bluuebunny/crossref_metadata_2025 huggingface dataset:
Literacies across Generations: Women’s Religious and Secular Identities in Siraiki Villages
Authors: Zubair Shirin
Published: April 2004

This article explores the intergenerational changes taking place in the lives of Siraiki-speaking women in Pakistan, in terms of their access to and uses of literacy. The first section draws a profile of the village community to acquaint the reader with various aspects of the rural life that interplay with the literacy repertoire of the community. After building a profile of the material culture and social structure of the community, followed by a brief description of the special days and occasions in the villages, the article examines women’s lives in the village and their experiences of various literacies. Focusing primarily on the variables of class and generation, this section throws light on women’s lives and literacies to show how inextricably these are intertwined. Some ideological issues relating to women’s space are also discussed, especially how access to secular literacies and electronic media impacts upon the changing identities of younger women.
Town Revenues and Taxes in Eighteenth Century Gujarat: An English East India Company Document
Authors: Hariharan Shantha
Published: April 2004

This article deals with information on taxes and revenues contained mainly in an English East India Company document recorded in 1773 in the Surat Factory Records, just after the Company conquered Broach territory from the Nawab of Broach. It is as contemporary a record as the Mirat-i-Ahmadi, about Mughal revenue and taxation matters, with many details of the rates and actual amounts collected of taxes at the microlevels. It can serve as a good source for scholars for crosschecking, grading and analysis. The article shows the large variety of taxes and indicates their potentially oppressive effects.
Implementing OASys: Lessons from Research into LSI-R and ACE
Authors: Robinson Gwen
Published: April 2004

This article draws on original research and other studies to explore a range of issues that probation areas are likely to face during implementation of the OASys risk/needs instrument. It considers how such instruments are viewed by practitioners and focuses in particular on how they perceive them to impact on their professionalism. The article concludes by encouraging a wider debate about the future of indeterminacy in assessment and elsewhere in probation practice.
Domestic Violence: Narrative and Solutions
Authors: Milner Judith , Jessop Dorothy
Published: April 2004

This article reports on the first year of a pilot programme based on solution-focused and narrative approaches to working with violent adults who were not receiving assistance to change their behaviour. These adults constituted two groups: violent women for whom there was no service provision at all; and violent men who were either unwilling or unable to attend any of the existing programmes.
Developing Good Practice with Racially Motivated Offenders
Authors: Dixon Liz , Court David
Published: April 2004

This article considers a number of issues relating to practice with racially motivated offenders, including a new typology that throws light on different offender profiles, the complexity of risk assessment and the need for training and effective multi-agency work. The authors consider the unique nature of offending and draw on experiences from the Greenwich Targeted Policing Initiative which is now being held up as a ‘beacon’ of good practice.
Broadening the Agenda Around What Works for Black and Asian Offenders
Authors: Durrance Pauline , Williams Patrick
Published: April 2004

As a result of concerns about the relatively narrow focus of proposed pathfinder programmes intended to address black and Asian offenders, the authors revisit theories and evidence relating to empowerment models. They argue that programme material which explicitly addresses the social and cultural context within which offending occurs might better engage black and Asian offenders and others who, it is argued, may find it difficult to relate to more established problemsolving approaches.
Policing Hate Crime. From Victim to Challenger: A Transgendered Perspective
Authors: Dittman Rebecca J.
Published: April 2004

The author describes her journey from being a victim of hate crime motivated by her transgender identity, to someone who is now actively challenging such prejudice, and related offending, through her work as an advisor to the Merseyside police force, with which she is helping to build stronger and more diverse community partnerships.
Irish Travellers: Ethnicity, Racism Andpre-Sentence Reports
Authors: Power Colm
Published: April 2004

This article examines the treatment of Irish Travellers in the criminal justice system. It provides a brief background to Irish Traveller ethnicity and then outlines the causes, extent and consequences of social marginalization, ethnic disqualification and criminalization in Britain’s Irish Traveller population. This leads to a discussion of criminal justice concerns through the examination of existing research on pre-sentence reports (PSRs) concerning Irish Travellers, and interviews with probation officers and others which helped to explore overt and embedded prejudice and racism in the language and construction of PSRs. The article finishes by assessing possible ways to ameliorate these injustices in the sentencing process.
Evidence-Based Probation and its Critics
Authors: Raynor Peter
Published: April 2004

Over the last decade the development of evidence-based approaches based on ‘What Works’ has become a central principle of probation policy, but has also been subject to a number of criticisms. These have included arguments that the new methods pathologize offenders, that they ignore social causes of crime, that they ignore diversity, and that they are being implemented before their efficacy has been demonstrated. This article responds to these and other criticisms in the light of available evidence and concludes that the future for evidence-based practice looks more promising than some critics have suggested.
Evaluating the Evaluators: Researching the Accreditation of Offender Programmes
Authors: Rex Sue , Bottoms Anthony
Published: April 2004

This article reports findings from the evaluation by the Institute of Criminology of the Joint Prisons and Probation Accreditation Panel, now known as the Correctional Services Accreditation Panel (CSAP), undertaken for the Home Office during 2002 and recently published as a Home Office Research Study.1 Drawing on the views of a range of stakeholders, observation of the Panel and review of the relevant literature and policy papers, we consider how the Panel has performed its central function of accrediting offender programmes and their delivery by the prison and probation services. We also consider the implications of our findings for its future work.
Mission Control: The Origins of a Humanitarian Service
Authors: Vanstone Maurice
Published: April 2004

In effect, this article is a summary of the first part of a larger piece of historical research, which in its entirety concentrates more on the writings of practitioners and interested outsiders. The result of this approach has produced a revised history of the probation service that challenges orthodox accounts, builds on the work of commentators like Bill McWilliams, and reflects on how a focus on practice as opposed to policy discourse renders different meanings to, and understandings of, the development of the concept during the 20th century. This article focuses on the origins and early period of probation history.
How Healthy is Your ‘Community of Practice’?
Authors: Lynch Richard
Published: April 2004

This article explores cultural change and situated approaches to learning as a basis for understanding developments in the daily life of the probation organization. These are highlighted in the concept of ‘communities of practice’ that describes learning in the everyday activities of practitioners’ work. It is argued that the future can be changed by greater attention to context specific knowledge-in-use through practitioner research.
Does Tougher Enforcement Lead to Lower Reconviction?
Authors: Hearnden Ian , Millie Andrew
Published: April 2004

It is increasingly argued that vigorous enforcement improves probation outcomes and reduces reconviction rates. Based on a recent study of the link between enforcement and reconviction rates, this article argues that vigorous enforcement is not necessarily synonymous with effective enforcement. It also contends that ensuring compliance is at least as important as adherence to National Standards.
The Relative Utility of ‘Pleasantness’ and ‘Liking’ Dimensions in Predicting the Emotions Expressed by Music
Authors: Ritossa Damian A. , Rickard Nikki S.
Published: April 2004

The relative utility of the ‘pleasantness’ and ‘liking’ dimensions in predicting emotions expressed by music was investigated. The sample of 121 undergraduates (79 female, 42 male) listened to four songs representing each of the four quadrants of the circumplex model of emotion and rated each song on pleasantness, liking, arousal, familiarity, and the expression of eight emotions. The findings indicated that the emotions expressed in these diverse pieces of music were quite reliably predicted by a combination of the arousal, pleasantness, and familiarity variables, although the amount of variance accounted for by these equations was moderate at best. Pleasantness also represented a more useful predictor of emotions expressed than did liking when the circumplex model of emotion was applied to the musical domain.
Gender Differences in Children’s Experience of Musical performance Anxiety
Authors: Ryan Charlene
Published: April 2004

The purpose of this study was to examine musical performance anxiety in children, with a focus on potential gender differences. Twenty-six sixth-grade students performing in a piano recital were monitored continuously on measures of heart rate and behaviour. Participants were interviewed in the months prior to the recital and they completed the State-Trait Anxiety Inventory for Children immediately after performing. It was found that girls’ heart rates rose through each recital stage (before playing and during playing). Boys’ heart rates rose minimally prior to performing but exceeded the girls’ while performing. Significantly more anxious behaviours were displayed by boys both prior to and while performing. Three sets of correlation and regression analyses (all children, girls-only, boys-only) were run on all anxiety measures. Several significant relationships in the ‘all children’ group seemed to be driven by a strong relationship in a single gender that was not apparent in the other gender.
Effects of Three Years of Piano Instruction on Children’s Academic Achievement, School Performance and Self-Esteem
Authors: Costa-Giomi Eugenia
Published: April 2004

This study of the effects of three years of piano instruction is based on a sample of 117 fourth-grade children attending public schools in Montreal. The children had never participated in formal music instruction, did not have a piano at home, and their annual family income was below $40,000 Can. Children in the experimental group ( n= 63) received individual piano lessons weekly for three years and were given an acoustic piano at no cost to their families. Children in the control group ( n= 54) did not participate in formal music instruction. Participants were administered tests of self-esteem, academic achievement, cognitive abilities, musical abilities, and motor proficiency at the beginning of the project and throughout the three years of piano instruction. The results indicated that piano instruction had a positive effect on children’s self-esteem and school music marks but did not affect their academic achievement in math and language as measured by standardized tests and school report cards.
Trace and Forgetting: Between the Threat of Erasure and the Persistence of the Unerasable
Authors: Greisch Jean
Published: April 2004

Ancient philosophers believed that three anecdotes are enough to characterize a philosophical temperament. As soon as I accepted the invitation to participate in a research devoted to the triple topic: ‘Trace, print, remains’, three anecdotes at once came to mind. I shall use them to establish a preliminary understanding of the concept of trace, which we shall subsequently approach from a more philosophical perspective.
Memory as a Freeze-Frame: Extracts from ‘Looking at War’
Authors: Sontag Susan
Published: April 2004

The war America waged in Vietnam, the first to be witnessed day after day by television cameras, introduced the home front to a new intimacy with death and destruction. Ever since, battles and massacres filmed as they unfold have been a routine ingredient of the ceaseless flow of domestic, small-screen entertainment. Creating a perch for a particular conflict in the consciousness of viewers exposed to dramas from everywhere requires the daily diffusion and rediffusion of snippets of footage about the conflict. The understanding of war among people who have not experienced war is now chiefly a product of the impact of these images.
The New Economy: What’s New, What’s Not
Authors: Harms John B. , Knapp Tim
Published: April 2004

In this article, the authors evaluate the New Economyaccording to its own claims of growing prosperityand rising standards of living. Using statistics and indicators from the recent economic expansion, theydemonstrate that many of the claims about the New Economy’s increasing prosperitywere highly suspect and remain so today. They conclude that the New Economy discourse is an ideological expression of an explicit political agenda favoring corporate interests.
Subsistence Wages and Household Production: Clearing the Way for an Analysis of Class and Gender
Authors: Quick Paddy
Published: April 2004

A theoretical analysis of capitalist relations of production shows that both the subsistence wage rate and the allocation of workers’ time between household and wage labor are determined by the household production function. In and of itself, this analysis tells us nothing at all about gender relations. It does, however, enable us to distinguish clearly between gender and class relations and thus to investigate their interrelationship.
On the Rise of the West: Researching Kenneth Pomeranz’s Great Divergence
Authors: Duchesne Ricardo
Published: April 2004

For a long time, scholars have tried to explain why Europe alone of the great civilizations of the world achieved a profound transformation in output and productivity in the nineteenth century. Ken Pomeranz’s The Great Divergence is a recent, highly praised intervention in this debate. He argues that, as late as 1800, Chinese living standards and productivity levels were comparable to European ones. What allowed England to industrialize first were plentiful supplies of coal and vast land-saving resources in the New World. But Pomeranz’s claims lack empirical credibility. Over the period 1700–1850, most of Western Europe was on a trajectory away from the Malthusian limitations of the old regime as a result of sustained improvements in both land and labor productivity. The ecological benefits provided to England by American imports were not significant compared to the actual and potential expansion of intra-European trade. China was unable to attain any industrial breakthrough despite enjoying a much greater “ecological windfall” from the acquisition of new territories in central and southwestern Asia after 1500.
The Real and Financial Components of Profitability (United States, 1952–2000)
Authors: Duménil Gérard , Lévy Dominique
Published: April 2004

Financial relations considerably alter the profile of the profit rate of nonfinancial corporations. Large rates are maintained to the end of the 1970s. Conversely, rates are diminished during the 1980s and 1990s. The average value of the profit rate of the financial sector is similar, though lower during the 1970s, due to low real interest rates and a stagnating stock market. The opposite is true during the neoliberal decades.
Fracture Behaviour of FRP Composite Laminates with Two Interacting Embedded Delaminations at the Interface
Authors: Chakraborty D. , Pradhan B.
Published: April 2004

This study deals with the delamination growth behaviour of FRP composite laminates having two embedded delaminations at the interface under uniaxial and transverse loadings. A full 3D FE analysis has been performed to calculate the interlaminar stresses at the interface responsible for delamination. The concept of fracture mechanics has been used to calculate the strain energy release rate components at the interface. Elliptical delaminations have been simulated to be present at the interface of two sublaminates each consisting of several plies, and the effect of the neighbouring delaminations on the other delamination has been studied under concentrated transverse loading as well as uniaxial tensile loading. Effects of delamination size, shape and the center distance between the two delaminations on individual strain energy release rate components have been evaluated to assess the delamination behaviour. It has been observed that the shape, size and the relative spacing of the two delaminations have a strong effect on the overlapping stress field, and the two delaminations grow in size to form a single delamination depending upon these parameters.
Significance of Processing Parameters on the Warpage of Rotationally Molded Parts
Authors: Liu Shih-Jung , Chen Chi-Feng
Published: April 2004

Part warpage caused by inappropriate mold design and processing conditions is one of the problems that confound the overall success of rotational molding technology. This report is devoted to investigate the effects of different processing parameter on part warpage. The first part of this report is to optimize the warpage of rotationally molded parts. An L’18 orthogonal array design based on the Taguchi method was conducted to optimize the warpage of rotationally molded thermoplastic parts. The second part of this report is to identify the relative significance of each processing parameter on the warpage of rotationally molded products. Experiments were carried out on a lab-scale rotational molding machine. The polymeric material used was linear low density polyethylene. After molding, the warpage of molded parts was characterized by a profile-meter. For the parameters selected in the main experiments, the cooling condition was found to be the principal parameter affecting the warpage of rotationally molded thermoplastics, while the effect of pigmentation was relatively limited.
Reprocessing Effects on the Properties of a Hybrid Nylon 6,6-Composite Reinforced with Short Glass and Carbon Fibers
Authors: Licea-Claveríe A. , Valdez J. O. , García-Hernández E. , Zizumbo A. , Álvarez-Castillo A. , Castaño V. M.
Published: April 2004

A hybrid nylon 6,6 short glass/carbon fiber composite has been studied. The effect of reprocessing on the microstructure and mechanical properties was evaluated for injection-molded products. Fiber size distribution, molecular weight of matrix, thermal transitions, Young modulus and impact strength are among the properties evaluated during nine reprocessing cycles by injection molding. For the first five injection cycles an increase in tensile strength, Young modulus and impact strength are observed whereas molecular weight and average fibers-size are decreased. Reprocessing after 5 cycles led to a decrease in mechanical properties. SEM images show that the matrix first recovers from its fractures (up to 5 cycles) and after that, fractures again accompanied by an increased fiber pull-out.
A Higher Order Displacement Model for the Plate Analysis
Authors: Shimpi R. P. , Arya H. , Naik N. K.
Published: April 2004

A higher order displacement model for laminated composite plates is presented. The displacement model has trigonometric terms in addition to thin plate terms and contains six unknowns. The model satisfies shear stress conditions at top and bottom of the plate. Governing equations and boundary conditions are obtained using virtual work principle. The present displacement model gives simple governing equations. The model has been applied to various simply supported rectangular isotropic, orthotropic and layered plates for static and free vibration analysis. This model yields better results as compared to other higher order displacement models.
Effects of Transverse Stitching and Hygrothermal Environment on Composite Wing T-Joints
Authors: Kumari Shyama , Sinha P. K.
Published: April 2004

The present paper deals with the effects of transverse stitching and hygrothermal environment at the web-skin interface of composite wing T-joints that are made of carbon fibre composite (CFC) materials. The T300 carbon fibres are considered for the transverse stitching. The statistical bundle strength based on the Weibull distribution function is used for the estimation of the joint strength. A thick composite shell finite element is specially developed taking into account the hygrothermal effects and is used for a detailed finite element analysis of composite T-joints. T-joints may be exposed to moisture and temperature during their service life. Under such circumstances moisture and temperature diffuse into T-joints. As a consequence, the stiffness and strength properties of the laminates are degraded. Moreover, since the laminas in the laminate cannot deform freely, residual stresses are introduced. All the normal and shear stresses are computed and the failure loads are also computed using various failure criteria to get better insight into the behaviour of laminated T-joints. Additional stresses due to hyghrothermal forces are also computed. The T-joint is supported along the length and a pull-out force is applied on the top of the web. It is found that the web-skin interface where load transfer is out of plane, is the critical zone for failure due to high transverse normal and shear stresses. Also, higher temperature and moisture levels introduce additional transverse normal and shear stresses that make the zone more critical. The present study also shows how the transverse stitching at the web-skin interface zone adds to the transverse strengthening of the interface laminates and helps the T-joints to sustain higher loads.
Anchorage Systems for Masonry Walls Strengthened with FRP Composite Laminates
Authors: Tan K. H. , Patoary M. K. H. , Roger C. S. K.
Published: April 2004

This study examined the anchorage of FRP systems in strengthening masonry walls against out-of-plane lateral loads. The anchorage methods utilized (i) improved bond; (ii) a fiber anchor bolt system; and (iii) an embedded bar system. Tests were carried out on eight walls of half-brick thickness and seven walls of full-brick thickness, strengthened with two different types of glass and one carbon FRP systems. Each wall was placed in a horizontal plane and simply supported along four sides without edge restraint, and then subjected to a uniformly distributed pressure applied using an air bag over a square area at its centre. Test results indicated that specimens without any anchorage measures showed premature failure by FRP debonding, while those provided with an anchorage system, failed by brick crushing or by punching shear at a much higher load. An analytical model is also presented to predict the failure load of FRP reinforced masonry walls failing in flexural compression or punching shear, and was found to predict test results well.
A Framework for Life-Cycle Cost Assessment of Composites in Construction
Authors: Hastak Makarand , Mirmiran Amir , Richard Deepak
Published: April 2004

The slow acceptance of composite materials in construction could be attributed to the high initial cost of composites compared to conventional materials and the limited information on life-cycle cost. This paper presents a unique framework for a probable life-cycle cost assessment model for composite materials in construction. The proposed model utilizes the historical life-cycle performance data for conventional materials, knowledge about material properties, and deterioration characteristics for new and conventional materials to effectively assess the life-cycle cost and behavior of composite materials in construction. The proposed model integrates deterioration characteristics of structural components under different environmental and loading conditions to establish performance envelopes. Monte Carlo simulation models are generated to evaluate various maintenance, repair, and rehabilitation (MR and R) strategies possible over the life-cycle. The life-cycle cost associated with each scenario is computed, at different discount factors, to obtain the optimum life-cycle cost for various material options. The specifics of the model are illustrated through an example.
Shear Buckling of Rectangular Composite Plates with Two Concentric Layups
Authors: Papadopoulos Lampros , Kassapoglou Christos
Published: April 2004

A method to calculate the buckling load of rectangular composite plates with two concentric layups under shear is presented. The method is based on a polynomial expansion of the out of plane displacement of the plate and energy minimization. The resulting generalized eigenvalue problem for the buckling load is solved using the bisection method. The predictions of the present method are found to be in excellent agreement with the special cases of isotropic plates or anisotropic plates with a single layup. For the case of two concentric layups, the method is found to be in good agreement with finite element predictions. The use of concentric layups in composite plates promises to significantly reduce their weight meeting the same buckling load requirements.
Void Content, Density and Weight Reduction Studies on Short Bamboo Fiber–Epoxy Composites
Authors: Rajulu A. Varada , Chary K. Narasimha , Reddy G. Ramachandra , Meng Y. Z.
Published: April 2004

Short bamboo fiber reinforced epoxy composites were developed with varying fiber content. The void content, density, and weight reduction of these composites were determined. The void content of these composites was found to be decreasing with increasing fiber content. The density of these composites was found to be decreasing with fiber content. The percentage weight reduction of these composites from the matrix was found to be increasing linearly. The bamboo fibers, and the epoxy resin system constituted lighter composites.
Fatigue Failure Mechanism and Crack Growth in Foam Core Sandwich Composites Under Flexural Loading
Authors: Kulkarni Nitin , Mahfuz Hassan , Jeelani Shaik , Carlsson Leif A.
Published: April 2004

The flexural fatigue response of foam core sandwich beams has been investigated. Sandwich panels were manufactured using an innovative coinjection resin transfer molding (CIRTM) process. S2-glass fiber with epoxy resins was used as face sheets over a PVC foam core. Testing was performed in a three-point flexure mode utilizing a newly designed fixture such that the localized indentation damage was minimal. Extensive fatigue data were generated for the S-N diagram and crack growth was monitored. Three distinct damage events were found. The first visible sign of damage initiation was a core-skin debond parallel to the beam axis. This debond propagated slowly along the top interface and eventually kinked into the core as shear crack and then grew in an unstable manner resulting in total specimen collapse.
Laser Transmission Welding of Semicrystalline Thermoplastics - Part II: Analysis of Mechanical Performance of Welded Nylon
Authors: Kagan V. A. , Pinho G. P.
Published: April 2004

Selecting thermoplastics for a wide industrial application (automotive, appliances, lawn and garden, power tools, etc.) strongly depends on the plastic material composition, part design, processing (molding and welding) conditions. The structure of used thermoplastics, mechanical properties and composition (reinforcements, fillers, additives, pigments, etc.) may have the greater influence and need to be characterized for optimum material selection for the laser transmission welding (LTW) application.

To provide a guide to nylon based thermoplastics selection for LTW applications we have evaluated the influence of specific material composition factors and properties, such as fiber-glass, mineral filler, impact modifier content, and color/pigment version on the Near InfraRed (NIR) transmission characteristics, including the laser wavelength (1.06 mm). The results of an optical characterization of nylon 6 based thermoplastics are discussed in the Part I of this report to ANTEC’ 2000 (Kagan, V. A., Bray, R. B. and Kuhn, W. P., ‘‘Laser Transmission Welding of Semi-Crystalline Thermoplastics - Part I: The Magical Solution, Proceedings of the SPE 58th Annual Technical Conference and Exhibits (ANTEC’2000)).

The mechanical performance (tensile strength at room temperature conditions) of nylon welded joints was evaluated in terms of the influence of transmission laser welding technology parameters (laser power, welding speed, laser beam spot sizes, clamp pressure, etc.) and thermoplastic composition (reinforcements, fillers, additives, pigments, etc.).

Technical results of this comprehensive evaluation (optical properties of nylon 6 based plastics and mechanical performance of welded joints) will assist plastic parts designers and technologists in selecting nylon based thermoplastics and developing new products using LTW technology. The purpose of Part II of this report is to increase understanding within the plastics engineering community regarding the usefulness and possible applicability of LTW technology for nylon made components.
An Elastic–Plastic and Residual Stress Analysis of Symmetric Laminated Cantilever Beam Under a Bending Moment
Authors: Callioglu Hasan , Aksoy Sami , Sayman Onur , Yildiz Hasan
Published: April 2004

An elastic–plastic stress analysis in symmetric woven steel fiber reinforced polyethylene thermoplastic matrix laminated cantilever beam under a bending moment is studied by using analytical method and the Bernoulli–Euler theory for small plastic deformations. The orientation of the plies is chosen as (0°)4, (15° / -15°)2, (30° / -30°)2 and (45° / -45°)2. The Tsai–Hill theory is used as a yield criterion. Elastic and plastic stresses are the highest at the upper and lower surfaces. The residual stress component of x is maximized at the upper and lower surfaces. However, when the plastic region is further expanded, it is the highest at the boundary of the elastic and plastic regions. The magnitude of the residual stress component of x is found to be the highest for (0°)4 orientations. The plastic flow is maximized at the upper and lower surfaces for (0°)4 orientations.
An Efficient Layerwise Shear-Deformation Theory and Finite Element Implementation
Authors: Zhou Xu , Chattopadhyay Aditi , Kim Heung Soo
Published: April 2004

A computationally efficient, layerwise shear-deformation theory for improving the accuracy of stress and strain predictions in the analysis of laminated shells with arbitrary thickness is presented. The theory is two-dimensional and displacement-based. The in-plane displacement field is modeled using the superposition of overall first-order shear deformation and layerwise functions that accommodate the complexity of zigzag-like in-plane deformation through the laminate thickness. By imposing the inter-laminar shear traction continuity, which is ignored by most conventional laminate theories, the accuracy of stress and strain predictions is improved. Moreover, the relations between structural variables that are defined for each layer are obtained through the use of inter-laminar continuity of stress and displacement. The relations are used to reduce the number of independent variables such that the number of structural variables is independent of the number of layer, which makes the model computationally attractive. The developed theory is implemented using finite-element technique. The accuracy and the range of application of the present theory are evinced using a cylindrical shell and a laminated plate with different thickness, for which exact elasticity solutions exist.
Stress Relaxation Behavior of Banana Fiber-Reinforced Polyester Composites
Authors: Pothan Laly A. , Neelakantan N. R. , Rao Bhaskar , Thomas Sabu
Published: April 2004

Stress relaxation behavior of banana fiber-reinforced polyester composites were investigated with special reference to the effect of fiber loading, fiber treatment, hybridization with glass fiber and also as woven fabric composites. It was observed that incorporation of fiber in the polyester matrix reduces the rate of relaxation. The nature of the relaxation curve was found to depend on the quantity of fiber as well as the surface characteristics of fiber used as reinforcement. The decrease in stress relaxation modulus was greatest for the neat polyester sample whereas it was at a minimum for composites with 40% fiber loading. Chemical modification of the fiber surface was found to affect the degree of adhesion and thereby the nature of relaxation at the initial stages. Of the various chemical modifications chosen in the present study, the decrease in stress was found to be the lowest for composites made out of banana fiber treated with NaOH. Hybridisation of banana fiber with glass was found to decrease the rate of relaxation further. However, stress relaxation values of woven glass and banana gave even lower values.
Relationship between Optical Properties and Optimized Processing Parameters for through-Transmission Laser Welding of Thermoplastics
Authors: Grewell David , Rooney Paul , Kagan Val A.
Published: April 2004

In previous studies, the results of an optical characterization (laser energy transmission, absorption, etc.) at a wide range of infrared wavelength for various nylon based plastics (unfilled and reinforced) with the influence of various colorants have been reported. In conjunction with these results, an analysis on optimized mechanical performance of the laser welded joints was also reported.

In this current paper, we will try to increase the understanding of the plastics engineering community regarding the relations between optical properties of thermoplastics and optimized processing parameters of through-transmission laser welding (simultaneous welding mode).
Bending Behavior of Piezo-Hygrothermo-Elastic Smart Laminated Composite Flat and Curved Plates with Active Control
Authors: Raja S. , Dwarakanathan D. , Sinha P. K. , Prathap G.
Published: April 2004

The actuation and sensing behavior of piezo-hygrothermo-elastic flat and curved plates with active control is presented. A finite element procedure involving coupled piezoelectric field with hygrothermal strain is derived using first order shear deformation theory and is implemented in a nine-noded Lagrangian plate element. The accuracy of the element to model the piezoelectric, pyroelectric, hygroelastic, and thermoelastic behaviors of flat and doubly curved plates is validated with standard benchmark problems. The directional actuation that represents the piezoelectric anisotropy is introduced in the analysis and a comparison is made with isotropic actuation to control the thermal and moisture induced deformation in the laminated plates. Numerical studies are carried out with different fiber orientations to capture the influence of piezoelectric anisotropy on the actuation and sensing characteristics of the active lamina. The directionally actuated piezoelectric lamina that has a reduced piezoelectric capability in transverse direction is efficient, if properly tailored along the fiber directions. However, it is observed that the isotropic actuation has the potential to control the thermal and moisture developed deflection in angle-ply and cross-ply laminates. The actuator lamina is efficient if placed on the top of curved laminates in controlling the deflection.
Tensile Properties of Epoxy Coated Natural Fabric Hildegardia Populifolia
Authors: Rajulu A. Varada , Rao G. Babu , Devi L. Ganga , Li X. H. , Meng Y. Z.
Published: April 2004

The natural fabric from the tree of Hildegardia populifolia was coated with epoxy and its tensile strength, elastic modulus, and the percent elongation at break were determined. The effect of sodium hydroxide and a silane coupling agent on the tensile properties of the fabric was also studied. It was observed that the tensile properties increased on alkali treatment but decreased when the silane based coupling agent was used.
First Ply Failure of Laminated Composite Plates - A Mixed Finite Element Approach
Authors: Ramtekkar G. S. , Desai Y. M. , Shah A. H.
Published: April 2004

First-ply failure (FPF) analyses of composite laminated plates have been presented in this paper. A 3-D layer-wise mixed finite element model developed by the authors (Ramtekkar, G.S., Desai, Y.M. and Shah, A.H. (2002). Mixed Finite Element Model for Thick Composite Laminated Plates, Mechanics of Advanced Materials and Structures, 9(2): 133-156.) has been employed for the computation of components of stress and strain. FPF has been predicted by using the maximum stress, the maximum strain, Tsai-Hill, Tsai-Wu and Hoffman failure theories. It has been observed that the 3-D failure theories have yielded approximately the same failure load as their 2-D counterparts because the failure of a lamina (ply) under flexure is primarily associated with the in-plane stress state. It has been demonstrated that the present methodology predicts the FPF load for cross-ply laminated plates very well. Results have been presented for cross-ply-angle-ply, symmetric-anti-symmetric and thin-thick plates to show important observations.
Fracture Propagation in Composites with Biaxial Fiber Reinforcement
Authors: Zhao Wenming , Minnetyan Levon , Chamis Christos C.
Published: April 2004

Fracture characteristics such as damage progression, work of fracture, ultimate fracture loads, and failure modes are evaluated by computational simulation for composites with biaxial braided fiber reinforcements. Several Graphite–Epoxy Mode I compact tension (C(T)) specimens with different biaxial fiber orientations are modeled and simulated. Damage initiation, growth, and propagation processes at the microscopic level are tracked, enabling a more insightful interpretation of the test results. The effects of ply-layup with various orientations of the braid axis with reference to the notch directions are investigated with respect to their influences on damage and fracture progression characteristics. Results validate the computational simulation method and identify fracture characteristics for biaxially reinforced composites.
Effects of Hygrothermal Cycling on Properties of Glass–Vinyl Ester Composite
Authors: Zhou Jianren , Zhong Yang
Published: April 2004

Hygrothermal freeze–thaw cycling exposures were performed on glass–vinyl ester composite to simulate harsh temperature and moisture conditions that the composite might encounter during their lifetime in services. The cycling conditions used were 80°C/saturated steam/48h⇔−17.8°C/dry/24 h. A characteristic moisture absorption behavior observed was that each time when the composite was taken out of the warm and humid environment and put into freezer, it exhibited a fast absorption of moisture, while the composite underwent an obvious desorption when moved from freezer to a warm humidity chamber. After the desorption at the very beginning of the thaw process, the composite showed a moderate absorption in the saturated steam at 80°C. This phenomenon was explained by the difference in thermal expansion rates of the fibers and the resin. Compression tests were conducted to investigate hygrothermal cycling effects on mechanical properties of the composite. The results showed that the degradation in compression strength for hygrothermally cycled composites was less significant than that of samples simply experienced isothermal holding at the same temperature and with the same exposure duration. Thermal analysis results indicated that glass transition temperature of the composite increased with an increase in hygrothermal cycling duration and leveled off after about 1000 h of the exposure, while thermal decomposition temperature of the composite was only slightly influenced by the hygrothermal exposures.
Reinforcement Parameters of Aligned Ellipsoidal Inclusions by the Generalized Mechanics-of-materials (GMM) Approach
Authors: Lim Teik Cheng
Published: April 2004

The aligned ellipsoidal inclusion composite is of particular interest as the shape of the inclusion can be manipulated to conform to various reinforcing geometry, such as long fiber, short fiber, particulate, flake, lamina, continuous ribbon and discontinuous ribbon. This paper demonstrates how the Young’s Modulus of such an orthotropic material can be approximated based upon combinations of the age-old mechanics-of-materials approach. By writing the Young’s Modulus in all three principal orthogonal directions in a nondimensionalized form, the indices of the inclusion volume fraction reveals the existence of a reinforcement parameter, which ranges from zero (for minimum reinforcing shape) to unity (for maximum reinforcing shape). The reinforcement parameters are independent from material behavior of the individual phases and the inclusion concentration. Semiempirical relationships between reinforcement parameters in these three orthogonal directions and the inclusion shape are obtained by curve-fitting at special conditions. This simplified method is conveniently executable and hence suitable for design of composite products that consist of ellipsoidal, or nearly ellipsoidal inclusions.
Effect of Material Nonlinearity on Symmetric Aluminum Metal–Matrix Laminated Composite Beams Under a Bending Moment
Authors: Sayman Onur , Çallioğlu Hasan , Meriç Cevdet , Can Nurdoğan
Published: April 2004

In this study, an elastic–plastic stress analysis is carried out on symmetric laminated composite beams subjected to a bending moment. The composite beam is to be strain hardening. The Tsai–Hill theory is used as a yield criterion in the solution. The Bernoulli and Euler hypotheses are assumed to be valid. The beam lay-up sequences are chosen as [90°/0°] s, [30°/−30°] s, [45°/−45°] s, and [60°/−60] s. The bending moment starting plastic yielding is found to be highest for [30°/−30°] s orientation. σ x residual stress component is found to be highest at the upper and lower surfaces. However σ x residual stress component becomes the highest at the elastic and plastic boundary for further expansion of the plastic region. The transverse displacement is obtained at the free end, numerically.
Moisture Distribution Profiles in RT-Cured Glass/Epoxy Laminates of Different Thicknesses
Authors: Revathi A. , Srihari Shylaja , Rao R. M. V. G. K.
Published: April 2004

Investigations were carried out on the moisture absorption behavior of RT-cured glass/epoxy composite specimens subjected to 333 K/Immersion in distilled water. Different laminate thicknesses (i.e., 0.25-2.25 mm) were studied for comparative evaluation of their moisture diffusion and distribution profiles across the thickness of the composite as a function of the exposure period.

Moisture absorption data showed that the equilibrium moisture levels (Mm) remained practically the same for different laminates of the same fiber weight fraction (i.e., 0.62). Further, the times of saturation (tm) increased with the laminate thickness, while the absorption rates (slopes of the absorption curves) showed a reverse trend.

It was also found that the Diffusion Coefficient (Dc) values of different thicknesses specimens ranged between 0.28 and 7.81(10 7)mm2/sec, indicating a negligible thickness effect on this diffusion parameter. The small variations of Dc (all of the order 10 7 mm2/sec) are attributed mainly to the variations in the edge areas for different thickness laminates.
Fatigue of Crosslinked and Linear PVC Foams under Shear Loading
Authors: Kanny Krishnan , Mahfuz Hassan , Thomas Tonnia , Jeelani Shaik
Published: April 2004

When a sandwich structure is subjected to transverse loads, the face sheets carry bending moments as tensile and compressive stresses and the core carries transverse forces as shear stresses. The core is typically the weakest component of the structure and is the first to fail in shear. In this study the shear fatigue behavior of two closed-cell cellular PVC foams, Divinycell HD130 (linear) and H130 (cross linked), with the same nominal density of 130 kg/m3, were investigated. Static shear tests reveal that HD130 foams are more ductile, have almost twice the energy absorption capability, and an extraordinary crack propagation resistance when compared to the H130 foams. Shear fatigue tests were conducted at room temperature, at a frequency of 3 Hz and at a stress ratio, R = 0.1 on the HD130 and H130 foams. S–N curves were generated and shear fatigue characteristics were determined. The number of cycles to failure for the linear foams was substantially higher than that of the cross-linked PVC foams. HD foams have smaller cells with thicker faces and edges. This microstructure supports absorption of larger amounts of liquid resin forming a resin rich sub interface zone just below the actual core skin interface. The high intrinsic toughness of the sub interface delays the initiation of fatigue cracks and thereby increases the fatigue life of the HD foams. For both foams, shear deformation occurs without volume change and the materials fail by shearing in the vicinity of the centerline of the specimen along the longitudinal axis. In both cases numerous 45° shear cracks form across the width of the specimen and are equidistantly spaced along the length of the specimen. The occurrence of these through the thickness shear cracks signals the final failure event during fatigue. Details of the experimental investigation and the evaluation of the fatigue performance are presented.
Computational and Experimental Characterization of Continuously Fiber Reinforced Plastic Extrusions: Part I – Short-Term Flexural Loading
Authors: Zheng Zhiyin , Engblom John J.
Published: April 2004

Experimental characterization of time-independent properties for rectangular hollow-cored continuous fiber reinforced commingled recycled plastic extruded forms under short-term flexural loading has been presented in this paper. Finite element based computer models have been developed to predict the effects of damage progression in such reinforced extruded plastic forms. Experimental results demonstrate that fiber micro-buckling and fiber–matrix interface failures occur during the static flexural loading environment. Experimental data also indicates that these damage modes significantly reduce the short-term flexural properties and should be avoided or minimized through optimizing the location of continuous reinforcement and using a coupling agent in enhancing interfacial bonding between reinforcement and matrix. “Damage dependent” finite element models were developed using different material property types to represent the glass-fiber roving, fiber–matrix interface and plastic matrix respectively. Material nonlinearity of the plastic matrix has been incorporated along with stress-based failure criteria to account for fiber–matrix interfacial shear failure and local fiber micro-buckling. A user-defined subroutine, part of an industry standard finite element software package, has been modified to accommodate the damage progression. The developed finite element based model(s) have correlated well with the short-term test results, and can provide a “design tool” in predicting fiber micro-buckling and fiber–matrix interfacial shear failure associated with future to-be-studied composite extrusions/forms under short-term loading.