, state math standards, and equation sheets. The workbook is designed to be used as a resource for CAD/CAM/CNC teachers in Washington State

Illustrative examples based on the ASCE standard specification for the design of cold-formed stainless steel structural members

PREFACE During the past four years, two methods were developed for the design of stainless steel structural members at the University of Missouri-Rolla with consultation of Professor T. V. Galambos at the University of Minnesota. One of the methods is based on the load and resistance factor design (LRFD) and the other is based on the allowable stress design (ASD). Both design methods are now included in the new ASCE Standard 8-90, Specification for the Design of Cold-Formed Stainless Steel Structural Members. At the September 21, 1990 meeting of the Control Group of the ASCE Stainless Steel Cold-Formed Section Standards Committee held in Washington, D.C., the urgent need for design examples using the new ASCE Standard was discussed at length. The University of Missouri-Rolla was asked to submit a proposal for preparation of such illustrative examples beginning October 1, 1990. During the period from October 1990 through December 1991, a total of 27 illustrative problems have been prepared as included herein. Most of the given data used for these examples are similar to those used in the 1986 edition of the AISI Cold-Formed Steel Manual except that for each problem, two examples are illustrated by using LRFD and ASD methods. The research work reported herein was conducted in the department of Civil Engineering at the University of Missouri-Rolla with the consulting work provided by Dr. Shin-Hua Lin and Professor T. V. Galambos. The financial assistance provided by the Nickel Development Institute and the Chromium Centre is gratefully acknowledged. Appreciation is also expressed to Dr. W. K. Armitage, Mr. J. P. Schade, Professor P. Van der Merwe and Professor G. J. Van den Berg for their technical review and suggested revisions

Heathland ecology and vegetation history of Tulloch Moor, Inverness-Shire

Tulloch Moor is part of the RSPB reserve at Loch Garten. It contains a very good example of Calluna-Arctostaphylos heath. The vegetation of the moor was examined by means of 44 2x2m sample plots. 32 of these were in 8 permanently marked 4x4m quadrats, and provide a baseline to measure future change. 7 plots outside the permanent transect showed further variation in the heathland vegetation. The data indicate that time since burning, colonisation by trees, and variation in soil type are the important factors in determining the present variation. Ordination separated the Tulloch Moor heath releves from those given by McVean & Ratcliffe (1962) for the Arctostaphyleto-Callunetum which more often included Pyrola media and Dicranum scoparium, however the heath releves were more similar to the Arctostaphyleto- callunetum than to Callunetum vulgaris. The vegetation history of Tulloch Moor was investigated by pollen analysis of a sample of peat and a surface sample of moss. The peat sample was not dated. The pollen analysis indicates that there was a period when the Moor, or at least the sampling locality, was much more wooded than now, mainly with pine and some birch. Prior to this there was an open heath with some trees, much as now. Following the wooded period, the tree cover declined to a low level, and then increased in the recent past to its present level. Characteristics and measurements of Ericales reference pollen were compared with those of fossil pollen, and the results of the different methods of identification were compared. Most of the fossil pollen tetrads were Erica tetralix which presently grows on the peat bog surface. Very few tetrads of Arctostaphylos pollen were found, and these were at or near the surface. Examination of the peat for charcoal fragments indicates that fires have occurred in the area throughout the period represented by the peat sample. Some peaks in charcoal abundance are followed by a decline in tree pollen, indicating that fire was a cause of tree decline

Course of study and a teacher's manual for a thirty-lesson course in engineering drawing.

Thesis (M.A.)--Boston Universit

Steel Deck Institute Diaphragm Design Manual First Edition

The Major Units Laboratory at West Virginia University has been involved in full-scale diaphragm studies for the past fifteen years. The work has covered tests on a wide range of deck panel types, metal building wall systems, panels with insulating concrete fill, and plywood assemblies, all used as diaphragms, and under static, cyclic, and dynamic loading. Connection performance, critical to diaphragm behavior, has been evaluated through an extensive test program covering arc-spot (puddle) welds, different types of screws, and power driven pins. These have established fastener strength limits and have been especially important for defining fastener flexibility factors

Electrical characteristics of quantum well solar cells.

Imperial Users onl

Understanding Acoustics

This open access textbook, like Rayleigh’s classic Theory of Sound, focuses on experiments and on approximation techniques rather than mathematical rigor. The second edition has benefited from comments and corrections provided by many acousticians, in particular those who have used the first edition in undergraduate and graduate courses. For example, phasor notation has been added to clearly distinguish complex variables, and there is a new section on radiation from an unbaffled piston. Drawing on over 40 years of teaching experience at UCLA, the Naval Postgraduate School, and Penn State, the author presents a uniform methodology, based on hydrodynamic fundamentals for analysis of lumped-element systems and wave propagation that can accommodate dissipative mechanisms and geometrically-complex media. Five chapters on vibration and elastic waves highlight modern applications, including viscoelasticity and resonance techniques for measurement of elastic moduli, while introducing analytical techniques and approximation strategies that are revisited in nine subsequent chapters describing all aspects of generation, transmission, scattering, and reception of waves in fluids. Problems integrate multiple concepts, and several include experimental data to provide experience in choosing optimal strategies for extraction of experimental results and their uncertainties. Fundamental physical principles that do not ordinarily appear in other acoustics textbooks, like adiabatic invariance, similitude, the Kramers-Kronig relations, and the equipartition theorem, are shown to provide independent tests of results obtained from numerical solutions, commercial software, and simulations. Thanks to the Veneklasen Research Foundation, this popular textbook is now open access, making the e-book available for free download worldwide. Provides graduate-level treatment of acoustics and vibration suitable for use in courses, for self-study, and as a reference Highlights fundamental physical principles that can provide independent tests of the validity of numerical solutions, commercial software, and computer simulations Demonstrates approximation techniques that greatly simplify the mathematics without a substantial decrease in accuracy Incorporates a hydrodynamic approach to the acoustics of sound in fluids that provides a uniform methodology for analysis of lumped-element systems and wave propagation Emphasizes actual applications as examples of topics explained in the text Includes realistic end-of-chapter problems, some including experimental data, as well as a Solutions Manual for instructors. Features “Talk Like an Acoustician“ boxes to highlight key terms introduced in the text

Reflectivity of plasmas created by high-intensity, ultra-short laser pulses

Experiments were performed to characterize the creation and evolution of high-temperature (T{sub e}{approximately}100eV), high-density (n{sub e}>10{sup 22}cm{sup {minus}3}) plasmas created with intense ({approximately}10{sup 12}-10{sup 16}W/cm{sup 2}), ultra-short (130fs) laser pulses. The principle diagnostic was plasma reflectivity at optical wavelengths (614nm). An array of target materials (Al, Au, Si, SiO{sub 2}) with widely differing electronic properties tested plasma behavior over a large set of initial states. Time-integrated plasma reflectivity was measured as a function of laser intensity. Space- and time-resolved reflectivity, transmission and scatter were measured with a spatial resolution of {approximately}3{mu}m and a temporal resolution of 130fs. An amplified, mode-locked dye laser system was designed to produce {approximately}3.5mJ, {approximately}130fs laser pulses to create and nonintrusively probe the plasmas. Laser prepulse was carefully controlled to suppress preionization and give unambiguous, high-density plasma results. In metals (Al and Au), it is shown analytically that linear and nonlinear inverse Bremsstrahlung absorption, resonance absorption, and vacuum heating explain time-integrated reflectivity at intensities near 10{sup 16}W/cm{sup 2}. In the insulator, SiO{sub 2}, a non-equilibrium plasma reflectivity model using tunneling ionization, Helmholtz equations, and Drude conductivity agrees with time-integrated reflectivity measurements. Moreover, a comparison of ionization and Saha equilibration rates shows that plasma formed by intense, ultra-short pulses can exist with a transient, non-equilibrium distribution of ionization states. All targets are shown to approach a common reflectivity at intensities {approximately}10{sup 16}W/cm{sup 2}, indicating a material-independent state insensitive to atomic or solid-state details