Showing papers in "Journal of Strain Analysis for Engineering Design in 1977"
TL;DR: In this paper, a new mechanism is proposed by which collapse proceeds progressively from one end of the tube, following the passage of a travelling hinge, and simple expressions are developed for mean collapse load and the energy absorbed during collapse of rigid-perfectly plastic tubes.
Abstract: Inextensional collapse modes are presented for the axial compression of thin-walled tubes. Shortening is achieved by folding about fixed hinge lines to form a number of flat triangular planes. A new mechanism is propounded by which collapse proceeds progressively from one end of the tube, following the passage of a travelling hinge.Simple expressions are developed for mean collapse load and the energy absorbed during collapse of rigid-perfectly plastic tubes.Comparison of collapse modes and predicted loads with those obtained from experiments on rigid P.V.C. tubes of various thickness, diameter and length give encouraging agreement.
167 citations
TL;DR: In this article, the applicability of the C∗ parameter for the prediction of creep crack propagation rates is considered, and a new method for estimating C ∗ is presented, the results from which show good agreement with those from an existing technique.
Abstract: The applicability of the C∗ parameter for the prediction of creep crack propagation rates is considered. A new method for estimating C∗ is presented, the results from which show good agreement with those from an existing technique. Experimental results from creep crack growth tests, conducted on a 1 Cr Mo V steel using both compact tension and single edge notch bend specimens, indicate that good correlation with C∗ is obtained once the effects of stress redistribution become negligible. Finally, comparisons are drawn between C∗ and other possible correlating parameters, and the limitations of each approach are discussed.
134 citations
TL;DR: In this article, a simple model for the demarcation of the initiation and stage I fatigue crack growth phases is introduced, and experimental cumulative damage data are used to determine the phase boundary between these two regimes, and an exponential accumulation of damage theory is invoked for each; here, damage is equated to crack length.
Abstract: A simple model for the demarcation of the initiation and stage I fatigue crack growth phases is introduced. Experimental cumulative damage data are used to determine the phase boundary between these two regimes, and an exponential accumulation of damage theory is invoked for each; here, damage is equated to crack length. Using both the model and the data, predictions are made of lifetime in double, treble and multilevel strain range tests. The theory successfully accounts for the load sequence effect, which is a consequence of the initiation period, and the effect of the difference between successive strain range levels. It is suggested that the Palmgren-Miner expression be replaced by individual expressions for the accumulation of damage in the separate phases of initiation and stages I and II fatigue crack propagation.
122 citations
TL;DR: In this paper, the authors investigated the propagation of fatigue cracks in notched and unnotched biaxially stressed plates and found that the rate of propagation is affected by both the stress field associated with the notch and the biaXial stress state of the bulk material.
Abstract: The propagation of fatigue cracks in notched and un-notched biaxially stressed plates is investigated. The rate of propagation is found to be affected by both the stress field associated with the notch and the biaxial stress state of the bulk material. It is found that the propagation rate of a crack from a notch may be predicted by the use of a theoretical notch contribution factor in conjunction with propagation data for a crack in un-notched material.
81 citations
TL;DR: In this paper, a universal method based on the characteristic geometric elements of the corresponding caustics (pseudocaustics) was developed, which leads to a system of singular integral equations, which was solved numerically by a collocation method of successive approximations.
Abstract: The caustics formed by illuminating straight deformable boundaries by a parallel, convergent or divergent light beam were used to determine the load distribution along these boundaries. A universal method based on the characteristic geometric elements of the corresponding caustics (pseudocaustics) was developed. This method leads to a system of singular integral equations, which was solved numerically by a collocation method of successive approximations. The singular points of the integrals were removed by integrating along regular paths determined by the optically obtained pseudocaustics. This procedure constitutes a new combined numerical-experimental method for solving singular integral equations with singularities of the Cauchy type. Several examples are given to show the potentialities of the method.
45 citations
TL;DR: In this article, the authors examined the effect of locking-in-stresses on inelastic buckling collapse of flat plated grillages and ring-stiffened cylinders.
Abstract: Structural engineers have for a long time accepted the importance of residual stresses when considering fracture modes of failure. It is only in the last quarter-century that attention has been focused on their adverse effect on ductile modes of failure and, in particular, on buckling collapse. The last decade has seen increased research activity, spurred on by recent failures in box-girder bridges.The nature and distributions of locked-in-stresses during hot and cold forming and during welding are outlined. The effect these have on inelastic buckling collapse of flat plated grillages and ring-stiffened cylinders is examined for all likely modes of failure. Experimental data are scarce, but they confirm that both forming and welding stresses can reduce the stiffness and strength of both types of structure very significantly. This is caused by a direct reduction in buckling stresses (as usually supposed), but equally important is the loss in stiffness due to early yield and other effects. In partic...
36 citations
TL;DR: In this paper, a method of assessing the effect of foundation settlement on tank ovalization at the top of floating roof storage tanks is presented. Butler et al. evaluated the extent to which foundation settlement limits tank ovalisation.
Abstract: A method of assessing the effect of foundation settlement upon the ovalization at the top of floating roof storage tanks is presented. The accuracy of the method is tested by comparison with field measurements and experiments on model tanks. Current design specifications for the permissible foundation settlement are reviewed and the extent to which they limit tank ovalization is assessed.
34 citations
TL;DR: In this paper, two methods of measuring shape are presented, and it is shown that extreme care must be used in analysing the results obtained from chord gauge readings which are often the most convenient to take.
Abstract: Most design codes require stiffened cylinders to be made circular to within ½ per cent on radius, and large penalties are incurred by exceeding the shape tolerance. The methods specified for checking on circularity vary greatly and they are vague in some cases and illogical in others.Two methods of measuring shape are presented, and it is shown that extreme care must be used in analysing the results obtained from chord gauge readings which are often the most convenient to take. The accuracy of the two methods is compared.
20 citations
TL;DR: In this article, the elastic strain induced in the plate and stiffeners due to contraction of the stiffener welds, and profiles of stiffener and plating after welding have been obtained.
Abstract: Methods for measuring residual stresses and distortions in welded structures are described and initial results are given of a survey being carried out during manufacture of warship hull sections. The stresses are determined by measuring the elastic strain induced in the plate and stiffeners due to contraction of the stiffener welds, and profiles of the stiffener and plating after welding have been obtained. The survey is intended to provide information for use in future design calculations of the buckling strength of ship hulls.
15 citations
TL;DR: In this article, the effects of cyclic shear strain-range and temperature on the accumulation of damage during constant and variable shear-strain range fatigue tests on a 1 per cent Cr-Mo-V steel are reported.
Abstract: The effects of cyclic shear strain-range, shear strain-rate and temperature on the accumulation of damage during constant and variable shear strain range fatigue tests on a 1 per cent Cr-Mo-V steel are reported.The hypothesis of linear accumulation of damage and the summation of cyclic fractions to unity are shown to be incorrect for interactions of time, cyclic and environmental processes which are considered in detail. Stage I cracks may be accelerated, retarded or stopped and new cracks nucleated. Nevertheless only 8 per cent of the cumulative damage tests in the high strain fatigue regime gave unsafe linear summation factors less than 0.8. None fell below 0.7.
14 citations
TL;DR: In this paper, a non-linear distribution of (211) interplanar spacing is shown to occur in textured steels, the reasons for the nonlinearity being marked texture, cold-formed structure and stresses.
Abstract: A non-linear distribution of (211) interplanar spacing is shown to occur in textured steels, the reasons for the non-linearity being marked texture, cold-formed structure and stresses. For stress evaluation it is recommended that the directions ψ be used, which are independent of texture. The paper gives the modified sin2ψ method, for both film and goniometer techniques, for predominantly uniaxial stresses.
TL;DR: In this paper, a general method of characterizing these parameters in the form of a P-u-A diagram is presented for both linear and non-linear load-displacement relationships at constant crack area.
Abstract: In the application of quasistatic energy analysis, the P-u-A diagram has been found a valuable supplement in illustrating the characteristics of crack propagation. The diagram is useful not only for evaluating fracture toughness under quasistatic conditions, but also for representing important fracture parameters such as stability criteria, crack speed, strain rate, fatigue, environmental effects, etc.A general method of characterizing these parameters in the form of a P-u-A diagram is presented for both linear and non-linear load-displacement relationships at constant crack area. This was achieved by polynomial representation of the diagram. The analysis was extended to cover crack propagation under multiple-loading conditions. By introducing a complementary strain-energy function, equivalent load and compliance, a method of solution has been devised to avoid the laborious computations which may otherwise be required if the loadings become numerous and complex. The computed values of fracture tou...
TL;DR: In this paper, the stress fields around cracks have been calculated for general yield conditions using two-and three-dimensional elasto-plastic finite-element programs, and compared with published data obtained by experimental techniques.
Abstract: The stress fields around cracks have been calculated for general yield conditions using two- and three-dimensional elasto-plastic finite-element programmes. These programmes were used to evaluate the Rice J-integral, and compare the values with published data obtained by experimental techniques.
TL;DR: In this article, an approximate analysis for the computation of buckling loads of biaxially compressed, simply supported, rectangular, moderately thick, laminated plates is presented based on the use of reduced plate stiffnesses as well as shear correction factors.
Abstract: An approximate analysis is presented for the computation of buckling loads of biaxially compressed, simply supported, rectangular, moderately thick, laminated plates. The analysis is based on the use of reduced plate stiffnesses as well as shear correction factors. By comparing the approximate buckling loads with those obtained from a full 3-dimensional analysis, it is demonstrated that the approximate analysis is sufficiently accurate for design purposes. A computer programme based on the approximate analysis is then used to derive a reasonably comprehensive set of dimensionless buckling-load vs plate-thickness-ratio curves.
TL;DR: In this article, the theoretical basis for the experimental determination of reference stresses from model tests is established for one-dimensional and complex stress systems, and a graphical method of obtaining the experimental reference stress is presented and used to determine reference stresses for the strain in beams in pure bending and the tip deflection of cantilever beams from room-temperature tests of lead-antimony-arsenic models.
Abstract: The theoretical basis of the experimental determination of reference stresses from model tests is established for one-dimensional and complex stress systems. A graphical method of obtaining the experimental reference stress is presented and used to determine reference stresses for the strain in beams in pure bending and the tip deflection of cantilever beams from room-temperature tests of lead-antimony-arsenic models. The results are compared with theoretical values.It is shown how prototype deformation can be predicted from a test of a model of the component, model material creep data and the strain of a uniaxial prototype material specimen tested at the reference stress. Errors in the prediction of prototype deformations are considered.
TL;DR: An analytical solution based on nonlinear beam theory has been derived to compute the variation of total cyclic potential energy in fatigue crack growth under conditions of gross plasticity as discussed by the authors, which is applicable to any geometry, providing fully tensile loading and cyclic creep occurs.
Abstract: An analytical solution based on non-linear beam theory has been derived to compute the variation of total cyclic potential energy in fatigue crack growth under conditions of gross plasticity. It was assumed that the variation in total potential energy with crack length was equal to the cyclic value of J, written as ΔJ = Jmax - Jmin where Jmax and Jmin are the maximum and minimum values of the contour integral J in the loading cycle. The solution is applicable to any geometry, providing fully tensile loading and cyclic creep occurs. It was applied to the contoured double-cantilever-beam (d.c.b.) geometry and ΔJ was found to be dependent upon load P, crack length a, number of cycles N and the strain hardening and cyclic creep properties of the material. The results obtained may be applied in the study of crack propagation at relatively small deflections.Fatigue crack growth rates were investigated experimentally under tensile cyclic conditions, leading to generalized plasticity. Tests were performed...
TL;DR: In this article, the residual stresses caused by weld shrinkage in a plate containing a central longitudinal weld were investigated and the results led to proposed values for the factors H and C in the simple Moxham formula, which are in reasonable agreement with theoretical predictions.
Abstract: A study was made of the residual stresses caused by weld shrinkage in a plate containing a central longitudinal weld. A theoretical analysis was developed in which the weld was treated as a moving concentrated heat source, through-thickness variations in temperature and stress being ignored. The equations were solved in finite-difference form and the stresses were computed at discrete stages during welding and cooling. Allowance was made for the variation of yield stress with temperature. Computed results were obtained for the bead-on-plate and butt welded cases.Residual stresses were measured in 40 flat plate specimens containing a central butt weld, with thicknesses ranging from 6 to 16 mm. The results led to proposed values for the factors H and C in the simple Moxham formula, which are in reasonable agreement with theoretical predictions.
TL;DR: In this paper, a series of tests are reported which support the proposal that fatigue crack growth rates are retarded by crack closure at low values of applied mean stress intensity, and the evidence presented indicates that closure occurs most readily at the specimen's free surfaces.
Abstract: A series of tests are reported which support the proposal that fatigue crack growth rates are retarded by crack closure at low values of applied mean stress intensity. In particular, the evidence presented indicates that closure occurs most readily at the specimen's free surfaces. This leads to dramatic changes in crack front profile under certain loading conditions.
TL;DR: In this paper, the authors derived the edge conditions for a cylindrical shell without a cutout, subjected to an asymmetric load, and combined the negatives of the stress resultants and stress couples at a given radius obtained from the above solution with a transverse shear force.
Abstract: The problem of stress concentration around cutouts in shells is an important one in the design of nuclear pressure vessels, boilers, pressure hulls of submarines, aircraft structures, pipe connections and tube and ball mills used in chemical industries. By using the finite-difference scheme suggested by Budiansky, the solution to the problem of a cylindrical shell without a cutout, subjected to an asymmetric load, is derived first. Then, the negatives of the stress resultants and stress couples at a given radius obtained from the above solution are combined with a transverse shear force to form the edge conditions for a circular cylindrical shell containing a circular cutout of radius a. The desired results are finally obtained by superposing these two solutions.
TL;DR: In this paper, a point-loaded, center-cracked (P.L.C.) plate was developed for fracture studies and the methods used to determine a satisfactory geometry for the specimen, in terms of the stability of cracking, are discussed, and results agreed well with those obtained experimentally.
Abstract: This paper describes the development of a point-loaded, centre-cracked (P.L.C.C.) plate in fracture studies. The methods used to determine a satisfactory geometry for the specimen, in terms of the stability of cracking, are discussed, and the results agreed well with those obtained experimentally. The stress intensity factor (KI) of the plate is presented for a wide range of H/W values, using a finite-element method based on a displacement-function approach. Fracture-toughness (Gc) tests, involving the use of a quasistatic energy concept, are conducted and used to check the accuracy of the computed KI-values. Good correlation is obtained between the stress and energy approaches.
TL;DR: The elastic behavior of a cylindrical shell subjected to radial load applied through two circumferential plate bracket attachments positioned diametrically opposite each other at the mid point of the shell is described in this article.
Abstract: The elastic behaviour of a cylindrical shell subjected to radial load applied through two circumferential plate bracket attachments positioned diametrically opposite each other at the mid l...
TL;DR: In this article, the load deformation behavior of thin plate crack specimens has been studied in detail using the moire technique, and this behaviour has been modelled by plane stress finite-element calculations.
Abstract: The load-deformation behaviour of thin plate crack specimens has been studied in detail using the moire technique, and this behaviour has been modelled by plane stress finite-element calculations. Agreement between experimental and numerical results suggests that behaviour of thin plate crack specimens can be modelled by the plane stress finite-element programme, and hence this programme can be used to calculate fracture data for plane stress crack geometries.
TL;DR: In this article, an exhaustive survey of the imperfections in the component parts of steel box girder bridges is presented, and an appraisal is made of compliance with the Merrison Interim Design Rules.
Abstract: Results obtained from an exhaustive survey of the imperfections in the component parts of steel box girder bridges are summarized. An appraisal is made of compliance with the Merrison Interim Design Rules, and tolerances are suggested.
TL;DR: In this paper, the influence of low-modulus overlays consisting either of a layer of uniform thickness over the whole weld or of an infill over the weld toe was examined.
Abstract: Finite-element analyses have been carried out on a specimen with transverse non-load-carrying attachments, to examine the influence of low-modulus overlays consisting either of a layer of uniform thickness over the whole weld or of an infill over the weld toe. The variables studied have included coating thickness and the shape, size and modulus of toe infills. It is shown that substantial reductions in stress concentration can be obtained by such coatings.
TL;DR: In this paper, the authors considered a thin annular plate having an inner clamp which provided a simple support and an outer clamp which provides either a simple supporting or a built-in edge.
Abstract: The problem considered here concerns a thin annular plate having an inner clamp which provides a simple support and an outer clamp which provides either a simple support or a built-in edge. The inner clamp supports a bending moment which tends to tilt it out of plane.A complete theoretical solution to the problem is presented for small deflections of the plate. Equations are derived for the deflections and stresses in terms of the applied bending moment, the plate geometry and the elastic constants of the plate material.Calculated results are compared with the trends of known values for plates with eccentric inner clamps.
TL;DR: In this paper, the stress concentration factors at long shallow circumferential grooves in round shafts under torsion have been investigated by theory and experiment, and the discrepancies between theoretical and experimental results are discussed.
Abstract: The stress concentration factors at long shallow circumferential grooves in round shafts under torsion have been investigated by theory and experiment. The discrepancies between theoretical and experimental results are discussed, and the results are also compared with Neuber's solution.
TL;DR: In this article, the authors lay down some general principles of good practice that will minimize distortion and the consequent residual stress which would be detrimental to the finished structure, and they also lay out some general guidelines for good practice to minimize distortion.
Abstract: This paper details various aspects of distortion, how these faults occur, how they may be avoided, and if not avoided, how they may be most easily alleviated.The costs of avoiding or alleviating distortion are most difficult questions to discuss in that the records of many manufacturing shops do not list them separately, and they are often included in normal fabricating shop costs.Finally, the author tries to lay down some general principles of good practice that will minimize distortion and the consequent residual stress which would be detrimental to the finished structure.
TL;DR: In this paper, the authors measured residual stresses and distortions during various stages of fabrication and erection of the Milford Haven Bridge and found that fabrication caused rather larger stresses than those estimated using the Merrison Rules, but distortions were kept within Merrison tolerances.
Abstract: Residual stresses and distortions were measured during various stages of fabrication and erection of the Milford Haven Bridge. Welding caused compressive residual stresses in the plate panels and tension in the stiffeners. The panels distorted in the direction of the stiffened side of the plate. Grit blasting and transporting caused an apparent reduction in the plate stress accompanied by a small increase in this distortion. These processes affected the magnitude of the stresses but not their distribution within a plate panel. Fabrication caused rather larger stresses than those estimated using the Merrison Rules, but distortions were kept within Merrison tolerances.
TL;DR: In this paper, the authors present an approximate solution for the stress distribution around two cylindrical holes intersecting at right angles in an infinite homogeneous, isotropic, elastic body, when the body is subjected to uniform tension at an infinite distance from the holes.
Abstract: The paper presents an approximate solution for the stress distribution around two cylindrical holes intersecting at right angles in an infinite homogeneous, isotropic, elastic body, when the body is subjected to uniform tension at an infinite distance from the holes. Stress concentration factors for a range of ratios of the hole radii are presented, both for the case when the two holes are infinitely long and for when the smaller hole is semi-infinite.
TL;DR: In this article, the use of a probabilistic approach in the form of a reliability analysis is recommended, and a description of a system suitable for this task given, and various levels of complexity which may be involved are described, and the problems of implementation outlined.
Abstract: The development of quality standards in shipbuilding is reviewed, and the need for an analytical assessment of standards identified.The use of a probabilistic approach in the form of a reliability analysis is recommended, and a description of a system suitable for this task given. The various levels of complexity which may be involved are described, and the problems of implementation outlined. The method is illustrated by an application of the system developed at Lloyd's Register of Shipping to assess suitable quality standards for initial imperfections in ship plating.To correlate the mathematical simulation of reliability with actual experience, use is made of technical information on structural damages from Lloyd's Register of Shipping Technical Records database.