bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress concentration caused by an oblique round hole in a flat plate under uniaxial tension
Authors: McKenzie H W , White D J 
Published: July 2007

Stress-concentration factors have been determined for oblique holes in flat plates by a method using frozen-stress photoelasticity. The ellipses formed at the intersection of the hole and the plate surfaces had their major axes perpendicular to the direction of application of the load. The maximum stress-concentration factor was found to increase with increasing angle of obliquity with respect to the normal to the plate but the experimental factors were found to be considerably lower than those predicted from a theory of Ellyin et al. Graphs are given which enable maximum stress-concentration factors to be obtained for oblique holes having a ratio of hole diameter to plate width of 0.1. It was found that, for the models tested, elliptical hole data gave a reasonable estimate of the maximum stress-concentration factors based on net area. Removing the feather edge of the hole, by applying various edge radii, did not alter the stress concentration appreciably except in so far as load-carrying area was reduced.
Centrifugal stresses in rotationally symmetrical gas-turbine discs
Authors: Fessler H , Thorpe T E 
Published: July 2007

The frozen-stress photoelastic technique has been used to determine stresses in hubs and diaphragms. Different hub sizes and shapes were studied for a typical shape of flat disc (middle surface plane). Shape and size are related to peak stresses. Conical discs, with different cone angles but having the same mass, were analysed and shown to be more highly stressed than flat discs.
Deformations of stacks of thin layers under normal compressive loads
Authors: Howells R I L , Probert S D , Jenkins J H 
Published: July 2007

Stacks, each consisting of 40 thin metallic layers, were compressed under loads of up to 5000 kg. Measurements of the electrical resistance of the stacks (i.e. for the 39 metal-to-metal contacts in series) revealed four distinct regions of deformation. The extent of these regions was marked by sharp changes in the slope of the curves obtained when load was plotted against electrical conductance. The first change occured at a load of approximately 200 kg, irrespective of layer size, roughness, or hardness. Two further transitions occurred at pressures equal to 2·5 and 22·5 per cent approximately of the surface hardness. Above the upper transition point the bulk properties play a large part in the mechanism of surface deformation.
Yield and subsequent flow behaviour of some annealed steels under combined stress
Authors: Rogan J , Shelton A 
Published: July 2007

Constant-stress-ratio tests under combined tension-torsion have been performed on annealed En 25 and En 24 steels. The sharp yield behaviour of these materials enabled the initial yield locus to be clearly defined and this was close to that predicted by the Tresca criterion. Post-yield behaviour showed marked room-temperature creep of the logarithmic form ∊ = a ln t+ c, by both the axial- and shear-strain components. The strain-rate ratios and the strain ratios were normal to the yield locus and remained so for increasing stress. The equivalent-plastic-work hypothesis did not produce satisfactory correlation of the combined-stress results and empirical equivalence of the strains was established by introducing a factor to account for the influence of combined stresses upon the magnitude of the resulting strains. This empirical equivalence also provided good correlation of the creep-strain rates and these results finally led to the complete correlation of the stress-strain-time behaviour of these materials at room temperature.
Effect of tensile prestrain on the yield locus of 1100-f aluminium
Authors: Williams J F , Svensson N L 
Published: July 2007

A series of combined stress tests in torsion-tension space is carried out on thin-walled tubes of 1100-F commercially pure aluminium. One initial and four subsequent yield loci are established to a maximum prestrain level of 14 per cent tensile plastic strain. The results are analysed in terms of a proposed, rationally based, yield criterion constructed according to statistical reasoning. It is shown that during prestrain a significant degree of geometrical distortion is undergone by the yield loci, accompanied by a strong Bauschinger effect and a flattening of part of the locus opposite to the loading point. It is found that the yield locus does not rotate during prestrain and, contrary to the case for torsion prestrain, exhibits evidence of a sharply rounded corner developing at the loading point. The proposed criterion is shown to fit the experimental results extremely well and the mechanism of distortion is explained in terms of a statistical model for work-hardening materials.
Stress and flexibility factors for multi-mitred bends subjected to out-of-plane bending
Authors: Bond M P , Kitching R 
Published: July 2007

A theoretical analysis has been developed to predict stress distributions and flexibility factors associated with out-of-plane bending of multi-mitred pipe bends. The estimated range of validity of the analysis is sufficient to include most practical multi-mitred pipe bends. Tests on a large-diameter, thin-walled, three-weld right-angled multi-mitred bend were undertaken and the results closely agreed with computations based on the analysis. Predictions for both flexibility factors and overall maximum-stress ratios from the analysis were almost identical with those given by an in-plane bending theory that had been developed from a similar method of approach.
Transient creep of a block compressed on opposite sides by elastic punches of the same width as the block
Authors: Ohashi Y , Nishitani T , Ishida M 
Published: July 2007

A method combining photoelasticity of an elastic body and photo-rheological stress analysis of a plastically flowing body may be applied to the experimental investigation of the contact problems between elastic tool and plastic workpiece which appear very often in plastic working. The transient creep of a block compressed on opposite sides by elastic punches of the same width as the block is analysed by the above-mentioned method.
Effect of Poisson's ratio on bonded rubber blocks
Authors: Holownia B P 
Published: July 2007

A theoretical analysis of bonded rubber blocks with circular cross-section under axial compression is obtained by the use of dynamic-relaxation solutions of classical elastic stress-strain equations. The Poisson's ratio ν for rubber is close to 0.5 which causes difficulties in the analysis because the general stress-strain equations of elasticity contain terms such as ν E/(1 + ν)(1 − 2ν) which approaches infinity when ν approaches a value of 0.5. The range of ν considered varies between 0.45000 and 0.49990 which covers all the natural-rubber compounds used, including pure natural gum which has a ν value of 0.49989 (1)∗. It is shown that the stress distribution within the block is significantly affected by the value of ν and the shape of the block. When a block of material with ν ∼ 0.5, bonded to its end plates, is thin, the stress developed within the block is high and nearly equal in all three directions, which suggests a hydrostatic type of pressure. Such a pressure would confirm the finding in (2) and (3) based on a semi-empirical analysis. When the block is thick this effect is absent. The present paper confirms that these effects follow from the fundamental assumptions of classical elasticity. The investigation also confirms that the dynamic-relaxation method converges satisfactorily even when the Poisson's ratio is very close to the value of 0.5000.
Three-dimensional photoelastic analysis in axially loaded thick plate with hole
Authors: Rubayi N A , Yadava V 
Published: July 2007

In this study three-dimensional photoelasticity is used to analyse the stress variation through different layers of a thick plate containing a circular hole and subjected to uniform tensile loading. The effect of the thickness/diameter ratios on the stress concentrations with thickness is investigated. The experimental results are correlated with the existing three-dimensional theoretical solutions. The data establish, both experimentally and theoretically, the precise location of the maximum-stress layers in plates having different thickness/diameter ratios and thus resolves the discrepancies which existed in previous studies.
Experimental evaluation of the fracture toughness (K1c) of an epoxy resin
Authors: Evans W T , Barr B I G 
Published: July 2007

Fracture-toughness tests were conducted on Araldite CT 200, in order to obtain K1c, the plane-strain, mode 1 critical stress-intensity factor. Two essentially different methods were used, namely the photoelastic method and the quasistatic energy method. In the photoelastic method, stress fringe patterns were analysed at load intervals up to failure and the stress-intensity coefficients obtained were compared with those from the boundary collocation method. In the energy method, two types of specimen geometry were tested, resulting in stable crack propagation. Good correlation was obtained between the two methods.
Steady-state thermal stresses in an elastic solid containing an insulated penny-shaped crack
Authors: Barber J R 
Published: July 2007

A solution is given for the steady-state thermal stress and displacement field in an infinite elastic solid containing an insulated penny-shaped crack. The problem is reduced to a mixed-boundary-value problem for the half-space, making use of Green's isothermal solution for the thick elastic plate in complex harmonic potentials and a particular thermoelastic solution due to Williams. In the axisymmetric case, the complex potential reduces to the real harmonic function used by Shail in his solution for the external crack. To illustrate the use of the method in both axisymmetric and non-axisymmetric problems, complete solutionsare given for (1) a uniform heat flow and (2) a linearly varying heat flow disturbed by an insulated penny-shaped crack.
Crack propagation with quasistatic energy analysis
Authors: Chow C L , Ngan K M 
Published: July 2007

In the application of quasistatic energy analysis, the P-u-A diagram has been found a valuable supplement in illustrating the characteristics of crack propagation. The diagram is useful not only for evaluating fracture toughness under quasistatic conditions, but also for representing important fracture parameters such as stability criteria, crack speed, strain rate, fatigue, environmental effects, etc. A general method of characterizing these parameters in the form of a P-u-A diagram is presented for both linear and non-linear load-displacement relationships at constant crack area. This was achieved by polynomial representation of the diagram. The analysis was extended to cover crack propagation under multiple-loading conditions. By introducing a complementary strain-energy function, equivalent load and compliance, a method of solution has been devised to avoid the laborious computations which may otherwise be required if the loadings become numerous and complex. The computed values of fracture toughness from the numerically represented P-u-A diagram, and the displacements evaluated with the equivalent compliance concept, compare well with those obtained experimentally.
The experimental determination of trajectories in geometrically similar plastic flows
Authors: Roth R N 
Published: July 2007

A new experimental method is presented for determining trajectories of flow for non-steady-state processes which exhibit geometric similarity (quasi-steady-state processes (1)∗). One process that is normally regarded as quasi-steady-state (plane strain wedge indentation) is investigated using this method. It is shown that this process satisfies the requirements of geometric similarity within experimental accuracy. Results are presented for wedge angles of 30°, 60° and 90° and a range of indentation depths up to approximately 3 mm. Finally, it is suggested how this method can be combined with well-known orthogonal-grid techniques to provide information for the calculation of effective strains throughout the deforming region.
Elastic stresses due to torque transmitted through the prismatic part of keyed connections part I: Effect of different fits and friction on standard shapes
Authors: Fessler H , Eissa M 
Published: July 2007

Photoelastic models of transverse sections through British Standard metric and inch keyed shafts and hubs (outside diameter = 2 × shaft diameter) have been loaded in torsion. Models with five different combinations of fits of shaft in hub, key in shaft, and key in hub, with three different surface conditions have been analysed over a large range of torques. Stress concentrations occurred at the six contact positions where there are discontinuities of profile of the chamfered key or of the shaft. Normalized peak stresses are presented for all tests and the effects of the controlled variables are discussed.
Bolting and loss of contact between cylindrical flat-flanged joints without gaskets
Authors: Hyde T H , Lewis L V , Fessler H 
Published: July 2007

Four bolts of a lightweight, steel, flanged joint were strain-gauged to measure bolt tension and bending. Three-dimensional, finite element analysis was used to determine bolt strains and gaps between the flanges due to axial tension and internal pressure for three different contact conditions. Two joints were tested. The front faces of the first joint were nominally flat while the second had a small negative cone angle (⋍ 0 degrees 15 minutes) so that flanges initially touched at the outside only. The non-linearity of experimental bolt strain with external load shows that the contact area around the bolts decreases with increasing axial tension. Comparison with the finite element predictions shows the rate at which the contact area diminishes. The finite element results also demonstrate that flange deflection is underestimated when contact area loss is ignored, and the consequences for leakage prediction are explained.
Single frequency seismic loading tests on pressurized branch pipe intersections machined from solid
Authors: Yahiaoui K , Moffat D G , Moreton D N 
Published: July 2007

Four CNC machined, equal-thickness branch pipe intersections ( dm/ Dm = 1 and 0.746) have been tested under conditions of internal pressure, simulated seismic loading that induced resonant in-plane run pipe bending and, in one case, a superimposed gravity stress. The manufacturing method and testing conditions are described and the behaviour of the branches is reported. The strain responses of the components show that ratchetting is clearly significant while the response moment data suggest that collapse may not be the failure mechanism under these loading conditions. Failure for all components occurred by cracks on the flanks in the branch hoop stress direction just above the junction.
Stress concentration factors for axial and shear loading applied to short flat bars with projections
Authors: Hardy S J , Pipelzadeh M K 
Published: July 2007

The finite element method has been used to obtain stress concentration factor data for flat ‘T’ shaped components, subjected to axial and shear loading, with both remote and local restraints being applied. The ratio of length to depth (or slenderness ratio) of the shank region is generally less than 3:1. For these short components under shear (or bending) loads, primary bending stresses are no longer dominant and transverse shear is an important secondary effect. Comparisons are made between the predictions with remote and local restraints in order to quantify the effect of localizing the restraints (or load).
Mechanisms-based constitutive equations for the superplastic behaviour of a titanium alloy
Authors: Zhou M , Dunne F P E 
Published: July 2007

Mechanisms-based constitutive equations are proposed for the high-temperature behaviour of a class of titanium alloys, for which the deformation mechanisms include diffusional creep, grain boundary sliding, dislocation creep and grain growth. A computational procedure has been developed for the determination of the constitutive equations from a material database. The constitutive equations and the procedure for their determination have been validated by modelling the behaviour of the titanium alloy Ti-6Al-4V at 927°C. It is shown that the procedure developed for the determination of the mechanisms-based constitutive equations can be used to identify the important deformation mechanisms in operation for particular stress, temperature and strain rate conditions. For the case of the Ti-6Al-4V material, the procedure developed correctly predicts the material hardening due to grain growth and indicates that an additional hardening mechanism operates. In addition, the procedure is able to identify grain boundary sliding as a predominant deformation mechanism. The constitutive equations, which are generic in nature, and the procedure for their determination are applicable over a range of materials and are suitable for modelling the macroscopic and the important microscopic aspects of material behaviour during processing. The equations may be readily determined using the procedure presented, which is highly suitable for development as an expert system, to completely automate the process.
The effect of the transverse component of the hip reaction on cement mantle stresses in a model of an implanted Exeter™ prosthesis
Authors: Colgan D , McTague D , O'Donnell P , Little E G 
Published: July 2007

Clinical studies have attributed considerable importance to the torsional loading of prosthetic femoral implants; however, the effect of this load has frequently been neglected in load simulations of the hip. The objective of this study, therefore, is to investigate the effects of the transverse joint load component in a model analysis of the proximal femur. Cement mantle stresses in a three-times full-size model of an Exeter™ total hip replacement were investigated using three-dimensional embedded strain transducers. Six sites were analysed for two separate loading configurations, namely the two-dimensionally loaded single-legged stance and the ‘toe off’ phase of gait which represents a three-dimensional hip reaction. Results showed a considerable variation in stem/cavity contact conditions due to the application of the transverse load component. Furthermore, large distal bending stresses are induced in the sagittal plane, with considerable shearing stresses due to torsion evident at all sites. The study highlights the significance of the transverse load and emphasizes the considerable limitations of finite element studies in modelling realistic load-dependent interface conditions.
Evidence-based policies and the meaning of success: the case of a road built under Design Build Finance and Operate (DBFO)
Authors: Shaoul Jean , Stafford Anne , Stapleton Pamela 
Published: July 2007

English
This article uses a case study approach based on documents provided by the Department for Transport’s executive Highways Agency, information in the public domain and interviews of key players associated with a ‘successful’ project to examine the nature of evidence-based policy. Few evaluations exist of whether public–private partnerships achieve their objectives and the study focuses on those objectives that specifically relate to the policy of using private finance: risk transfer; building to time and budget; and innovation. We conclude that ‘success’ is determined at a micro level on the basis of technical achievement but that broader social and financial objectives on which the policy is based have not been assessed.
Synthesis of Hierarchically Porous Carbon Monoliths with Highly Ordered Microstructure and Their Application in Rechargeable Lithium Batteries with High‐Rate Capability
Authors: Hu Y.‐S. , Adelhelm P. , Smarsly B. M. , Hore S. , Antonietti M. , Maier J. 
Published: July 2007

AbstractIn this paper, we report on Li storage in hierarchically porous carbon monoliths with a relatively higher graphite‐like ordered carbon structure. Macroscopic carbon monoliths with both mesopores and macropores were successfully prepared by using meso‐/macroporous silica as a template and using mesophase pitch as a precursor. Owing to the high porosity (providing ionic transport channels) and high electronic conductivity (ca. 0.1 S cm–1), this porous carbon monolith with a mixed conducting 3D network shows a superior high‐rate performance if used as anode material in electrochemical lithium cells. A challenge for future research as to its applicability in batteries is the lowering of the irreversible capacity.
Cover Picture: Preparation of Rectangular WO3·H2O Nanotubes Under Mild Conditions (Adv. Funct. Mater. 11/2007)
Authors: Wang Z. , Zhou S. , Wu L. 
Published: July 2007

AbstractThe synthesis of WO3 · H2O nanotubes under mild conditions is reported by Limin Wu and co‐workers, of Fudan University, P.R. China on p. 1790. The synthesis is carried out with the aid of polyaniline (PANI). The PANI molecules are intercalated into tungsten oxide layers to provide a driving force for the formation of nanotubes from nanosheets. By this approach, the nanosheets can be directly rolled into nanotubes. This method could be applied to many other materials that possess layered/lamellar structures for forming nanotubes.WO3·H2O nanotubes are successfully synthesized with the aid of intercalated polyaniline (PANI) under relatively mild conditions. More interestingly, the WO3·H2O nanotubes have a rectangular cross‐section structure formed through a rolling mechanism. Scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, thermogravimetric analysis, Fourier‐transform infrared analysis, UV‐vis‐near‐IR spectroscopy, selected‐area electron diffraction, and vibrating‐sample magnetometry analysis are employed to characterize the morphology, structure, and properties of the nanotubes.
Preparation, curing kinetics, and thermal properties of bisphenol fluorene epoxy resin
Authors: Dai Zhen , Li Yanfang , Yang Shuguang , Zong Chengzhong , Lu Xukui , Xu Jian 
Published: July 2007

AbstractDiglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) was synthesized to introduce more aromatic structures into an epoxy resin system. The structure of DGEBF was characterized with Fourier transform infrared and 1H‐NMR. 4,4′‐Diaminodiphenylmethane (DDM) was used as the curing agent for DGEBF, and differential scanning calorimetry was applied to study the curing kinetics. The glass‐transition temperature of the cured DGEBF/DDM, determined by dynamic mechanical analysis, was 260°C, which was about 100°C higher than that of widely used diglycidyl ether of bisphenol A (DGEBA). Thermogravimetric analysis was used to study the thermal degradation behavior of the cured DGEBF/DDM system: its onset degradation temperature was 370°C, and at 700°C, its char yield was about 27%, whereas that of cured DGEBA/DDM was only 14%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007