Showing papers in "Journal of Strain Analysis for Engineering Design in 1988"
TL;DR: The application of the SPATE technique to two different composite material specimens is described and the results are critically discussed in this article, where the relevant theory which permits a quantitative interpretation of the thermoelastic response from orthotropic materials is outlined.
Abstract: The application of the thermoelastic technique (SPATE) to two different composite material specimens is described and the results are critically discussed. The relevant theory, which permits a quantitative interpretation of the thermoelastic response from orthotropic materials, is outlined.
94 citations
TL;DR: The neutron diffraction technique for measuring residual stresses non-destructively in an aluminium alloy weld has been examined in this article, and the results showed that the technique can be used to determine residual stresses in an aluminum alloy weld.
Abstract: The neutron diffraction technique for measuring residual stresses non-destructively in an aluminium alloy weld has been examined. Calibration experiments have been performed to determine th...
41 citations
TL;DR: In this article, a single pass butt-welding of a pipe is studied, where low heat input has been used to obtain high cooling rate with adherent martensite in the final phase transformation in the heat affected zone.
Abstract: Single pass butt-welding of a pipe is studied. Low heat input has been used to obtain high cooling rate with adherent martensite in the final phase transformation in the heat affected zone. Strains and stresses have been measured during and after welding on the pipe outer surface. Deviations from rotationally symmetric strain and stress fields in the pipe are studied. Two different analytical solutions for the residual stress field from the literature are discussed. The experimentally obtained residual stresses are compared with those analytical solutions. Qualitatively good agreement between experiments and analytical solutions was obtained, although the analytical solutions do not consider effects of phase transformations.
34 citations
TL;DR: In this article, perfect clamped torispherical shells subjected to external pressure are analyzed using the BOSOR 5 shell buckling program, where various values of the knuckle radius to diameter ratio (r/D) and the spherical cap radius-to-thickness ratio (Rs/t) were studied, as well as four values of σyp, the yield point of the material.
Abstract: Perfect clamped torispherical shells subjected to external pressure are analysed in the paper using the BOSOR 5 shell buckling program. Various values of the knuckle radius-to-diameter ratio (r/D) and the spherical cap radius-to-thickness ratio (Rs/t) were studied, as well as four values of σyp, the yield point of the material. Buckling/collapse pressures, modes of failure and the development of plastic zones in the shell wall were determined. A simple diagram is presented which enables the failure mode in these shells to be predicted. The collapse pressures, pc, were also plotted against the parameter Λs (√(pyp/pcr)). When the controlling failure mode was axisymmetric yielding in the knuckle, the collapse pressure curves depended on the value of σyp, which is unusual. However, when the controlling failure mode was bifurcation buckling (at the crown/knuckle junction), the collapse pressure curves for the various values of σyp all merged, i.e., they were independent of σyp. This latter situation is...
29 citations
TL;DR: In this paper, an experimental investigation was conducted to study the dependence of packing geometry on the dynamic load transfer in two-dimensional granular aggregate chains, where the granular media was simulated with two dimensional granular aggregates.
Abstract: An experimental investigation was conducted to study the dependence of packing geometry on the dynamic load transfer in two dimensional granular aggregate chains. The granular media was sim...
26 citations
TL;DR: In this article, the torsional stiffness and hysteresis data of axially-preloaded strands are presented for axially preloaded strands, and the match between experimental results for an old and fully bedded-in 39 mm diameter, 91 wire spiral strand and theoretical predictions is very encouraging.
Abstract: Carefully conducted experimental studies of the torsional characteristics of substantial structural strands are reported. The match between experimental results for an old and fully bedded-in 39 mm diameter, 91 wire spiral strand and some theoretical predictions is very encouraging. The theory, which has been reported elsewhere, treats the individual layers of wires in a strand as orthotropic sheets and, via established results in contact stress theory, takes full account of the frictional interactions between wires.Static and dynamic torsional stiffness and hysteresis data are presented for axially-preloaded strands. Strain gauging of individual wires showed significant scatter, but the match between theory and the mean of the experimental data for a position remote from the termination was good, using the same assumed value of the friction coefficient for all tests.For an old strand, random loading can significantly increase the level of torsional hysteresis above that found for regular cyclic l...
25 citations
TL;DR: In this paper, the authors investigated the contact problem in which an elastic strip is indented by a rigid body (punch) of arbitrary shape, and compared the results with Meijers' asymptotic analytic solutions.
Abstract: This paper investigates the contact problem in which an elastic strip is indented by a rigid body (punch) of arbitrary shape. Both bonded and unbonded strips are considered.A numerical method due to Gladwell (1)† is shown to be a direct and effective technique for analysing the effect of any punch whose profile is a polynomial of degree n, over a range of a/t (semi-contact width to a depth ratio) which is of practical interest 0 ≤ a/t ≤ 10 for Poisson's ratio 0 ≤v ≤ 0.5.For the cylindrical punch results are presented and compared with Meijers' asymptotic analytic solutions (2). For small a/t agreement is very good as expected. For a/t large, however, there are some large discrepancies which can be traced to an error in Meijers— expression for pressure distribution when v ≠ 0.5. Results are also presented for both the flat and the linear punch.
22 citations
TL;DR: In this paper, a straight steel strand of three layer (12/6/1) construction, having a core wire diameter of 3.66 mm and 3.33 mm diameter helical wires, was performed under conditions of full end-fixity, partial restraint, and ends free from torsional restraint.
Abstract: Tensile tests were performed on a straight steel strand of three layer (12/6/1) construction, having a core wire diameter of 3.66 mm and 3.33 mm diameter helical wires, under conditions of full end-fixity, partial restraint, and ends free from torsional restraint. The torque generated under tensile load was recorded as well as the strand extension and rotation over a 600 mm gauge length. Wire tensions and bending moments in the outer layer of helical wires were determined at the mid-strand position from the outputs of strain gauges in groups of three with parallel grids and mounted parallel to the wire axis on the crown of each wire.The rate of strand extension under tensile load was found to be greater in tests with reduced torsional restraint, the greatest rate occurring in the free-end test. The strand rotation rate was also found to be greatest in the free-end test. The greatest difference from the theoretically predicted rates occurred in a free-end test with increasing load; predicted values...
20 citations
TL;DR: In this article, the theoretical relationship between relieved in-plane displacements and residual stresses, which are needed for data reduction in a moire interferometric version of hole drilling method, are obtained.
Abstract: In this paper, the theoretical relationships between relieved in-plane displacements and residual stresses, which are needed for data reduction in a moire interferometric version of hole drilling method, are obtained. The analysis includes the case of linearly varying biaxial stresses. The theoretical relationships are then used for generating on a computer the corresponding moire interferometric fringe patterns thus simulating the experimental response under known loading conditions. Various effects due to the degree of residual stress biaxiality, the strength of the linear stress term, the direction of sensitivity of the moire grid, and the value of the Poisson's ratio are illustrated.
18 citations
TL;DR: In this article, an analytical model for stamped ring wave springs is proposed, based on the theory for circular beams loaded normal to the plane of curvature, which profits from the adoption of Castigliano's theorem as a tool for mathematical treatment.
Abstract: An analytical model for stamped ring wave springs is proposed, based on the theory for circular beams loaded normal to the plane of curvature. The model profits from the adoption of Castigliano's theorem as a tool for mathematical treatment. Closed-form expressions for both load—deflection and load—stress relationships are presented. Because of the particular shape of the spring in the undeformed configuration, the load—deflection curve is found to be appreciably bilinear in character. A similar but less pronounced behaviour is displayed also by the relationship between load and internal stresses. The analytical results are compared to earlier theoretical findings and are shown to correlate well with experimental measurements.
16 citations
TL;DR: In this article, a compact mixed-mode fracture specimen is described, which can be used for any combination of mode-I and mode-II stress intensities, including static, fatigue, creep, or creep/fatigue conditions.
Abstract: A practical, compact mixed-mode (CMM) fracture specimen, which can be used for any combination of mode-I and mode-II stress intensities, is described The loading system, which is suitable for high temperature testing, is also described The specimen can be used for mixed-mode testing under static, fatigue, creep, or creep/fatigue conditionsThe stress-intensity factors (KI and KII) for the complete range of loading conditions have been obtained by finite element and photoelastic methods Nodal displacement, stress, and contour integral methods, using the finite element results all gave practically the same stress intensity factors These were in reasonably close agreement with the results obtained using shear stress distributions obtained from the photoelastic tests
TL;DR: In this article, a new method for design analysis of bicycle frames is presented, which relies on measurements of rider induced loading to perform a stress analysis of a bicycle frame and is based on ANSYS, a commercially available finite element code.
Abstract: Presented in this paper is a new method for design analysis of bicycle frames. The new method relies on measurements of rider induced loading to perform a stress analysis of a bicycle frame. The vehicle for the stress analysis is ANSYS, a commercially available finite element code. Through application of individual measured loads, the method examines the corresponding nodes of maximum stress. Polar plots are developed to illustrate the variation of stress as a function of crank arm angle. Polar plots are also developed for the nodes experiencing the maximum total stress. Such a procedure enables the contribution of individual measured loads to the maximum stress to be ascertained. With this information, not only are the important loads for design analysis identified, but also the structural members of relative high and low stress are determined. Accordingly, these results have application to the detailed design of individual structural members.To illustrate the new method, stress analysis of an al...
TL;DR: In this paper, the authors found that the growth rate of crack growth in the 32%−Ni−20%−Cr alloy Incoloy 800 H at 800°C is correlated with the fracture mechanics parameter C∗ integral.
Abstract: Creep crack growth rates in the 32%−Ni−20%−Cr alloy Incoloy 800 H at 800°C are correlated with the fracture mechanics parameter C∗ integral. This was done by experimental and numerical inve...
TL;DR: In this paper, an approximate simple theoretical solution is developed for infinitesimal plane and axisymmetric strain deformations for blocks of elastic material with Poisson's ratio between 0 and 0.5 bonded to rigid end plates.
Abstract: An approximate simple theoretical solution is developed for infinitesimal plane and axisymmetric strain deformations for blocks of elastic material with Poisson's ratio between 0 and 0.5 bonded to rigid end plates. The explicit form of solution, developed for shape factor, S, between 0 and ∞, is easy to use and compares well with published experimental results. It is also comparable with previous theoretical investigations and expected behaviour.
TL;DR: In this paper, four bolts of a lightweight, steel, flanged joint were strain-gauged to measure bolt tension and bending, and three-dimensional finite element analysis was used to determine bolt strains and g...
Abstract: 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 g...
TL;DR: In this paper, the effect of varying elastic constants on the failure strength of composites is investigated and the limits in the variation of the Poisson's ratio for this composite lamina are identified.
Abstract: Tensor polynomial, maximum stress, and maximum strain criteria are considered in an investigation of the effect of varying elastic constants on the failure strength of composites. By expressing each criterion in the alternative stress or strain space they are made explicitly dependent on elastic constants as well as strength parameters. The significance of this result is highlighted by an example of the variation in failure envelope produced by altering the Poisson's ratio of the composite material. In particular the failure envelopes for a high strength graphite/epoxy resin (SP-286/T300) composite lamina are examined as a function of variations in the material's Poisson's ratio. The limits in the variation of the Poisson's ratio for this composite lamina are identified.
TL;DR: In this paper, out-of-plane bending tests were carried out on eight E-glass reinforced polytester resin, 90 degree pipe bends of 250 mm diameter and 250 mm bend radius.
Abstract: Out-of-plane bending tests were carried out on eight E-glass reinforced polytester resin, 90 degree pipe bends of 250 mm diameter and 250 mm bend radius. Each bend specimen tested had 1175 mm long tangent pipes attached, and construction was by hand lay-up, the glass being in the form of chopped strand mat (either 2.4 kg/m2 or 3.6 kg/m2). In all cases low loads were applied so that deformations were sensibly linear. Strains and displacements were measured and distributions were compared with estimates calculated from pipe bend theory for isotropic materials under plane stress, but modified for composites by using separate moduli for direct and bending stress conditions. Further measurements were taken for internal pressure (only) loadings on five of the specimens, and finally for out-of-plane flexure loading combined with constant pressure. Again measured values were compared with theory. Results are discussed in relation to a typical design procedure for such pipe components.
TL;DR: In this article, a numerical solution method for frictionless, two-dimensional contact problems involving punches with slope discontinuities or sharp corners is presented, which employs a finite Hilbert transform to remove computational difficulties associated with the logarithmic pressures encountered within such contacts.
Abstract: This paper presents a numerical solution method for frictionless, two dimensional contact problems involving punches with slope discontinuities or sharp corners. The solution method presented employs a finite Hilbert transform to remove computational difficulties associated with the logarithmic pressures encountered within such contacts. A complementary (smooth) problem may then be solved using a rapidly convergent Chebyshev expansion which requires relatively few terms to achieve accurate results. The algebraic (square root) pressure singularities encountered at the ends of certain contacts are also easily resolved, being implicit in the series solution used. The solutions to several problems on the half plane are compared with those obtained directly, and a comparison with analytic solutions is made. In the knowledge that the method gives efficient and accurate half plane solutions, it is then extended to problems involving layers of finite depth. In particular, symmetric wedge indentation on bo...
TL;DR: In this article, a strain-based tensor polynomial failure criterion for anisotropic materials is proposed with explicit derivations given in both strain and stress space, and the viability of the proposed criterion is shown by its application to a graphite-epoxy resin lamina under plane stress.
Abstract: Abstract A strain-based tensor polynomial failure criterion for anisotropic materials is proposed with explicit derivations given in both strain and stress space. The physical distinction between this strain-based criterion and the current stress-based tensorial criterion of Tsai and Wu, is clarified. The viability of the proposed criterion is shown by its application to a graphite—epoxy resin lamina under plane stress. The allowed loadings and failure envelope of this lamina are predicted. Comparison is made with existing failure criteria (both stress-based and strain-based), in particular the maximum stress, maximum strain, and Tsai-Wu criteria.
TL;DR: In this paper, a method for aligning any goniometer for which the specimen and the detector can move independently was proposed, which can also be used for other goniometers.
Abstract: A method is proposed to align any goniometer for which the specimen and the detector can move independently. Originally the method was developed for a stress-goniometer, but it can also be used for other goniometers.The method consists of an algorithm that calculates the misalignment from the peak positions of the diffraction X-ray beam measured on a metal powder specimen, rotated in several positions (2θ—ψ curves). The algorithm then indicates quantitatively how much the different parts of the apparatus must be adjusted. Only numerical calculations are used and there is no need for special instruments.The algorithm can be easily written into a computer program and makes the alignment a fast and extremely accurate operation.
TL;DR: In this article, the problem of a circular disc with a central hole and a symmetrical array of non-central holes subjected to rotation and radial tension at its outer circumferential periphery is analyzed.
Abstract: The problem of a circular disc with a central hole and a symmetrical array of non-central holes subjected to rotation and to radial tension at its outer circumferential periphery is analyse...
TL;DR: In this article, it has been shown that the tool stresses oscillate in a regular manner during the formation of each chip segment and the results obtained have lead to a better understanding of the chip formation process and provide a more complete description of the stress conditions experienced by the cutting tool.
Abstract: In the high speed machining of metals it has been established that the shearing process is frequently non-uniform resulting in a serrated chip with highly localised shearing. This type of chip formation is promoted solely by the properties of the material being machined and is not initiated by vibrations or resonances of the machine structure. It has been found that this type of unsteady, shear localised chip form can be duplicated when polyethylene is machined at low speeds with araldite cutting tools. By means of a photoelastic technique the variations in tool stress associated with these non-uniform chip forms has been revealed during the machining process. The photoelastic results clearly show that the tool stresses oscillate in a regular manner during the formation of each chip segment. The results obtained have lead to a better understanding of the chip formation process and provide a more complete description of the stress conditions experienced by the cutting tool.
TL;DR: In this paper, the formal similarity between the equation governing the diffusion of a substance through a "porous" isotropic material and the heat conduction equation for the temperature distribution in a homogeneous solid is examined, and its use as a basis for the photoelastic study of transient thermal stresses is explored.
Abstract: The formal similarity between the equation governing the diffusion of a substance through a “porous” isotropic material and the heat conduction equation for the temperature distribution in an isotropic homogeneous solid is examined, and its use as a basis for the photoelastic study of transient thermal stresses is explored.
TL;DR: In this paper, a number of neutral loading experiments according to classical plasticity theory were made and the usefulness and limitations of the rule of kinematic hardening were examined, and it was further shown that the results from recent experiments are particularly relevant to the appraisal of modern developments to plasticity.
Abstract: An examination is made of a number of neutral loading experiments according to classical plasticity theory. For work hardening materials the question as to whether plastic deformation occurs during neutral loading depends strongly upon the deformation produced from initial loading. Initial elastic loading with a subsequent stress path that follows the boundary of the initial vield surface is truly neutral with a wholly elastic response. However, when plastic strain is produced from initial loading then plastic flow is produced from a subsequent stress path that follows the boundary of a surface that is an isotropic expansion of the initial yield surface. Since this violates the assumption of isotropic hardening the usefulness and limitations of the rule of kinematic hardening are examined. It is further shown that the results from recent experiments are particularly relevant to the appraisal of modern developments to plasticity theory.Neutral loading without work hardening will produce plastic flo...
TL;DR: In this article, a revised set of finite width correction (Y) factors relating to the single-edge-notch (SEN) tension testing of orthotropic materials in opening mode I were presented.
Abstract: Values for finite-width correction (Y) factors relating to the single-edge-notch (SEN) tension testing of orthotropic materials in opening mode I were presented previously. These have since been found to be in error, in some cases substantially so, and a revised set of factors is presented.