Showing papers in "Journal of Strain Analysis for Engineering Design in 1991"
TL;DR: The finite element method has been used to obtain elastic stress data for simply-supported short beams with uniformly distributed loading and short built-in beams subjected to shear displac... as mentioned in this paper.
Abstract: The finite element method has been used to obtain elastic stress data for simply-supported short beams with uniformly distributed loading and short built-in beams subjected to shear displac...
39 citations
TL;DR: In this paper, the authors presented a method for obtaining the full-slip stiffness matrix as regards coupled extensional-torsional characteristics of spiral strands and found that the model predicts a (very nearly) symmetrical stiffness matrix which is in agreement with published experimental observations.
Abstract: Simplified routines are presented for obtaining useful information on the macroscopic level as regards the magnitude of interwire/interlayer deformations. Axial hysteresis is shown to vary considerably with the type of strand construction: parametric studies on various constructions covering a wide range of cable (and wire) diameters and lay angle have been used to obtain a simple method of estimating maximum hysteresis and the associated load range/mean ratio at which it occurs. A method has also been presented for obtaining the full-slip stiffness matrix as regards coupled extensional-torsional characteristics. In particular, it is found that unlike certain previously available theories, the present model predicts a (very nearly) symmetrical stiffness matrix which is in agreement with published experimental observations. Numerical examples are presented to facilitate the use of the present paper to forecast various aspects of the behaviour of other spiral strands. Practical implications of inclu...
38 citations
TL;DR: In this article, the use of the finite element method for predicting the fillet stress distribution experienced by loaded spur gears is described, and the location of finite element model boundary and the element mesh density are investigated.
Abstract: This paper describes the use of the finite element method for predicting the fillet stress distribution experienced by loaded spur gears. The location of the finite element model boundary and the element mesh density are investigated. Fillet stresses predicted by the finite element model are compared with the results of photoelastic experiments. Both external and internal spur gear tooth forms are considered.
35 citations
TL;DR: In this paper, finite element data have been combined with experimental data to produce design curves and an associated equation, which will allow the calculation of the effective stress factors (ESF) for a wide range of piping branch junctions for both internal pressure and all six external moment load categories.
Abstract: Finite element data have been combined with experimental data to produce design curves and an associated equation, which will allow the calculation of the effective stress factors (ESF) for a wide range of piping branch junctions for both internal pressure and all six external moment load categories. The data suggest that modifications are required in design procedures for some geometries for internal pressure loading. For branch out-of-plane loading the present data agree reasonably well with ASME III design rules, but extend these to cover the full range of diameter ratios up to d/D = 1.0.
31 citations
TL;DR: The boundary element method as mentioned in this paper is a boundary-oriented technique that is very appropriate for this purpose, and it can overcome a number of the difficulties associated with its main rival, the finite element method.
Abstract: Structural optimization is often confined to sizing simple design variables, such as plate thicknesses and bar cross-sectional areas, while the geometric shapes of components remain largely unchanged. Shape optimization is more complex, changing the shape of the boundary, subject to appropriate constraints. The boundary element method, being a boundary-oriented technique is very appropriate for this purpose. It can overcome a number of the difficulties associated with its main rival, the finite element method. Firstly, because of the continuously changing geometry. the accuracy of the finite element analysis using the initial mesh of elements may become inadequate during the optimization process. Secondly, if during this process, the finite element mesh has to be re-generated, the cost is relatively high. Finally, and most importantly, the sensitivity analysis in the calculation of the derivatives with respect to the design variables may be obtained directly in the boundary element approach rather...
28 citations
TL;DR: In this article, an effective method is developed for determining the individual stresses from the trace of the stress tensor (isopachics) in a region adjacent to an arbitrarily-shaped traction-free boundary of a loaded component.
Abstract: An effective method is developed for determining the individual stresses from the trace of the stress tensor (isopachics) in a region adjacent to an arbitrarily-shaped traction-free boundary of a loaded component. The approach is facilitated by the fact that the stresses throughout such a region can be described completely in terms of only one complex potential. Equilibrium and compatibility prevail within the region, and the traction-free boundary conditions are satisfied. The concept is expected to be particularly useful for thermoelastic stress analysis.
27 citations
TL;DR: The finite element method has been used to study the monotonic and cyclic elastic-plastic stress and strain characteristics of hollow tubes with axisymmetric internal projections subjected to repeated axial loading as discussed by the authors.
Abstract: The finite element method has been used to study the monotonic and cyclic elastic–plastic stress and strain characteristics of hollow tubes with axisymmetric internal projections subjected to monotonic and repeated axial loading This paper compares finite element strain predictions with values estimated using simple notch stress–strain conversion equations for two geometries and a range of nominal stresses From this study, an intermediate equation (m = 05) is suggested for low cycle fatigue life predictions The results have been normalized with respect to material properties so that they can be applied to geometrically similar components made from other materials which can be represented by the same material models
21 citations
TL;DR: In this article, the elastic load-displacement analysis of coned disc springs using the finite element method (FEM) is presented, which considers the geometrical non-linearity of such springs within the working range using 8-noded isoparametric elements.
Abstract: The elastic load-displacement analysis of coned disc springs using the finite element method (FEM) is presented. The analysis considers the geometrical non-linearity of such springs within the working range using 8-noded isoparametric elements. The springs are analysed for a uniformly distributed axial load around the upper inner boundary with the lower outer boundary constrained vertically and other edges kept free. Verification of the present technique is obtained by analysing reference problems. Good correlation between the computed results and referenced data can be drawn.
19 citations
TL;DR: In this article, the sliding contact between a rigid cylindrical punch and an elastic strip of finite thickness was studied and the strip was either in adhesion with a rigid foundat or not.
Abstract: This paper is concerned with the sliding (full slip) contact between a rigid cylindrical punch and an elastic strip of finite thickness The strip is either in adhesion with a rigid foundat
16 citations
TL;DR: In this article, the axial hysteresis of multi-layered helical strands is predicted from first principles using orthotropic sheet theory for wire compliances derived from results in available contact stress theories, normal forces on the interwire/interlayer contact patches are estimated.
Abstract: This paper addresses the problem of predicting the axial hysteresis in multi-layered helical strands from first principles.Using previously reported orthotropic sheet theory for helical strands with wire compliances derived from results in available contact stress theories, normal forces on the interwire/interlayer contact patches have been estimated. Using such data, the full slip histories on the contact patches from the micro-slips on the periphery at low loads, to the onset of gross slip at higher loads and beyond are predicted. It is shown that cable overall axial hysteresis is dominated by the frictional energy dissipation over the line-contact patches within individual layers.Strand overall hysteresis is predicted by two rather different theoretical methods which provide an analytical double check. In the first method, the overall load-deflection curve, as derived by a previously reported orthotropic sheet model is used to follow the loading and subsequent unloading response of an axially p...
15 citations
TL;DR: In this article, the results of a series of tests in which high strength fasteners, socket head set screws (SHCS), were tightened to yield as a means of generating maximum clamping force were presented.
Abstract: This paper presents the results of a series of tests in which high strength fasteners, socket head set screws (SHCS), were tightened to yield as a means of generating maximum clamping force. The tightening tests were performed with the aid of a microprocessor controlled torque wrench and a torque–tension testing rig. Load cells fitted to the test rig provided an accurate measurement of the joint clamp load and the faster thread and underhead torque distribution under a range of lubrication conditions. Measurements were made during tightening to yield, under static load condition after yield tightening, and during loosening. The results obtained established that the lubrication conditions dramatically affect the magnitude of the maximum clamp load achieved on the joint and the torque distribution on the fastener. The results also enabled an estimate to be made of the coefficient of friction on the various mating surfaces during the tightening and loosening of the fastener. It was shown that the des...
TL;DR: In this paper, a bending analysis for cross-ply laminates containing matrix cracks is presented, where the cracks are modelled as aligned slit cracks across the ply thickness and transverse to the laminate plane.
Abstract: A bending analysis is presented for cross-ply laminates containing matrix cracks. The cracks are modelled as aligned slit cracks across the ply thickness and transverse to the laminate plane. The distribution of cracks is assumed to be statistically homogeneous corresponding to an average crack density. The results are given for symmetrically and antisymmetrically laminated plates with a given density of matrix cracks. The effect of reduction in the laminate stiffness is studied by plotting the ratio of the centre deflection of cracked and uncracked laminates against the aspect ratio, crack density, and relative layer thicknesses. It is observed that the amount of increase in the plate deflection depends on the stacking sequence as well as on the relative thicknesses of layers.
TL;DR: In this paper, the authors used structural finite elements to calculate stress intensity factors from displacement-prescribed boundary conditions on a subregion containing a crack, whose boundary can be any arbitrary contour within the physical structure.
Abstract: Stress intensity factors are obtained from displacement-prescribed boundary conditions on a subregion containing the crack. The subregion, whose boundary can be any arbitrary contour within the physical structure, is analysed numerically using structural finite elements. Nodal boundary displacements of this subregion are obtained photomechanically using a smoothing finite element representation. The technique requires little experimental information and is unaffected by rigid body motions. It is numerically stable and accurate - even in the presence of significant experimental scatter - and the measured data need not come from the immediate vicinity of the crack. The method's practicality is demonstrated by determining the stress intensity factors in a compact tension specimen from moire-measured displacements at locations away from the crack tip.
TL;DR: In this paper, the stress distributions in shouldered shafts in tension and in torsion were calculated by the finite element method (FEM) for notch radii that are of technical interest.
Abstract: The stress distributions in shouldered shafts in tension and in torsion were calculated by the finite element method (FEM) for notch radii that are of technical interest.The calculated stress concentration factors Kt and relative stress gradients normal to the surface were compared with values given in a well-known handbook used by many designers, and with literature, respectively. From this comparison it appears that:–Kt values for a shouldered shaft in tension are up to 30 percent higher than the values given in mentioned handbook;–the relative stress gradients can, within the range of notch radii r that was investigated, be approximated by 2/r for the tension case and 1/r for the case of torsion.Publication of reliable results from FEM calculations of stress concentrations are recommended in order to improve or extend the usability of the design data which are now available.
TL;DR: In this article, a simple procedure for estimating the stress intensity factor of a continuous crack at the root of a circumferential notch in a round bar is presented, and numerical solutions for equivalent notched and un-notched geometries are compared.
Abstract: A simple procedure for estimating the stress intensity factor of a continuous crack at the root of a circumferential notch in a round bar is presented. Numerical solutions for equivalent notched and un-notched geometries are compared. The resulting correction term for notches is formulated as a polynomial equation using only notch geometric parameters and is used in conjunction with the conventional stress intensity calibration for the un-notched configuration.
TL;DR: In this paper, the authors proposed the anisotropic yield function of the sixth degree, which is able to include the effects of the third deviatoric stress invariant and initial anisotropy, by combining Drucker's yield function with Hill's quadratic yield function.
Abstract: By means of combining Drucker's yield function with Hill's quadratic yield function, the anisotropic yield function of the sixth degree is proposed. It is able to include the effects of the third deviatoric stress invariant and initial anisotropy. The experimental evaluation is made on thin-walled cylindrical specimens of mild steel (in the fully annealed condition and the stress-relief annealed condition after a tensile pre-strain) and 2024 aluminum alloy (in the -0 and -T6 tempered conditions). By applying proportional combined loadings of axial load, internal pressure, and torsion to the specimens, a change of yield stress with a rotation of the principal stress axes and a difference between the directions of the principal stress and principal strain increment are examined Under tension–internal pressure and tension–torsion, the yield surfaces and strain behaviour are determined. The fully annealed steel is almost isotropic for yielding although it reveals the effect of the third deviatoric str...
TL;DR: In this article, the stiffness derivative method was employed to obtain the energy release rate and thus the stress intensity factor of an externally loaded bolt, and this confirmed the results of the first measurement.
Abstract: This paper deals with the measurement of the residual stress on the thread root of an M30 bolt. The results are used in the computation of the stress intensity factor – on the cracked bolt – generated by the prior residual stresses. The optimum measurement parameters have been carefully chosen: relative position between the X-ray beam and the sample, and the irradiated spot size. The results are tensile type stresses in the bolt surface – the opposite to the few existing bibliographic data. A test is performed to check the sign of these residual stresses on the externally loaded bolt, and this confirms the results of the first measurement. The stress computation is carried out by the finite element method. The stiffness derivative method is employed to obtain the energy release rate and thus the stress intensity factor.
TL;DR: An automatic data logging system has been developed for the capture of uniaxial creep test data and a robust and reliable optimization scheme has been devised for the determination of the creep constitutive equations for a material.
Abstract: Methods have been developed for the determination of a suitable stress range over which uniaxial creep tests should be carried out in order to find the best constitutive equations for the material. The method is based on a proposed empirical relation and Ashby deformation mechanism maps.An automatic data logging system has been developed for the capture of uniaxial creep test data and a robust and reliable optimization scheme has been devised for the determination of the creep constitutive equations for a material.The above methods have been combined in an expert system that enables the user without specialist knowledge to carry out uniaxial creep tests to determine the best creep constitutive equations for a material. The system is stored on two floppy disks and is run from any IBM compatible microcomputer.The expert system has been used to determine the creep constitutive equations for copper.
TL;DR: By combining Drucker's yield function with Hill's quadratic yield function, an anisotropic yield function of the sixth degree was proposed in this article, where the effects of the third deviatoric stress invariant and initial anisotropy were also included.
Abstract: By combining Drucker's yield function with Hill's quadratic yield function, an anisotropic yield function of the sixth degree is proposed. The effects of the third deviatoric stress invariant and initial anisotropy are also included. Experimental evaluation is made on 1050 aluminium tubes under multiaxial stress states. The tubes in the as-received condition are subjected to progressive reductions in the hot extruding and cold drawing processes. They are annealed by heating at 200 °C for 1 h. By applying proportionally combined loadings of axial load, internal pressure, and torsion to the specimens, a change of yield stress with a rotation of the principal stress axes and a difference between the directions of the principal stress and principal strain increment are examined. In the tension-internal pressure stress field, it is found that this aluminum tube exhibits orthotropic anisotropy of high strength in the tangential direction. The yield surface in the tension-torsion stress field lies outsid...
TL;DR: In this article, an exact linear elasticity solution developed by the author for the decay of self-equilibrating end loads applied to a hollow circular cylinder is extended to determine decay rates for a compound circular cylinder of two materials having different stiffness; only axisymmetric loads are considered.
Abstract: An exact linear elasticity solution developed by the author for the decay of self-equilibrating end loads applied to a hollow circular cylinder is extended here to determine decay rates for a compound circular cylinder of two materials having different stiffness; only axisymmetric loads are considered. The results are of interest not only as a quantification of Saint-Venant's Principle (SVP), but also because the minimum decay rate indicates the rate of load transfer and hence the maximum extent of a transition region where load is transferred from one cylinder to another. As with the semi-infinite plane strain sandwich, one of the few other geometries amenable to mathematical analysis, rates of decay can be so slow that routine invocation of SVP is not justified.The rate of load transfer from a stiff inner cylinder to a more flexible concentric cylinder is affected by the ratio of the elastic properties and also the diameter ratio. For load transfer to be effected over minimum distance the differ...
TL;DR: In this article, the surface and die away distance to unity of stress concentration factor have been found on typical geometries of ''T» butt and cruciform joints using finite elements.
Abstract: Values of the surface and the die away distance to unity of stress concentration factor have been found on typical geometries of «T» butt and cruciform joints using finite elements
TL;DR: In this article, a series solution method is presented for analyzing sharp asymmetric dry contact problems, which provides an exact representation for the pressure inside the contact, the contact width and also the displacement outside the contact for the frictionless two-dimensional problem of a rigid indentor acting on an elastic half-plane.
Abstract: A series solution method is presented for analysing sharp asymmetric dry contact problems. It provides an exact representation for the pressure inside the contact, the contact width and also the displacement outside the contact for the frictionless two-dimensional problem of a rigid indentor acting on an elastic half-plane. The first part of the paper describes how the method can be used for symmetric and asymmetric punches without slope discontinuities. In the second part the method is modified to overcome the Gibbs phenomenon so that it can be applied to any punch, symmetric or asymmetric, with or without slope discontinuities. Finally, two analytic approaches are described and compared with the present solution method.
TL;DR: In this article, a technique is described for manipulating strain gauge data obtained from tests on structural steel ‘H’ sections such that individual force components may be identified. But the results obtained from experimental tests on beam columns exhibited excellent agreement with the corresponding predictions of a sophisticated nonlinear finite element analysis.
Abstract: A technique is described for manipulating strain gauge data obtained from tests on structural steel ‘H’ sections such that individual force components may be identified. The technique recognises the different structural actions present when open sections deform in a full three-dimensional fashion (compression, major and minor axis bending, and warping) covering both elastic and elastic–plastic behaviour. The results obtained from experimental tests on beam columns exhibited excellent agreement with the corresponding predictions of a sophisticated non-linear finite element analysis.
TL;DR: In this paper, a highly accurate elasto-plastic hybrid/mixed finite element method has been presented to obtain the total field displacement, strain, and stress distribution of these welded joints under the critical fracture condition.
Abstract: Nickel-iron type cast iron electrodes are widely used in welding QT600–3 nodular iron. In order to obtain the total field displacement, strain, and stress distribution of these welded joints under the critical fracture condition, a highly accurate elasto-plastic hybrid/mixed finite element method has been presented in this paper. Also, the corresponding plane stress element model has been given. In addition, this paper describes macro-imitation of the brittle structure in the welded joints. The calculated displacement results are in good agreement with the experimental measurement by using the Moire fringe method. The reasons of fracture under the lower tensile stress are also discussed.
TL;DR: In this paper, a measurement device has been developed which permits the six individual components of three-dimensional deformation to be monitored, and a comparison between the deformations measured using the device, and those predicted using a column sub-assemblage finite element model is also presented.
Abstract: As part of an extensive experimental study into the influence of semi-rigid connections on the behaviour of steel columns, a measurement device has been developed which permits the six individual components of three-dimensional deformation to be monitored. The theory used to process the measured deformations and the subsequent testing of a prototype device is described. A comparison between the deformations measured using the device, and those predicted using a column sub-assemblage finite element model is also presented.
TL;DR: In this paper, a parametric failure criterion for fiber-reinforced laminae under plane stress loading conditions is presented, which leads to an improved correlation between experimental data and analytical failure envelopes for this material.
Abstract: After a brief review of failure criteria for anisotropic materials, a new parametric failure criterion for fibre-reinforced laminae under plane stress loading conditions is presented. Using previously published experimental data for paper-board, it is shown that this criterion can lead to an improved correlation between experimental data and analytical failure envelopes for this material.
TL;DR: The methods of estimating the creep-fracture mechanics parameter C[t] proposed by Riedel, Webster, Ainsworth, and their respective co-workers have been reviewed and extended.
Abstract: The methods of estimating the creep-fracture mechanics parameter C[t] proposed by Riedel, Webster, Ainsworth, and their respective co-workers have been reviewed and extended. Quantitative estimates for C[t] have been obtained for the infinite centre cracked plate (CCP) and compact tension (CT) specimens using uniaxial creep strain and rupture data for 1 CrMoV steel at 565°C. It has been shown that the estimates substantially differ for each method and on the assumed state of stress.The creep material parameters for 1CrMoV at 565°C are shown to be different for stresses above and below 200 MPa. In selecting the appropriate material parameters for estimating C[t] the reference stress technique is used. At high stresses the greatest estimate of C[t] is obtained from Webster's method, the lowest obtained from Ainsworth's approach and an intermediate estimate obtained using methods proposed by Riedel. At low stresses, where stress redistribution from an initial elastic condition dominates, it has shown...
TL;DR: The transfer matrix method as mentioned in this paper gives freedom for the thickness of the plate, and the pressure across it, to be any functions of radius, and for the plate to be supported at any radius, or at any radii, in whatever manner is relevant.
Abstract: This work arose from a design exercise which required a less constrained treatment of annular plates than is available from standard formulae. The transfer matrix method gives freedom for the thickness of the plate, and the pressure across it, to be any functions of radius, and for the plate to be supported at any radius, or at any radii, in whatever manner is relevant. Natural frequencies and mode shapes may be calculated by including the inertia terms in the matrices. Its limitation is that only axially symmetrical deformation and modes are covered by the method.