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Showing papers in "Journal of Strain Analysis for Engineering Design in 1986"


Journal ArticleDOI
TL;DR: In this paper, a discrepancy between experimental results and the generally accepted theory for the load distribution occurring in the threads of a nut-bolt connection is highlighted, and a modified theory has been modified to allow for this effect by using finite element analysis to determine the varying stiffness of the threads.
Abstract: A discrepancy between experimental results and the generally accepted theory for the load distribution occurring in the threads of a nut-bolt connection is highlighted. This occurs at the loaded end of the bolt and is caused by the changing geometry of the thread form of the nut as the thread emerges from the loaded face of the nut. The result is a thread form which is not complete and which is progressively more flexible as the loaded face of the nut is approached. This results in a reduction of the load carried by these incomplete threads. Sopwith's analytical theory has been modified to allow for this effect by using finite element analysis to determine the varying stiffness of the threads. The results of this modified theory compare well with those from three-dimensional photoelastic analyses of the loads in the threads of two bolts fitted with conventional nuts.

36 citations


Journal ArticleDOI
TL;DR: In this article, a bicycle frame has been analyzed as a three-dimensional framework and stresses and deflections predicted using a finite element computer program, and theoretical results for simple loading case were compared with strain gauge measurements in laboratory tests.
Abstract: A bicycle frame has been analysed as a three-dimensional framework and stresses and deflections predicted using a finite element computer program. Theoretical results for simple loading case were compared with strain gauge measurements in laboratory tests.More complex loading cases representing common cycle racing situations were analysed. The largest stresses in the frame were bending stresses. Stresses in the region of 300—400 MN/m2 were predicted in the down tube and right chain stay during starting and stresses of about 250 MN/m2 at the front of the top tube and down tube during severe braking.

19 citations


Journal ArticleDOI
TL;DR: In this article, an isoparametric quadratic formulation of the boundary integral equation (BIE) method for two-dimensional elasto-plastic analysis is presented.
Abstract: An isoparametric quadratic formulation of the boundary integral equation (BIE) method for two-dimensional elasto-plastic analysis is presented. The initial strain approach is adopted but, unlike in finite element analysis, it is capable of accurately treating perfectly-plastic and weakly strain-hardening materials. Two methods of evaluating internal stress and strain rates, namely, via the elementwise numerical differentiation of the displacement rates, and the pointwise use of integral identities, are included in the solution algorithm, and their relative efficiency is discussed. The use of correction factors is suggested in some cases to ensure that the von Mises flow rules are implemented in a consistent manner. Results to test problems are given and compared with exact or existing approximate solutions.

18 citations


Journal ArticleDOI
TL;DR: In this paper, the angle of taper and the number of tapered threads in a nut were determined to give the lowest maximum stress concentration in the bolt for an ISO nut-bolt connection subject to axial loading.
Abstract: The angle of taper and the number of tapered threads in a nut necessary to give the lowest maximum stress concentration in the bolt were determined for an ISO nut—bolt connection subject to axial loading. Thirty-eight frozen stress models were analysed and it was found that a two degree taper for 5.5 threads from the loaded face of the nut reduced the maximum normalised tensile stress in the bolt by 41 per cent from 5.17 to 3.07.It was observed that if the angle of taper was too large the stress concentration produced at the junction of the parallel and tapered threads could negate the beneficial effects of the taper geometry.

18 citations


Journal ArticleDOI
TL;DR: In this article, the effects of pre-strain on fracture toughness of steels were examined by using a simple cumulative damage model of microvoid growth and coalescence, and it was demonstrated that an approximate blunting solution enables the models to be applied readily.
Abstract: The effects of prestrain on the fracture toughness of steels are examined by using a simple cumulative damage model of microvoid growth and coalescence. First the effects of a shear prestrain on the mode III toughness at a single temperature are calculated in order to obtain guidance on how best to approximate the stress—strain curve after pre-strain. Then the models are used to examine the influence of a uniaxial pre-strain on the values of mode I toughness on the upper shelf. The mode I analyses require crack tip blunting solutions, and it is demonstrated that an approximate blunting solution enables the models to be applied readily. Numerical results for various amounts of pre-strain are calculated by taking material properties typical of an A533B steel. It is found that the effects are generally small for the material properties considered.

16 citations


Journal ArticleDOI
TL;DR: In this paper, the authors consider the circumstance of the loads changing in-phase and out-of-phase, and present a full analysis leading to ratchetting rates, showing that the ratchet rates are less than those given by Bree.
Abstract: The work of Bree (1)† led to an understanding of the behaviour of a thin cylinder when subjected to an alternating through-wall thermal gradient together with a continuous internal pressure. Other physical situations require the same understanding when such a cylinder is subjected to these loads, but when both are cyclical in nature. We consider here the circumstance of the loads changing in-phase and out-of-phase. Bree type diagrams depicting zones of elastic, shakedown, plasticity, and ratchetting regimes are presented. A full analysis leading to ratchetting rates is given. It is found that for both in-phase and out-of-phase loading the ratchet rates are less than those given by Bree.

16 citations


Journal ArticleDOI
John Sweeney1
TL;DR: In this paper, a finite-width correction factor for orthotropic materials has been calculated using a J integral implemented on results from finite element analyses, which depends on the ratio of principal normal compliances S11/S22 and another dimensionless quantity involving the material compliances.
Abstract: Calculations of finite-width correction factors, Y, for mode I SEN tension testing of orthotropic materials have been made using a J integral implemented on results from finite element analyses. Y depends on the ratio of principal normal compliances S11/S22 and another dimensionless quantity involving the material compliances. Aspect ratio is fixed at 1 and normalized crack depth varies between 0.3 and 0.6. S11/S22 is fixed at four values; 20, 10, 1/10, and 1/20. Ranges of the other dimensionless material parameter relevant to existing materials are chosen. The use of linear interpolation for Y at intermediate values of S11/S22, and the relevance of the results to specimens with aspect ratios in excess of 1, are discussed. Y is presented at each value of S11/S22 in the form of a Chebyshev series in two variables. The results show that, if Y factors already established for isotropic materials are used to calculate stress intensity values for orthotropic specimens, errors in the stress intensity fac...

13 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the BERSAFE finite element computer program to model an equal diameter branch pipe intersection of mean diameter/thickness ratio 24.5 and compared the predicted stresses with results from tests on a 254 mm (10 inch) diameter welded branch junction, and also with the values from the current UK power piping code BS 806.
Abstract: The authors have used the BERSAFE finite element computer program to model an equal diameter branch pipe intersection of mean diameter/thickness ratio 24.5. Previous results for internal pressure and the two in-plane bending moments are augmented by the present results for the two out-of-plane and the two twisting moment load categories. The predicted stresses are compared with results from tests on a 254 mm (10 inch) diameter welded branch junction, and also with the values from the current UK power piping code BS 806.

13 citations


Journal ArticleDOI
TL;DR: In this paper, the internal forces and contact zones of a split ring inserted into a circular housing are examined analytically, numerically, and experimentally, and the results obtained show that only one third of the ring periphery is in contact with the housing and that the effects of the shear strain on the contact pressure profile are appreciable.
Abstract: The internal forces and contact zones of a split ring inserted into a circular housing are examined analytically, numerically, and experimentally. The mechanical components which can be likened to such a configuration are illustrated. The results obtained show that only one third of the ring periphery is in contact with the housing and that the effects of the shear strain on the contact pressure profile are appreciable.

13 citations


Journal ArticleDOI
TL;DR: In this article, a 600 lines mm phase grating is used in conjunction with a specularly reflecting (in some cases mirrored) object, to obtain contours of out-of-plane displacement.
Abstract: A high sensitivity technique for out-of-plane displacement is demonstrated. A 600 lines mm phase grating is used in conjunction with a specularly reflecting (in some cases mirrored) object, to obtain contours of out-of-plane displacement. Initial patterns due to low quality optics are eliminated by a double exposure technique employing carrier (or mismatch) fringes. Beams with cracks are used to experimentally demonstrate this technique.

12 citations


Journal ArticleDOI
TL;DR: In this article, the dynamic contact of an explosively excited disc with another disc or a halfplane was studied and dynamic photoelastic recordings showed the development of the time-dependent contact area and the formation of the highly complex diffraction pattern.
Abstract: This paper deals with the dynamic contact of an explosively excited disc with another disc or a half-plane. Dynamic photoelastic recordings show the development of the time-dependent contact area and the formation of the highly complex diffraction pattern.

Journal ArticleDOI
TL;DR: In this article, a procedure for enhancing finite element stress predictions is described, and the efficiency of the process is demonstrated by application to test cases, where the authors demonstrate that the procedure can be used to improve the performance of test cases.
Abstract: The formulation and implementation of a procedure for enhancing finite element stress predictions is described. The efficiency of the process is demonstrated by application to test cases.

Journal ArticleDOI
TL;DR: In this paper, the authors performed creep crack growth tests on compact tension specimens of 2 1/4CrlMo, C-Mn, and AISI 316 weld metals at 565°C, at 360 and 390°C respectively.
Abstract: Creep crack growth tests have been performed on compact tension specimens of 2 1/4CrlMo, C—Mn, and AISI 316 weld metals at 565°C, at 360 and 390°C, and at 600°C, respectively. The data have...

Journal ArticleDOI
TL;DR: In this article, an explicit formulae for the examination of plate post-buckling behaviour is presented. Butler et al. used the coefficients used in the equations were derived on the basis of curve fitting to a large number of computer solutions and are applicable to any buckle half wavelength or rotational restraint condition normally found in engineering structures.
Abstract: Explicit formulae are presented for the examination of plate post-buckling behaviour. Plates with simply supported loaded ends and having simply supported, fixed, or some intermediate, elastic restraint on edge rotation are considered, and it is assumed that the unloaded edges are free to wave in their own plane. The coefficients used in the equations were derived on the basis of curve fitting to a large number of computer solutions and are applicable to any buckle half wavelength or rotational restraint condition normally found in engineering structures. These equations are sufficiently simple to provide extremely rapid predictions of plate behaviour on any small microcomputer.Comparisons are made with some existing published results and the effects of imperfections, degree of edge rotational restraint, and buckle half wavelength are illustrated. The behaviour predicted for plates in the far post-buckling range is examined and shown in comparison with the design formula of von Karman. It is sugge...

Journal ArticleDOI
TL;DR: In this article, the numerical boundary integral equation (NBE) was employed for the stress analysis of a cylindrical cylinder with a radial cross-bore, and the maximum percentage overstrain that can be induced in the cylinder with k = 2.0 without re-yielding occurring when the radial hole is introduced, is found to be only 35 per cent.
Abstract: The numerical boundary integral equation method for three-dimensional elastostatics is employed for the stress analysis of a thick-walled cylinder with a radial cross-bore. The geometries considered are for cylinders with radius ratio k = 2.0 and 2.25, and with the cross-bore radius one-quarter that of the cylinder bore. Results showing the elastic stress distributions in an internally pressurized un-autofrettaged cylinder with the radial hole are presented. Using the classical superposition principle, the stress redistributions in partially autofrettaged tubes, due to the introduction of a cross-bore after autofrettage, are also obtained. The maximum percentage overstrain that can be induced in the cylinder with k = 2.0 without re-yielding occurring when the radial hole is introduced, is found to be only 35 per cent. The corresponding percentage overstrain for the cylinder with k = 2.25 is 27.5 per cent. From the computational results, it is also found that the variations of the resultant residua...

Journal ArticleDOI
A Kato1
TL;DR: In this article, a design formula has been derived to estimate stress concentration factors of grooved shafts with several kinds of groove shapes, based on the analytical result for infinitesimal grooves and for finite grooves, with the numerical values found by other investigators.
Abstract: A design formula has been derived to estimate stress concentration factors of grooved shafts with several kinds of groove shapes. This formula was based on the analytical result for infinitesimal grooves and for finite grooves the experimental values found by the author and others, with the numerical values found by other investigators. Over a wide range of groove sizes, the formula agrees fairly well with the numerical values of Nishitani et al. Comparison with Neuber's formula shows that his formula gives much lower values than the present one, especially for deep grooves.

Journal ArticleDOI
TL;DR: In this paper, an evaluation of the electropotential method for deriving the crack length in a sheet metal specimen is carried out and compared with an existing analytical and numerical method for calculating the relationship between electropotor and crack length.
Abstract: An evaluation of the electropotential method for deriving the crack length in a sheet metal specimen is carried out. Comparisons are made between an existing analytical and numerical method for calculating the relationship between electropotential and crack length. The numerical method allows an exact representation of the specimen geometry which enables the influence of asymmetrical crack growth on the electropotential to be examined. A case study to analyse this effect on the electropotential is discussed which indicates that underestimation of the crack length will occur which becomes increasingly significant as the voltage probes across which the electropotential is measured are placed closer to the crack. The paper shows that a compromise must be made with regard to voltage probe positioning between the desired sensitivity of the potential reading and tolerated vulnerability to asymmetric crack growth. Comparisons between experimental and theoretical derived potential crack length relationshi...

Journal ArticleDOI
TL;DR: The C* creep crack parameter, which characterises the stress and strain-rate fields in the vicinity of a crack tip, appears to correlate creep crack growth data better than any other parameter proposed to date.
Abstract: Many engineering components operate at temperatures high enough for creep to occur. These components inevitably contain cracks and/or crack-like flaws, which can propagate under creep conditions. The C* creep crack parameter which characterises the stress and strain-rate fields in the vicinity of a crack tip, appears to correlate creep crack growth data better than any other parameter proposed to date (1) (2)1. Reference stress concepts have been used to obtain equations for estimating C* (e.g., (3x6)). The equation derived by Harper and Ellison (3) has proved to be extremely useful because it allows C* values to be obtained from experimentally determined load-line displacement rates. Their derivation incorporates the use of an approximate limit load reference stress. This implies that the resulting formula for C* contains an error as a result of the use of the approximate limit load reference stress. This note contains a derivation in which a more accurate definition of reference stress is used. By comparing the resulting expression for C* with that of Harper and Ellison (3), it can be seen that the use of an approximate reference stress does not necessarily cause a significant error in the C* formula.

Journal ArticleDOI
TL;DR: In this article, a method to measure residual deformation in welded plates is presented, where an optical technique, called white light speckle, is used to record the released residual deformations.
Abstract: A method to measure residual deformation in welded plates is presented. An optical technique, called white light speckle, is used to record the released residual deformations. The method is destruc ...

Journal ArticleDOI
D Hui1
TL;DR: In this paper, the elastic and viscoelastic deflections and stresses of non-homogeneous rectangular or infinite floating ice plates subjected to central distributed lateral loads, where the loading region is of rectangular shape, or concentrated loads, were analyzed.
Abstract: This paper deals with the elastic and viscoelastic deflections and stresses of non-homogeneous rectangular or infinite floating ice plates subjected to central distributed lateral loads, where the loading region is of rectangular shape, or concentrated loads. The analysis takes into account the variation of Young's modulus of ice in the thickness direction. The Rayleigh—Ritz procedure is used to obtain the elastic solution for the deflections and bending moments, while the viscoelastic solution is obtained from the elastic response using the correspondence principle. Closed form Bessel-type elastic and viscoelastic solutions are obtained for infinite floating ice plates. Comparisons are made between the time-dependent response of infinite and finite square floating ice plates.

Journal ArticleDOI
TL;DR: In this paper, the buckling behavior of six horizontal storage vessels is assessed using two computer-based buckling programs, NASTRAN and BOSOR4, and the specific gravity of the liquid contents required to cause buckling in the support region was obtained by using the computer programs and also by using an equivalent cylinder length with the existing formulations given in the British Pressure Vessel Code, BS 5500 for axisymmetric loading.
Abstract: By using two computer-based buckling programs, NASTRAN and BOSOR4, the buckling behaviour of the support region of six horizontal storage vessels is assessed. The vessels are supported on twin saddles shown in Fig. 1(a) and of diameter/thickness ratios from 312 to 1154, and lengih radius ratios from 4 to 6.5. They were chosen to provide a range of typical vessels in present use. The specific gravity of the liquid contents required to cause buckling in the support region was obtained by using the computer programs and also by using an equivalent cylinder length with the existing formulations given in the British Pressure Vessel Code, BS 5500 for axisymmetric loading. Comparison of these approaches is used to validate a procedure for finding an allowable buckling stress, hitherto not available for this component.

Journal ArticleDOI
TL;DR: In this article, Monte Carlo simulation techniques are used in conjunction with pivotal quantities of the two parameter Weibull distribution (or three parameter WeIBull distribution with prescribed threshold stress) to calculate confidence bands for the probability of failure of thin annular discs subjected to centrifugal loading.
Abstract: Monte Carlo simulation techniques are used in conjunction with the pivotal quantities of the two parameter Weibull distribution (or three parameter Weibull distribution with prescribed threshold stress) to calculate confidence bands for the probability of failure of thin annular discs subjected to centrifugal loading. The theoretical predictions, assuming either volume or surface defects govern failure, are compared with experimental fracture data.

Journal ArticleDOI
TL;DR: In this article, a metallic cylinder (e.g., a rocket motor case) circumferentially reinforced with a pre-strained fibre overwind with viscoelastic properties is developed for calculating the pressure for first yield in the metallic case and the optimum winding conditions for both short and long times.
Abstract: : Nomographic design procedures are developed for a metallic cylinder (eg a rocket motor case) circumferentially reinforced with a pre-strained fibre overwind with viscoelastic properties Techniques for calculating the pressure for first yield in the metallic case and the optimum winding conditions for both short- and long-times are presented, together with a technique for determining the maximum fibre stress Design examples are presented with each nomogram in turn and the graphical results are compared with exact numerical results

Journal ArticleDOI
TL;DR: This paper shows that a microcomputer can be used for the analysis of a bulk metal forming process where there are both geometric and material non-linearities, and an elastic-plastic finite-element method is used, with SSS-Fortran as the computing language.
Abstract: In recent years microcomputers have become more powerful and for some purposes are now able to compete with minis and mainframe computers. It is now possible to implement a wide variety of CAD packages and linear finite-element stress analysis programmes on microcomputers, but the solution of non-linear problems - for example, forging - is more complex.This paper shows that a microcomputer can, nevertheless, be used for the analysis of a bulk metal forming process where there are both geometric and material non-linearities. The programs give reliable estimates of metal flow, grid distortions, stress, and strain distributions in the workpiece, as well as the forming force. An elastic-plastic finite-element method is used, with SSS-Fortran as the computing language. The results of such simulations can be used in-house to form the basis of improved forging die design, and, hence, a better final product, without the need for much of the expensive and time-consuming experimental trials currently practi...

Journal ArticleDOI
TL;DR: In this article, a method of designing power transmission drive shafts is described based on two interactive computer programs, which can model shafts of any configuration and under any system of loads and supports.
Abstract: A method of designing power transmission drive shafts is described based on two interactive computer programs. The first program can model shafts of any configuration and under any system of loads and supports. The program is based on the finite element method. Reducing the size of the stiffness matrix by storing only the parameters in the matrix bandwidth and by overlaying the stiffness matrices, the problem of using finite element analysis on small memory microcomputers can be solved. A menu allows the designer to specify machine elements, such as spur or bevel gears or pulleys, to be positioned at any point along the shaft. The user can give information of the power transmitted, speed, and details of the physical dimensions of the machine elements which then enables the program to determine the force vectors and apply these to the shaft nodes.The second program determines the design factors of safety on the basis of both static and cyclic loads. For cyclic loads the factors of safety are based ...

Journal ArticleDOI
TL;DR: In this article, an approximate method based on the reference stress concept for carrying out "moving-crack" calculations, under creep conditions, is presented, where creep crack growth is assumed to be related to the C∗ parameter.
Abstract: An approximate method, based on the reference stress concept, for carrying out ‘moving-crack’ calculations, under creep conditions, is presented. Creep crack growth is assumed to be related to the C∗ parameter. The predictions obtained correlate well with detailed, ‘moving-crack’, finite element calculations.Preliminary calculations, to assess the adequacy of finite element meshes and the effect of variations in material properties on the accuracy of predictions, can be carried out quickly and relatively cheaply. The usefulness of the technique is illustrated by using it to show the effect of the magnitude of the crack growth increment assumed and of the value of critical crack tip opening displacement (the initiation parameter assumed) used.

Journal ArticleDOI
TL;DR: In this paper, the optimization of the angle-stiffened panel under compression using the feasible direction method is studied, with the result that the process of calculation is greatly simplified.
Abstract: The optimization of the angle-stiffened panel under compression using the feasible direction method is studied in this paper. We could only take the most critical constraint into account for each iteration when using the feasible direction method, with the result that the process of calculation is greatly simplified. It is beneficial for stability and convergence of the design process that the design variables in each iteration are modified once by some experience formulae, if necessary. The illustrative examples and the comparison of the numerical results of this paper with those of another paper indicate the effectiveness and efficiency of the method presented here.

Journal ArticleDOI
TL;DR: In this paper, a variable load tension-compression creep machine (±50 kN) is described, which overcomes the disadvantages of servo-hydraulic and recirculating ball screw testing machines.
Abstract: The design and development is described of a variable load tension-compression creep machine (±50 kN) which overcomes the disadvantages of servo-hydraulic and recirculating ball screw testing machines. The use of dead weight levers to apply specimen loads ensures the achievement of low running costs. Screwed end specimens are used with a 25.40 mm parallel sided gauge length and a diameter of 12.70 mm. It is shown that, provided modest rates of loading (0.4 kN/s) are used, high accuracy ‘through zero’ loadings can be achieved. The machine has been shown to operate satisfactorily for long periods under tension-compression high temperature creep.

Journal ArticleDOI
TL;DR: In this article, the effect of the friction conditions between the flange and ring was investigated and the use of recesses on the back faces of flanges, to control the load position, was investigated.
Abstract: Finite element and photoelastic methods of stress analysis have been used to study the effects of pressure loading on the behaviour of swivel ring flanges. The use of recesses on the back faces of flanges, to control the load position, were investigated. The effect of the friction conditions between the flange and ring were also considered. It was found that the inclusion of a recess can significantly reduce the highest stresses, which occur in the flange/hub fillet radius. The friction conditions between the flange and ring were also found to have a significant effect on the stresses.