bluuebunny/crossref_metadata_2025 huggingface dataset:
The Antimicrobial Activity of Vancomycin in the Presence and Absence of Sodium Carboxymethyl Starch
Authors: Claudius John S , Neau Steven H , Kenny Michael T , Dulworth Jacqueline K
Published: October 2002

The purpose of this work was to determine any effects the presence of sodium carboxymethyl starch may have on the antimicrobial activity of vancomycin given a previously described interaction between vancomycin and sodium carboxymethyl starch. In particular, the in-vitro activity of vancomycin against two clinically relevant bacteria, Staphylococcus aureus and Enterococcus faecalis, was studied in the presence of varying concentrations of sodium carboxymethyl starch.

From two independent studies conducted using an agar dilution method, it appeared that the binding of vancomycin to sodium carboxymethyl starch had no effect on the in-vitro antimicrobial activity of vancomycin. The minimum inhibitory concentration of vancomycin against S. aureus in the presence of as much as 1 mg mL−1 sodium carboxymethyl starch was similar to that of the control where no sodium carboxymethyl starch was added (1–4 μg mL−1 vs 1–2 μg mL−1, respectively). Likewise, the minimum inhibitory concentration of vancomycin against E. faecalis in the presence of 1 mg mL−1 sodium carboxymethyl starch was also similar to that of the control where no sodium carboxymethyl starch was added (1–4 μg mL−1 vs 1–4 μg mL−1, respectively). However, there may be factors in the in-vitro method, such as high ionic strength, that could disrupt the interaction between vancomycin and sodium carboxymethyl starch. Therefore, the possibility of diminished vancomycin activity in-vivo cannot be ruled out. A small percentage (8–10%) of vancomycin was determined to be bound to sodium carboxymethyl starch in broth media.

Given these results, the impact of sodium carboxymethyl starch on the in-vitro antimicrobial activity of vancomycin is expected to be minimal. Binding studies could not be conducted with gelled agar due to its semi-solid state.
Crystallization of Paracetamol from Ethanol-water Solutions in the Presence of Polymers
Authors: Kachrimanis K , Malamataris S
Published: October 2002

We have examined the effect of polymer nature and concentration on yield and micro-meritic, melting and compression properties of paracetamol crystals obtained from ethanol-water solutions using the solvent-change technique. Agar, gelatin, polyethylene-glycol (PEG) and polyvinylpyrrolidone (PVP) were the polymers used. These four polymers have different solubility in ethanol and water.

It was found that the yield of crystallization may increase by up to 8% with agar, gelatin and PEG, polymers that are insoluble in ethanol, while the soluble PVP reduces yield by 14%. The size of crystals increased due to the addition of polymers and changed almost in parallel with the crystal yield for agar and gelatin. Gelatin resulted in the biggest crystals, agar in the most equidimensional (aspect ratio 1.45 and roundness 147) and PVP in the most elongated (aspect ratio 1.89 and roundness 2.13). PEG resulted in the most agglomerated crystals. Yield pressure, Py, decreased in the following order: agar > PEG > gelatin > PVP, which is the same order for the enthalpy of fusion. Gelatin and PEG significantly decreased the elastic recovery of tablets (0.05 level), probably due to plastic deformation of crystals and fragmentation of agglomerates, respectively.

Crystallization of paracetamol in the presence of polymers by the solvent-change (ethanol-water) technique may permit increase of crystal yield, alteration of crystal shape and improvement of compression behaviour during tableting.
Renal and Cardiovascular Role of the Neuropeptide Y Y1 Receptor in Ischaemic Heart Failure Rats
Authors: Zhao Xiao-He , Sun Xiang-Ying , Bergdahl Anders , Edvinsson Lars , Hedner Thomas
Published: October 2002

The cardiovascular role of the neuropeptide Y Y1 receptors in-vivo and in-vitro in ischaemic heart failure was evaluated by using the novel neuropeptide Y Y1 selective antagonist BIBP 3226 (R-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]-D-arginine-amide).

In pithed rats, incremental doses of BIBP 3226 inhibited the exogenous neuropeptide Y induced pressor response in a dose-related fashion and a bolus injection of BIBP 3226 (0.5 mg kg−1) significantly shifted the pressor response curve of exogenous neuropeptide Y to the right. The potentiation effect to exogenous neuropeptide Y on the pressor response to preganglionic sympathetic nerve stimulation in ischaemic heart failure rats as well as on the contractile response to noradrenaline in renal arteries in sham-operated animals were also inhibited by the neuropeptide Y Y1 antagonist. In conscious ischaemic heart failure rats, incremental doses of BIBP 3226 (0.125-1 mg kg−1) significantly reduced basal blood pressure and heart rate.

Compared with sham-operated rats, neuropeptide Y by itself induced no contraction and no potentiation on noradrenaline elicited contraction in renal artery of the ischaemic heart failure rat. Furthermore, under in-vivo conditions, BIBP 3226 did not influence basal renal function or the response to exogenous neuropeptide Y on urinary volume, urinary sodium and urinary potassium.

Our results demonstrate that although there is a downregulation of the Y1 receptors by ischaemic heart failure, Y1 receptors are still mainly involved in cardiovascular actions of exogenous neuropeptide Y and play a role in maintaining basal blood pressure and heart rate in ischaemic heart failure. However, our data do not imply any significant role of Y1 receptors on basal renal function in the ischaemic heart failure rat model.
Piping elbows with cracks Part 1: A parametric study of the influence of crack size on limit loads due to pressure and opening bending
Authors: Yahiaoui K , Moffat D G , Moreton D N
Published: October 2002

Finite element analyses of cracked short-radius piping elbows are reported. Both axial and circumferential cracks, centred about the bend crown or intrados respectively, are considered. The defects are internal, with depth-thickness ratios a/t in the range 0.25 ≤ a/t ≤ 1.0. Since the aim is to assess limit loads, the analysis assumes elastic-perfectly plastic material behaviour with no geometric non-linearities. The loadings considered are (a) opening bending moment, (b) internal pressure and (c) combined loading of steady pressure, set at the design value of the pipe elbow, with a superimposed monotonically increasing opening bending moment.

For each type of loading, the general component behaviour, by consideration of the global deformation with increasing load, is reported. Limit load values for each case are presented and the relative reductions in load-carrying capacity, compared with that predicted for a defect free elbow of the same material and dimensions, are given.
Rim and pole failures from elliptical bulging of oriented orthotropic sheet metal
Authors: Rees D W A
Published: October 2002

Two criteria of instability are required to predict the failure in rolled sheet metal when bulged by lateral pressure through elliptical dies. The attainment of a pressure maximum is observed when the ratio of the lengths of the ellipse axes approaches unity. In nearly circular bulges this marks the onset of failure by diffuse necking under a falling pressure in the polar region. Dies with sharper elliptical apertures produce plane strain failures under a rising pressure in the region of the rim. In stretching flat sheet a local instability occurs when the rim force attains its maximum. The influence of sheet curvature upon plane strain fracture alters the limiting strain. Predictions of the critical pressure are derived for each failure and applied to an automotive aluminium alloy sheet (Alusuisse AC 120). The theory confirms experiments that show plane strain failure as a cut-off point in the plot of pressure versus height.

A maximum pressure marks the start of a failure by diffuse pole thinning. In contrast, edge failures occur with uniform thinning from pole to rim along the minor axis of the ellipsoid bulge. A generalized theoretical approach accounts for each failure with an r variation in the plane of the sheet and orientation of the ellipse axes to the rolling direction. The tests reported refer to alignments between the roll direction and both axes of five elliptical dies with different aspect ratios. Pole failures provide positive forming limit strains for biaxial stress ratios between 0.5 and 1. Rim failures supply the limiting plane strains.
Brief note: Some observations on the parametric relationships in Hertzian fretting fatigue tests
Authors: Hills D A , Urriolagoitia-Sosa G
Published: October 2002

The external variables controlling the key quantities found in a Hertzian-type fretting fatique test are found, and it is shown that the key surface tractions are determined by the shearing force, while the surface displacements depend strongly on the normal contact pressure. These apparently paradoxical results contrast with the normally used form of the solutions and throw light on the interpretation of experimental results.
On the extraction of notch stress intensity factors by the post-processing of stress data on the free edges of the notch
Authors: Ciavarella M , Demelio G
Published: October 2002

Following on the lines of a previous paper dedicated to cracked components by Ciavarella et al., here the case of a notch of semi-angle α is considered. Contrary to the crack case (α = 180°), the free edges of the notch are easily accessible to experimental analysis; moreover they provide information about all the terms of the Williams series expansion of the stress field about the notch apex, including the most important, i.e. the symmetric and antisymmetric singular term notch stress intensity factors (N-SIFs), whereas for the crack case the mode I N-SIFs cannot be extracted from those stresses. Another important different feature is that symmetric and antisymmetric N-SIFs have different singularities, and in several cases they are so close that their contributions tend to overlap. Therefore, a simple procedure is here proposed to use radial stresses, to separate their symmetric and antisymmetric contributions a priori by computing the sum and difference of the stresses on the two edges, to post-process these quantities in the ‘asymptotic region’ with standard least-squares techniques and to extract the N-SIFs. The method is applied to a simple case known in the literature and solved by means of a boundary element code, and the results are almost coincident with previous results, even with quite coarse mesh discretizations.
The determination of the residual strains and stresses in a tungsten inert gas welded sheet of IN718 superalloy using neutron diffraction
Authors: Dye D , Roberts S. M , Withers P. J , Reed R. C
Published: October 2002

The residual stress state in a tungsten inert gas (TIG) welded sheet of IN718, a high-strength nickel-based superalloy, has been characterized using neutron diffraction. The measurements were performed using a time-of-flight diffractometer, which allowed lattice strains from the γ-γ′ {111} and γ-γ′ {311} composite peaks to be compared with the Reitveld-refined spectra. Residual stresses were estimated using plane-specific values of Young's modulus and Poisson's ratio for the {311} and {111} peaks, and the macroscopic material response for the Reitveld-refined data. These values were obtained from a theoretical analysis of existing data after Kröner.

The weld considered was an autogenous TIG weld 180mm long placed centrally on to a 2mm × 100mm × 200mm solution heat-treated sheet of IN718. The strain was mapped over the central 140mm of the plate; within this region, the measured strains were almost constant along the length, with the peak bulk longitudinal strain of 1700 × 10-6 detected 4mm from the weld centre, in the heat-affected zone. The corresponding peak longitudinal stress was 270 MPa, and the tensile region 11 mm wide, with the longitudinal residual stresses typically up to 2.5 times greater than those in the transverse direction. It was also found that, while in-weld stresses derived from analysis of single peaks may be incorrect due to textural and compositional effects, those derived from Reitveld refinement of the entire spectrum showed reasonable agreement with those obtained from incremental hole drilling measurements made with the Matthar-Soete method.
Beneficial residual stress from the cold expansion of large holes in thick light alloy plate
Authors: O'Brien E. W
Published: October 2002

Beneficial residual compressive stress is induced around fastener holes by the process of cold expansion in civil aircraft. Fatigue performance is enhanced by increasing the allowable fatigue stress levels which are accounted for in the design.

Much work exists that explains both the cold-expansion process and its effects when applied to smaller diameter holes and smaller plate thicknesses, i.e. 12mm or less. Since the introduction of larger diameter holes and larger plate thicknesses of 25mm and greater to current large civil aircraft, investigations have revealed that the cold-expansion process has several unique features that are attributable to the larger size. While superficially the two scales of component may appear to have both static and dynamic similitude, in fact the scaling is not total when the complete manufacturing system is considered. All the dimensions are scaled up with the important exception of the flat portion of the mandrel; it is this easily missed feature that gives rise to the significant three-dimensional effect under investigation.

This paper is written from an industrial perspective and reviews the result of experimental stress analyses that demonstrate the difference in the process between small and large holes. Strains were measured in the time domain and the strain progression against time indicates definite three-dimensional effects in the process which are compared with a closed-form solution and a three-dimensional finite element analysis.
Assembly stresses in taper-locking shaft couplings Part 1: Photoelastic work
Authors: Cook I T , Fessler H , Hyde T. H , Warrior N. A
Published: October 2002

The aim of this work was to determine assembly stresses in taper-locking assemblies, to seek simple methods of calculating the important stresses and to test their validity. Four models were analysed: a coupling only, two models with hollow shafts and one on a solid shaft, surrounded by a hub. Hoop-radial maximum shear stresses were compared with thick-cylinder calculations. There was good agreement except for the frictional effects due to circumferential sliding of slit rings between continuous (unslit) rings.
Thermal effects on the development of plastic zones in thin axisymmetric plates
Authors: Alexandrov S , Alexandrova N
Published: October 2002

A simple thermoelastic-plastic problem is solved analytically to show a thermal effect on the development of plastic zones in thin plates. The temperature field is assumed to be uniform but monotonically varying with the time. The material of the plate obeys the von Mises yield criterion with a constant yield stress. It is shown that a negligible rise of temperature may lead to a significant growth of the plastic zone. Even though stress analysis only is needed in the plastic zone to illustrate this effect, a complete closed-form solution to the problem is given.
A review and detailed examination of non-layered conformal contact by finite element analysis
Authors: Fagan M J , McConnachie J
Published: October 2002

This is the first of two papers concerned with conformal contact and considers the fundamental conditions arising in non-layered configurations. This work was part of a research programme concerned with the development of a water-lubricated axial piston pump, in which the combination of contacting materials and contact conditions are critical. Finite element analysis was used to study cylindrical and spherical conformal contacts, with the models being validated by comparison with known analytical solutions. The models are shown to be extremely accurate and both types of contact are thoroughly investigated in this paper. The same models are then developed further to examine the contact conditions in conformal layered contacts, which to date has received very little attention, and this is the subject of the second paper.
Localization of plastic deformation during high strain rate torsion testing of rolled homogeneous armour
Authors: Fellows N A , Harding J
Published: October 2002

A recently developed technique which allows a study of the localization of plastic flow during high-speed torsion testing is briefly described. High-speed photographs showing successive stages in the deformation of three rolled homogeneous armour (RHA) steel specimens are presented. Three stages are identified corresponding to uniform shear, localized shear and the propagation of ductile failure. The results are analysed to estimate the conditions under which localization and subsequent ductile fracture are initiated. The results are compared with a previous study on a soft iron.
Wire strain variations in normal and overloaded ropes in tension-tension fatigue and their effect on endurance
Authors: Evans J. J , Ridge I. M. L , Chaplin C. R
Published: October 2002

This paper investigates wire strain variations in tension-tension fatigue for two six-strand rope constructions under normal and overloaded conditions. It has been found that for ropes in tension there is a considerable variation in wire strains both on different wires at the same cross-section and to a marginally lesser extent along the length of the same wire. It has also been found that a Lang's lay rope has a wider variation of strains than the identical ordinary lay rope. Load cycling has been found to reduce the distribution slightly for an initial period, around 8 per cent of the rope's life (for the load range used), after which the variations in wire strains do not change significantly for the rest of the life of the rope. Tests involving initial overload have shown a considerable reduction in wire strain variation. By way of an example for an ordinary lay rope an initial overload caused the wire strain standard deviation to decrease from 22 per cent of mean to 11 per cent of mean and was accompanied by an increase in rope endurance by a factor of 2.4. A statistical model has been used to illustrate the influence of strain range distribution on the fatigue endurance of a rope using a Gaussian probability distribution. It is suggested that wire strain distribution (measured by standard deviation as a percentage of mean) provides a good indicator of rope manufacturing quality.
A comparative study of three-dimensional and two-dimensional finite element analyses for intersecting shells
Authors: Skopinsky V. N
Published: October 2002

In this study, the numerical procedure for the three-dimensional finite element analysis of shell intersections is presented. The paper includes a description of the modified mixed variational formulation, a model of an eight-node three-dimensional finite element and a computer program for stress analysis of the intersecting shells. The comparison of stress results obtained using the three-dimensional computer program with experimental data is given. The results of a comparative study of the three-dimensional and two-dimensional finite element analyses for stress distribution in the intersection region and the maximum effective stress are presented for normally intersecting cylindrical shells under internal pressure loading.
Characteristic parameters for stress distribution along the intersection of tubular Y, T, X and DT joints
Authors: Chang E , Dover W. D
Published: October 2002

Analysis of large-scale fatigue testing results has shown that the fatigue strength of offshore welded tubular joints is not dependent on the hot spot stress alone but is also significantly influenced by stress distributions around the intersection which are normally represented by several characteristic parameters. The through-thickness distribution for example is characterized by degree of bending. In order to represent the stress distribution along the intersection, the average stress concentration factor (SCF) concept was suggested and used in empirical stress intennsity factor (SIF) models. However, this parameter alone is not enough to characterize the stress distribution along the intersection. Furthermore, there is no parametric equation available to predict this parameter. For this reason, a new concept, stress distribution concentration factor (SDCF), has been proposed in this study to describe the spread of stress distribution along the intersection. Systematic thin shell finite element analyses have been conducted for 330 different tubular Y, T and 330 X and DT joints, typical of those used in offshore structures, subjected to different modes of loading. On the basis of these results, a set of parametric equations has been derived for the average SCF and SDCF as a function of non-dimensional joint geometric ratios a, β, γ, τ and ϑ for each mode of loading and for both the chord and brace sides of the intersection of tubular welded Y, T, X and DT joints.
Twisted impregnated yarns: Transverse tensile strength
Authors: Naik N. K , Singh M. N
Published: October 2002

Twisted yarns are normally used for increasing the lateral cohesion of filaments and also for ease of handling. In this paper, an analytical method is presented for predicting the effective transverse tensile strength of the twisted impregnated yarns made of continuous filaments. In the analysis, a varying degree of twist in filaments at different radii of the yarn is considered. The effect of the twist angle on the transverse tensile strength properties of the twisted impregnated yarns is presented. It is seen that there can be an increase in transverse tensile strength of the twisted impregnated yarns compared with that of the corresponding impregnated strands.
Interference contact between a pin and plate with a hole
Authors: Hou J. P , Hills D. A
Published: October 2002

This paper is concerned with the stress state induced by a radial force applied to a circular shaft, shrink fitted into a plate. Conditions for the avoidance of separation and slip are considered, together with the overall strength of the contact. The problem is considered as a complete or receding contact, and solutions are developed by two independent routes, which bracket the perfectly lubricated and adhesive bounds to the problem, and which provide a versatile design route.
Elastic-plastic finite element analysis for oblique cutting with a discontinuous chip of 6-4 brass
Authors: Lin Z-C , Lin Y-Y
Published: October 2002

If the workpiece material experiences tremendous strain during the chip formation process or brittle material undergoes fracture in the primary deformation zone when the chip is only partly formed, the segmented chip formed under the above conditions is called a discontinuous chip. With the introduction of the tool inclination angle geometry, an elastic-plastic finite element model is developed for oblique cutting of discontinuous chip. The tool is P20 while the workpiece is made of 6-4 brass. The initial crack location, the direction of crack growth and variations of discrete chips are examined under the condition of a low cutting speed. These predictions are made possible by application of the strain energy density theory. The initial crack was formed in the (d W/d V)maxmin region (i.e. the maximum region among many of the strain energy density minima) of the chip surface and grew progressively along the stationary values of the strain energy density function. The direction of crack growth was based on the maximum strain energy density curve along the surface. The fracture process on the other chip layers was identical with that on the chip surface and occurred in sequence until it reached the chip free surface. The plastic deformation and friction result in a high equivalent stress on the chip surface above the tool tip, especially at the place of crack formation. As more residual stress is present after cutting, degradation of the workpiece prevails and should be accounted for.
The dynamic stability of a laminated truncated conical shell with variable elasticity moduli and densities subject to a time-dependent external pressure
Authors: Aksogan O , Sofiyev A. H
Published: October 2002

This study considers the dynamic stability of a laminated truncated conical shell with variable elasticity moduli and densities in the thickness direction, subject to a uniform external pressure, which is a power function of time. Initially, the dynamic stability and compatibility equations of a laminated elastic truncated conical shell with variable elasticity moduli and densities, subject to an external pressure, have been obtained. Then, employing Galerkin's method, those equations have been reduced to a system of time-dependent differential equations with variable coefficients. Finally, applying a mixed variational method of Ritz type, the critical dynamic and static loads, the corresponding wave numbers and the dynamic factor have been found analytically. Using those results, the effects of the variations in elasticity moduli and densities, the number and ordering of the layers, the semivertex angle and the power of time in the external pressure expression are studied via pertinent computations. It is observed that these factors have appreciable effects on the critical parameters of the problem in the heading.
Creep-damage predictions in thin-walled structures by use of isotropic and anisotropic damage models
Authors: Altenbach H , Huang C , Naumenko K
Published: October 2002

Two typical material models describing isotropic and anisotropic creep-damage processes in metals and alloys are applied to the simulation of the mechanical behaviour of transversely loaded thin plates. Numerical solutions of the initial boundary value problem have been obtained by use of both the solid- and the shell-type finite elements. The simulation results for a rectangular plate show the sensitivity of long-term predictions to the material models, the element types as well as the boundary conditions. The influence of these factors on the creep lifetime predictions is discussed.
Simplified non-linear analysis of plates subjected to hydrocarbon explosions
Authors: Louca L. A , Wadee M. A
Published: October 2002

An elastic Lagrangian formulation for an unstiffened plate subject to blast loading is presented. Building on a previous formulation, which accounted for membrane strains from purely out-of-plane displacement, the addition of in-plane stretching highlights the importance of membrane action. Numerical results of the resulting system of non-linear differential equations from the new model are compared with a non-linear finite element analysis package in terms of the various displacements and membrane strains, with good correlation.
Residual stresses in induction-hardened gear teeth mapped by neutron diffraction
Authors: Korsunsky A. M , James K E , Aylott C , Shaw B. A
Published: October 2002

Surface-hardening treatments are used in order to enhance the resistance of mating gear teeth surfaces to wear and fatigue crack initiation. The treatments create a compressive residual stress state near the tooth surface, which acts to impede crack initiation and propagation. Accurate determination of this residual stress field is important for quantifying the effect of treatment and optimizing the processing conditions. Neutron diffraction provides a powerful non-destructive experimental tool for residual stress evaluation. By collecting residual strain data for three different orientations, the principal stress directions and values can be mapped. This paper describes the procedure used for building such maps using the G5.2 spectrometer at Laboratoire Léon Brillouin, Saclay, and presents the results obtained for an induction-hardened gear.
Strain gauge measurement of wheel-rail interaction forces
Authors: Jönsson J , Svensson E , Christensen J T
Published: October 2002

A theoretical basis for quasi static determination of wheel—rail interaction forces using strain measures in the foot of the rail is given. Vlasov's theory for thin-walled beams is used in combination with continuous translational and rotational elastic supports based on smoothing out the stiffness of the rail sleepers. The smoothing out of the rotational elastic support has traditionally not been done. The use of this model is validated by the decay lengths of the problem and through finite element analysis. The finite element analysis is performed using discrete sleeper stiffness and Vlasov beam elements. The sensitivity of the measuring technique to parameter variations is illustrated and an example shows the simplicity of the proposed direct measuring technique.
The interpretation of the strain-dependent Poisson's ratio in auxetic polyethylene
Authors: Alderson K L , Alderson A , Evans K E
Published: October 2002

The strain-dependent behaviour characteristic of auxetic (i.e. having a negative Poisson's ratio) polymers has been modelled using a simple geometric model which consists of rectangular nodules intecronnected by fibrils. Careful consideration of the correct form of the model to use depending on the experimental method employed to test samples of auxetic ultra high molecular weight polyethylene (UHMWPE) has resulted in very good agreement between the experimental and theoretical Poisson's ratios and total engineering strain ratios when the deformation is predominantly due to hinging of the fibrils.

Auxetic UHMWPE has been processed to yield a very wide range of Poisson's ratios depending on its microstructural parameters (i.e. nodule shape and size, fibril length and the angle between the fibril and nodule). These can be predicted using the model, allowing the possibility of tailoring Poisson's ratio of the material.
The viscoelastic model on endochronic theory
Authors: Liu C S , Yang T W , Wu W H
Published: October 2002

Based on the endochronic theory, a viscoelastic model is developed, in which the intrinsic time is defined as a function of real time. By defining hardening functions, the creep and relaxation equations are derived directly from the differential constitutive equation and are then used to simulate the mechanical properties of pure polycrystalline magnesium. It is proved that the proposed viscoelastic model is very useful for analysing creep and relaxation problems.
A new static failure criterion for ductile materials
Authors: Wang S-J , Dixon M W
Published: October 2002

A new static failure criterion is proposed with a function of the stress state as well as the material properties (the ratio of ty /Sy), which is based on the experimentally determined ratio of Ty to Sy and includes the maximum shear stress theory and the von Mises-Hencky theory as special cases. The new criterion has a great potential to fit the experimental data and appears to fit better the very limited experimental data found in the open literature.
A procedure for equation fitting of computer-generated design data
Authors: Fok W C , Tooth A S
Published: October 2002

A procedure is developed to enable the data obtained from an exhaustive computer exercise, using finite elements, to be presented in the form of best fitted equations for use in Design Standards. Although the example chosen is directed towards the analysis of a horizontal hot oil storage vessel, the method developed can be used to obtain a best fitted equation for any set of generated or measured data. The resulting parametric equations can, thereafter, be used manually or, alternatively, programmed for a personal computer.
Stress intensity factors and fatigue life of beams in reversed bending
Authors: Moobola R , Hills D A , Nowell D
Published: October 2002

Two problems concerning the propagation of transverse cracks through beams are studied with a crack modelled as a distribution of dislocations. The first consists of a surface breaking normal crack present in reversing bending, where it is shown that for deep cracks two cycles of loading are experienced for each cycle of applied load. The second is an initially buried normal crack, where stress intensity factors affecting propagation both towards the surface and into the beam are evaluated. The effect on the life of each of these components is then considered for a representative material.
Prediction of elastic—plastic displacements of tubular joints under combined loading using an energy-based approach
Authors: Hyde T H , Leen S B
Published: October 2002

A series of 24 geometrically and materially non-linear finite element analyses of a simply supported YT tubular joint, with axial loads on the T- and Y-brace ends, was carried out to collapse, using solid three-dimensional element models. The analyses all have proportional and monotonic loading histories (i.e. radial load paths) and each analysis has a different T-brace to Y-brace load ratio so that the series ranges over all four quadrants of the two-dimensional load space. The results of the analyses are processed and combined by means of an energy approach, specifically a generalization of Castigliano's theorem on displacements using the concept of complementary work. A prediction method is thus developed to determine the non-linear, elastic-plastic, force-displacement responses of the joint for arbitrary (in-plane) radial load paths in the two-dimensional load space of the structure. One immediate application envisaged is the development of an elastic-plastic ‘joint finite element’ for use in the collapse prediction of tubular structures. The method is potentially applicable to a range of structures and loading scenarios, including other tubular joint types, both uniplanar and multiplanar, with bending moments and/or torques as well as transverse and axial loads.
A new calculation procedure for non-uniform residual stress analysis by the hole-drilling method
Authors: Petrucci G , Zuccarello B
Published: October 2002

The hole-drilling method is one of the most used semi-destructive techniques for residual stress analysis in mechanical parts. In the presence of non-uniform residual stress, the stress field can be determined from the measured relaxed strains using several calculation methods, but the most used one is the so-called integral method. This method is characterized by some simplifications that lead to approximate results, especially when the residual stress varies abruptly. In this paper a new calculation procedure called the spline methods is proposed, which allows these drawbacks to be overcome. Numerical simulations and an experimental test have corroborated the best performance of the proposed technique with respect to the calculation procedures used at present.
A review of automated methods for the collection and analysis of photoelastic data
Authors: Ajovalasit A , Barone S , Petrucci G
Published: October 2002

Photoelasticity is one of the most widely used full-field methods for experimental stress analysis. However, the collection of photoelastic parameters can be a long and tedious process. The advent of automated photoelastic systems has allowed the experimentalists to speed up the rate of analysis and to perform more complex investigations.

This paper provides a survey of recent methods of automated photoelasticity developed in the last 20 years, i.e. methods of the fringe centres, half-fringe photoelasticity, phase-stepping photoelasticity, methods based on the Fourier transform, spectral content analysis (SCA) and RGB (red, green, blue) photoelasticity.
Moiré strain analysis: An introduction, review and critique, including related techniques and future potential
Authors: McKelvie J
Published: October 2002

The moire fringe method is described and reviewed with particular reference to its application in strain analysis. The theory is briefly dealt with, followed by a discussion of the common methods used to analyse the information that the fringes contain and then certain non-obvious limitations are discussed. The generic grid-preparation techniques and optical arrangements are described. Moire interferometry is dealt with at some greater length, and questions that are frequently raised concerning moire in comparison to somewhat similar methods are addressed. Specific difficulties are indicated and the work concludes with a consideration of some recent work that may influence future developments of the method. Of necessity, there is much reliance on reference to quoted works.
Influence of the volume fraction of fibre-reinforced orthotropic composite on the mode-I stress intensity factor
Authors: Ramesh K , Yadav A K , Sethuraman R
Published: October 2002

In the case of infinite bodies involving self-equilibrating loads, stress intensity factors (SIFs) for isotropic and orthotropic materials are the same. However, when the specimen is bounded, material orthotropy does influence the value of SIFs. Delale and Erdogan evaluated the mode-I SIF by solving singular integral equations numerically and showed that the SIF can be greater than the isotropic material value for certain types of orthotropic materials and can be smaller than the isotropic material value for certain other types of materials. They also observed that the mode-I SIF is not altered when either the crack is parallel or perpendicular to the fibre. These observations are verified by finite element analysis. The contours of iso-chromatics observable in a photoelasticity experiment are plotted to verify the suitability of finite element (FE) modelling and discretization. Using the FE code developed, the variation of the mode-I SIF for a single-edge notched (SEN) specimen as a function of volume fraction for unidirectional glass fibre-polyester laminate is obtained. The volume fraction is varied from 0.1 to 0.8 and the a/w ratio is varied from 0.1 to 0.8 in steps of 0.1. The contours of isochromatics observable in a photo-orthotropic elasticity experiment are plotted for the case of the a/w ratio of 0.3 as a function of fibre volume fraction.
Finite element modelling of the interaction of residual stress with mechanical load for a crack emanating from a cold worked fastener hole
Authors: Pavier M J , Poussard C G C , Smith D J
Published: October 2002

A three-dimensional finite element simulation has been conducted for the cold working of a fastener hole in an aluminium plate. The simulation predicts the residual stress distribution resulting from the cold working process where an oversize mandrel is pulled though the fastener hole. Following the cold working simulation, unidirectional tensile mechanical load is applied to the plate and the resulting redistribution of stress predicted. Parallel through-the-thickness cracks emanating from the hole are then introduced into the model and crack opening displacements and stress intensity factors are predicted along the crack front as a function of applied mechanical load.

The finite element simulation shows that cold working has a beneficial effect by reducing the stress intensity factor for a crack under applied mechanical load compared to a non-cold-worked plate. However, this improvement is less than would be expected if the cold working process is idealized as the application of a uniform radial expansion at the hole edge.
Substrate stress concentrations in bonded lap joints
Authors: Wang C H , Heller M , Rose L R F
Published: October 2002

A method based on the successive boundary stress correction approach is presented for the determination of the stress concentration in substrates of adhesively bonded joints with square edges or spew fillets at the ends of the overlap. The emphasis is given to developing an estimate of the stress elevation at the end of a bonded joint while the issue of corner singularity at the substrate-adhesive interface is not addressed in detail. It is shown that the adhesive shear stress which acts on the substrates is the main cause of the stress concentration; the adhesive peel stress has little effect. To circumvent the deficiencies of existing bonded joint theories which generally predict a maximum adhesive shear stress at the ends of the adhesive layer, an eigenfunction solution has been derived for the shear stress distribution near the ends of the overlap. Based on the improved adhesive shear stress solution presented here, the stress concentration determined from the present theory is found to be in good agreement with finite element results.
Effect of the type of creep constitutive equation on strain and stress distributions of notched cylindrical bars under tension creep
Authors: Majima T , Liu Q , Haruki K
Published: October 2002

A finite element calculation was performed to investigate the effect of differences in the type of creep constitutive equation on the distributions of strain and stress on the net section of notched cylindrical bars subjected to large deformation. Three different types of creep constitutive equation were employed; they are of primary-tertiary creep, primary-secondary creep and tertiary creep. The effect of type of creep constitutive equation on the creep strain components versus deformation at the net section 2 In(d0/d) relations and on the distribution of axial creep strain decreases with decreasing notch radius. For a small notch radius the values of creep strain components on the net section are determined to a high degree of accuracy only by two factors of notch radius and 2 In(d0/d). The deep concave distribution of axial creep strain and high strain concentration are maintained during creep deformation. The axial and equivalent stresses versus 2 In(d0/d) relations are strongly affected by the difference in type of creep constitutive equation.
Sliding contact between a blunt wedge and an elastically dissimilar half-plane
Authors: Truman C E , Sackfield A , Hills D A
Published: October 2002

Closed-form expressions for the contact pressure between a blunt wedge and an elastically dissimilar half-plane are presented. It is demonstrated that for practical values of the material mismatch parameter, β, and coefficient of friction, f, the results do not differ significantly from the elastically similar problem.
Film data reduction from Taylor impact tests
Authors: House J W , Aref B , Foster J C , Gillis P P
Published: October 2002

A high-speed photographic film record of a Taylor impact experiment was analysed to determine the strain, strain rate and stress. The stress was calculated on the basis of an interpretive analysis by Taylor involving the motion of a plastic wave in the material. The data on drawn OFE copper produced stresses from 300 to 400 MPa, for strains between 0 and 45 per cent. The strain rate approximation produced a peak value of 11 000 s−1. The strain rate data showed a wide range of values in the plastically deforming region.
An experimental and finite element study of the non-linear force-displacement characteristics of tubular YT-joints under combined axial loading
Authors: Leen S B , Hyde T H
Published: October 2002

This paper describes an experimental and finite element investigation of the non-linear elastic-plastic force-displacement response of a simply supported tubular YT-joint under a range of ratios of the T- to Y-brace applied loads, in order to develop an understanding of the dependence of the joint response on loading path. The experiments consist of the static testing of simply supported tin-lead alloy models of tubular YT-joints under combined, proportionally applied T- and Y-brace-end axial forces. A number of different finite element approaches are presented and discussed via comparison with the test results. An improved version of the energy-based elastic-plastic prediction procedure of the present authors is presented; this is shown to represent a framework for the determination of the non-linear local joint T- and Y-brace force-displacement responses to arbitrary radial loading paths in the load space. The work is considered relevant to the simplification of tubular framework analysis methods for the calculation of accurate collapse loads, incorporating non-linear joint behaviour.
Stresses in a confocal elliptic ring subject to uniform pressure
Authors: Batista M
Published: October 2002

The classical problem of plane elasticity, namely a confocal elliptic ring subject to external and internal pressure, is considered. The general equations based on the Muskhelishvili method are derived and a new exact analytical solution of the problem is presented. Three numerical examples and a stress concentration diagram are also given.
On the feasibility of determining discrete photoelastic parameters using the multi-load method
Authors: Tomlinson R A , Patterson E A
Published: October 2002

An alternative method for the determination of three-dimensional stresses in photoelastic models is discussed. The model is sectioned into discrete, imaginary slices and a relationship is derived between the retardation and isoclinic angle of each slice and characteristic photoelastic parameters measured using a transmission polariscope. An illustration of the multi-load method is given and the practical application of the technique is discussed.
Experimental determination of stress concentrations in orthotropic composites
Authors: Baek T H , Rowlands R E
Published: October 2002

Determining stress raisers necessitates accurate knowledge of the stresses on the edge of the geometric discontinuity. Recognizing difficulties in obtaining measured stresses at the edge of a hole or notch, the least-squares method, in conjunction with a Laurent series representation of the stress functions and local collocation, is used to evaluate reliable stresses on the boundary of holes in loaded composites from measured data away from the hole. Advantages over previous such hybrid analyses include the fact that few measured input data are required, that they can be arbitrarily located and that only a very few terms are needed in the stress function representation. The approach is illustrated for stress input as well as moire-measured displacements. Application to each of the three classes of orthotropy is deliberately addressed.
Calculation of interior point stresses in two-dimensional boundary element analysis of anisotropic bodies with body forces
Authors: Shiah Y C , Tan C L
Published: October 2002

The true boundary integral equation, based on the so-called direct formulation of the boundary element method (BEM), for two-dimensional anisotropic elasticity with body forces has only recently been reported in the literature. It involved transforming a volume integral term associated with the body forces into integrals around the surface of the domain. In the general case, this transformation for anisotropic elasticity gives rise to a series of line integrals along paths which traverse the domain, but their numerical evaluation does not pose any difficulties for the solution of the unknown boundary displacements or tractions. Similarly, the displacements at interior points of the anisotropic domain can be directly calculated using Somigliana's identity for displacements. However, because of the presence of the extra line integrals in this identity as well, the strains, and hence the stresses, at these points cannot be obtained by simple direct differentiation of the identity. In this paper, the mathematical difficulties associated with the determination of interior point stresses for an anisotropic domain with body forces using the BEM are discussed and overcome. The corresponding Somigliana's identity for strains is derived, from which the stresses at the interior point may be obtained. The veracity of the formulation is then demonstrated by three examples.