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Showing papers in "Journal of Strain Analysis for Engineering Design in 1992"


Journal ArticleDOI
TL;DR: In this paper, a brief review of both the destructive and non-destructive techniques used for detecting and characterizing defects and damage is presented, and the ability of each technique to identify the various fracture mechanisms involved in the failure of long fibre reinforced composites is discussed and their overall suitability for damage detection evaluated.
Abstract: In this paper the various failure modes which occur in long fibre composites are described and discussed. The significance of each of these fracture mechanisms, in terms of their energy-dissipating capacity as well as their effect on the residual load-bearing properties, is considered. A brief review of both the destructive and non-destructive techniques used for detecting and characterizing defects and damage is presented. The ability of each technique to identify the various fracture mechanisms involved in the failure of long fibre reinforced composites is discussed and their overall suitability for damage detection evaluated.

186 citations


Journal ArticleDOI
TL;DR: In this article, three and four point bending tests are compared both analytically and experimentally, and damage was observed under the loading roller in addition to the i.i.d.
Abstract: Three and four point bending tests are compared both analytically and experimentally. In all the three point bending tests, damage was observed under the loading roller in addition to the i...

57 citations


Journal ArticleDOI
Abstract: A previous adhesive joint analysis that accommodated non-linear adhesive behaviour is extended to model the elasto-plastic response of the adherends. The resulting analysis models the joint as an adherend-adhesive sandwich capable of sustaining any combination of end load conditions, thus enabling a wide variety of adhesive joints to be modelled. The adhesive is assumed to behave as a coupled set of non-linear shear and tension springs, and the adherends as cylindrically bent plates which yield under the action of combined tension and bending. The complete problem is reduced to a set of six non-linear first-order ordinary differential equations which are solved numerically using a finite-difference method. In this way a reasonable assessment of adhesive stresses and strains can be obtained easily, without resorting to the complexity of a two-dimensional finite element solution. A comparison between the results from these two methods has been made and is presented in this paper after the outline of...

51 citations


Journal ArticleDOI
TL;DR: In this paper, three kinds of joints between bonded, elastically dissimilar components loaded in tension are studied, each involves a plane interface, but with various changes in geometry at the outside edge of the bond.
Abstract: Three kinds of joints between bonded, elastically dissimilar components loaded in tension are studied. Each involves a plane interface, but with various changes in geometry at the outside edge of the bond. These geometric features are intended to avoid singularities which would otherwise arise there, and should therefore inhibit peeling of the joint and hence the formation of a crack. Explicit equations describing the necessary conditions in terms of the elastic parameters of the bonded components are given.

40 citations


Journal ArticleDOI
TL;DR: In this paper, the boundary integral equation (BIE) method for two-dimensional general anisotropic elasticity, based on the quadratic isoparametric element formulation, is extended to treating some inclusion problems.
Abstract: Numerical methods for stress analysis are increasingly being employed in the micromechanics of solids. In this paper, the boundary integral equation (BIE) method for two-dimensional general anisotropic elasticity, based on the quadratic isoparametric element formulation, is extended to treating some inclusion problems. All the cases analysed involved an elliptical zirconia inclusion in an alumina matrix, noting that ZrO2–Al2O3 is an advanced ceramic increasingly used in structural applications. The BIE results are compared with those calculated using Eshelby's equivalent inclusion approach where possible, and excellent agreements between them are obtained. The present work demonstrates the suitability of using this numerical technique for analysing such problems and, in particular, the ease with which it may be used even in the case of general anisotropy.

32 citations


Journal ArticleDOI
A Kato1
TL;DR: In this paper, a new design equation for stress concentration factors is presented based on theoretical results of semi-infinite plates with a notch under tension and also numerical results of strips and shafts with finite notches under tension or bending.
Abstract: A new design equation for stress concentration factors is presented in this paper. This equation is an empirical equation and has been derived based on theoretical results of semi-infinite plates with a notch under tension and also numerical results of strips and shafts with finite notches under tension or bending. It gives stress concentration factors of notched strips and grooved shafts under tension or bending with one expression. This equation can be applied to various shapes of notches and loading conditions and is very convenient for a practical use. Values calculated by this equation are found to be closer to the numerical results recently published than those calculated by Neuber's formula.

29 citations


Journal ArticleDOI
TL;DR: In this article, the problem of a local dent on a pressurized pipe was studied and burst pipe tests on 17 dented pipes showed that the pipe failures were generally insensitive to the existence of the local dents.
Abstract: The problem of a local dent on a pressurized pipe is studied in this paper. Two case problems of dent are considered - a plain local dent (a smooth local dent without a surface defect), and a local dent associated with a loss of thickness defect. The strain gauging test and the finite element analysis on the plain local dent showed that the strain distributions in the local dent are different from those of a long and continuous dent. The maximum hoop strain in the local dent is located at the flank of the dent, along the dent axial axis, whereas in the case of the long dent, it is located at the root of the dent. In addition, the peak stress in the local dent is generally lower than that in the long dent. To estimate the stress concentration in the local dent using the analysis for the long dent would be grossly overestimated. The burst pipe tests on 17 dented pipes showed that the pipe failures were generally insensitive to the existence of the local dents. The pipe failures were found to be due ...

29 citations


Journal ArticleDOI
TL;DR: In this article, an extension of the Ramaswamy, Stouffer, and Laflen unified elastic-viscoplastic theory was presented to represent a strain rate insensitive aluminium alloy namely 7050-T7451 alloy.
Abstract: This paper presents an extension of the Ramaswamy, Stouffer, and Laflen unified elastic–viscoplastic theory which uses internal state variables to represent a strain rate insensitive aluminium alloy namely 7050-T7451 alloy. The model constants are evaluated from the results of a uniaxial tensile test, with strain hold at saturation, and a fatigue loop. Strain holds in the saturated region of tensile monotonic curves resulted in significant amounts of stress relaxation. The material response is cyclically stable and reveals a strong Bauschinger effect. There is a significant reduction in the yield stress between the initial yield and the subsequent tensile yield stress observed after a fully reversed fatigue cycle. All of these material characteristics were predicted successfully.

16 citations


Journal ArticleDOI
TL;DR: In this paper, the basic principle of positive strain energy density of an anisotropic linear or non-linear elastic solid imposes bounds on the values of the stiffness and compliance tensor components.
Abstract: The basic principle of positive strain energy density of an anisotropic linear or non-linear elastic solid imposes bounds on the values of the stiffness and compliance tensor components. Although rational mathematical structuring of valid intervals for these components is possible and relatively simple, there are mathematical procedures less strictly followed by previous authors, which led to an overestimation of the bounds and misinterpretation of experimental results.

16 citations


Journal ArticleDOI
TL;DR: In this paper, the frozen stress technique is compared with other experimental and numerical techniques, and the requirements for frozen stress work are set out and the types of results which can be obtained are stated.
Abstract: The frozen stress technique is compared with other experimental and numerical techniques. The frozen stress technique gives elastic stresses due to steady loading, but is the only experimental technique which can give interior stresses; the others are limited to free surfaces, but can be used to give plastic and creep strains. The requirements for frozen stress work are set out and the types of results which can be obtained are stated.Finite element analysis is the only real alternative for the interior of components and surfaces which are inaccessible due to the proximity of other components.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the response of a large diameter and a multi-layered spiral strand to an applied moment is considered in some detail for a given mean axial load, and the response is investigated in large-scale experiments.
Abstract: The response of a large diameter and a multi-layered spiral strand to an applied moment is considered in some detail for a given mean axial load. Carefully conducted large-scale experiments...

Journal ArticleDOI
TL;DR: In this article, the structural merits of lip-type nuts engaging with ordinary bolts are assessed experimentally by means of frozen-stress photoelasticity, and it is found that a nut with a lip covering 60 percent of total height reduces the stress concentration in the screw by nearly 40 percent with respect to a standard nut of equal height and outside diameter.
Abstract: The structural merits of lip-type nuts engaging with ordinary bolts are assessed experimentally by means of frozen-stress photoelasticity. Thread pitch, lip radial thickness, and lip length are selected as design variables and scanned for possible effect on the maximum stress within the connection. In this respect, the length of lip is shown to play a major role while the other parameters have no decided effect. It is found that a nut with a lip covering 60 percent of total height reduces the stress concentration in the screw by nearly 40 percent with respect to a standard nut of equal height and outside diameter. This improvement is achieved without producing higher stresses in the nut than in the screw.

Journal ArticleDOI
TL;DR: In this article, a procedure has been proposed to modify the conventional finite element method so as to allow the elastic stresses along the free boundaries of two-and three-dimensional structures to be determined with improved accuracy.
Abstract: The conventional finite element method shows its weakness in determining the stress distributions along free boundaries. This is because the chosen element displacement functions do not implicitly satisfy the conditions which prevail at the free boundaries. A procedure has been proposed to modify the conventional finite element method so as to allow the elastic stresses along the free boundaries of two- and three-dimensional structures to be determined with improved accuracy. The results obtained by this modified method for a two-dimensional problem are compared with both a photoelastic and a traditional finite element solution. The comparison shows that the modified solution is in better agreement with the photoelastic test data as compared with the traditional solution. The results obtained by the modified method for a three-dimensional problem is compared with a traditional finite element solution and the former is found to be superior.

Journal ArticleDOI
TL;DR: In this paper, the authors measured and predicted residual stress distributions in a fatigue pre-cracked and a plastically overloaded A533B steel beam using the neutron diffraction technique.
Abstract: The measurement and prediction of residual stress distributions in a fatigue pre-cracked and a plastically overloaded A533B steel beam are described. The residual stresses were obtained experimentally using the neutron diffraction technique. Finite element analysis was employed to predict the elastic-plastic response and residual stresses introduced after overloading. Comparison of the experimental results have been made with the finite element predictions (for both plane stress and strain conditions) averaged over the same sampling volume used to make the neutron diffraction measurements. It has been found that good agreement is achieved away from the near crack tip region. However, close to the crack tip the measured compressive residual stresses are significantly smaller than predicted. This difference is attributed to the A533B steel exhibiting a Bauschinger effect and yielding at a lower stress after a stress reversal.

Journal ArticleDOI
TL;DR: In this article, the residual stress and strain fields are obtained by the non-linear axisymmetric boundary element method (BEM) for an autofrettaged pressure vessel with a cone and cylinder connection.
Abstract: This paper presents analysis and experimental research on an autofrettaged pressure vessel with a cone and cylinder connection. Non-linear loading stresses and strains and the unloading residual stresses and strains are considered. The residual stress and strain fields are obtained by the non-linear axisymmetric boundary element method (BEM). The results of the BEM are verified by means of the finite element method (FEM) program ADINA and compared with autofrettaged high pressure experiments. It is concluded that the calculated residual strains are in reasonable agreement with those determined experimentally.

Journal ArticleDOI
TL;DR: In this paper, simple and explicit forms of solution are developed for finite (non-linear) deformation of bonded blocks, in plane or axisymmetric strain, with special reference to compressible elastic materials.
Abstract: Bearings for bridges, earthquake isolation bearings for buildings, and elements in vehicle suspensions may be made from one or more layers of elastomer between rigid steel plates to which the elastomer is bonded. Using simplifying assumptions based on previous work, simple and explicit forms of solution are developed for finite (non-linear) deformation of bonded blocks, in plane or axisymmetric strain, with special reference to compressible elastic materials. The qualitative behaviour of the explicit form of solution is reasonable and on linearizing it agrees with published experimental and theoretical results for small deformation. The explicit form of solution also compares well with such experimental results as are available for finite deformation and with finite element calculations. Application of the results to laminated blocks, where compressibility is expected to be important is illustrated, and an assessment of the effect of the bulk compressibility of the rubber is offered.

Journal ArticleDOI
TL;DR: In this paper, a theoretical insight is given into the non-linear free bending characteristics of axially preloaded and large diameter sheathed spiral strands experiencing high external hydrostatic pressure in, for example, deep water floating platform applications.
Abstract: A theoretical insight is given into the non-linear free bending characteristics of axially preloaded and large diameter sheathed spiral strands experiencing high external hydrostatic pressure in, for example, deep water floating platform applications.The theoretical model takes geometrical non-linearities and interwire friction fully into account. It is capable of estimating variations of strand plane-section bending stiffness, (EI)eff, and hysteresis as a function of the imposed radius of curvature, magnitude of the external pressure, and level of mean axial load.An oversight in a previously reported analytical model for following the reductions in strand flexural rigidity due to interlayer slippage has also been identified and subsequently corrected. In addition, the corrected model (which assumed small deflections) has been extended to cover geometrical non-linearities due to changes in lay angle and helix radius.Numerical results are presented for a large diameter (102 mm OD) sheathed spiral s...

Journal ArticleDOI
TL;DR: In this paper, an energy potential function has been established using total Lagrangian strains for computer modelling of finite deformation of leather in shoe lasting, and a practical last simulator, composed of a cylindrical last and uni-axial leather strip, has been developed to model a one-dimensional simulation of the lasting process.
Abstract: Previously developed constitutive equations are presented and discussed for shoe upper leather which undergoes large deformation. An energy potential function has been established using total Lagrangian strains for computer modelling of finite deformation of leather in shoe lasting. A practical last simulator, composed of a cylindrical last and uni-axial leather strip, has been developed to model a one-dimensional simulation of the lasting process. Experiments have been carried out to study the effects of different friction characteristics at the leather-last interface. The experimental results for the variation of the lasting force with the last displacement are presented and shown to be closely predicted by the computer models based on the multi-axial constitutive equations.

Journal ArticleDOI
TL;DR: In this paper, one shape of the Y-T joint has been die-cast in a tin-lead alloy and the results are presented non-dimensionally as Ultimate Strength Reduction Ratio (USRR) i.e., as fractions of (simply calculated) bending moments which would have ensured failure of the brace remote from the joint.
Abstract: One shape of ‘Y—T’ joint has been die-cast in a tin-lead alloy. Twenty-one models have been tested in in-plane or out-of-plane bending, loading one or both braces. The results are presented non-dimensionally as Ultimate Strength Reduction Ratios (USRR) i.e., as fractions of (simply calculated) bending moments which would have ensured failure of the brace remote from the joint.The results from the tin-lead models agreed with relevant results from steel models. Parametric equations derived mainly from ‘T’ joint data predict the failure of 90 degree braces well, but underestimate the strength of 45 degree braces in in-plane and out-of-plane bending. Plastic collapse occurs on the compressed side of the braces before tearing on the tension side.

Journal ArticleDOI
TL;DR: In this article, the results indicated that damage due to creep caused a larger increase in fatigue crack growth rate than a simple superposition model would predict, and also creep appeared to have a more dominant influence than fatigue on crack growth direction.
Abstract: Creep–fatigue tests were carried out on Jethete M152 at 550°C under mode I, mode II, and mixed mode (K1/KII ≈ 1.6) conditions. The results were correlated and compared with corresponding fatigue and creep data. The results indicated that damage due to creep caused a larger increase in fatigue crack growth rate than a simple superposition model would predict. Also creep appeared to have a more dominant influence than fatigue on crack growth direction.

Journal ArticleDOI
TL;DR: Several alternative test specimens for the determination of the fracture strength of a brittle material have been studied as mentioned in this paper, including a ring-supported ball-loaded thin circular disc, a disc symmetrically supported on three equispaced balls and loaded at the centre through a fourth ball, a cylinder under axial compressive point-loading, and a pure shear beam specimen.
Abstract: Several alternative test specimens for the determination of the fracture strength of a brittle material have been studied. These include a ring-supported ball-loaded thin circular disc, a disc symmetrically supported on three equispaced balls and loaded at the centre through a fourth ball, a cylinder under axial compressive point-loading, and a ‘pure shear’ beam specimen. The stress distributions in these specimens have been determined photoelastically and the stress data used to interpret fracture test data for batches of each specimen made from reactor-grade graphite. The stochastic nature of the fracture data has also been considered.

Journal ArticleDOI
D Redekop1, F Zhang1
TL;DR: In this article, the effect of local loads applied on a sectorial toroidal shell (pipe bend) is considered and a linear elastic shell theory solution for local loads is first outlined.
Abstract: In this study the effect of local loads applied on a sectorial toroidal shell (pipe bend) is considered. A linear elastic shell theory solution for local loads is first outlined. The solution corresponds to the case of a shell simply supported at the two ends. Detailed displacement and stress results are then given for a specific shell with loadings centred at three positions; the crown circles, the extrados, and the intrados. These results are compared with results for a corresponding cylindrical shell. The paper concludes with a table summarizing results for characteristic displacements and stresses in a number of shells, covering a wide range of geometric parameters.

Journal ArticleDOI
TL;DR: In this article, the effects of the overlap length and number of steps on the joint strength are studied. And the predicted results agree fairly well with the experimental initial cracking strengths, but the experimental final fracture strengths of the joints increase with the overlap lengths and with the number of step steps.
Abstract: Deformation and strength of stepped-lap bonded joints under static tensile loading are investigated both analytically and experimentally. The joints used in this study consist of the same metal adherends of carbon steel and an adhesive of epoxy resin. The effects of the overlap length and number of steps on the joint strength are studied. The joint strength is predicted by applying the strength criteria on the adherends, the adhesive and their interfaces in the joint. The predicted results agree fairly well with the experimental initial cracking strengths. The experimental final fracture strengths of the joints increase with the overlap length and with the number of steps.

Journal ArticleDOI
TL;DR: In this article, an existing Fourier series analysis for calculating flexibility factors and strain distributions in such components with constant thickness subjected to in-plane bending moments is extended to include typical thickness variations.
Abstract: Glass reinforced plastic (GRP) pipe bends as used in the process plant industry are often made by hand lay-up and, because of overlapping of layers in the construction, are prone to thickness variations sometimes approaching ± 50 percent of the mean thickness An existing Fourier series analysis for calculating flexibility factors and strain distributions in such components with constant thickness subjected to in-plane bending moments is extended to include typical thickness variations Results are expressed in closed form, and their practical implications are discussed The theoretical results are also discussed in relation to experiments on two GRP pipe bends having nominal inside pipe diameters of 250mm and mean pipe radii of 250mm where the resin was polyester and the E-glass reinforcement consisted of three layers of 06 kg m−2 chopped strand mat and one layer of 06kg m−2 woven rovings

Journal ArticleDOI
C Grant1
TL;DR: In this paper, a computer-based solution is developed for thin-walled sections comprising an arboric bracket, which can be used to determine the shear center of the sections.
Abstract: Shear centre is an important geometric property of thin-walled sections that can be difficult to determine in practice. A computer based solution is developed for sections comprising an arb...

Journal ArticleDOI
TL;DR: In this paper, a moire shearing interferometry, used to analyse the interference effect in a particular optical set-up by the Fourier series method, is proposed and the slope fringe patterns of different shallow shells with eccentric holes are also given by this method.
Abstract: A moire shearing interferometry, used to analyse the interference effect in a particular optical set-up by the Fourier series method, is proposed in this paper. The slope fringe patterns of different shallow shells with eccentric holes are also given by this method.

Journal ArticleDOI
TL;DR: In this article, a simple solution for the flexibility calculation of curved profiles having a rectangular thin-walled cross-section is presented, with some assumptions related to geometric details about the shape of the deformed structure, aiming at an economic and accurate solution.
Abstract: This paper presents a simple solution for the flexibility calculation of curved profiles having a rectangular thin-walled cross-section. Some assumptions related to geometric details about the shape of the deformed structure are included in the present analysis, aiming at an economic and accurate solution. Results concerning the distortion of the transverse section are compared with the corresponding data from the solution with a thin shell finite element analysis. A flexibility factor for the structure analysed here is presented as a graphical result.

Journal ArticleDOI
TL;DR: The results of finite element calculations have been used to show that an analytical solution for the stresses in the vicinity of crack-like notches with elliptical and hyperbolic shaped ends gives accurate results for narrow, semi-circular ended notches as mentioned in this paper.
Abstract: The results of finite element calculations have been used to show that an analytical solution for the stresses in the vicinity of crack-like notches with elliptical and hyperbolic shaped ends gives accurate results for narrow, semi-circular ended notches It is also shown that the peak stresses can be obtained from the stress intensity factor for an equivalent crack and the notch tip radius Finite element solutions for narrow, rectangular notches with rounded corners, have also been used to show that the peak stresses in such notches can be obtained by using a notch shape factor to modify the peak stress values for semi-circular notches The shape factor depends only on the notch width to corner radius ratio

Journal ArticleDOI
TL;DR: Longitudinal tensile tests have been conducted on unidirectional SiC fibre reinforced 6061 aluminium matrix composites in the annealed and as-manufactured conditions as discussed by the authors. But the results are presen...
Abstract: Longitudinal tensile tests have been conducted on unidirectional SiC fibre reinforced 6061 aluminium matrix composites in the annealed and as-manufactured conditions. The results are presen...

Journal ArticleDOI
TL;DR: In this paper, the interaction of a framed structure with a foundation beam resting on an elastic medium, representing the soil, has been studied using the photoelastic method, and the contact pressure distribution, the fibre stress in the foundation beam and frame structure, as well as the stresses in the elastic medium have been compared with theoretical results obtained by idealizing the soil as an elastic half plane, and elastic half space.
Abstract: The interaction of a framed structure with a foundation beam resting on an elastic medium, representing the soil, has been studied using the photoelastic method. The contact pressure distribution, the fibre stress in the foundation beam and frame structure, as well as the stresses in the elastic medium, have been obtained. These have been compared with theoretical results obtained by idealizing the soil as (a) elastic half plane, and (b) elastic half space. It is shown that the photoelastic method can provide an easy solution to this type of problem if the soil can be idealized as an elastic continuum.