bluuebunny/crossref_metadata_2025_split huggingface dataset:
STRESSES DUE TO CONCENTRATED LOADS IN RESTRAINED BENDING TESTS
Authors: CHEUNG Y. K. , DAVIES J. D. , NATH P. 
Published: October 2008

The paper describes an analytical method using finite element techniques for evaluating the “pinching” stresses in a beam subjected to opposing concentrated forces acting on upper and lower faces. These conditions arise in restrained modulus of rupture tests on concrete beams when it is required to know the magnitude of these local stress concentrations in relation to the normal “straight line” flexural stress field.The analytical values are compared with results taken from a photo‐elastic model with suitably simulated loading conditions. There is excellent correlation between the patterns of principal shear contours as plotted from the finite element solution and the isochromatic lines observed in the loaded model.
Electrical noise
Authors: BARNES S. G. 
Published: October 2008

An important consideration in the measurement of high accuracy, low level, differential data signals is the effect of electrical interference or ‘noise’.The various techniques which can be used to minimise these effects, or reduce them, are considered. Typical sources of noise encountered in instrumentation systems are discussed and the additional problems associated with transmission systems are described. An analysis of the fundamental noise problem, capacitive coupling, is presented and an outline of the design principles which are necessary for accurate, noise–free measurements is given.
Stress measurement by X–ray diffraction using film techniques
Authors: ANDREWS K. W. , GREGORY J. C. , BROOKSBANK D. 
Published: October 2008

For some X–ray stress measurement applications the photographic film methods may be preferred to diffractometer methods. The principles applied to the former are reviewed and the accuracy and sources of error are examined. The main procedures include the standard ‘two exposure’ method (including the use of the sin2 method), and the use of a relationship depending on the asymmetry of rings at oblique incidence. A number of apparent errors in the literature are explained and resolved. The simplest formula for the second method takes the form s̀=k.δR.In the most favourable cases the accuracy of stress measurement is of the order of ±30 MN/m2 or ±2 ton f/in2. Larger errors arise for hardened surfaces with microstresses, and are likely to be larger for the second method. Both methods obviously give the most favourable results when sharp diffraction rings are obtained. However with proper care and appreciation of the factors considered, practically usefulresults are obtained under most circumstances. The treatment is illustrated by particular reference to surface residual stress measurement on steels.
Brush coating of resists for normal and high frequency moiré techniques
Authors: DE CALUWÉ M. 
Published: October 2008

A limitation on the use of normal moiré technique may be the practical difficulties which can be encountered on coating the resist layers for the production of etched gratings. A description is given of a simple coating method which can be applied to any testpiece and which requires only a brush and some skill on the part of the operator.The method can also be used to coat resist layers suitable for the production of high frequency gratings of more than 1 000 lines/mm (25400 lines/in).
Accurate measurement of residual stress on any steel using the centre hole method
Authors: BEANEY E. M. 
Published: October 2008

The centre hole method has been shown to be a simple and reasonably accurate method of measuring residual stress. With a 1.6 mm diameter hole, the method can be applied on operational plant and the equipment required is sufficiently portable for use on site. Its application has, however, been limited to use on low‐strength steels, due to problems associated with forming the hole.This paper describes the development of an air‐abrasive technique for forming the hole, which allows the centre hole method to be used on any steel with a measurement accuracy of better than±8%.
A five‐component strain gauge wind tunnel dynamometer
Authors: MOLLAND A. F. 
Published: October 2008

The design, construction and calibration of a five‐component dynamometer is described. The dynamometer was constructed primarily for the testing of ship control surfaces including, in particular, skeg rudders; it has facilities for the independent adjustment of angle of attack, and the derivation of the forces and moments, on both rudder and skeg.An outline of the specialised design requirements is given. The basic design concept is described together with the reasons for the choice of shear flexures and their dimensions, strain gauges, circuits, bridge voltages and instrumentation. Following a brief description of the calibration rig and programme, the calibration results and origins of interactions are described and discussed.It is concluded that the relatively small size of the interaction corrections and overall measuring accuracy of the dynamometer confirm the choice of the overall design concept and design details.
Effect of temperature on vibrating wire strain gauges
Authors: MARSHALL J. K. , HUNTER P. 
Published: October 2008

Vibrating wire strain gauges attached to buried pipe can exhibit changes in strain readings when subjected to changes in ground temperature. It is essential that the correct interpretation is placed upon the readings. An analysis is given which, it is suggested, will give true pipe strain values from the indicated strain readings. Two solutions are outlined, a graphical analysis which tends to be intuitive and a theoretical analysis which derives a solution from first principles.True strain in the pipe is influenced by thermal effects due to changes in ground temperature, and mechanical effects due to the constraint placed upon the pipe by the surrounding soil. Both analyses consider the thermal and mechanical components of true strain and the theoretical analysis enables these individual components to be determined from the indicated strain readings.
Two simple methods for deformation demonstration and measurement
Authors: SEVENHUIJSEN J. 
Published: October 2008

A problem in the area of the investigation of structural behaviour is the elastic plastic deformation in the vicinity of disturbances like crack tips. Intrinsically the deformation can be measured by measuring the deformation of a grid on the surface in the vicinity of the disturbance. The paper describes a new simple grid system. The grid system consists of the picture layer of a selected photo printing paper. The picture layer is pealed off its carrier and is bonded on the polished specimen surface by means of a fresh cyanoacrylate cement. This system can sustain deformations up to 40% and has a very good contrast. A square grid is bonded on the local surface, the grid is photographed at several load values and later the negatives are magnified and read by means of an image analyser.A relevant question arising in the investigation of the buckling of a metal sheet with Z‐section stringers is how the sheet and the stringers deform relative to each other. This is answered by bonding drinking straws perpendicular to the surface of the specimen at several locations. When the surface rotates out of plane the free ends of the straws show relatively large displacements which have been recorded by means of a 35 mm film camera. The free ends of the straws have been provided with small white disks with central black dots. Films are read by means of an image analyser. Very small differences in rotations between the stringer heads and the sheet can be detected before the specimen collapses.
The prediction and measurement of axial forces, bending moments and accelerations in an engine connecting rod
Authors: TILBURY R. J. 
Published: October 2008

An engine connecting rod was fitted with two accelerometers, an axial force bridge and a bending moment bridge. These transducers enabled the acceleration components (along the connecting rod axis and perpendicular to it), the axial force and the bending moment, to be measured at the transducer locations.A theoretical method of analysis was carried out and a computer programme was developed, for use on a PET computer, to execute the repetitive calculations of the above mentioned quantities.The connecting rod was fitted into a Ford two‐litre OHC automotive engine. A few components were manufactured to complete the test rig.Three engine tests were conducted using combinations of engine load and cylinder gas pressure. The outputs from the transducers were recorded on photographic film from a galvanometer recorder. The traces were then analysed to reveal the variation of the dynamic properties with crankshaft angle.The experimental and theoretical results of the three tests were compared. The experimental accelerations and axial force were in close agreement with the predicted results. However, the experimental and the predicted bending moment distribution, did not agree at all well.
A simple graphical method to determine the action of a system of retarders
Authors: KESHAVAN S. Y. 
Published: October 2008

Graphical methods for the study of the transformation of polarised light are essentially pictorial representations of the changes in the polarisation of light as it passes through a system of polarisers and retarders. The analysis is common in both photoelasticity and crystallography. These graphical methods are useful:

In finding the changes in the light ellipse parameters as the polarised light passes through various elements of the polariscope, without cumbersome calculations.
In finding the characteristic parameters of a particular light path in a three dimensional photoelastic model or for a series of linear retarders.
In estimating various errors in the elements of the polariscope.

In the proposed method, knowing the characteristic parameters along a particular light path, a simple graphical method for determining the linear retarders which cause the variation of polarisation of light along the light path is illustrated.In a general loaded three dimensional photoelastic model, the characteristic parameters can be found at intervals along the light path. This graphical method makes use of the characteristic parameters and splits the light path into individual retarders which cause the combined effect for the light path.
Three methods to ascertain proper compensation in a general system of retarders
Authors: KESHAVAN S. Y. 
Published: October 2008

One can regard a three dimensional photoelastic model as a general system of linear retarders. These linear retarders can he individually separated out using a compensator. In the general case, a compensator can he used to cancel the combined effect of the linear retarders up to a certain required point along the light path. The discrete linear retarders from the point of entry of light to the model to the point along the light path under consideration can be replaced by a resultant optically equivalent model which is characterised by three discrete quantities called the characteristic parameters.1 If the compensator cancels the characteristic retardation completely and is orientated along the axis of the linear retarder of the optically equivalent model for any general light path, such a configuration of the compensator would correspond to the ideal case of compensation. However there could exist, for any particular three dimensional model, particular values of characteristic parameters, which, along with the value of retardation introduced by the compensator would result in a resultant optically equivalent model having the same primary and secondary characteristic directions2 as in the ideal case of compensation. This can lead to a misinterpretation of the results.In this paper three very simple methods have been described to ascertain the correct positioning of the compensator.
Minimum intensity seeking positions in polariscope set‐ups
Authors: Keshavan S. Y. 
Published: October 2008

Conventional polariscope set‐ups like the plane polariscope or the dark or bright field set‐ups specify the positions of the various optical elements with respect to the polarising axes of the photoelastic model for determining the isoclinic and isochromatic parameters.In this paper, it is shown that such specification is not necessary since, for any light path, the positions of the optical elements for an absolute minimum in intensity of the light emerging from the analyser are unique. To illustrate this, the case of a general retarder introducing a retardation 2δ at an azimuth θ with respect to the axis of the polariser is discussed and the conditions for the determination of the isoclinics and isochromatics are obtained.
Extension to the blind hole drilling technique for residual stress determination with airabrasive hole forming
Authors: Owens Alan 
Published: October 2008

For an austenitic clad ferritic steel plate it was necessary to determine the residual stress state between the austenitic surface and a region below the austenitic/ferritic interface.The thickness of claddings was 6 mm and to determine the stress variation between the surface and 8 mm an incremental analysis is required. Any material removal en masse in conjunction with small hole residual stress measurements would have resulted in a stress redistribution and hence a distortion in the stress field being measured. In conjunction with strain change measurements on the other face the sensitivity would not have been sufficient. These two options assume that a thin layer of material over relatively large areas can be removed by a non‐stress inducing technique.A blind hole residual stress measurement using a 13 mm diameter hole 13 mm deep will facilitate accurate incremental analysis to a depth of 8 mm.The end mill method of hole forming cannot be used with stainless steels because of the random damage effect which is induced in the readings. The airabrasive method which induces no damage effect was used.The standard airabrasive method of hole forming produces a 2 mm diameter and a 2 mm deep hole.The modification of the standard airabrasive system is discussed which enables 13 mm diameter and 13 mm deep holes to be formed.A deviation from the standard hole/gauge layout geometry has been investigated due to non‐availability of suitable standard rosettes, and a significant increase in sensitivity has been obtained.The incremental stress results for the austenitic layer and the austenitic/ferritic interface are discussed using the results from 1.6 mm, 3.2 mm and 13 mm diameter/deep holes.
Photographic evaluation techniques in photoelasticity—Part 1
Authors: Meyer M. L. , Mehrotra C. L. 
Published: October 2008

Sharp boundaries or thin lines seen on high contrast or Agfacontour photographs of optical fringes are interpreted as equidensity lines and calibrated for fractional order or isoclinic angle. Systematic variation of exposure determinants changes their positions and parameters so that the entire photographed field can be evaluated from sets of photographs either taken directly or copied from one or a few low contrast negatives. Photogrammetry resolves spatial detail down to 0002mm spot size and relates photoelastic results to model outlines and deformation measured on the same films.The practical aspects of photography, exposure variations and evaluation are treated in this overview published in two parts. Part 1 covers photographic methods and application to isochromatics, Part 2 evaluation and calibration for fractional orders with examples, application to isoclinics and a summary of main features.
Wire tensions and bending moments in axially loaded seven wire strand
Authors: Utting W. S. , Jones N. 
Published: October 2008

Carefully instrumented tensile tests were performed on a straight single steel strand of seven‐wire construction having core and helical wire diameters of 3–66 mm and 3–33 mm, respectively, and a lay angle of 14‐6d̀. Strain gauges in groups of three with their grid axes parallel and having a common backing were attached to all six helical wires at the mid‐strand position. For loading within the linear range of the load‐extension response (all tests) and load‐rotation response (in tests with free and partial torsional restraint of the ends) the outputs from these strain gauges were used to compute wire tensions and bending moments. Strand extension, rotation and torque generated under axial load (fixed‐end and partial torsional restraint) were also recorded.Test results showed that the share of the total strand load taken by the helical wires decreased as the torsional restraint on the strand was reduced. The mean tension in the helical wires was found to be 27‐5% smaller in the free‐end tests than in fixed‐end tests for a given strand load. Theoretical predictions underestimate this reduction in tension by up to 80%. Bending moments in the wires were found to be about 8% less than predicted in the fixed‐end condition and over 20% smaller in the free‐end condition.As expected, the slope of the linear regions of the load‐extension and load‐rotation plots decreased as the torsional restraint was reduced. However, the rate of decrease in the case of load‐extension plots was found to be less than predicted theoretically and the rotation measured was generally less than predicted theoretically. This is consistent with the helical wire tensions being smaller than the predicted values since the tangential components of these reduced tensions would have less effect in their unwrapping action on the strand under increasing axial load.
Pressure Vessel Proof Tests and BS 5500
Authors: Procter E 
Published: October 2008

A recent BSSM meeting organised by the Pressure Systems Technical Group discussed proof testing of pressure vessels, with particular reference to nozzles etc which fall outside the normal design route and require stress analysis testing. The references in BS 5500 to brittle lacquer, strain gauges and competent persons were of particular concern, as were the interpretation of pressure/strain plots.The BS 5500 design route is based on a shakedown approach. The paper attempts to describe shakedown and relate it to pressure/strain observations during proof testing. In this way the reader should be more able to make judgments.
Residual stress measurements in a cruciform welded joint using hole drilling and strain gauges
Authors: Pang H.L. , Pukas S.R. 
Published: October 2008

Residual stress measurements were made close to the toe of each fillet weld on a load carrying cruciform welded specimen by the hole drilling technique. A standard milling guide with high speed air turbine was used in conjunction with bonded resistance strain gauge rosettes. Experimental calibrations of the method were conducted under known uniform uniaxial tension loads.A simple incremental drilling technique was used to determine the stress gradient with hole depth. Measurements were also made both at zero load and known tensile loads in order to study the interaction between residual stresses and the applied loads.
The early days of the Saunders‐Roe foil strain gauge
Authors: Jackson Peter G Scott 
Published: October 2008

Peter Stein wrote to me in 1987 enclosing advance information on his proposed celebrations to mark the 50th anniversary of the resistance strain gauge in Portland, Oregon, and inviting WSM to become a ‘sponsor’ which was a way of raising funds to pay for the key pioneers and personalities to attend. For a modest sum one could sponsor an individual, and it suddenly occurred to me that one man who ought to be at the ‘party’ was Peter Jackson, who invented the foil strain gauge at Saunders‐Roe in the early 1950's.I joined Saunders‐Roe shortly after he left, and have spent most of my working life involved in the design, development, manufacture, selling or application of foil strain gauges. I had never met Peter, and I wasn't even sure if he was still ‘with us’.I had heard that he had relatives still on the Isle of Wight and after some discreet enquiries I found that he was living in California.I promptly sent off the sponsors fee to Peter Stein and told him I was sponsoring the inventor of the foil strain gauge who was resident in California, and he tracked down Peter Jackson and invited him to the conference, although I didn't know he would be there.It was quite a moving moment when someone tapped me on the shoulder in Portland and said “are you Les Window? I'm Peter Jackson”….
Experimental method for determining through thickness residual hoop stresses in thin walled pipes and tubes without inside access
Authors: Jr. J R Sorem , Shadley J R , Rybicki E F 
Published: October 2008

The determination of through thickness residual stresses in pipes and pressure vessels is of growing interest because of emphasis placed on life prediction, design, and failure analysis of piping systems. Most of the through thickness residual stress measurement techniques require the placement of gauges on the outside and inside of the pipe. These methods are severely hampered when gauges cannot be placed on the inside of the pipe. This constraint could arise for small diameter pipes, long pipes or for pipes that have been used in a service condition causing corrosion or fouling of the inner surface.This paper focuses on the first step of a three step procedure for determining residual hoop stresses in thin walled pipes and tubes. The method described is designed for cases where it is impossible to place gauges on the inside of the pipe. The method yses biaxial strain gauges on the outside of the pipe and involves a through thickness axial cut of the pipe. Based on the change in strain on the outside of the pipe, changes in the hoop residual stress distribution due to the axial cut are obtained with the method presented here. The method provides a means to evaluate changes in stresses on both the outside surface and the inside surface of the pipe as well as an evaluation of the change in through thickness hoop stress distribution at any location in the pipe cross section. This paper further demonstrates that the problem of shortening long pipes to enable placement of gauges on the inside of the pipe can result in the loss of significant residual stress information.
A numerical and experimental study of the yield surfaces in cross shaped aluminium plates
Authors: Olivito R. S. , Stumpo P. , Surace L. 
Published: October 2008

AbstractThe behaviour of metals can be described through knowledge of its yield surfaces and constitutive relationships. Starting from this point, numerical and experimental analyses were developed about the yield surface evolution in aluminium cross shaped sheets subjected to incremental hardening. The results of using both the Szczepinski & Miastkowski experimental technique and an F.E.M. code for solving non‐linear stress and strain problems, which uses a macro‐programming language, were compared. The influence of the chosen offset and of the loading path on the shape and evolution of the yield surfaces were analysed. The determination of such surfaces and their evolution with the increase in plastic deformation is still of great importance.
Transducer interconnection with a standard fieldbus
Authors: Jordan J.R. 
Published: October 2008

AbstractThis paper discusses fieldbus systems and introduces MIL‐STD‐1553B, IEC International Fieldbus, Arcnet, Bitbus and The Local Operating Network as examples of the world‐wide fieldbus activity. The main features of fieldbus instrumentation are introduced and communication protocols, safety and condition monitoring applications, and smart instrumentation are discussed.