bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Concern and Environmental Behavior in Foley, a Small Town in Minnesota
Authors: Hallin Per Olof
Published: March 2007

Research on environmental concern is extensive, and studies have identified factors that determine environmental behavior. These factors, however, are often related to specific behaviors, such as recycling, and they are not applicable to environmental behavior in a general sense. Most studies have also failed to measure correlations among the variables studied. This lack of comprehensive understanding suggests the need for explorative and qualitative approaches. This article examines households' and individuals' environmental behavior from the perspectives of human geography and ethnography. Its objective is to explore motives for environmental actions, as well as to identify major impediments to changed behavior. Twenty households, 10 households with high environmental activity and 10 households with low environmental activity, were selected from among the respondents to a community-wide questionnaire distributed in Foley, a small town in Minnesota. Research methodology was qualitative: ethnographic interviews. The article's main conclusion is that people cite a wide variety of reasons for their behavioral change. This conclusion itself reflects the difficulties in identifying the factors that determine environmental behavior. In this article, five groups of conserving informants are identified: the Depression generation, children of the Depression generation, the Vietnam generation, role models, and gradual evolvers. Among non-conserving informants, three reasons for not taking environmental action emerged: lack of time, no monetary reward, and inconvenience. The findings indicate that a variety of measures and strategies must be developed to change people's behavior.
Landscapes of Fear and Stress
Authors: Nasar Jack L. , Jones Kym M.
Published: March 2007

Fear of crime is a major urban stressor. Certain areas-hot spots of fear-evoke higher levels of fear than others. In conditions of general wariness, certain proximate cues should evoke site-specific fears. This research examined 3 proximate cues to fear: physical entrapment, and 2 aspects of concealment-hiding places and dark spots. Twenty-six college females walked a route after dark and reported their feelings into a recorder. Content analysis of the comments revealed that concealment and, to a lesser extent, entrapment evoked fear. Such knowledge can inform policy to reduce fear and stress.
People in High Latitudes
Authors: Steel G. Daniel , Suedfeld Peter , Peri Antonio , Palinkas Lawrence A.
Published: March 2007

The personality of the polar sojoumer has been of interest to psychologists for a number of years. Using the NEO Five Factor Inventory, this study examined the general personality factors of the polar worker compared to a normative populaffon, and how these factors differ according to the worker's occupational classification and the polar region in which he or she is working. It was found that polar workers scored higher than a normative group on all factors except Neuroticism. Comparisons across occu pational groups showed that scientists were lower than military personnel on Extra version and lower than technicaVsupport staff on Agreeableness and Conscientious ness. The analysis by polar region indicated that Antarctic workers were higher than Arctic personnel on Extraversion, Agreeableness, and Conscientiousness. A group of Italian Antarctic personnel, completing a translated form of the NEO-FFI, scored lower than the rest of the polar groups on all factors. These findings are discussed in light of various features of the polar environment and Gunderson's 3-predictor model of polar adaptability.
Models of Preference for Outdoor Scenes
Authors: Peron E. , Purcell A. T. , Staats H. , Falchero S. , Lamb R. J.
Published: March 2007

Predictions derived from three models of the relations between cognitive processing of and preference responses to outdoor scenes were examined. Twelve scene types were identified, ranging from the inner city to large-scale natural environments found in the Sydney region of Australia, the Padua region of northern Italy, and the Netherlands. In two experiments, participants from the three locations made preference, familiarity, and typicality judgments of all examples of each scene type, with the participants from Sydney and Padua making judgments of the stimuli from both locations while the Dutch participants judged the stimuli froll all three locations. The results of the experiments were most consistent with a preference-for-differences model, with only limited evidence for a preference-for-prototypes model. The largest effect on preference was related to scene type, an effect that is difficult to explain using either of the models of preference. It is argued that this presents a significant problem if it is accepted that preference is considered an important aspect of environmental experience.
Transforming Inner-City Landscapes
Authors: Kuo Frances E. , Bacaicoa Magdalena , Sullivan William C.
Published: March 2007

How would inner-city residents respond to the incorporation of trees and grass in their neighborhoods? Law enforcement officials have argued that, in these settings, trees and other forms of vegetation increase fear. Tree density, tree placement, and levels of grass maintenance were manipulated in photo simulations of neighborhood outdoor space. One hundred residents of Chicago's Robert Taylor Homes living adjacent to the space rated the images with respect to preference and sense of safety. Although tree placement (subspaces created by trees, formality of arrangement) had little effect on sense of safety and no effect on preference, both tree density and grass maintenance had strong effects on preference and sense of safety (η2s from .49 to .89). Surprisingly, tree density and grass maintenance increased both preference and sense of safety. Results suggest that-contrary to some views-trees and grass maintenance can increase sense of safety in inner-city neighborhoods.
Umbilical Cords and Digital Fibre-Optics
Authors: Menzies Heather
Published: March 2007

This essay critically describes today's globe-spanning digital communication networks as the core medium of globalization, delivering both a new world order of corporate domination and a deeply personal experience of alienation. It also argues for an ecological approach to communication both as a critique and as a way of resisting globalization, through its focus on embodied relationships and time.
Moroccan Berberity, Representational Power and Identity in Video Films
Authors: Carter Sandra Gayle
Published: March 2007

A long-term struggle between the Moroccan state and its large Berber culture-groups lies at the heart of this article about Moroccan Berber-language media, specifically video films in Tachelhit. The article analyzes the historical context of Moroccan nation-state constraints on Berber identity, with a special focus on the repression of media, particularly audiovisual media, in Berber languages. Included is discussion of a newly emergent form of Moroccan alternative media - Tachel-hit-language video films - and their multiple functions for Berbers. Berber-language video films recuperate marginalized Berber speakers into nationally and internationally circulating media as both producers and consumers, and break the stranglehold of Moroccan state-controlled media and culture. They help support the Berber ethnic revival/national heterogeneity movement, they represent and valorize within context cultural forms that are `folklorized' at the national level, and they insert new representers, representations and subjects into Berber cultural memory.
Telecommunications Divestment
Authors: McCormick Patricia K.
Published: March 2007

This article examines the undemocratic process of telecommunications divestment in Jamaica and Trinidad and Tobago. The divestment of the telecommunications sector was largely prompted by each state's inability to service external debt. Despite espousing the importance of public participation in the ownership of state-owned enterprises being divested, the governments each limited or excluded nationals from ownership of the telephony companies. Divestment of the telecommunications sector was principally undertaken through private negotiations with Cable and Wireless which has historically provided service to former British colonies. This continued colonization of the telecommunications sector is at odds with the democratic structure of both states.
Arab Television Goes Commercial
Authors: Ayish Muhammad I.
Published: March 2007

Taking the current debate on commercialism in broadcasting as a point of departure, this study sheds light on the promise of private television as a viable alternative to government-controlled broadcasting in the Arab world. It compares programme outputs carried by two satellite broadcasters belonging to two different models of television: the privately controlled commercial model represented by the London-based Middle East Broadcasting Centre (MBC) and the government-controlled model represented by the Egyptian Space Channel (ESC). The study found that both channels seem to devote a fair amount of programming time to reach audiences in the Arab world and beyond. Yet, MBC was found to be far less entertainment oriented in its content than was the government-controlled ESC. MBC was especially distinguished in its Western-style programmes compared to ESC's mostly traditional formats. MBC news was also modelled on Western, especially American news programmes which draw on the report as the basic unit of the newscast. The article concludes that based on this preliminary study, private television in the Arab world seems to hold many promises for the development of broadcasting, long monopolized by governments.
Asian NICs' Broadcast Media in the Era of Globalization
Authors: Hong Junhao , Hsu Yu-Chiung
Published: March 2007

This study examines the trend of commercialization in the broadcast media in Asia's four newly industrialized countries (NICs) - Taiwan, South Korea, Singapore and Hong Kong - and its impact and implications. The central theme of this study is to investigate the `Asian characteristics' of media commercialization and their significance and limits. The direct and indirect, immediate and profound impact and the various implications in the Asian political and social context are discussed. As the focus of the study is on the four Asian NICs, changes in other Asian countries are also discussed as a reflection of some general traits of the region. In particular, this research suggests that: (1) the trend of media liberalization and deregulation in Asian NICs has been mainly manifested through media commercialization, and: (2) the most profound significance of media commercialization in the Asian political and social context is that media commercialization is an alternative or indirect way to achieve media democratization, which is the first step toward political and social democratization.
Colonial commercial forest policy and tribal private forests in Madras Presidency: 1792-1881
Authors: Saravanan Velayutham
Published: March 2007

The article attempts to highlight the colonial commercial forest policy vis-à-vis tribal private forests in the Kalrayan hills of Salem and Baramahal region of Madras Presidency during the late eighteenth and nineteenth centuries (1792-1881). Further, it analyses the different strategies employed by the colonial government to encroach upon private forests, dis regarding the traditional rights of the tribals. It concludes that the British administration intruded into tribal areas merely to bring the abundant forest resources under its sole control to further commercial interests, and not to protect them from the contractors or preserve the environment.
From Outer Words to Inner Worlds
Authors: Marshak Robert J. , Keenoy Tom , Oswick Cliff , Grant David
Published: March 2007

Drawing primarily on the articles published in this edition of The Journal of Applied Behavioral Science, this article examines two significant lacunae in the organizational discourse literature. First, the authors examine the methodological and practical implications of incorporating a discourse-sensitive perspective into everyday organizational analysis. Second, the authors explore the potential insights to be gained from discourse analysts developing a more focused methodological and substantive concern with the inner worlds from which discourse springs.
Back on the Way to Empowerment
Authors: O’Connor Ellen S.
Published: March 2007

This article presents a historical perspective on empowerment through an exposition of the writings of Ordway Tead (1891-1961) and early-20th-century debates as to the relationship between capitalism and democracy and specifically the balance of power among workers, managers, and owners. The article connects the empowerment literature to these debates toward an empowerment discourse that is historically grounded and politically oriented. This move also affords a broad time perspective from which to understand the development of empowerment as a concept in management thought.
Understanding Workplace Empowerment as Inclusion
Authors: Prasad Anshuman
Published: March 2007

This article situates workplace empowerment within the broader principle of inclusion and offers a historical analysis of the discourse of difference in America since the 1930s with a view to developing a deeper understanding of the dynamics of empowerment in the American workplace. The article identifies two primary themes, namely, discrimination and diversity, as constituting the discourse of difference and investigates the differing historical contours of these two themes over the period of this study. The article argues that, during different years, these two themes came to attain different levels of salience that held important implications for inclusion and empowerment in the American workplace.
Procedural Justice as a Two-Dimensional Construct
Authors: Erdogan Berrin , Kraimer Maria L. , Liden Robert C.
Published: March 2007

Procedural justice is generally thought of as a unidimensional construct. In this article, it is argued that in the performance appraisal context procedural justice can be conceptualized as two-dimensional: system procedural justice and rater procedural justice. Regression results from a study of one organization in Turkey support this distinction. Due process characteristics and employee characteristics were differentially related to two dimensions of procedural justice. Specifically, perceived validity of performance criteria, knowledge of performance criteria, and organizational level of employees were related to system procedural justice, whereas perceived performance feedback and fair hearing were each positively related to rater procedural justice.
When is Helping Helpful?
Authors: Higgins Monica C.
Published: March 2007

This research investigates how expectations of evaluation and the timing of help giving affect an individual’s ability to perform on a learning task. Results suggest that help given by a nonevaluative other facilitates performance improvement, irrespective of timing, whereas help given by an evaluative other can inhibit performance improvement, depending on timing. Exploratory analyses regarding individuals’ cognitive and behavioral reactions to helping interventions provide insight into underlying mechanisms that account for the relationships observed.
Building Bridges for Refugees
Authors: Lawrence Thomas B. , Hardy Cynthia
Published: March 2007

In this article, the authors examine the dynamics of bridging organizations in activist domains. The purpose of these organizations is to serve as a link between other organizations and individuals. Drawing on a comparative case study of three national refugee systems, they develop a typology of bridging organizations based on the degree to which each organization shares the values of other organizations in the domain: center extension, border federation, pure bridge. The center extension shares the values of center organizations, transmitting them to the border. The border federation operates much closer to the border, voicing its values and negotiating on its behalf with the center. The pure bridge is a classic bridging organization: It attempts to incorporate values from both center and border, mediating, translating, and negotiating them in an attempt to connect the two sides in a workable relationship.
African Cultural Dimensions in Cuba
Authors: Smallwood Lawrence L.
Published: March 2007

"The greatest remorse of revolution is that it is never finished. It is the forces of dynamic change erupting a mountain, growing the grass, eroding the land with a trickle... persistently as a summer breeze unto autumn."1
Restructuring African American Families in the 1990s
Authors: Barker Narviar Cathcart , Hill Joseph
Published: March 2007

Many of today's families are hurting. Here are some reasons why. One reason is divorce. Divorce hurts children in many ways. Children of divorced parents must learn to cope with the loss of one parent, and sometimes they have to move away from friends and family. That's hard. Another reason is economics. Parents who lose their jobs and single mothers who don't make enough money to buy proper food may send their children to school hungry and may risk joining the ranks of the homeless. That's harder. Still another reason is socialization. Children reared in chaotic families develop serious behavior disorders. They lack structure, autonomy, and self-determination. They learn loneliness, rejection, and dysfunctional behavior. That's hardest. —Barker, speech, 1993
A Method of Predicting the Nonlinear Behavior of Laminated Composites
Authors: Petit P.H. , Waddoups M.E.
Published: March 2007

This paper presents an analytical technique for determining the stress-strain response up to ultimate laminate failure for a laminated composite consisting of orthotropic lamina with nonlinear stress-strain behavior. The procedure, which has been programmed for a digital computer, will produce a laminate stress-strain curve up to ultimate failure. The technique is restricted to the prediction of ultimate strength for plane anisotropic laminates with midplane symmetry sub jected to biaxial membrane loads. Comparisons are made between analytical predictions and experimental results. The basic concepts of ultimate and limit strength design as applied to an advanced com posite structure are discussed.
Analytical Study of Hugoniot in Unidirectional Fiber Reinforced Composites
Authors: Tsou F.K. , Pei Chi Chou
Published: March 2007

A theory based on flow across a selected control volume is devel oped to predict the Hugoniot of a shock moving along the longitudinal direction of a unidirectional fiber reinforced composite. From this theory the Hugoniot of a composite may be calculated from the equa tions of state of its constituents. The shear force along the matrix-fiber interface can also be computed. A sample calculation using polyethyl ene as matrix and beryllium as fiber has been made. The calculated shock Hugoniot are not far from linear.
The Effect of Boundary Conditions on the Response of Laminated Composites
Authors: Whitney J.M.
Published: March 2007

The effect of boundary conditions on the bending, vibrations, and buckling of unsymmetrically laminated rectangular plates is in vestigated. Five sets of boundary conditions corresponding to various clamped and simply-supported edges are treated. The effect of in- plane boundary conditions is shown to be a function of fiber orienta tion within the laminate. Numerical results also show that the effects of bending-extensional coupling can be severe for all the boundary conditions considered. The applicability of the reduced-bending- stiffness approximation is also explored.
Thermal and Thermoelastic Properties of Isotropic Composites
Authors: Budiansky Bernard
Published: March 2007

The results of theoretical estimates are given for several thermal and thermoelastic constants of macroscopically isotropic composite materials. The composites considered consist of random mixtures of N isotropic constituents, at least ( N — 1) of which are presumed to be distributed in a particulate fashion, with the particles roughly spherical in shape. The results are based on "self-consistent" calcula tions, details of which are given in appendices.

Equations (some of which are old, but are repeated for con venience) are given for the following quantities: elastic constants, thermal expansion coefficients, heat capacities (at constant volume and constant pressure), thermal conductivity, and, finally, Gruneisen and related constants.
Steady Wave Analysis of Wave Propagation in Laminates and Mechanical Mixtures
Authors: Munson D.E. , Schuler K.W.
Published: March 2007

A mechanical theory is developed for the propagation of steady waves in laminated media. This analysis treats wave propagation parallel and perpendicular to the laminate plates. It predicts the response of the composite from a knowledge of the component vol ume fractions and mechanical equation of states. Under the restric tion of fluid or hydrodynamic materials, the results yield a hydro dynamic prediction which is independent of composite geometry. Consequently, the analysis is equally applicable to mechanical mix tures. Theoretical calculations are compared to experimental Hu goniot results for a cloth laminate quartz phenolic, a plate laminate and three mechanical mixtures of Al2O3 in epoxy. Excellent agree ment is obtained at low stresses, if the expected deviations caused by material strength are recognized. Thermodynamic effects caused by deviations of the loading path from that of a single shock become more predominant as the stress increases. Models describing both the strength and thermodynamic effects are discussed.
Theoretical Post-Yielding Behavior of Composite Laminates Part II-Inelastic Macromechanics
Authors: Foye Raymond L.
Published: March 2007

This is the second of two papers which present the results of an investi gation that relates the post-yielding mechanical behavior of symmetric laminates, made from unidirectional composites, to the non-linearities in the fiber and matrix materials. The analysis consists of a single ply and a laminate analysis. The single ply portion uses a finite element idealization of the minimum repeating segment of each unidirectional layer as a means of deriving the required ply properties. The laminate portion considers each ply as a homogeneous anisotropic layer, in the context of a conven tional laminate analysis. The manner in which these two approaches are combined and their application to a particular boron/epoxy system is dis cussed here. This type of analysis is useful for verifying stability or deflec tion margins and accurately enforcing a variety of strength criteria.
Ultrasonic Resonance Measurements of Sound Velocity in Thin Composite Laminates
Authors: Chang F.H. , Couchman J.C. , Yee B.G.W.
Published: March 2007

An ultrasonic resonance technique for compressional and shear waves velocity measurements in thin composite laminates is described. The method utilizes a computer digitizing scheme and Fourier transform from time to frequency domain. Results showed an eight percent difference in compressional wave velocity across plies for specimens of two different fiber/resin systems. No difference was observed for specimens having different ply-orientations within a system. Shear wave velocity in one specimen was found to be 46% of the compressional wave velocity. The new technique could also be used for thickness measurements in thin-skin honeycomb structures.
Electrostrictive Stress Concentrations in an Elastic Dielectric Containing Two Rigid Spherical Conductors
Authors: Warren William E.
Published: March 2007

A linear uncoupled theory of electrostriction defined in the bispherical coordinate system is utilized to investigate stress concentrations in an infi nite elastic dielectric containing two rigid spherical electrically conducting inclusions. The elastic dielectric is assumed homogeneous and isotropic so that piezoelectric effects are not present. After a general development of the theory, the specific problem of the two conductors held at a constant electrical potential difference is considered in detail. Effects of the relative sphere spacing on the stress field and the displacement of the rigid spher ical conductors for this applied electrical potential are obtained and pre sented graphically.
Graphite Fiber Reinforced Sn-Pb Investment Castings
Authors: Miyase A. , Piekarski K.
Published: March 2007

Investment casting technique was applied to produce tensile test spec imens of graphite fiber reinforced Sn-Pb alloy. To assure good wetting characteristics of the fibers by the liquid metal, they were electroplated with copper. Depending on the pouring conditions (controls of tempera tures and centrifuging force) several types of bonding between the fibers and the matrix were observed: a) No bond between copper-plated fibers and the matrix, b) Mechanical contact between the copper coating and the matrix, c) Formation of the intermetallic phases between copper and Sn-Pb alloy, and d) Dissolution of copper coating and direct contact between the fibers and the matrix.

Tensile testing of specimens revealed direct dependence of the effi ciency of the reinforcement on the type of the interface formed between the fibers and the matrix. Optimum conditions existed when the electro plated copper had reacted with the Sn-Pb alloy, forming intermetallic phases.
Applications of the Average Stress Failure Criterion: Part I — Tension
Authors: Nuismer R.J. , Labor J.D.
Published: March 2007

Results are presented for the fracture strengths of several Gr/Fp (AS/3501-5) laminates containing countersunk holes and normal and slant cracks. Countersinks are treated as effective uniform holes and slant cracks as effective normal cracks. It is shown that the average stress criterion leads to acceptable strength predictions for all cases considered.
Comparison of Single and Muilti-Hole Bolted Joints in Glass Fibre Reinforced Plastic
Authors: Pyner G.R. , Matthews F.L.
Published: March 2007

Data is presented on the strength of single and multi-hole joints in laminated glass fiber reinforced plastic plates bolted to a steel fitting. The laminate lay-up was (—45/0/—45/0°)s. The results suggest that the joint strength, expressed as the load/bolt, decreases as the joint geometry be comes increasingly complex.
On the Specimen Dependence of Unidirectional Boron/Aluminum Fracture Toughness*
Authors: Reedy E.D.
Published: March 2007

Fracture toughness, as commonly defined for unidirectional boron/ aluminum, was measured with center-notched, compact tension, and vari ous sized three-point bend specimens. All coupons were cut from the same plate of material. The values of fracture toughness determined were found to be specimen dependent, thus indicating that fracture toughness is not a material property for the size and type of specimens tested. The failure mode was also found to be specimen dependent. Crack growth colinear with the notch occurred in the center-notched and three-point bend speci mens, while the crack initiated and propagated perpendicular to the notch tip in compact tension specimens. The failure of linear elastic fracture mechanics to define a material property for these specimens was attributed to extensive matrix yielding in regions remote from the notch tip. The existence of widespread matrix yielding was confirmed with a strain gaged, center-notched tensile specimen.
Bounds of Effective Thermal Conductivity of Short-Fiber Composites
Authors: Nomura Sechi , Chou Tsu-Wei
Published: March 2007

This paper presents bounds of effective thermal conductivities for mul ti-component unidirectional short-fiber composites, based upon an ap proach originally developed by the authors for composite effective elastic moduli. A perturbation expansion of the local temperature gradient is developed by using a Green's function tensor. The effective thermal con ductivity can be expressed in series form and the correlation functions of thermal conductivity have been evaluated up to the third order term. It also has been shown that the series expressions obtained by Kröner, and Zeller and Dederichs are approximations of the present solution. The pre sent solution also coincides with Beran's results for statistically isotropic materials, and provides tighter bounds than those of Hashin and Shtrik man, whose approach is equivalent to considering the correlation function up to the second order.
Evaluation of the Curing of Structural Adhesives by Ultrasonic Interface Waves Correlation with Strength
Authors: Rokhlin S.I.
Published: March 2007

An ultrasonic interface wave can be excited at the interface between two solid bodies, joined by a thin adhesive film. The velocity of the interface wave is con trolled by the shear modulus of the adhesive, and hence the interface wave can be used for evaluation of the curing of the adhesive. This method makes it possible to perform measurements in situ at the required temperature and pressure. The technique allows a clear recording of all phases of the curing pro cess : softening of the prepreg and its transition to the liquid phase, and the beginning and the termination of the polymerization reaction. It is shown that the ultrasonic data satisfactorily predict changes in the mechanical bond strength in the course of curing.
An Experimental Study of the Effect of Prestressed Loose Carbon Strands on Composite Strength
Authors: Zhifan Chi  , Chou Tsu-Wei
Published: March 2007

The purpose of this work is to demonstrate experimentally the strength behavior of composites reinforced with prestressed fiber strands. In a preceding article, a theoretical analysis of the feasibility of strength enhancement by fiber prestressing has been demonstrated. In this paper, fiber prestressing is achieved by bending of the loose bundles and the weak points of the fibers are thus eliminated. The experimental results show that after prebending the fibers to an appropriate level the strength of composites can be enhanced. Although the increase in composite mean strength is small, the varia tion of composite strength is greatly reduced, and the strength at high survivability level is enhanced most significantly.
Stress Distribution Around a Semi-Circular Edge-Notch in a Finite Size Laminated Composite Plate Under Uniaxial Tension
Authors: Lakshminarayana H.V.
Published: March 2007

A computationally efficient finite element model that can provide accurate numerical solutions to the problem of a semi-circular edge-notch in a finite size laminated composite plate under uniaxial tension is presented. Numerical results showing the effect of composite material proper ties and laminate designs on the stress field are also presented and discussed.
Influence of Thick Section Welding on The Properties of Composites Adjacent to the Weldments
Authors: Raghava R.S. , Kolek R.L. , Kaye K.S.
Published: March 2007

The influence of short term high temperature exposure on mechanical properties of graphite/epoxy (Hercules: AS-4/3501-6) in the immediate vicinity of weldments has been examined. An exposure test simulating a welding process has been developed, and specimens from unidirectional and (0°/90°) laminates were exposed to short term high temperature found adjacent to weldments. The influence of welding parameters on temperature distribution away from the weld for 1/4" and 1/2" thick steel plates was measured.
Surface Anisotropy in the Expansion Behavior of Laminated Quasi-Isotropic Composites
Authors: Piccarolo S. , Titomanlio G.
Published: March 2007

The surface thermal strains of two quasi-isotropic graphite fiber-epoxy resin laminates were measured with the strain gage technique. The resulting data was direc tionally dependent; the related surface anisotropy varied inversely with the sample dimensions and varied directly with the single lamina anisotropy ratio.
Analysis and Optimization of a Tubular Lap Joint Subjected to Torsion
Authors: Hipol Philip J.
Published: March 2007

This analysis considers a tubular lap joint comprised of a steel tube adhesively bonded to a composite tube subjected to torsion. A finite element method is employed to characterize the stress concentration associated with the boundary layer effect in the end region of the adhesive layer. Through the selective perturbation of geometric and material properties, a parametric evaluation is conducted in which the peak stress and its gradient are reduced. A number of design guidelines are subsequently drawn based on the results of this evaluation.
Composite Laminates with Negative Through-the-Thickness Poisson's Ratios
Authors: Herakovich Carl T.
Published: March 2007

A simple analysis using two-dimensional lamination theory combined with the ap propriate three-dimensional anisotropic constitutive equation is presented to show some rather surprising results for the range of values of the through-the-thickness ef fective poisson's ratio vxz for angle-ply laminates. Results for graphite-epoxy show that the through-the-thickness effective poisson's ratio can range from a high of 0.49 for a [90] laminate to a low of -0.21 for a [±25]S laminate. It is shown that negative values of vxz are also possible for other laminates.
Evaluation of a Double Lap Composite Clamped Joint
Authors: Roberts Jack C.
Published: March 2007

Double lap joints consisting of [05/905]2s, [905/05] 2s and [+455/-455]2s graphite epoxy laminates clamped between metal were pulled to failure in tension. The clamp load, loading rate and surface finish of both the composite inner and metal outer laps were varied to find their effect on the failure load. At clamp loads of 18 to 45 kN the [905/05]2s laminates had approximately equal loads at failure. However, as the clamp load increased to 45 kN, the [O 5/905]2s laminate had a higher load at failure than the [+455/-455]2s laminate. In all cases joint failure occurred as slip between the composite inner lap and the metal outer laps at static coefficients of friction of 0.3 to 1.06. The ef fect of metal or composite surface finish and loading rate on the failure load were found to be minimal for the amount of data taken. Joint efficiency (joint strength/ composite tensile strength) was between 75% and 95% for the [+455/-45 5]2s laminate and 10% to 20% for either the [05/90 5]2s or [905/05]2s laminates.
A Model for the Thermal Response of Polymer Composite Materials with Experimental Verification
Authors: Henderson J.B. , Wiebelt J.A. , Tant M.R.
Published: March 2007

The thermal response of a polymer composite material undergoing decomposition has been modeled. A one-dimensional transient thermal model with an nth order ap proximation for the rate of decomposition was applied. The model was tested by ex perimentally measuring the temperature profiles during decomposition for a glass- filled phenol-formaldehyde polymer composite. Additionally, the specific heat and thermal conductivity of the virgin and char components, heat of decomposition, and the kinetic parameters were experimentally determined and used as input to the model. The predicted temperature profiles are in good agreement with experimental temperatures obtained using a radiant heat flux apparatus.
Acoustic Emission from Single and Multiple Kevlar 49 Filament Breaks
Authors: Hamstad Marvin A. , Moore Richard L.
Published: March 2007

Acoustic Emission (AE) was monitored during single filament tension tests of Kevlar 49 fiber. AE was also monitored during dry and lubricated bundle tests of the same material. These later tests were carried out in such a way that the individual filament breaks could be independently verified. Statistical studies were made of the AE event characterization parameters for the source mechanism of filament failure. Studies of effect of cumulative damage, test fixturing, first vs. second AE sensor hit, and friction between fibers were made. Characterization by AE events made up of multiple filament fractures was examined relative to events due to single filament fracture in a bundle. These results are preliminary studies prior to using AE to study fundamental variables which control damage progression in fiber composites upon repeated loading.
Theoretical Modelling of the Effect of the Interfacial Shear Strength on the Longitudinal Tensile Strength of Unidirectional Composites
Authors: Shih G.C. , Ebert L.J.
Published: March 2007

An approach coupling Rosen's cumulative damage model [1,2] and Piggott's elastic-slip stress transfer model [3,4] is presented here, to demonstrate the effect of the interfacial shear strength on the longitudinal tensile strength of unidirectional fiber-reinforced polymer composites. It was found numerically that an interface strong in shear would in crease the longitudinal tensile strength of the composite marginally. According to the ap proach developed, in the situations where the fiber strengths scattered markedly, or where the coefficient of friction between debonded fibers and matrix is very small, an increase in the interfacial shear strength would enhance the longitudinal tensile strength in a relatively significant manner. Additionally, an interface layer was introduced in Piggott's elastic-slip stress transfer model, so as to render the model conceptually more nearly cor rect.
Three Dimensional Thermal Stresses in Angle-Ply Composite Laminates
Authors: Griffin O. Hayden
Published: March 2007

Three-dimensional linear finite element analysis is used to compute the room tempera ture stress distributions and shapes of angle ply graphite/epoxy laminates of the form [+θ n/-θ n] S with values of θ ranging from 15 ° to 75° . Analyses were performed with pro per boundary conditions and with improperly assumed symmetry conditions. Results in dicate that angle ply laminates with "clustered" plies will exhibit a tendency to delaminate at diagonally opposite corners. Earlier work by the author predicted the initiation of trans verse matrix cracks at the free edge in cross-ply laminates of the form [0 n/90 n] S. In angle- ply laminates of the form [+θ n/-θ n] S, however, the results indicate that matrix cracks will be initiated in the interior of the laminate, resulting in potential difficulties for ex perimental efforts using optical methods to detect cracking.
An Ideal Clamping Analysis for a Cross-Ply Laminate
Authors: Valisetty R.R. , Murthy P.L.N. , Rehfield L.W.
Published: March 2007

Different elementary clamping models are discussed for a three layer crossply laminate to study the sensitivity of clamping to the definition of cross-sectional rotation. All of these models leave a considerable residual warping at the edges. Using a complimentary energy principle and principle of superposition, an analysis is conducted to reduce this residual warping. This led to the identification of exact interior solution corresponding to the ideal clamping. This study also suggests a presence of stress singularities at the corners and be tween different layers near the fixed edge.
Constitutive Relations of a Cracked Composite Lamina
Authors: Nuismer R.J. , Tan S.C.
Published: March 2007

An approximate elasticity theory solution is given for the stress-strain relations of a cracked composite lamina. These relations are written in the familiar form of two- dimensional compliances appropriate for use with laminated plate theory, and include the effects of non-mechanical strains. It is shown explicitly that the cracked lamina com pliances depend upon the overall laminate construction in which the lamina is contained.
Effective Stress Fracture Models for Unnotched and Notched Multidirectional Laminates
Authors: Tan S.C.
Published: March 2007

Three models are proposed for the ultimate strength prediction of multidirectional unnotched and notched composite laminates. These models utilize a characteristic length and a proposed failure criterion that requires the longitudinal strength parameters and stress distribution of a lamina within a laminate. The characteristic length for the second model: effective average stress model is independent of the opening shape and that for the third model: minimum strength model can be related in a simple form. Comparisons show that the ultimate strength predictions for unnotched and notched laminates both agree very well with experimental data for graphite/epoxy materials system. A direct relation between the fracture toughness and the unnotched laminate strength (determined analytically) is also obtained.
Optimum Design of Variable Composite Flywheel
Authors: Georgian John C.
Published: March 2007

A composite flywheel is designed using a composite of low density and high strength for the center portion, with constant stress as the design criteria and a constant thickness outer portion using a high density composite attached at the boundary of the constant stress disk. This combination produces the maximum energy density for a flywheel energy stor age system.
The Effects of Geometry, Rate and Temperature on the Mode I, Mode II and Mixed-Mode I/II Interlaminar Fracture of Carbon-Fibre/Poly(ether-ether ketone) Composites
Authors: Hashemi S. , Kinloch A.J. , Williams J.G.
Published: March 2007

A detailed study on the interlaminar failure of carbon-fibre/poly(ether-ether ketone) unidirectional composite (termed PEEK composite: "APC-2" from ICI (UK) plc) is presented. A fracture mechanics approach has been adopted and Mode I, Mixed-Mode I/II and Mode II tests have been conducted and the effects of specimen geometry, test rate and test temperature have been investigated. It is shown that for the interlaminar fracture of the PEEK composite the value of the interlaminar fracture energy, G,, generally in creases as the crack propagates through the composite, i.e., a rising "R-curve" is observed. Thus, it is not usually possible to assign one unique value to the interlaminar fracture energy, Gc, for any given Mode of loading for the PEEK composite. We have therefore defined both an initiation value, Gc(init), and a steady-state propagation value, Gc(s/s prop). The variation of these parameters with the Mode of loading, method of precracking and the test temperature is described in detail. From optical and electron microscopy studies it is shown that in Mode I the "R-curve" behaviour mainly arises from the degree of fibre-bridging increasing as the interlaminar crack grows, whilst in Mode II it appears to mainly arise from the increasing degree of microcracking and plastic deformation damage which develops around the tip of the advancing crack. The failure loci for the in terlaminar fracture of the PEEK composite have also been established, and various theo retical models to describe these data are considered.
Analysis of Thick Section Composite Laminates Using Effective Moduli
Authors: Sun C.T. , Liao W.C.
Published: March 2007

Three-dimensional effective moduli are used in the analysis of thick lami nates consisting of a large number of repeating identical sublaminates. Local stresses and strains in the laminae are recovered from the global average stresses and strains. A global- local method is developed in which the effective modulus theory is used to model the thick laminate except for the local region where accurate stresses are desired. Evaluative ex amples involving delamination cracks and free edge stresses are presented.
Autoclave Curing — Comparisons of Model and Test Results
Authors: Ciriscioli Peter R. , Qiuling Wang  , Springer George S.
Published: March 2007

Tests were performed measuring the temperature, ionic conductivity, and compaction in 16 to 200 ply thick graphite-epoxy laminates made of either Fiberite T300/976 (tape or fabric) or Hercules AS/3501-6 (tape). The data were compared to results calculated by the Loos-Springer CURE model. Good agreement was found between the model results and the data indicating that the model can be used to select the cure cycle. It is also shown that the cure cycle recommended by the manufacturer may result in ex cessive temperatures and in incomplete compaction and cannot be used to manufacture "thick" or even moderately thick composites.
Effects of Hydrostatic Pressure on In-Plane Shear Properties of Graphite/Epoxy Composites
Authors: Shin E.S. , Pae K.D.
Published: March 2007

In order to determine effects of the fiber orientation on the pressure de pendent in-plane shear properties of continuous graphite fiber reinforced composites, mandrel-wrapped tubes are tested in torsion in the specially designed high pressure torsion test apparatus that is capable of containing pressure up to 7 Kbar.

The shear properties that are determined include the in-plane shear modulus, shear yield strength and fracture strengths (maximum stress), and the strain to fracture as a function of hydrostatic pressure and fiber orientation. These results are then compared with those of the epoxy resin matrix without fibers and (0°) composite samples also tested under hydrostatic pressure. In all cases, the shear properties increase with increasing pressure but in different rates depending on the fiber orientation. The increase in the strengths and the toughness is manifested in the change in the modes of fracture. Visual and SEM examination are made to study fracture surface morphology and possible frac ture mechanisms.
A Technique for Tensile Fatigue and Creep Testing of Fiber-Reinforced Ceramics
Authors: Holmes John W.
Published: March 2007

An experimental technique for the elevated temperature tensile fatigue and creep testing of fiber-reinforced ceramics is discussed. The experimental approach utilizes edge-loaded specimens with rectangular gage-sections. Novel furnace and grip designs which allow testing in air to 1500°C are provided. The specimen, furnace and grip designs discussed in the paper have been successfully used to test unidirectional and cross-ply SiCf/Si3N 4, SiCf/SiC, Cf/SiC and SiCf/calcium-aluminosilicate composites.
The Relationship between Tensile and Flexural Strength of Unidirectional Composites
Authors: Wisnom Michael R.
Published: March 2007

Weibull theory predicts a higher strength in bending than in tension. How ever it assumes that failure initiates from a critical defect, whereas many unidirectional composites fail gradually in bending. A model has been developed of the composite as a bundle, each element of which consists of a small bundle of fibres. The resin is assumed to stabilise the bundle against buckling under compression, whilst allowing the individual elements to split and behave independently in tension. This model also predicts higher strength in bending than in tension, with a ratio of similar order of magnitude to that pre dicted by Weibull theory. The new model provides an explanation for the different strengths in bending and tension which is consistent with the progressive, noncatastrophic failure process which is often observed in bending tests of unidirectional composites.
Effect of Radial Clearance between Bolt and Washer on the Bearing Strength of Composite Bolted Joints
Authors: Herrington P.D. , Sabbaghian M.
Published: March 2007

When composite materials are bolted together, the relative diameters of the bolt hole, the constraining washer and the bolt itself have a profound effect on the ulti mate bearing strength. Previous studies have investigated the effects of clearance between the bolt and the hole diameter. In this study, the effect of the difference between the bolt diameter and the inside diameter of the washer, which provides the lateral constraint at the edge of the hole, is examined. To explain the significant variation of bearing strength with bolt-to-washer clearance, a model is proposed to explain the mechanics of load transfer and the lateral deformation at the edge of the hole. The test results, using a quasi-isotropic graphite epoxy laminate, support the proposed model and provide data for designers.