bluuebunny/crossref_metadata_2025_split huggingface dataset:
MOIRÉ STRAIN GAUGES
Authors: KOSTAK BLAHOSLAV , POPP KAREL 
Published: October 2008

General features of the use of spiral grids in the Moiré technique are analysed theoretically. Equations of various types of Moiré fringe patterns are presented, which relate to superposition of circular, spiral, and parallel‐line grids.Goniometric compensation is proposed on Moiré fringes. The question of differentiation of the sign of strain is solved. Comparison is made with pure circular‐grid systems.The principles developed are aimed at strain measurements with the use of Moiré gauges.
COMPARISON OF FRINGE MULTIPLICATION AND TARDY COMPENSATION METHODS FOR A FROZEN STRESS INVESTIGATION
Authors: KENNY B. , HUGILL J. W. 
Published: October 2008

SummaryA practical application of the fringe multiplication method is described. Using techniques reported by Post, the method was found to be convenient and less time consuming than the normal Tardy compensation technique which was used as a comparison. For the cases studied it was found that fringe multiplications of 7x gave equivalent fringe order distributions to the Tardy technique.
STRUCTURAL MODEL ANALYSIS WITH THERMOPLASTICS
Authors: WALLACE G. 
Published: October 2008

The use of small scale models as an experimental method of analysing structural behaviour offers an attractive solution to many problems, and thermoplastics can be considered profitably as structural materials for such models. Xylonite was probably the first thermoplastic used in this way, but its relatively poor dimensional stability often proved a serious disadvantage.In the present paper vybak is advocated as a superior material, for which bonding and strain gauging techniques have been established. Comparisons are made between the material properties of vybak and other thermoplastic materials, and examples of experimental work with vybak models are given.
THE SLIT SOURCE AND GRATING METHOD IN PLANE STRESS PROBLEMS
Authors: THEOCARIS P. S. , KOUTSABESSIS A. 
Published: October 2008

A simple method is presented for measuring partial slopes of transparent specimens in plane stress. A monochromatic slit source is used to illuminate a line amplitude grating and the transparent specimen is interposed between the slit and the grating. The deformed lateral surfaces of the loaded speciment distort the lines of the grating and yield contours of equal partial slope of the specimen in a direction normal to the direction of the rulings of the grating.The method is used for determining the magnitude and gradients of the sum of principal stresses in plane elastic problems.
RESISTANCE MATERIALS FOR HIGH‐TEMPERATURE STRAIN MEASUREMENT
Authors: GRINDROD A. , NODEN J. D. 
Published: October 2008

The performance of some commercially available base and noble metal resistance alloys usable as strain sensors in high temperature strain gauges is experimentally assessed with emphasis on the determination of post yield strain under these conditions.In order for Cu‐Ni resistance alloys to be used satisfactorily at 600 deg.C, gross surface oxidation must be prevented by an argon shield and the surface of the sensor must be pre oxidised to inhibit grain boundary attack from partial pressure of oxygen in the argon atmosphere.
LEAST SQUARES SMOOTHING OF EXPERIMENTAL DATA USING FINITE ELEMENTS
Authors: HINTON ERNEST , IRONS BRUCE 
Published: October 2008

AbstractA program for interpreting Moire fringe data using a digital computer is described. The finite element technique overcomes certain intrinsic defects of existing methods which use polynomials, and promises to give better results, especially where stress concentrations are present. An experimental example compares the technique with the polynomial technique.
The development and evaluation of a fatigue crack length monitoring system for liquid environments
Authors: JERRAM K. , PRIDDLE E. K. 
Published: October 2008

The requirements for measurement of crack initiation and propagation are discussed briefly with particular reference to situations of liquid environments where conventional methods are unsuitable.A technique based on measurement of stiffness has been developed to give continuous record of crack length and a knowledge of crack initiation from a fatigue crack propagation test. The data obtained for EN3A mild steel in air and various liquid environment are in agreement with published values.
Design and manufacture of high precision strain gauge dynamometers and balances at the O.N.E.R.A. Modane Centre
Authors: DUBOIS M. 
Published: October 2008

The Modane–Avrieux Large Wind Tunnel Department of O.N.E.R.A. designs equips and calibrates single or multi–component dynamometers and balances for tests in its own facilities. It also undertakes such work as requested by external organisations. The capacities of these instruments range from 0.01 N (0.002 Ibf) to 1 000 kN (100 tonf) and the general accuracy is of the order of 10–3.The principles and processes governing the design, fabrication and calibration of these transducers are described.
An alternative definition of material properties
Authors: MEDLAND A. J. 
Published: October 2008

The stresslstrain relation is initially discussed in general form. The normal matrix formulation employing the Lamé Constants and the more ‘practical’ formulation based on the Elastic Modulus and Poisson's Ratio are detailed.An alternative approach employing the wave speeds of the material as the basic material parameters is discussed. This approach has a number of advantages over the present tensile testing methods. The main advantages are that the properties can be obtained on the actual part or specimen without resorting to destructive testing means, and the data can be collected with the same strain gauge equipment that is to be employed in subsequent testing procedures.The problem associated with the measurement of short duration, low amplitude pulses is discussed and the broad details of the required instrumentation are given.Two simple experiments are illustrated in which firstly, the wave velocity in a bar is obtained and secondly, the dilatational and shear wave speeds are obtained in a plate structure.
Measurement of the thermoelastic coefficient of metals by strain gauges
Authors: DUBOIS M. 
Published: October 2008

The modulus of elasticity E of metals and alloys varies, usually, when the ambient temperature θ changes, which is a drawback in most metro logic applications. A thermoelastic coefficient TCE equal to (ΔE/Δθ)/E can be defined. This article shows how this quantity can be measured, dynamometrically and statically, with safety and precision, on a metallic specimen, made of the material under study, on which strain gauges with a known thermal coefficient TCK are bonded.Experiments carried out at the ONERA Modane‐Avrieux Centre during the manufacture of more than one hundred dynamometers, made of several kinds of metals and gauges, showed that the TCKs, given by the gauge manufacturer, were more stable than the TCEs, which justifies a sufficiently fine measurement of the latter. The TCE values of six different materials, lying between ‐0.44×103 and + 0.33×103, have been determined to within 0.02×10‐3 without particular precautions. An absolute precision better than 0.01×10‐3 may be obtained by this process, which also makes it possible to determine the modulus of elasticity E and the Poisson's ratio v.
Protection of strain gauges for long‐term stability
Authors: WELSH R. L. , DODD P. 
Published: October 2008

SUMMARYA strain gauge encapsulation and protection system is described which ensures the long term stability of resistance strain gauges. Protected gauges have been subjected to normal outdoor conditions for a period of 2 years together with over 40 temperature cycles to 60°C and 215 strain cycles to 800 micro‐strain. Zero shift has not exceeded 40 microstrain.
An investigation of the dynamic and static stresses in universal bearing H‐piles
Authors: FARID M. U. 
Published: October 2008

As part of continuing research on steel bearing piles, an investigation was carried out by British Steel Corporation in an attempt to gather data which will illuminate the areas of contention for limiting stress levels to be raised, thereby allowing economies to be made and customers' confidence to be increased in selecting steel bearing piles for a particular application.To assess the characteristics of dynamic and static loading, a strain gauge measurement technique was used. Blow by blow stress analyses were carried out. In total 700 blows were examined. The full record of 700 blows and static observations can be obtained from The We/ding Research Department, of BSC's Teeside Laboratories, Middlesbrough.The results reveal that during the course of driving the pile through hard strata, the impact stresses were 0.6 to 0.7 times the minimum yield stress, at the last blow. These impulsive stresses had no discernable effect on the structure of the piles. Results obtained suggest that considerable increase in design stresses might safely be adopted for steel bearing piles. One of the aims of this long term research is to produce a dynamic testing system which gives more accurate results than can be obtained from traditional methods.
A three dimensional photoelastic study of the stress distributions in double helical epicyclic gears
Authors: ALLISON I. M. , HEARN E. J. 
Published: October 2008

This paper reports on part of a research programme which was carried out using two‐ and three‐dimensional photoelastic model techniques in order to analyse the stress distributions in a double‐helical epicyclic gear design incorporating typical features of production gear units.The paper describes the testing of two three‐dimensional models, one subjected to torque loading, i.e. tooth forces; the other to combined rotational and torque loading. Note is made of some of the problems inherent in the design and loading of complex models such as those used in the tests and of the solutions developed to overcome the difficulties.Attention is devoted to the analysis of contact loads and load distribution, maximum sub‐surface stresses, maximum root fillet bending stresses and the geometry of the lines of contact. General conclusions are drawn and an indication given of the subsequent extensive two‐dimensional test programme which was carried out.
A study of the saddle stresses arising from the support of a cylindrical vessel
Authors: TOOTH ALWYN S. , WILSON JOHN D. 
Published: October 2008

The design method widely used for the support of cylindrical vessels is that contained in BS 55001 which is based on the work of Zick2 published in 1951. In recent years, however, the theoretical analysis of this problem has received some attention,3–7 thus enabling the vessel stresses and displacements to be determined for supporting saddles of various degrees of flexibility. In this paper the saddle itself is examined, 1) experimentally, using photoelasticity, and 2) analytically by the shell analysis of refs5–7, together with a Finite Element approach. It is found that the theoretical approach used to determine saddle stresses is very sensitive to—

the type of finite element used for the saddle, and
the boundary assumption at the saddle base.

From a general stress analysis point of view, the paper should provide a warning to designers that the results obtained from finite element analyses always contain the above inherent problems. A comparison with the photoelastic results enables this to be studied. In particular the agreement between the theoretical and experimental approaches lends credence to the analytical approach used in refs5–7 and to the value of an optimum design approach for the vessel and its support.
The design of a multi‐purpose multi‐component strain gauge dynamometer
Authors: Millward A. , Rossiter J. 
Published: October 2008

The design, construction and calibration of a multi‐purpose multi‐component strain gauge dynamometer is described. The dynamometer was constructed for use with a free surface water channel, which can also be used as a water tunnel or a cavitation tunnel. In this experimental facility, the large speed range available (0·03 to 6·1 m/s) and the variety of projects encountered require the measurement of a wide range of loads in several different configurations. The dynamometer system has been based on a unit block concept so that the blocks can be assembled into a suitable configuration and complexity of components to suit each particular problem.The basic design concept is described together with the calibration results and the magnitude of the interactions. It is concluded that the overall accuracy of the dynamometer blocks and the absence of interaction coupled with the versatility of the system confirm the choice of the original design.
Strain measurement standards—an outline
Authors: Mackinnon J. A. 
Published: October 2008

Strain measurement techniques are being used more frequently today to check that manufactured components are at a safe stress level in service. Designers are also requiring strain gauge tests on prototypes to confirm that the theoretical calculations are realistic and designs are economic.Against this background the measurement engineer finds himself under pressure to produce test results quickly and sometimes to justify them. Strain measurement standards would have an important role in convincing customers that tests have been carried out in an approved manner and could be the measurement engineer's defence in the case of disputed results.A suggested range of standards and codes of practice is described, from the anticipated BSI Standard on Strain Gauge Calibration to a proposed standard on strain gauge application and possible specifications on instrumentation for static and dynamic measurement. The need for strain measurement technician training and possible participationin the National Testing Laboratory Accreditation Scheme, NATLAS, is also discussed.
Recent developments achieved in China about the centre hole relaxation technique for residual stress measurement
Authors: Hu Chun‐Nong 
Published: October 2008

The paper introduces recent developments achieved in China regarding the centre hole relaxation technique for residual stress measurement. A special device developed by the author for the small blind hole drilling and measuring is described. Some examples of application of this method by using this special device are given. They include stress measurement of:

Stiffened top flange of the test section of a railway steel box girder bridge.
The butt weld joints of the ‘15 MnVNi’ alloy steel thick plates.
The welded side frames of a diesel locomotive.
A technique for dynamic tensile testing of metals
Authors: Al‐Mousawi M. M. , Deans W. F. 
Published: October 2008

A technique is described for obtaining full dynamic stress/strain curves in tension up to strain rates of 100s‐1. In conjunction with a high speed servo‐hydraulic machine, a low inertia extensometer has been developed to facilitate measurement of specimen tensile strain up to fracture.The benefits of the technique are highlighted in relation to currently available methods for dynamic stress/strain measurement.
A prototype for a resistive extensometer as a strain measuring standard
Authors: Bergqvist B. , Scherling G. 
Published: October 2008

The design, handling and calibration of a prototype to a resistive extensometer with 10 mm measuring length is described.It stands on the test specimen via pins with conical tips. These end in hard metal spherical calottes with 16 micron nose radius. The manufacturing and maintenance of these tips was described earlier.The extensometer is calibrated on a bending beam to 1 mm/m strain, using the loading and deflection equipment developed at the FFA and described earlier.The total extensometer inaccuracy, i.e. the sum of estimated systematic errors and random errors, the latter expressed as the 2σ confidence interval about the mean, is about 400 × 10‐4%, for 60 reproduced calibration tests.With the extensometer, it was shown that the beam, which was machined and hardened from an alloy with 1.4% Cr and 1.4% Ni and has a moderate hardness of Hv 430, does not show any kind of inhomogeneity in Young's modulus, within the resolution of the indicator.Therefore, the extensometer is suitable for the determination of bonded resistance gauge factors, even if a total error of only ±0.1% is required. The prototype described can therefore be used as a strain measuring standard.
Simulated seismic loading on reinforced concrete beam/column connections
Authors: Scott R H , Gill P A T 
Published: October 2008

Laboratory tests to investigate the seismic behaviour of five reinforced concrete external beamlcolumn connection specimens, by subjecting the beams to a series of slow load reversals, are described. The first three tests were undertaken as an extension of a static (non‐seismic) test programme and were primarily carried out for the purposes of rig development. The two further test specimens contained additional links in the connection zone to make them representative of current seismic practice in the U.S.A. These two specimens were subjected to a series of slow load reversals specifically intended to simulate seismic effects.With the first three specimens, complete destruction of the connection zone was achieved after only four or five cycles; the last two specimens withstood ten and twelve cycles respectively. One of these latter specimens failed due to the development of a plastic hinge at the beaml column junction, the other by plastic hinges forming in the column above and below the beam. Detailed information regarding the form of the reinforcement strain distributions developed during these tests is presented, data being obtained using reinforcement internally strain gauged with electric resistance strain gauges. Each specimen contained around 230 such gauges.
Assessment of strain gradients affecting the performance of 3‐D strain rosettes – relevant to the analysis of cement mantle strains in total hip replacements
Authors: Tague D. Mc , Little E. G. 
Published: October 2008

AbstractA large scale model analysis, using embedded strain gauges, of the strain distribution in the cement mantle surrounding a femoral prosthesis is underway. In order to predict, and so avoid, positions of locally high strain gradients in this model, a finite element and experimental analysis of a similar problem was undertaken. For this purpose, a loose fitting rectangular steel insert inside a surrounding rectangular epoxy sheath was used to model an extreme case of the torsional and bending components of hip joint load. The axial component of joint load was modelled using an axisymmetric finite element model of a tapered shaft. The finite element results were used to determine suitable positions for embedding gauges in the experimental model. Results showed that the finite element analysis failed to adequately model the close sliding fit between the steel insert and epoxy. Altering the experimental model to artificially replicate the finite element contact conditions produced good correlation in bending, with experimental strains agreeing with simple bending theory to within 6%. Satisfactory correlation under torsional loading was not obtained, but strain magnitudes were low. Predicted positions for embedding gauges give conservative results, lessening the possibility of strain gradient induced error in the large scale model test of the cement mantle and prosthesis.
The use of composite materials in vehicle mounted tanks
Authors: Butler S. 
Published: October 2008

AbstractGlass reinforced polyester is used for the design of 5500 litre vehicle mounted tanks which carry a variety of liquids to farms. The main panels of the tanks are designed as flat or slightly domed membranes using a theory which depends on resistance to the membrane tension by ‘in plane’ shear within the panel. The vehicle dynamic loading can only be estimated and therefore the tanks have been developed from experience over some years. The primary problem in the design follows from the forced bending strain at the edges of the membrane panels, that is, the corners and joints of the tanks. Strain controlled testing of both the glass fibres and the GRP laminates is used to determine the acceptable limiting strain in the tanks for the operating conditions. The main panel design has not given any problems but care was essential to keep the local strain at comers and joints within the strain limit for the GRP.
Measurement of cab mounting point loads
Authors: Allison I.M. , Nurse P. 
Published: October 2008

AbstractA transducer measuring three orthogonal force components has been incorporated in the flexible mountings of a lorry cab so that the dynamic response of the system is unchanged. The instrumentation used to monitor and record the mounting point forces, both during calibration of the transducers, and subsequent road trials has been described. Values of the Cartesian components measured at the front and rear cab mounting points during passage of the loaded vehicle over a simulated Australian road are presented, and the maximum values determined.
Comparison of dynamic initiation toughness measured by strain gauges and the shadow optical method
Authors: Hermann R. , MacGillivray H. J. , Dear J.P. 
Published: October 2008

AbstractThe deformation and fracture behaviour in dynamically loaded Charpy specimens of BS11 rail steel were studied by two different measuring techniques. The transient records obtained from straingauges were compared with results obtained simultaneously by the shadowoptical method. Good agreement was obtained when measuring and comparing the stress intensity factor K in the initial stages of deformation behaviour prior to crack initiation. During fast fracture, the shadow optical method indicated the influence of dynamic effects on crack propagation.
In‐situ stress determination used in structural assessment of concrete structures
Authors: Owens A. 
Published: October 2008

AbstractLarge span, post‐tensioned bridges are now regularly subjected to spot checks. Bridge assessment requires a knowledge of the design pre‐stress and of any losses that may have occurred since stressing. The assessing engineer is often faced with a lack of information, such as no detailed drawings, no confirmation that build was to design, and it is at this stage that on‐site in‐situ stress determination can be used to progress the investigation. The methods for in‐situ stress determination are based upon the measurement of strain distribution due to local stress relief and the relationship of the strain redistribution to the in‐situ stress state. The adaptation of the centre hole technique to the in‐situ stress determination in reinforcement, stressing tendons and concrete and the necessary site requirements are explained.