Showing papers in "Journal of Strain Analysis for Engineering Design in 1985"
TL;DR: In this paper, a noncontact, full-field, stress analysis technique based on the measurement of the intensity of infra-red radiation emitted from the surface of a cyclically loaded body is applied to series of metallic specimens (including beams in bending, the ‘Brazilian’ disc, and a simple pure-shear testpiece).
Abstract: A new non-contact, full-field, stress analysis technique based on the measurement of the intensity of infra-red radiation emitted from the surface of a cyclically loaded body is applied to series of metallic specimens (including beams in bending, the ‘Brazilian’ disc, and a simple pure-shear testpiece) and critically appraised.
151 citations
TL;DR: In this paper, a neutron diffraction method has been applied to measure residual stresses in rings sliced from as-recieved and autofrettaged thick-walled steel tubing.
Abstract: A neutron diffraction method has been applied to measure residual stresses in rings sliced from as-recieved and autofrettaged thick-walled steel tubing. The principles of neutron diffraction are outlined and the method is described. A comparison is made with results obtained using the more traditional Sachs boring technique. It is shown that satisfactory agreement is achieved between the two procedures and that the neutron diffraction method can be used with acceptable accuracy to measure residual stress non-destructively in bulk samples of steel several centimetres thick.
99 citations
TL;DR: In this article, a general method is presented to evaluate the contact stresses and the contact area from the full field photoelastic data, which utilizes the least squares technique in conjection.
Abstract: A general method is presented to evaluate the contact stresses and the contact area from the full field photoelastic data. The procedure utilizes the least squares technique in conjection w...
36 citations
TL;DR: In this paper, an extrometer was designed to record simultaneously the extension and rotation over a predetermined gauge length of a wire rope strand with polyester resin and silica filler in conical end grips which are capable of full end fixity, partial restraint, or zero torsional resistance.
Abstract: Experimental tests are reported on wire rope strands subjected to static axial loads. The wire rope strands are held with a polyester resin and silica filler in conical end grips which are capable of full end fixity, partial restraint, or zero torsional resistance (free ends). Strain gauge load cells monitor the tensile load and the associated twisting moment developed in a strand which is restrained at both ends. A new instrument (‘extrometer’) was designed to record simultaneously the extension and rotation over a predetermined gauge length. Strain gauges are used to measure the surface strains on the wires in the outer layer of the strand.Preliminary tests on seven-wire strands demonstrate that the extrometer instrument provides reliable results. The extension and rotation characteristics recorded on a seven-wire strand under tensile load agree reasonably well with the corresponding theoretical predictions, but the wire surface strains reveal an unequal load sharing between nominally identical ...
29 citations
TL;DR: Paperboard strength under biaxial normal plus shear stresses is predicted using Hill-type criteria (including Tsai-Hill, Norris, Fischer, and Ashkenazi) as discussed by the authors.
Abstract: Paperboard strength under biaxial normal plus shear stresses is predicted using Hill-type criteria (including Tsai-Hill, Norris, Fischer, and Ashkenazi). Results are compared throughout all four quadrants with experimental data obtained from on- and off-axis uniaxial coupons, cylinders, and cruciform specimens. The Norris and Fischer theories predict observation quite well except at higher values of shear stress where they become too conservative. The Tsai-Hill theory is conservative throughout. Simplicity of both analysis and implementation, plus need for only minimal experimental input data, are signficant advantages of Hill-type criteria. Moreover, their reliability for paper is comparable to that of other published results. Other strength theories will be addressed in subsequent papers.
29 citations
TL;DR: In this paper, a two-dimensional plane-stress finite element model was used to determine the strain energy release rate of a crack in a circular cross-section of a bar.
Abstract: A bar of circular cross-section is modelled with two-dimensional plane-stress finite elements. The bar has a crack at its edge, the front of which is a circular arc. The ends of the bar remote from the crack are subjected to either an axial load or a bending moment in the plane of symmetry of the cracked section. The strain energy release rate of the crack is determined from a finite element model as the rate of change of elastic energy in the bar for successive positions of the circular arc crack front. The values of strain energy release rate so determined are found to be comparable with existing results obtained from three-dimensional finite element analyses. The effect of curvature is found to cause a reduction in the strain energy release rate compared to that for a straight fronted crack of the same maximum depth in a bar under the same loading conditions. The results obtained are superimposed to obtain strain energy release rates for the circular are crack edge subjected to a combined tensi...
23 citations
TL;DR: In this article, the effects of possible stress concentration at the ends are considered and compared with theoretical results for a variety of biaxial loading conditions under various combinations of internal pressure and axial tension or compression.
Abstract: Fifty, 100 mm diameter ± 75 degree filament wound E glass fibre/epoxy resin tubes have been tested to destruction under various combinations of internal pressure and axial tension or compression. The test equipment and procedures are described. The method of reinforcing and gripping the ends of the specimens avoided end failures. The effects of possible stress concentration at the ends are considered. Experimental fracture stresses are presented and compared with theoretical results for a variety of biaxial loading conditions.
21 citations
TL;DR: In this paper, six photoelastic frozen stress models of ISO nut-bolt connections loaded in pure tension were studied and four of these models had modifications to the threads at the load bearing end of the nut.
Abstract: Six photoelastic frozen stress models of ISO nut-bolt connections loaded in pure tension were studied. Four of these models had modifications to the threads at the load bearing end of the nut. These modifications included tapered truncation of the thread crests and taper of the whole thread form for a portion of the nut length.The maximum stress in the bolt always occurred within one pitch of the load bearing face of the nut. Truncating threads increased the maximum bolt stresses. Tapering the whole thread form reduced the maximum stress and produced a more uniform load distribution in the bolt.The conditions at the load bearing face of the nut were found to influence the load distribution in the bolt threads more than the stress concentrations in the bolt.
16 citations
TL;DR: In this paper, a finite element model of the lug of a pin-lug assembly is used to calculate the stresses in the lug, assuming a rigid pin and negligible friction between the pin and the lug.
Abstract: The stresses in the lug of a pin-lug assembly can be easily calculated using a finite element model of the lug, provided the load distribution is known. Described in this paper is a technique which utilizes the finite element mesh of the lug to model the loading on the lug at the pin-lug interface. The technique has been incorporated into a finite element program which was then used to calculate the stresses in the lug. These calculated results, assuming a rigid pin and negligible friction between the pin and the lug, were compared with those obtained from a photoelastic study and agreement was found to be good.
15 citations
TL;DR: Experiments on the buckling and ultimate capacity of thin-walled steel web plates containing circular and square cut-outs are reported in this paper, where 64 tests were carried out on plates containing e...
Abstract: Experiments on the buckling and ultimate capacity of thin-walled steel web plates containing circular and square cut-outs are reported. Some 64 tests were carried out on plates containing e...
13 citations
TL;DR: In this paper, the authors investigated fracture toughness in terms of J and COD at or beyond initiation to ductile tearing using mainly three point bend pieces of HY130 steel in a variety of proportions.
Abstract: Fracture toughness in terms of J and COD at or beyond initiation to ductile tearing were investigated using mainly three point bend pieces of HY130 steel in a variety of proportions. J values are adjusted for crack growth to obtain the resistance curve (R-curve).The R-curve was observed to become shallower with increasing width and thickness of test piece, and for longitudinal (TL) rather than short transverse (TS) crack propagation, but steeper with scaling to smaller absolute sizes, and decreasing thickness and width. For full thickness plates, the R-curve for tension was much steeper than bending. Discussion is given on the size requirements for a geometry independent R-curve, according to the present test data.
TL;DR: In this paper, the stress concentration factors at circumferential grooves in round shafts under torsion have been investigated by experiment and the copper electroplating method has been used to measure the stresses at groove roots.
Abstract: The stress concentration factors at circumferential grooves in round shafts under torsion have been investigated by experiment. The copper electroplating method has been used to measure the stresses at groove roots. The experimental results are compared with Neuber's solution and the numerical values reported previously.
TL;DR: An alternative approach to arrive at the fundamental solution of the boundary integral equation (BIE) for axisymmetric elastostatic problems with rotational body force is presented in this paper.
Abstract: An alternative approach to arrive at the fundamental solution of the boundary integral equation (BIE) for axisymmetric elastostatic problems with rotational body force is presented The formulation is implemented in an elastostatic BIE axisymmetric program using isoparametric quadratic elementsThe method is applied to rotating disks of constant or variable thickness and linearly tapered The results compare very well with avaialable analytical and numerical solutions
TL;DR: The results of 27 creep crack growth tests performed on four different specimen types (CT, 3PB, ECP, and CCP) are reported in this paper, where a lead alloy, previously used as a creep "model material" was used.
Abstract: The results of 27 creep crack growth tests performed on four different specimen types (CT, 3PB, ECP, and CCP) are reported. A lead alloy, previously used as a creep ‘model material’ was used. Of the parameters commonly used to correlate creep crack growth data, the C∗ parameter was found to be the best for the lead alloy data. It is concluded that the lead alloy may be useful for ‘modelling’ the creep crack growth rates in components made of other materials with similar creep ductilities.
TL;DR: In this article, three simple material models are used to calculate the amount of primary plastic strain accumulated in this type of problem, which leads to closed form solutions that overestimate the accumulated in experiments performed by Lebey et al. to model these situations.
Abstract: Some structural situations encountered in the design of the liquid metal fast breeder reactor (LMFBR) can be reduced to problems where an element of material is subjected to a constant primary load and a cyclic secondary strain. Three simple material models are used to calculate the amount of primary plastic strain accumulated in this type of problem. The analyses lead to closed form solutions that overestimate the amount of strain accumulated in experiments performed by Lebey et al. (2)† to model these situations.
TL;DR: In this paper, an analytical study was performed to investigate the flexibility of nozzless in pressure vessel heads and the results showed that the nozzles in hemispherical and ellipsoidal pressure vessel head can be adapted to different shell parameters.
Abstract: An analytical study is performed to investigate the flexibility of nozzless in pressure vessel heads. Classical thin shell theory is employed. Radial flexibility factors for nozzles in hemispherical and ellipsoidal pressure vessel heads are presented as graphs of non-dimensional shell parameters.
TL;DR: In this article, the combined effects of imperfections in the form of the meridians and meridional cracks in axially loaded cylindrical shells are studied by means of a finite element program capable of handling well defined, discrete cracks.
Abstract: The combined effects of imperfections in the form of the meridians and meridional cracks in axially loaded cylindrical shells are studied by means of a finite element programme capable of handling well defined, discrete cracks. Two basic mechanisms are shown to occur in shells in such a state: first, a redistribution of vertical load away from the cracked zone, and second, a redistribution from hoop membrane to meridional bending action.The mechanics of behaviour of shells with imperfections in the geometry and cracks are systematically studied by examining the effects of shell, imperfection, and crack characteristics, so that the dominant parameters controlling the linear elastic response of the shell can be isolated. Numerical experiments show that those parameters that influence the behaviour in an uncracked imperfect shell also influence the stresses accompanying cracking.
TL;DR: By rotating the reference grating in its own plane, the sensitivity of the shadow moire method can be continuously varied as discussed by the authors, which can additionally assist in distinguishing hills and valleys in foot pressure measurement.
Abstract: By simply rotating the reference grating in its own plane, the sensitivity of the shadow moire method can be continuously varied. This approach can additionally assist in distinguishing hills and valleys. Application to foot pressure measurement is demonstrated.
TL;DR: In this article, a method of fracture toughness testing is proposed in which cylindrical surface-notched specimens are tested in torsion, and the results show that the values of K1 which are induced are not sensitive to the precise shape of the notch.
Abstract: A method of fracture toughness testing is proposed in which cylindrical surface-notched specimens are tested in torsion. Analyses are presented which show that the values of K1 which are induced are not sensitive to the precise shape of the notch. Also, the existence in the torsion specimen of a non-constant remote stress, and a curved specimen surface, are shown by finite element modelling to have only a small effect on the K1 values. These findings are used to justify the use of simple models to analyse results from the proposed test.
TL;DR: In this paper, mode I and mode II stress intensity factors are found for a slant straight crack buried in an elastic half-plane, and the form of the solutions is appropriate only for cases in which the crack remains open, though with modification interfacial Coulomb friction may be accommodated.
Abstract: Mode I and mode II stress intensity factors are found for a slant straight crack buried in an elastic half-plane. Loading is in the form of point forces applied to the crack faces so that the solutions given can then be used as Green's functions in solving half-plane problems where the surface load is arbitrary. The form of the solutions is appropriate only for cases in which the crack remains open, though with modification interfacial Coulomb friction may be accommodated.
TL;DR: In this article, the authors describe a set of thermal shock experiments on copper plates between room temperature and 250°C and compare the experimentally observed creep rates with the predictions of two alternative simplified methods of analysis.
Abstract: The paper describes a set of thermal shock experiments on copper plates between room temperature and 250°C. The experimentally observed creep rates are compared with the predictions of two alternative simplified methods of analysis. The first involves rapid and slow cycle solutions which are computed using finite elements for two constitutive equations derived from the same constant stress data. The second involves upper bounds derived from shakedown solutions. It is shown that conservative results can be computed provided an appropriate relationship between average strain rate and cyclic stress history is known. The experimental data shows a sharp transition from a rapid cycle to a slow cycle condition as the load is increased above the high temperature shakedown limit.
TL;DR: In this paper, seven identical stepped beams, made of a lead alloy, were loaded by steady tension and cyclic bending, and three bending moments superimposing equal hogging and sagging were used in the tests.
Abstract: Seven identical stepped beams, made of a lead alloy, were loaded by steady tension and cyclic bending. Three bending moments superimposing equal hogging and sagging were used in the tests. Six different tensions were also used. After test of 15 cycles, most beams were re-loaded with a greater mean tension and the same cyclic bending moment. Strains were measured in the (circular arc) fillets at the step and in the shank.Ratchetting strains per cycle decreased during each test; steady values were estimated and related to the load magnitudes. The common use of the 0.2 per cent proof stress as the yield stress for an equivalent elastic-perfectly-plastic materials has been shown to be extremely conservative.
TL;DR: In this article, a constitutive model which exploits the unique time and regain-coupled creep response of these materials is presented, which is then used to predict the creep response as a function of regain using experimental data obtained from a few simple tests on cellulosic handsheets.
Abstract: For a class of materials called regain-rheologically simple, creep curves at various regain states can be shifted along the time axis in such a manner as to generate a single (master) curve. A constitutive model which exploits the unique time and regain-coupled creep response of these materials is presented. The model is then used to predict the creep response as a function of regain using experimental data obtained from a few simple tests on cellulosic handsheets.
TL;DR: In this article, the results from three lead alloy stepped beam components, subjected to steady axial load and cyclic bending, are compared with predictions based on elastic-perfectly plastic, isotropic hardening, and kinematic hardening material behaviour models.
Abstract: Finite element programs are often used, without experimental verification, to predict the elastic-plastic behaviour of components, but most programs only contain simple material behaviour models. In this paper, the results from three lead alloy stepped beam components, subjected to steady axial load and cyclic bending, are compared with predictions based on elastic-perfectly plastic, isotropic hardening, and kinematic hardening material behaviour models. These comparsions show that under severe load conditions, in which cyclic plasticity occurs, none of these simple models provides good predictions for the ratchetting behaviour of the beams. This is because the models do not accurately describe the cyclic elastic-plastic behaviour of the lead alloy which is similar to that of many engineering materials. It is concluded that the simple elastic-plastic material behaviour models included in most finite element packages will have to be extended to include more accurate models of material cyclic behavi...
TL;DR: In this article, the static response of a rectangular curved panel to a central radial loading is examined, both for the panel alone and when reinforced at its centre by a circular pad containing a concentric hole.
Abstract: The static response of a rectangular curved panel to a central radial loading is examined, both for the panel alone and for the panel when reinforced at its centre by a circular pad containing a concentric hole. The examination comprises tests on a physical model, in which point displacements and strains are measured, and numerical studies using the finite element method with two markedly different types of element in turn. The object is to study the quality of the correlation between the results of the physical experiments and the two types of finite element analysis, and it is demonstrated that such correlation is good. Particular considerations is given to the finite element modelling of the pad/panel combination and it is shown that because of the relatively large rigidity of the pad it is possible to provide viable finite element models for the panel behaviour by eliminating the pad from consideration.
TL;DR: In this article, a yield zone which is able to both shear and rotate has been obtained for a material with a square yield criterion, which is then used in analyses to obtain upper bounds on the collapse loads for masonary infills with openings.
Abstract: The work done in a yield zone which is able to both shear and rotate has been obtained for a material with a square yield criterion. Yield zones which either rotate or shear only are shown to be special cases. These yield zones are then used in analyses to obtain upper bounds on the collapse loads for masonary infills with openings in framed structures. Lower bounds on the collapse load are also obtained. In all cases analysed the discrepancies between the upper and lower bounds on the collapse load are small. Using the results obtained from the analyses, proposals are made for a design method for infilled panels with openings.
TL;DR: In this article, the three-dimensional axisymmetric boundary value problem of pressure vessels with torispherical drumheads is analyzed easily and accurately by the use of the indirect fictitious boundary integral method.
Abstract: The three-dimensional axisymmetric boundary value problem of pressure vessels with torispherical drumheads is analysed easily and accurately by the use of the ‘indirect fictitious-boundary integral method’. The analysed configurations are similar to each other but have different thicknesses. The comparison of the resent results with photoelasticity and shell theory solutions makes it clear that the shell theory based on Love's first approximation is very reasonable. Additionally, a vessel with hemispherical drumheads with varying thickness from cylinder to head, which is noteworthy for reducing the maximum stresses in the vessel, is studied.
TL;DR: In this article, two approaches have been suggested to predict the conditions for ductile crack propagation from a pre-existing defect, i.e., the T approach of Paris et al. and the I approach of Turner, based on the stability of the equilibrium state between the applied value of the J integral and the J versus crack extension material resistance curve.
Abstract: One mode by which a structure can fail in an unstable manner is ductile crack propagation from a pre-existing defect. Two approaches have been suggested to predict the conditions for such an instability. These are the T approach of Paris et al. and the I approach of Turner. The Paris T approach is based on the stability of the equilibrium state between the applied value of the J integral and the J versus crack extension material resistance curve. Under linear elastic conditions instability may be interpreted as occurring when the second differential of available energy (with respect to crack extension exceeds that required for crack extension. In the elastic-plastic regime this interpretation is lost and the tearing modulus approach uses the J integral as a crack tip field characterising parameter. The Turner approach, on the other hand, is based on the balance between the energies available and required for crack extension. Under linear-elastic conditions instability occurs when the first differe...