bluuebunny/crossref_metadata_2025 huggingface dataset:
Autonomy and motivation: which comes first?
Authors: Spratt Mary , Humphreys Gillian , Chan Victoria
Published: October 2002

When motivation has been discussed in relation to autonomy in language learning, it has often been put forward as a product of autonomy. This paper suggests a more complex relationship in which motivation in many cases precedes autonomy. It discusses some of the relevant literature and presents results from a large-scale study of Hong Kong tertiary students.

The study aimed to assess students’ readiness for learner autonomy in language learning by examining their views of their responsibilities and those of their teachers’, their confidence in their ability to operate autonomously and their assessment of their level of motivation to learn English. It also investigated their actual practice of autonomous learning in the form of both outside and inside class activities. Results indicated that motivation played a key role in this readiness, and this led the authors to look at the relationship between autonomy and motivation as revealed in the study and in the literature.

The findings lead the authors to conclude that motivation is a key factor that influences the extent to which learners are ready to learn autonomously, and that teachers might therefore endeavour to ensure motivation before they train students to become autonomous.
A field study of occupant controlled lighting in offices
Authors: Moore T , Carter DJ , Slater AI
Published: October 2002

A study of 14 open-plan offices equipped with occupant controlled general lighting recorded achieved workstation lighting conditions at a number of times of the year. The results confirmed the occurrence of a wide range of workstation lighting levels, many significantly below CIBSE Code recommendations, with average electrical loadings due to lighting in the order of 55% of maximum. System con-figuration had a significant influence on luminaire output, illuminances and energy consumption. In general the lowest luminaire outputs were in buildings where the default reset level was to a low output, with the highest outputs being in buildings having high reset levels and large control groups. In addition locally sited control devices were associated with lower luminaire output.
Preradiation Chemotherapy in Primary High-Risk Brainstem Tumors: Phase II Study CCG-9941 of the Children’s Cancer Group
Authors: Jennings Mark T. , Sposto Richard , Boyett James M. , Vezina L. Gilbert , Holmes Emi , Berger Mitchell S. , Bruggers Carol S. , Bruner Janet M. , Chan Ka-Wah , Dusenbery Kathryn E. , Ettinger Lawrence J. , Fitz Charles R. , Lafond Deborah , Mandelbaum David E. , Massey Vicky , McGuire Warren , McNeely Lee , Moulton Thomas , Pollack Ian F. , Shen Violet
Published: October 2002

PURPOSE: This Children’s Cancer Group group-wide phase II trial evaluated the efficacy and toxicity of two chemotherapy arms administered before hyperfractionated external-beam radiotherapy (HFEBRT).

PATIENTS AND METHODS: Thirty-two patients with newly diagnosed brainstem gliomas were randomly assigned to regimen A and 31 to regimen B. Regimen A comprised three courses of carboplatin, etoposide, and vincristine; regimen B comprised cisplatin, etoposide, cyclophosphamide, and vincristine. Both arms included granulocyte colony-stimulating factor. Patients were evaluated by magnetic resonance imaging after induction chemotherapy and HFEBRT at a dose of 72 Gy.

RESULTS: Ten percent ± 5% of regimen A patients objectively responded to chemotherapy. For combined induction and radiotherapy, 27% ± 9% of patients improved. The neuroradiographic response rate for regimen B was 19% ± 8% for chemotherapy and 23% ± 9% after HFEBRT. Response rates were not statistically significant between regimens after induction or chemotherapy/HFEBRT. Event-free survival was 17% ± 5% (estimate ± SE) at 1 year and 6% ± 3% at 2 years. Survival was significantly longer among patients who responded to chemotherapy (P < .05). Among patients who received regimen A induction, grades 3 and 4 leukopenia were observed in 50% to 65%, with one toxicity-related death. For regimen B, severe leukopenia occurred in 86% to 100%, with febrile neutropenia in 48% to 60% per course.

CONCLUSION: Neither chemotherapy regimen meaningfully improved response rate, event-free survival, or overall survival relative to previous series of patients with brainstem gliomas who received radiotherapy with or without chemotherapy.
Fulvestrant, Formerly ICI 182,780, Is as Effective as Anastrozole in Postmenopausal Women With Advanced Breast Cancer Progressing After Prior Endocrine Treatment
Authors: Howell A. , Robertson J.F.R. , Quaresma Albano J. , Aschermannova A. , Mauriac L. , Kleeberg U.R. , Vergote I. , Erikstein B. , Webster A. , Morris C.
Published: October 2002

PURPOSE: To compare the efficacy and tolerability of fulvestrant (formerly ICI 182,780) and anastrozole in postmenopausal women with advanced breast cancer progressing after prior endocrine treatment.

PATIENTS AND METHODS: Patients (n = 451) with advanced breast cancer were randomized to receive fulvestrant 250 mg as a once-monthly (one × 5 mL) intramuscular injection or an oral dose of anastrozole 1 mg in this open, parallel-group, multicenter trial. The primary end point was time to progression (TTP). Secondary end points included objective response (OR) rates, defined as complete response (CR) or partial response (PR), duration of response (DOR), and tolerability.

RESULTS: Patients were followed for a median period of 14.4 months. In terms of TTP, fulvestrant was as effective as anastrozole (hazard ratio, 0.98; confidence interval [CI], 0.80 to 1.21; P = .84). Median TTP was 5.5 months for fulvestrant and 5.1 months for anastrozole. OR rates showed a numerical advantage for fulvestrant (20.7%) over anastrozole (15.7%) (odds ratio, 1.38; CI, 0.84 to 2.29; P = .20). Clinical benefit rates (CR + PR + stable disease ≥ 24 weeks) were 44.6% for fulvestrant and 45.0% for anastrozole. Median DOR was 15.0 months for fulvestrant and 14.5 months for anastrozole. Both treatments were well tolerated, with 3.2% and 1.3% of fulvestrant- and anastrozole-treated patients, respectively, withdrawn from treatment because of an adverse event.

CONCLUSION: Fulvestrant was as effective as anastrozole. These data confirm that fulvestrant is an additional, effective, and well-tolerated treatment for advanced breast cancer in postmenopausal women whose disease progressed on prior endocrine therapy.
Treatment With Ibritumomab Tiuxetan Radioimmunotherapy in Patients With Rituximab-Refractory Follicular Non-Hodgkin’s Lymphoma
Authors: Witzig Thomas E. , Flinn Ian W. , Gordon Leo I. , Emmanouilides Christos , Czuczman Myron S. , Saleh Mansoor N. , Cripe Larry , Wiseman Gregory , Olejnik Teresa , Multani Pratik S. , White Christine A.
Published: October 2002

PURPOSE: Rituximab is commonly used as a single agent or in combination therapy for non-Hodgkin’s lymphoma (NHL). Ibritumomab tiuxetan radioimmunotherapy targets the same antigen as rituximab and has demonstrated efficacy in rituximab-naïve NHL. This study evaluated ibritumomab tiuxetan in the treatment of rituximab-refractory follicular NHL.

PATIENTS AND METHODS: Eligible patients were refractory to rituximab; this was defined as no objective response to rituximab (375 mg/m2 weekly for 4 weeks) or time to progression (TTP) of ≤ 6 months. The ibritumomab tiuxetan treatment regimen consisted of pretreatment with rituximab (250 mg/m2 intravenously on days 1 and 8) to deplete peripheral blood B cells, then yttrium-90 ibritumomab tiuxetan (0.4 mCi/kg; maximum, 32 mCi) intravenously on day 8, administered on an outpatient basis. An imaging/dosimetry dose of indium-111 ibritumomab tiuxetan (5 mCi) was injected after rituximab (day 1) in 28 patients.

RESULTS: Fifty-seven patients were treated. The median age was 54 years, 74% had tumors ≥ 5 cm, and all were extensively pretreated (median, four prior therapies; range, one to nine). The estimated radiation-absorbed doses to healthy organs were below the study-defined limit in all patients studied with dosimetry. The overall response rate for the 54 patients with follicular NHL was 74% (15% complete responses and 59% partial responses). The Kaplan-Meier–estimated TTP was 6.8 months (range, 1.1 to ≥ 25.9 months) for all patients and 8.7 months for responders. Adverse events were primarily hematologic; the incidence of grade 4 neutropenia, thrombocytopenia, and anemia was 35%, 9%, and 4%, respectively.

CONCLUSION: Ibritumomab tiuxetan radioimmunotherapy is effective in rituximab-refractory patients. The only significant toxicity is hematologic.
Randomized, Placebo-Controlled Trial of Clodronate in Patients With Primary Operable Breast Cancer
Authors: Powles Trevor , Paterson Sandy , Kanis John A. , McCloskey Eugene , Ashley Sue , Tidy Alwynne , Rosenqvist Kirsi , Smith Ian , Ottestad Lars , Legault Sandra , Pajunen Marjo , Nevantaus Auli , Männistö Esa , Suovuori Anne , Atula Sari , Nevalainen Jaakko , Pylkkänen Liisa
Published: October 2002

PURPOSE: The development of bone metastases depends on tumor-induced osteoclastic resorption of bone, which may be inhibited by the antiosteolytic bisphosphonate clodronate. Given to patients with primary breast cancer, clodronate might reduce the subsequent incidence of bone metastases.

PATIENTS AND METHODS: This double-blind, multicenter trial accrued 1,069 assessable patients with operable breast cancer between 1989 and 1995. All patients received surgery, radiotherapy, chemotherapy, and tamoxifen as required. Patients were randomized to receive oral clodronate 1,600 mg/d or a placebo for 2 years starting within 6 months of primary treatment. The primary end point was relapse in bone, analyzed on an intent-to-treat basis, during the medication period and during the total follow-up period (median follow-up, 2,007 days). Secondary end points were relapse in other sites, mortality, and toxicity.

RESULTS: During the total follow-up period, there was a nonsignificant reduction in occurrence of bone metastases (clodronate, n = 63; placebo, n = 80; hazards ratio [HR], 0.77; 95% confidence interval [CI], 0.56 to 1.08; P = .127). During the medication period there was a significant reduction in the occurrence of bone metastases (clodronate, n = 12; placebo, n = 28; HR, 0.44; 95% CI, 0.22 to 0.86; P = .016). The occurrence of nonosseous metastases was similar (clodronate, n = 112; placebo, n = 128; P = .257), but there was a significant reduction in mortality (clodronate, n = 98; placebo, n = 129; P = .047) during the total follow-up period.

CONCLUSION: Clodronate, given to patients with primary operable breast cancer, may reduce the occurrence of bone metastases, although this reduction was only significant during this medication period. There was a significant reduction in mortality.
Cell Type-Specific Expression and Coregulation of Murine Resistin and Resistin-Like Molecule-α in Adipose Tissue
Authors: Rajala Michael W. , Lin Ying , Ranalletta Mollie , Yang Xiao Man , Qian Hao , Gingerich Ron , Barzilai Nir , Scherer Philipp E.
Published: October 2002

Adipocytes are the exclusive or predominant source of several secreted proteins that exert profound effects on systemic carbohydrate and lipid metabolism. Resistin, a 10-kDa adipose tissue specific secretory protein, has recently been implicated in exerting a negative effect on systemic insulin sensitivity. It is, however, not known how resistin mediates this insulin-desensitizing effect or what regulatory mechanisms control resistin expression. Resistin-like molecule-α (RELMα), a homolog of resistin originally identified by its upregulation in asthmatic lung, is another secreted protein expressed in adipose tissue. The regulation of RELMα in adipose tissue and its relationship to resistin expression has not been addressed so far. Here, we demonstrate that the expression of resistin and RELMα are similarly regulated in adipose tissue despite the fact that RELMα is exclusively expressed in the stromal vascular fraction of adipose tissue and not in adipocytes. Interestingly, this coregulation is limited to adipose tissue as the expression of RELMα in lung is independent of metabolic regulation. Additionally, we show that resistin and RELMα levels are not subject to regulation by proinflammatory stimuli. Finally, acute hyperglycemia leads to up-regulation of resistin and RELMα transcription in various adipose depots.
Delivery of Lipoplexes for Genotherapy of Solid Tumours: Role of Vascular Endothelial Cells
Authors: Dass Crispin R , Su Tao
Published: October 2002

The cells constituting a solid tumour may vary considerably due to biological disparities, but for a solid tumour to pose as a threat to its host, an adequate blood supply has to be established. Although neovascularisation may have dire consequences for the host, it provides a common route by which tumours in general may be reached and eradicated by drugs. The fact that a tumour's vasculature is relatively more permeable than healthy host tissue means that selective delivery of drugs may be achieved. A closer examination of the role played by the cells making up the tumour vascular bed, vascular endothelial cells (VECs), is required to facilitate design of ways for enhancing drug delivery to solid tumours via the vascular route.

VECs have two major roles in the body, barrier and transport, both of which are highly pertinent to drug delivery. This review discusses the factors regulating VEC function, and how these cells may be manipulated in-vivo to improve the selective delivery of lipoplexes, carriers for gene therapy constructs, to solid tumours. It also discusses how genotherapeutic drugs may be targeted against tumour VECs on the premise that by killing these cells, the tumour itself will perish.
Skin Delivery of Oestradiol from Deformable and Traditiona Liposomes: Mechanistic Studies
Authors: El Maghraby Gamal M M , Williams Adrian C , Barry Brian W
Published: October 2002

Deformable vesicles and traditional liposomes were compared as delivery systems for oestradiol to elucidate possible mechanisms of drug delivery through human skin. Accordingly, epidermal permeation of oestradiol from optimized deformable vesicles and traditional liposome formulations was studied under low dose non-occluded conditions. Five mechanisms were investigated. A free drug mechanism compared low-dose permeation through skin with drug release determined after separation of the free drug. Penetration enhancement was researched by studying skin pretreatment with empty vesicles. Improved drug uptake by skin was monitored by dipping stratum corneum into different formulations for 10 min and determining drug uptake. The possibility that intact vesicles permeate through the epidermis was tested by comparing permeation from 136-nm vesicles with that from > 500-nm vesicles, assuming that penetration depends on vesicle size. The possibility that different entrapment efficiencies in alternative formulations could be responsible for the difference in delivery was also evaluated.

Lipid vesicles improved the skin delivery of oestradiol compared with delivery from an aqueous control. Maximum flux (Jmax) was increased 14- to 17-fold by use of deformable vesicles and 8.2- to 9.8-fold by use of traditional liposomes. Deformable vesicles were thus superior to traditional liposomes. Drug release was negligible over the period during which skin flux was maximum. Pretreatment with empty vesicles resulted in an enhancement ratio of 4.3 for pure phosphatidylcholine (PC) vesicles but the enhancement ratio ranged from only 0.8 to 2.4 for other formulations. Vesicles increased drug uptake into the stratum corneum 23- to 29-fold. Relative flux values obtained from small and large vesicles were similar. No correlation was found between entrapment efficiency and skin delivery.

The results showed no evidence of a free drug mechanism, but revealed a possible penetration-enhancing effect for pure PC vesicles, although this was not the only mechanism operating. The positive uptake suggested that lipid vesicles increased drug partitioning into the skin. The data provided no evidence for in-vitro liposome penetration through skin as distinct from vesicle penetration into the stratum corneum.
Stress distribution in a rotating elastic functionally graded material hollow sphere with spherical isotropy
Authors: Chen W Q
Published: October 2002

The stress distribution in a rotating, spherically isotropic, functionally graded material (FGM) spherical shell that has its elastic constants and mass density as functions of the radial coordinate is exactly investigated in the paper. Three displacement functions are employed to simplify the basic equations of equilibrium for a spherically isotropic, radially inhomogeneous elastic medium. By expanding the displacement functions in terms of spherical harmonics, the basic equations are finally turned into an uncoupled second-order ordinary differential equation and a coupled system of two such equations. Exact analysis of a steadily rotating spherical shell with the material constants being power functions of the radial coordinate is carried out and a numerical example is presented.
An inductive procedure for determining the stresses in multi-material components under steady state creep
Authors: Hyde T H , Sun W , Tang A , Budden P. J
Published: October 2002

A general formulation obtained based on an inductive procedure is presented for the stress distribution in multi-material power-law creeping structures. The ratios of the nominal creep rates for the various materials are explicitly included in the formulation. It is only necessary to define the effects of the stress exponent n. The results are generalized to the case where n varies between materials. The formulation allows the effects of the material properties to be easily assessed and the results of parametric analyses to be presented in compact and easily manageable forms.
Application of isotropic points extracted using computerized photoelastic experiment to design structural members
Authors: Umezaki E , Shimamoto A
Published: October 2002

This study investigates a method for optimally designing structural members with holes, which are made to decrease the weight of and to pass pipes and wires through these members. In this method, first the isotropic points, where the principal stresses are equal, are automatically extracted on an image with the directions of principal stresses obtained from the computerized photoelastic experiment. The finite element method is then used for analysing the models with holes differing in size at an isotropic point extracted experimentally. Finally, the hole size is determined, comparing with stress distributions around those holes. The present method is applied to a T-shaped plate subjected to a compressive load. As a result, the stresses in models with holes at locations different from the isotropic point are higher than those with the same-size hole at the isotropic point. Therefore the proposed method is effective for optimally designing structural members with holes.
Inverse modelling of constitutive parameters for elastoplastic problems
Authors: Faurholdt T. G
Published: October 2002

To obtain an improved identification of constitutive parameters to be used in finite element method simulations of elastoplastic deep-drawing processes an inverse method was applied using an explicit finite element code to simulate material tests. This problem was addressed by formulating the constitutive parameter identification as an optimization problem. The method was to minimize the objective function defined as the error between the result from the material test and the result from the finite element simulation. The optimization technique is based on the Levenberg-Marquardt method. The objective function was established in a least-squares sense where the design variables were the constitutive parameters of the material. The inverse method was started and, when a global optimum was reached, a set of constitutive parameters were identified. This was performed for both a linear hardening model and a power-law hardening model. It is shown that the inverse method predicts two models which qualitatively show the same overall characteristics for the investigated material.
A procedure for the solution of general contact problems for the elastic half-space
Authors: Truman C. E , Hills D A , Sackfield A
Published: October 2002

In this paper an efficient numerical procedure for the efficient solution of general three-dimensional elastic contacts where the bodies in the neighbourhood of the point of contact may be represented as half-spaces is described. The solution relies on a piecewise-linear approximation to the true contact pressure distribution.
Modelling of the hardening characteristics for superplastic materials
Authors: Cheong B H , Lin J , Ball A. A
Published: October 2002

Combined analötical and numerical techniques and procedures have been developed to characterize the hardening due to grain growth for materials under superplastic deformation. The conventional grain growth rate equation is modified to enable accurate modelling of isothermal and plastic-strain-induced grain growths for different microstructures of a titanium alloö. A set of unified viscoplastic constitutive equations for Ti-6Al-4V at 927 °C, which incorporates isotropic hardening and grain growth, has been fullö determined from experimental data for different initial grain sizes and strain rates. Close agreement between the predicted and experimental stress-strain relationships is achieved. In addition, the contributions of hardening constituents, such as strain rate hardening, isotropic hardening and the hardening due to grain growth are modelled.
Stress analysis of cylindrical shells with nozzles due to external run pipe moments
Authors: Xue M. D , Wang H. H , Hwang K. C
Published: October 2002

In this paper the analytical results of two normally intersecting cylindrical shells subjected to external moments on the ends of main shells are presented. The thin shell theoretical solutions are obtained on the basis of the modified Morley equation for the main shell with a cut out with large diameter ratio and of the Goldenveizer equation for the branch tube with a nonplaner end. The results are in good agreement with the previous test results and with Moffat's three-dimensional finite element method results. The design curves based on the present solution can be applied to d/D ≤ 0.8 successfully.
On the prediction of elastic-plastic generalized load-displacement responses for tubular joints
Authors: Leen S. B , Hyde T. H
Published: October 2002

An energy-based method is presented for the prediction of the elastic-plastic force-displacement and/or moment-rotation responses of tubular joints for arbitrary radial loading paths under the action of up to four combined forces and moments. The method is based on the results of a sample of load paths obtained from computational models or measured from experimental tests. The work is important in the context of the elastic-plastic behaviour of structures in general and in particular as a basis for the development of single elastic-plastic tubular joint elements. The method employs normality of the generalized displacement vector to level hypersurfaces of total (elastic-plastic) complementary work.
The strengths of steels under combined static tensile and torsional loading
Authors: Wang S-J , Wang S-Y , Chen S-C , Dixon M. W , Huey C. O
Published: October 2002

A new static yield criterion was reported previously by Wang and Dixon with a function of the stress state as well as a material property (the ratio of ty/Sy), which includes the maximum shear stress theory and the von Mises-Hencky theory as special cases. To evaluate this static yield criterion, experimental tests on steels under a combination of static tensile and torsional loading were conducted. The result shows that the new criterion appears to fit the very limited experimental data
High-speed fracture studies on bimaterial interfaces using photoelasticity—a review
Authors: Shukla A
Published: October 2002

Dynamic photoelasticity and high-speed photography have been combined to study fracture of bimaterial interfaces in the subsonic and intersonic regimes. The response of isochromatic fringes to various interface fracture parameters is investigated. Next, a series of experiments is conducted with specially designed specimen geometries under different loading conditions to encompass the whole range of interfacial crack propagation behaviours. The photoelastic data obtained from these experiments is carefully analysed to obtain the crack velocity, complex stress intensity factor, mode mixity and dynamic energy release rate. Finally a fracture criterion in the subsonic regime is proposed and validated with the experimental results.
The design of hydrodynamically lubricated journal bearings against crack propagation
Authors: Ciavarella M , Decuzzi P , Monno G
Published: October 2002

Following a recently published paper, the likelihood of radial crack propagation from the surface of a hydraulically lubricated journal bearing is studied, under the hypothesis of the previous paper, i.e. assuming a half-Sommerfeld pressure distribution in an infinitely elongated bearing. Simple results are obtained and the effect of the lubricant is estimated. A complete set of stress intensity factors is given.
Development of new inverse boundary element techniques in photoelasticity
Authors: Chen D , Becker A. A , Jones I. A , Hyde T H , Wang P
Published: October 2002

This paper presents a number of possible algorithms for inverse boundary element (BE) techniques applied to photoelastic analysis. The BE technique is shown to be an ideal companion to photoelastic analysis since, unlike the finite element (FE) method, the interior solutions can be represented by unconnected points rather than by discretized elements. From the photoelastic principal stress information obtained at a sufficient number of internal points, the unknown boundary conditions can be reconstructed using the inverse boundary element method (BEM). The inverse BE theory and numerical formulation are presented for problems involving Cartesian stress components and are then extended to photoelastic stress analysis. The inverse BE approach follows two stages. In stage 1, the photoelastic stress measurements of the differences in principal stresses and their directions at the interior points are used to compute the unknown boundary conditions on the surface. In stage 2, the individual stress components are calculated by the forward BEM using the computed boundary conditions from stage 1. The effect of scatter of the experimental results is also included in the analysis. A number of examples are presented in this paper and are shown to be in excellent agreement with other solutions.
Modelling of rotors with three-dimensional solid finite elements
Authors: Nandi A , Neogy S
Published: October 2002

A shaft is modelled using three-dimensional solid finite elements. The shear-deformation and rotary inertia effects are automatically included through the three-dimensional elasticity formulation. The formulation allows warping of plane cross-sections and takes care of gyroscopic effect. Unlike a beam element model, the present model allows the actual rotor geometry to be modelled. Shafts with complicated geometry can be modelled provided that the shaft cross-section has two axes of symmetry with equal or unequal second moment of areas. The acceleration of a point on the shaft is determined in inertial and rotating frames. It is found that the finite element formulation becomes much simpler in a rotating frame of reference that rotates about the centre-line of the bearings with an angular velocity equal to the shafts spin speed. The finite element formulation in the above frame is ideally suited to non-circular shafts with solid or hollow, prismatic or tapered sections and continuous or abrupt change in cross-sections. The shaft and the disc can be modelled using the same types of element and this makes it possible to take into account the flexibility of the disc. The formulation also allows edge cracks to be modelled. A two-dimensional model of shaft disc systems executing synchronous whirl on isotropic bearings is presented. The application of the two-dimensional formulation is limited but it reduces the number of degrees of freedom. The three-dimensional solid and two-dimensional plane stress finite element models are extensively validated using standard available results.
Elastic and elastic-plastic finite element analysis of hollow tubes with axisymmetric internal projections under combined axial and pressure loading
Authors: Hardy S. J , Pipelzadeh M. K , Gowhari-Anaraki A. R
Published: October 2002

This paper discusses the behaviour of hollow tubes with axisymmetric internal projections subjected to combined axial and internal pressure loading. Predictions from an extensive elastic and elastic-plastic finite element analysis are presented for a typical geometry and a range of loading combinations, using a simplified bilinear elastic-perfectly plastic material model. The axial loading case, previously analysed, is extended to cover the additional effect of internal pressure. All the predicted stress and strain data are found to depend on the applied loading conditions. The results are normalized with respect to material properties and can therefore be applied to geometrically similar components made from other materials, which can be represented by the same material models.
The influence of punch blunting on the elastic indentation response
Authors: Korsunsky A. M
Published: October 2002

Elastic solutions of a family of axisymmetric problems concerning frictionless contact between a rigid punch and a semi-infinite substrate are considered using the method of Green and Zerna and of Collins. The analysis is relevant to the interpretation of experimental results in materials indentation testing, e.g. when substrate properties need to be determined from load—displacement traces, and precise information about the indenter tip shape is crucial.

Commonly used solutions for ideal punch shapes, e.g. those having spherical or conical tips, may only be viewed as approximations since, in practice, indenter tips are neither perfectly round nor infinitely sharp. In order to illustrate the influence that small variations in punch shape may have on the contact behaviour, analytical solutions for a blunted Hertzian indenter and a rounded cone are obtained in parametric form, and their asymptotic behavioural the extremes of low and high loads is investigated. A smooth punch is then considered of a general shape, given by a power series, and the resulting general solution is used as a basis for developing an inverse problem formulation of the tip shape calibration procedure. The method allows the best match between the measured and predicted load-displacement dependencies to be established. An example of the application of this procedure to the analysis of some nanoindentation data is presented.
High-temperature oxidation and the prediction of creep life for 0.5Cr-0.5Mo-025V steel
Authors: Evans M
Published: October 2002

Creep life assessment of thick-sectioned components such as steam pipes and headers have traditionally been made from uniaxial creep tests conducted in air on specimens of relatively small diameter. As a consequence of oxidation, such creep life assessments although safe are likely to underestimate the available life of such components. Owing to economic pressures there is currently a great need to quantify the size of this conservatism so that such components can be safely operated beyond their original design life. Yet there are few inert atmosphere data available from which this can be directly achieved. This paper suggests a way of incorporating oxidation data into the 0 projection method so as to enable life predictions of thick-sectioned pipes (where the effects of oxidation can be ignored) to be made from short-term tests conducted in air on small-diameter specimens. The paper shows that the resulting model is capable of analysing results from tests conducted in air under test conditions that give a life of up to 100 h and from this accurately predicting the life of thick-sectioned specimens (oxide free) operating under stress-temperature conditions that give a creep life of up to 60000 h. The proposed method for adjusting these predictions to produce estimates of the life of small-diameter specimens operating in air at test conditions giving a life of up to 60000 h is also shown to work well.
The dynamic analysis of piping systems using pseudo-dynamic techniques
Authors: de Melo F J M Q , Carneiro J. A. O , Lopes H. R , Dias Rodrigues J F , Gomes J F Silva
Published: October 2002

This paper describes an application of pseudo-dynamic techniques to the dynamic analysis of piping structures. Essentially it consists in coupling a direct time integration algorithm, such as the Newmark method, to an experimental step. At each time step the integration algorithm generates a displacement vector of the structure, which is prescribed for the test specimen. This is mounted in a rigid test rig fitted with a set of displacement actuators and load cells at the level of the structure degrees of freedom. The load cells allow the reading of the internal restoring force vector, which is fed back to the direct time integration algorithm in an actual time step. Further calculations for the velocity and acceleration vectors will define a new structure configuration by evaluating a new displacement vector referred to the next time step. This procedure makes it possible to assess experimentally a realistic stress distribution at sections of complex shape piping parts. The method is a precise tool in dynamic analysis and, on being carried out in a quasi-static procedure, it operates with less expensive equipment than is necessary in real dynamic test.
Vibratory stress relief—an investigation of the torsional stress effect in welded shafts
Authors: Munsi A S M Y , Waddell A. J , Walker C. A
Published: October 2002

In this study the effect of torsional vibration on residual stresses was investigated. Three types of shaft specimen were processed, namely (a) a homogeneous shaft, (b) a shaft welded on a circumferential line and (c) a spot-welded shaft. The first two types of shaft showed some redistribution in the residual stresses under applied torsional loads. On the spot-welded shafts the residual stresses were found to decrease significantly at a very low level of vibration induced stress.
Residual stress state behaviour under fatigue loading in pipeline welded joints
Authors: Fonseca M P Cindra , Teodósio J. R , Rebello J. M A , da Cruz A B Correia
Published: October 2002

Compressive residual stress state behaviour under fatigue of the welded joints of a pipeline were investigated. The regions on the intersection between the welded joints of the longitudinal pipe manufacturing seam and the circumferential welded joints of the pipeline construction were investigated. Stress-controlled fatigue loading was carried out at various stress ratios of the yield strength of the base metal. Surface residual stresses were introduced in samples by shot-peening treatment and were measured using X-ray diffraction techniques. The results showed that compressive residual stresses which, unless they are relieved or inverted during the process of fatigue loading, make crack initiation difficult.
Macroscopic fretting variables in a splined coupling under combined torque and axial load
Authors: Leen S. B , Richardson I. J , McColl I. R , Williams E. J , Hyde T. R
Published: October 2002

A three-dimensional study of frictional contact in a helical splined coupling for the assessment of macroscopic fretting variables is presented. The study is based on an experimentally validated finite element model of the coupling under combined torque and axial loads. The effect of axial profile modification for reduced contact stresses in spline teeth and the effect of friction coefficient are considered. The motivation for the work is the need for representative information about fretting variable distributions in splined couplings for the development and application of simplified fretting test configurations.
Buckling of a spherical shell embedded in an elastic medium loaded by a far-field hydrostatic pressure
Authors: Fok S-L , Allwright D. J
Published: October 2002

Elastic buckling of a spherical shell, embedded in an elastic material and loaded by a far-field hydrostatic pressure is analysed using the energy method together with a Rayleigh—Ritz trial function. For simplicity, only axisymmetric deformations are considered and inextensional buckling is assumed. The strains within the structure that are pre-critical are assumed to be small for the linear theory to be applicable. An expression is derived relating the pressure load to the buckling mode number, from which the upper-bound critical load can be determined. It is found that the presence of the surrounding elastic medium increases the critical load of the shell and the corresponding buckling mode number. However, the results also show that the strain of the shell at the point of instability may not be small for typical values of material and geometric constants.
Upper and lower bound limit and shakedown loads for hollow tubes with axisymmetric internal projections under axial loading
Authors: Hardy S. J , Gowhari-Anaraki A. R , Pipelzadeh M. K
Published: October 2002

In this paper, the elastic compensation method proposed by Mackenzie and Boyle is used to estimate the upper and lower bound limit (collapse) loads and the upper and lower bound shakedown loads for hollow tubes with axisymmetric internal projections subjected to axial loading. The method is based on an iterative elastic analysis procedure and the application of lower and upper bound limit load theorems. Four different geometries with a range of stress concentration factors (from low to high) are considered. Elastic-plastic finite element predictions for collapse and shakedown pressure are found to be within these upper and lower bound estimates.

The method is particularly useful because it is founded on an iterative elastic approach and does not require extensive and complex elastic-plastic finite element computations.
Local strain for fatigue strength of welded structures
Authors: Dattoma V , Pappalettere C
Published: October 2002

Field criteria, which are usually applied in fracture mechanics to ensure the structural integrity of cracked components, are extended to the fatigue design of welded joints, whose weld toe can be assimilated to a notch with a small tip radius. In particular, fatigue strength in terms of strain rather than of stress has been determined by applying stress cycles with different stress ratios R = σmin/σmax. Finally, for the evaluation of the fatigue strength of welded joints in structural steel, a strain curve versus different R ratios is given to be compared with the service measured local strain at the weld toe.
Analysis of neutron diffraction strain measurement data from a round robin sample
Authors: Daymond M. R , Johnson M. W , Sivia D. S
Published: October 2002

Neutron diffraction strain data taken at 18 neutron facilities on a shrink-fit ring and plug round robin sample have been analysed using a Bayesian approach. The quality of data, quoted uncertainties and positional accuracy achieved are compared. Overall, the results of the exercise were consistent, and the majority of the laboratories obtained actual measurement uncertainties of 100με or less. The sample was measured under the auspices of the Versailles Project on Advanced Materials and Standards Technical Working Area 20 (VAMAS TWA 20), initiated to develop a recommended, standard procedure for making stress measurements in crystalline materials by neutron diffraction. This round robin study was carried out to determine the capabilities and reliability of the technique.
The application of a new and robust weighting scheme for establishing theta projection parameters to 1CrMoV rotor steel
Authors: Evans M
Published: October 2002

Reservations about the need to weight the estimated theta parameters within the theta projection technique have often been expressed. However, the fact that the theta values are estimated values and are therefore not certain quantities necessitates the need to weight each theta value by some measure of its reliability. Traditionally, the weights have been calculated under the assumption that the random errors around an experimental creep curve are first-order autocorrelated. Using short-term data collected at the Interdisciplinary Research Laboratories in Swansea for 1CrMoV steels, this paper shows that such an assumption is generally incorrect and presents an alternative estimator for these weights. This estimator is robust in that it requires no assumptions to be made about the nature of the autocorrelation. When applied to these short-term creep data these robust weights are well behaved and alter the theta interpolation/extrapolation functions in such a way that excellent predictions are made for the longer-term rupture times published by the National Research Institute of Metals in Japan. Failure to use a weighting scheme within the theta projection technique is shown to have a detrimental impact on such long-term predictions.
On the wavelet time-frequency analysis algorithm in identification of a cracked rotor
Authors: Zou J , Chen J , Pu Y P , Zhong P
Published: October 2002

Based on the hinge crack model and the local flexibility theorem, the local flexibility of a cracked rotor due to the crack and the modified function of the opening and closing of the crack are given; the corresponding dynamic equation of the cracked rotor is modelled; the numerical simulation solutions of the cracked rotor and the uncracked rotor are obtained. By the continuous wavelet time—frequency transform, the wavelet time-frequency properties of the uncracked rotor and the cracked rotor are discussed; the difference between the wavelet time-frequency properties of the cracked rotor and those of the uncracked rotor is presented. A new detection algorithm that uses the wavelet time-frequency transform to identify the crack is proposed. The influence of the sampling frequency on the accuracy and validity of the wavelet time-frequency transform is analysed by numerical simulation research; the preferred sampling frequency is suggested. The experiments on the cracked rotor and the uncracked rotor demonstrate the validity and availability of the algorithm in the identification of the cracked rotor in engineering practices.
Simple formulae for the stress concentration factor for two- and three-dimensional holes in finite domains
Authors: Wang Q. Z
Published: October 2002

First, based on an approximate analysis, simple closed-form expressions of the stress concentration factor (SCF) for two- or three-dimensional models with a circular hole or a spherical cavity in a finite domain are derived. Then, an asymptotic method is adopted to improve the accuracy of the derived solutions for an extremely large circular hole or spherical cavity, when the remaining ligament approaches zero. Exact limit SCF values for these two kinds of models were given by Koiter; these values are used for the adjustment of the coefficients in the SCF expressions. Finally, simple SCF formulae for these finite domain problems are obtained, their accuracy is demonstrated to be very good by comparison with the available data from the literature, and the asymptotic validity is guaranteed.
Analysis of displacement and strain field around a bimaterial interfacial region by stress couple theory and experiment
Authors: Kang Y-L , Fu D-H , Wang G-F , Yu S-W , Pan X-J
Published: October 2002

This paper is concerned with the determination of displacement and strain fields within the interfacial region of a bimaterial specimen under shear loading. The analysis is based on the couple stress theory. The measurements are made by means of phase shift moiré interferometry which has been recognized as a useful measuring method by combining moiré interferometry with the phase shift technique and image processing. The results obtained by phase shift moiré interferometry show that the distribution of the shear strain, rotation angle and rotation gradient at the interface region are changing rapidly. The results show good agreement with those predicted by stress couple theory.
An analytical temperature-dependent collocation model for preloaded rubber cylinders
Authors: Kari L
Published: October 2002

The non-linear temperature-dependent stiffness of an axially preloaded rubber cylinder is examined by an analytical collocation model, where influences of temperature, cylinder diameter and length, material parameters and prestrain are investigated. The rubber is assumed to be incompressible with the deviatoric response determined by an extended neo-Hookean free energy function, embodying a temperature shift function, being directly proportional to the temperature and to the temperature-dependent rubber density. The model is based on a semi-inverse method where the motion is split into two deformations: the first, a homogeneous temperature expansion, while the second, a preload deformation where material planes parallel to the bonded metal plate in the rubber cylinder are assumed to remain parallel, with the boundary conditions on the free rubber surface satisfied by collocation. The stiffness depends strongly on the preload—particularly for larger diameter-length ratios—and on the temperature covering —60 to + 60° C, where the shift function factor directly proportional to the temperature is found to play the greatest role. Contrary to other semi-inverse models, this model coincides at vanishing preloads with a well-known linear formula while extending the applicable shape factor range to cover shape factors typically found for vibration isolators.
Evaluation of the fatigue life of a sintered machine element under the sliding/rolling contact condition based on fracture mechanics
Authors: Yoshida A , Ohue Y , Ishikawa H
Published: October 2002

In order to evaluate the surface durability of sintered machine elements, the fatigue lives of 28 kinds of sintered roller under a sliding/rolling contact condition were estimated using Paris's law based on linear fracture mechanics. The fatigue tests were conducted using a two-cylinder testing machine. The stress intensity factor for the mode II under the Hertzian contact condition was calculated using the finite element model. The value of the stress intensity factor became larger as the crack length became longer to the contact surface, and the value of the stress intensity factor range was independent of the crack angle. It could be clarified that the fatigue lives of the sintered rollers depended on the pore diameter and the hardness. It was obvious that the pore distribution has to be taken into consideration to estimate the fatigue lives of the sintered rollers more precisely.
A two-term stress function approach to evaluate stress distributions in bonded joints of different geometries
Authors: Lazzarin P , Quaresimin M , Ferro P
Published: October 2002

The paper presents a method for the evaluation of the singular stress fields in bonded joints of different geometries. The stress distributions are represented by a two-term stress expansion, under the hypothesis that both the first and the second terms are in the variable separable form. The method is based on the stress function approach, where the formulation is completed analytically and the resulting set of ordinary differential equations is solved numerically.

The capability of the formulation to account for the actual elastic properties of the substrates allows an accurate description of the singular stress field to be obtained even in the case of joints made of materials with comparable elastic properties. The influence of adhesive joint design parameters such as the type of joint, geometry and material properties on the generalized stress intensity factors will also be presented and discussed.