bluuebunny/crossref_metadata_2025 huggingface dataset:
The nature of room temperature creep
Authors: Moreton D. N. , Sellings D. P.
Published: October 2008

This note is aimed at highlighting hat may be inaccurate thinking of the nature of cold (logarithmic) creep ‐ i.e. creep hich may be observed in most steels at room temperature (20d̀C). There is a dearth of information on this topic although engineers have come to regard cold creep as a ‘time dependent plastic’ deformation. As such it is assumed that the assumptions of plasticity are obeyed during the creep process.
Application of digital image analysis to strain measurement at elevated temperature
Authors: Turner J L , Russell S S
Published: October 2008

Digital imaging techniques are applied to the measurement of surface displacement and strain at elevated temperatures. A simple surface preparation using high temperature paint together with a CCD video camera for digital imaging serve as the basis for the measurements. Mathemetical correlation of the surface intensity pattern between reference and deformed states is used to measure local surface deformation. The method is non‐contacting and full field. Displacement and strain measurements have been made at temperatures to 600°. Coefficients of thermal expansion of three metals have been measured using this technique and compared to strain gauge and handbook values. Limitations and potential extensions of the method are discussed.
Stress corrosion and corrosion fatigue of metals in high temperature aqueous environments
Authors: Congleton J.
Published: October 2008

The dissolved oxygen content of water influences the susceptibility of austenitic stainless steels and reactor pressure vessel steels to environment assisted cracking by raising the electrochemical potential. The relevance of this fact to the integrity of welded stainless steel constructions, deaerator vessels and reactor pressure vessels steels is discussed. In particulal, the use of slow strain rate test procedures involving applied electrochemical potential control is discussed as a means of assessing the susceptibility to cracking of materials in a range of aqueous environments.
Fatigue life prediction at a ship deck/superstructure intersection
Authors: Hugill P N , Sumpter J D G
Published: October 2008

Difficulties arise in identifying an appropriate method to predict fatigue life for the weld joint at the intersection of a ship's deck and superstructure. The problem relates to the gross stress concentration and rapidly changing stress at this location. Variations on the ‘hot spot’ stress approach to fatigue life analysis are reviewed, and applied to results from an experimental programme of fatigue tests on welded joints. Finally tentative recommendations are made for a procedure to predict fatigue life of the structure.
The flexural fatigue performance of plain and fibrous concretes
Authors: Butler J E
Published: October 2008

If fatigue cracking is going to occur in concrete structures then it is more likely due to repeated flexural loadings rather than direct compression or tension. Typical examples are road and airfield pavements, bridges, offshore constructions and structures likely to experience earthquakes. Also many of these loadings have a dynamic character and a knowledge of material behaviour at rapid stressing rates as an essential preliminary requirement to understanding flexural fatigue performance. Therefore since flexural loadings are frequently encountered in practical situations then the flexural test is probably one of the most useful types to be used in the examination of both the fatigue behaviour of concrete and its ultimate strength developed at rapid loading rates.

Although the designer regards concrete as an homogeneous material, it consists of two phases, the active hardened cement phase, which is the binding material to the inert phase, the aggregate. Concrete behaviour can therefore be complex and aspects interpreted at either the macroscopic, microscopic or molecular level. The composite nature of concrete may be further complicated by the introduction of steel reinforcement. Over the last few years there has been a general research interest with the incorporation of small quantities of fibres in concrete. Steel fibres of dimensions 10mm to 60mm in length, 10m to 60 m in diameter, with material properties ranging from 150 GN/m 2 to 200 GN/m 2 in elastic modulus and 700 N/mm2 to 200 N/mm2 in tensile strength may be introduced at the mixing stage in proportions between 0.5% and 3.5% of concrete volume. The consequent enhancement in flexural strength is substantial and the likelihood of a similar improvement in fatigue performance needed to be demonstrated.

It has also been common practice when conducting modulus of rupture tests, to use 500mm × 100mm × 100mm specimens for mixes incorporating fibres. When casting such specimens there is a danger of fibres not being randomly orientated. Thus for this investigation, beams of 1500 times 200 times 200mm have been used. The selection of larger beams also makes instrumentation more manageable and the dimensions may be more comparable with those associated with most practical applications.

Some fifty fatigue tests have been completed supported by a further five hundred strength and control tests. A complete series of strain, deflection and crack development histories have been observed. An appropriate form of S‐N curve has been adapted for the examination of results. Models explaining the behaviour of both plain and fibrous concretes have been proposed and a method of flexural fatigue performance prediction has been formulated.
Inegrated autocorrelation method for plastic strain determination
Authors: Dal Y Z , Tay C J , Chiang F P
Published: October 2008

This paper presents an integrated autocorrelation method for the measurement of plastic deformation in metallic materials. The method employs a laser beam to illuminate the test objects. The diffracted images are digitised, recorded and processed on a computer based image processing system. The subsequent speckle pattern correlation analysis yields information on the surface deformation of the test objects. The technique is applied to brass tensile specimens and it is found that the integrated autocorrelation coefficient is linearly proportional to the plastic shear strain. For the range of plastic strain measured the error involved would be less than 10%.
Measurements of mechanical properties of alpine skis in the laboratory
Authors: Mackinnon J A
Published: October 2008

A few years ago Ian McMillan, the editor of the magazine SKIING, UK requested NEL to carry out tests on a batch of skis. For some time his magazine had been publishing information from a German testing laboratory on the mechanical properties of skis but he had decided to try to organise his own tests in the hope of giving his readers better information on different types of skis in a manner easier for them to understand. The author was asked to try to set up the tests because of personal interest in skiing so a meeting was arranged with Ian McMillan and his technical advisor, Gustaf Fischnaller. an Austrian who now runs a ski school at Glenshee, in Scotland. He has seen ski tests being carried out in Austria and could describe the test methods. After extensive discussion, a decision was taken on a range of tests designed to provide information on how the skis would behave on snow.
Towards full field automated photoelastic analysis of complex components
Authors: Patterson E A , Wang Z F
Published: October 2008

The design of a automated system for photoelastic analysis of complex components is described, and an outline of the theory used in its operation is given. The potential of the system for providing detailed data over the full field of view is demonstrated by the analysis of a slice from a model of a bolt.
Measurement of dynamic response and failure of pipework
Authors: Beaney E M
Published: October 2008

Pipework in nuclear power stations is designed to withstand the effects of earthquakes. The current methods of design are known to be very conservative and lead to the inclusion of large numbers of pipework restraints. These restraints are only included to limit stresses in the unlikely event of an earthquake but they can, under some circumstances, increase stresses during comparatively frequent thermal transients and thus their unnecessary inclusion is undesirable.

With the ultimate objective of reducing aseismic design conservatism the experimental work, described in this paper, has been conducted at Berkeley Nuclear Laboratories (BNL) to investigate the response and failure of pipework under high levels of dynamic excitation. The initial work was aimed at response prediction, but it is now clear that the improvement of failure criteria is a preferred route to reduce design conservatism. The measurement of high strains and dynamic yield performance of materials has necessitated the development of novel measurement techniques which have wider application in other areas. This experimental work is now finished, and the results are being used to support a change in the design codes.
Apparent strains in unmounted strain gauges at high temperature
Authors: Francis A , Haynes K
Published: October 2008

A detailed investigation into the source of the unmounted apparent strains in resistance strain gauges over a temperature range of 20°C to 550°C is presented. Different measuring systems give different values of unmounted apparent strain. Formulae for two different measuring systems relating the unmounted apparent strains to resistance values are derived. Values computed from these formulae using measured values of resistance are compared with values of unmounted apparent strains measured directly. In addition, formulae which are essential in order to relate the actual strain to the indicated strain are derived for each of the systems. It is shown using the derived expressions that the magnitude of the unmounted apparent strains can be reduced considerably by connecting a shunt resistor across the active element.
Techniques for the investigation of the ratchetting behaviour of piping components under internal pressure and simulated seismic loading
Authors: Yahiaoui K. , Moffat D. G. , Moreton D. N.
Published: October 2008

The ratchetting behaviour of piping components under internal pressure and simulated seismic loading has been investigated using special fixtures and a standard laboratory universal testing machine fitted with a fatigue module. Experimental arrangements are presented for testing plain pipes with or without thinned sections, elbows and tee branch junctions under in‐plane dynamic bending; similar fixtures and arrangements could be used for reducers and flanged connections and other types of loadings. Input accelerations up to 5g have been achieved and the results demonstrate that a great deal can be learnt about piping component behaviour from such simple arrangements and without resorting to sophisticated or expensive experimental techniques. The necessary instrumentation and algorithms for the analysis of results are described. Some sample results are included and discussed in terms of overall piping component behaviour. Two recommendations are suggested to more realistically simulate typical earthquake input spectra.
Time dependent principal stress analysis by the hybrid method of photoviscoelasticity and boundary element
Authors: Laermann K. H. , Yuhai Chen
Published: October 2008

In this paper the basic relations in linear isotropic photoviscoelasticity have been discussed theoretically in detail. A new routine to solve the time dependent principal stress without the measurement of isoclinics has been found. As a proof of the method, examples are illustrated at the end of this paper.
The role and benefits of testing in product quality management
Authors: Pomeroy R. V.
Published: October 2008

A key requirement for most engineered items is the ability to withstand the various loads that may be applied under conditions of use and of abuse that may reasonably be foreseen. To ensure that the strength requirement is satisfied, the designer must evaluate the levels of applied stress using appropriate calculation methods or by physical experiment. This paper considers the respective roles of computational and experimental methods of stress analysis, discussing the impact of changes in functional capability. Reference is made to the modern certification environment and the requirements of quality assurance, particularly related to the training of engineers and technicians in the necessary skills.

The paper aims to present a balanced view of the role of experimental stress analysis, identifying areas where there are clear benefits. Some concluding comments are made regarding education, training and vocational qualifications.
Fatigue testing of interlocking Stainless Steel
Authors: Chen Z. , Reuben R. L. , Owen D. G.
Published: October 2008

An interlock tube, usually made of stainless steel, is one of the key structural components for both bonded and unbonded flexible pipes of composite construction. The fatigue performance of this component is an important factor in determining the long term integrity of the entire pipe.

This paper presents an experimental technique developed for the establishment of the basic fatigue characteristics of such interlock tubes. Details of the fatigue testing method, the specimen design, preparation and calibration procedures will be described in conjunction with tests carried out on 254 mm interlock tube samples.

One of the most important results from this work is that, by careful design and machining of the specimen, the mode of failure seen in full scale pipe samples can be reproduced on small specimens in a laboratory using a fatigue machine. The significance of this is that it is possible to obviate the necessity for expensive full scale composite pipe testing, provided that an accurate description of the loading conditions imposed on components of the composite is available.
Stress‐strain analysis of a biaxial tension cruciform specimen for tests under creep conditions
Authors: Waniewski M. , Wolf U. , Brietbach G.
Published: October 2008

A flat cruciform specimen for experimental tests either in the elastic or the inelastic range is investigated. Mutually perpendicular biaxial tension forces applied to the edges of specimen arms produce in its thinnest part in plane biaxial stresses. The stated goal of the study is to assess the extent to which a uniform stress state is achieved within the thin, central gauge area of the specimen. It is shown, by applying the FE code ABAQUS, that in the transition between the thin and the thick part of the specimen stress concentrations occur and that the redistribution of stress due to creep will not produce a more uniform stress state. An isotropic, elastic ‐ viscoplastic constitutive description has been employed within the context of small deformations. The calculations were carried out for three different ratios of biaxial loading. The results are displayed for both the initial (i.e. immediately following load application) stress distribution and the steady state stress distribution within the specimen. Experimental validation is discussed.
A new cheap pressure foil
Authors: Bourgois R. , Bel J.
Published: October 2008

Fuyi pressurefilms are very popular for the measurement of pressures between flat surfaces. This method cannot however be adopted in an aqueous medium. The present paper offers a cheap solution based on the variation of transparency with pressure of a commercial packing film.
The failure of an armour faced conveyor connector
Authors: Rudd W.J. , Osselton J.E.
Published: October 2008

The combined use of modern metallurgical techniques for fracture examination, laboratory test data and fracture mechanics calculations allows metallurgical failures to be examined in a quantitative manner. Complex load histories and environments can result in more than one sub‐critical cracking mechanism occurring in a component. Quantitative understanding of the rate determining cracking process is a necessary prerequisite to rectifying the problem.

The following case study describes a connector from an armour faced conveyor which failed in service. The failure investigation involved fractography, stress analysis, material property evaluation and fracture mechanics calculations. Fractographic evidence indicated a stress corrosion failure mechanism. Calculations of critical crack sizes showed that stress corrosion cracking alone could not account for the fracture. It was concluded that the failure was due to a sequence of three cracking processes which preceded unstable ductile fracture. Firstly, frictional heating caused rubbing or quench cracks typically 0.5–1 mm deep. Secondly, corrosion fatigue cracks grew several millimetres allowing the third fracture process, stress corrosion cracking, (SCC) to initiate and grow. In the situation described here, this process was much faster than corrosion fatigue.

The influence of defect size due to rubbing cracks and the influence of KISCC have been compared with the corrosion fatigue life of the component. An increase in KISCC and hence critical defect size for SCC has been shown to increase the corrosion fatigue life of the component by a large factor. A change in design would also alleviate the problem of SCC by reducing the static stress, which is the driving force for SCC.
Holographic investigation into the mechanical behaviour of engineering ceramics
Authors: Chirico G. Di , Rossi R.
Published: October 2008

The complex loading conditions to which a structural component is customarily subjected require a knowledge of the material responses to combined stresses, while almost all the data available for ceramic materials are obtained from uniaxial tests. It is necessary, therefore, to study the behaviour of engineering ceramics using specimens of proper shapes subjected to biaxial stresses and testing methods that enable high sensitivity monitoring and real time analysis of the surface strains. In this respect, an optical technique such as conjugate wave holographic interferometry gives satisfactory results. Characterisation tests are carried out on diametrically loaded discs in order to evaluate Young's modulus and Poisson's ratio of some classes of ceramic materials.
A temperature calibration of a temperature/strain transducer based on two strain gauges
Authors: Cappa P. , McConnell K. , Zachary L.
Published: October 2008

The operation of a temperature/strain transducer, called “duplex gauge”, based on two electrical resistance strain gauges, that are temperature compensated for use on materials with different coefficients of linear expansion, was briefly recalled. Three steel specimens were equipped with “duplex gauges” and were subjected to temperature variations and no external loads were applied. The chosen experimental setup (i) to measure the outputs of the gauge temperature compensated for steel and titanium silicate and (ii) to impose known temperature, assured good accuracy and precision in evaluation of the temperature calibration curve. The obtained results showed that the strain differences could be considered, at least for the experimental arrangement examined, a linear function of temperature over the range of 20 to over 140°C. The prepared calibration chart, that allows the correction of temperature induced apparent strain, will be used in future research when generic temperature and strain fields are applied to specimens.
Measurements for the Bloodhound project: a historical account
Authors: Collins S.J.
Published: October 2008

The paper covers the design of the transducer based measuring equipment required to support the development of a guided missile system. The exciting challenges presented by such a project are highlighted including the extent to which ingenuity was stretched. The plethora of devices which were spawned by these endeavours had many future applications in the commercial world and is a pointer to the type of secondary benefits that can ensue.
Measurement of in plane residual displacement due to interference fitting by TV‐holographic interferometry
Authors: Chan Yiu Wing
Published: October 2008

Experimental measurements of the in plane residual displacement field surrounding the cold expanded holes in aluminium plates of 100mm × 100mm × 10mm were made using the technique of TV‐holographic interferometry. A special cold expansion fixture was designed to produce precise radial interferences of 0.015mm and 0.025mm at the hole walls. The experimentally determined displacement fields were compared with those obtained by finite element predictions. The experimental results showed good agreement with those obtained by finite element analysis. These results demonstrate that the TV‐holographic interferometry technique can be used as an effective technique for general deformation investigations.
Experimental errors in the application of photoelastic coatings on human femurs with uncemented hip stems
Authors: Cristofolini Luca , Cappello Angelo , Toni Aldo
Published: October 2008

The investigation of the stress distribution in the proximal femur is of primary relevance when testing hip prostheses. Most of the in‐vitro research to date, has been conducted with strain gauges. However, the photoelastic coatings provide a field vision of the state of strain and of the most stressed points. The purpose of this work was to validate the application of photoelastic coatings to intact and implanted human femurs. Coatings of various thickness were bonded to two regions: the surface of the diaphysis, and the resection surface of the neck. A theoretical study was conducted on a geometrical model of the diaphysis to quantify some of the experimental errors. The reinforcing effect was found to be far the most important source of error for the coating of the diaphysis. Other possible sources of error such as Poisson's coefficient mismatch, incorrect light incidence angle and uneven coating thickness were also examined. Due to the uneven distribution of such errors, any correction seems impossible. The results must therefore be considered only qualitatively, as a complement to the strain gauging. The coating of the resection surface of the neck of the femur suffers much less from the reinforcing effect, but the coating is more sensitive to Poisson's coefficient mismatch. In this second application, quantitative results can be satisfactorily obtained.
Strains measured on plane and curved surfaces by means of the shearographic method ‐ Part 1
Authors: Steinchen W. , Schuth M. , Yang L. X.
Published: October 2008

The shearographic interferometry is employed as a nondestructive full field, optical testing method without contact. Fringes of constant strain (so called isotase, tasis (Greek)=strain) can be observed in real time on the surface of the investigated machine parts and are represented by the shearograms. Using shearography two states of deformation are recorded by doubly exposing a Holotest film in an ordinary camera or stored by an image processing system. In the telelens of the camera a shearing element inside or outside the focus is integrated. Rigid body motions of the specimen are not recorded. Local deformation irregularities caused by a defect under or on the surface of the specimen create strain concentrations; the homogeneous surrounding is poorly superimposed by an interference pattern, e.g., in the case of the internal pressure differential for testing tubes1. The shearogram shows dark and bright fringes which are the functions of the displacement derivative. The holographic interferometry measures the out of plane deformations directly. A term of the out of plane strain can be determined by the shearographic method2 as well as the in plane strain fringes under certain conditions which are described in the following. For this purpose the fringe patterns generated by the basic types of loading are presented and compared with the photoelastic patterns showing obvious analogies. The magnitude of the shearographic strain components is nearly the same when measuring by means of strain gauges or determining theoretically as is shown for one case.
Applications of experimental techniques to solid mechanics and materials science research in telecommunications and electronics
Authors: Dudderar T.D.
Published: October 2008

In the effort to support the rational development of reliable, manufacturable leading edge communications technologies, a broad variety of experimental mechanics and materials techniques have been developed and/or applied at the AT& Bell Laboratories in Murray Hill, NJ. Much of the emphasis in this paper is on the application of optical methods to the conduct of experimental mechanics and materials research relevant to the telecommunications and electronics industries. It will also describe the role such research plays in supporting the development of a new process or product.

This paper is based on a presentation at the BSSM/SEM International Conference on “Advances in engineering measurements” held at The University of Edinburgh, 30 August to 01 September 1994.
Progress in experimental stress analysis for Airbus aircraft design
Authors: O'Brien E.W.
Published: October 2008

Advanced experimental stress analysis techniques have been increasingly used on large aircraft structures to provide stress data for both design and numerical analyses validation. In the past these techniques tended to be limited to the structural test phase which is subsequent to the design and manufacture stage. Experimental stress techniques have had to become more sophisticated and utilised much earlier in the programme in order to meet the ever increasing demands for competitive, aircraft design, performance and reliability. Currently the techniques have applications from the earliest design stage through to final in‐service support engineering. Photoelastic stress analysis was one of the earliest and most powerful experimental design tools in use at Filton, however, the range of techniques is continually being extended to meet the technological demands of new designs. This has involved keeping abreast of a wide array of sciences to identify and develop new physical procedures for stress related experimental analysis. Progress is reviewed in this paper as well as the vision for the future within the context of Airbus aircraft design. The economic and technical pressures to move towards more automation and image processing are discussed including the requirement to provide data that is more user friendly to conventionally trained design and stress engineers.
Strain gauge proof hydraulic testing of commercial pressure vessels
Authors: Taylor D.A.W.
Published: October 2008

Some aspects of the philosophy of shakedown are presented relevant to the requirement of the British pressure vessel code British Standard BS 55(X): 1994 for proof hydraulic pressure tests on vessels containing features not covered in the design rules within BS 55(X). The difficulties in achieving the objective of the test are discussed. Examples are provided from the experiences gathered from such proof hydraulic tests on over 50 commercial pressure vessels.
Three fringe photoelasticity ‐ use of colour image processing hardware to automate ordering of isochromatics
Authors: Ramesh K. , Deshmukh Sanjeev S.
Published: October 2008

The early application of digital image processing (DIP) technique to automate photoelastic analysis is based on black and white (B & W) image processing systems. The various methodologies reported can be traced to rely upon one or several features of a B &W DIP system. With the advancements in computer technology, nowadays colour image processing systems are available at affordable prices. A systematic study has been carried out on how to use the red green blue (RGB) value recorded using a colour image processing system for determining fringe orders up to 3 in a fringe field. The study has revealed that instead of directly using RGB values corresponding to a dark field image, if the difference of RGB values between bright anddarkfield images is used, the number of noise points is less. Experiments have been carried out for several arbitrary lines in a circular disk under diametral compression and the results are found to be good.
Effect of plasticity on the residual stress measurement using the groove method
Authors: Petrucci G. , Zuccarello B.
Published: October 2008

The mechanical methods based on milling rectilinear or annular grooves on a component's surface and measurement of relaxed strains are some of the most used semi‐destructive methods for the determination of residual stresses. These are evaluated from the relaxed strains by means of equations based upon the linear elastic theory. In this paper the errors due to yielding localised at the bottom of the groove have been investigated. The analyses were carried out by means of the finite element technique varying the most important parameters involved. The experimental results show a good agreement with the numerical ones.
The good, the bad and the ugly: An engineer's view of product liability litigation in the United States
Authors: Fourney M.E.
Published: October 2008

This talk presents a cross section of case studies which exemplified the best and the worst of the system. The technical aspects of each case, along with the legal theories and the final resolution is discussed. The author will present his philosophical prospective of the process based on over 25 years experience.
On the correction of plasticity effect at the hole edge when using the centre hole method for measuring high welding residual stress
Authors: Yan Zhao Hai , Wu Shi Yao , Yi Pei , Pin Lei Yong , Jun Chen Yue
Published: October 2008

Significant error caused by plasticity at the hole edge may arise when measuring sufficiently high welding residual stress by means of the hole drilling method. According to elastoplastic theory, a critical parameter of plastic deformation round the centre hole is obtained. On the basis of this critical parameter, a simple method is proposed to correct the stresses for the plasticity effect. It is shown in the experiments with welded joints that the correction method may improve the accuracy of high residual stress measurement.
New techniques in the elastic analysis of arch bridges using image processing
Authors: Prentice D.J. , Ponniah D.A.
Published: October 2008

The importance of the masonry arch in Britain's infrastructure has never been more significant than at the present time with ever increasing axle loads under new EEC regulations The searches have been shown to be significantly affected by the overlying fill. The effect of this fill is being investigated by a number of methods employing a variety of experimental techniques. This paper presents one such new technique of examining the effects of the fill through monitoring zones of strain on an arch model subjected to load. The model arches were constructed in timber with a dry granular fill and approximately 90 tests were carried out to investigate the effect of load position, fill depth and pier stiffness. Image analysis of the tests permitted identification of the areas of strain within the fill and arch barrel and the location of the hinges at higher loads. Finite element (FE) analysis was used to model the arch in its elastic range and comparisons of the FE strain contour plots with the equivalent images illustrated the validity of using image processing for the determination of the strain characteristics. The practical applications of using such a technique are subsequently highlighted and commented on.
Non‐contact strain measurement using metal foil gauges with the application of the laser speckle method
Authors: Kato Akira , Nakai Hidetoshi , Tanabe Kiyoshi , Nagase Yasuo
Published: October 2008

This paper presents a new method to measure cyclic strain with no contact using metal foil gauges assisted by the laser speckle method. When aluminium foil is pasted on a specimen and the specimen is loaded cyclically, slip bands are produced on the foil surface. There is a fixed relation between density of the slip bands and the strain amplitude or loading cycles depending on the foil material. Thus the fatigue strain of the base metal can be estimated by observing the surface change of the metal foil by the slip bands at a constant number of loading cycles. The method presented in this paper is intended to make a non‐contacting strain measurement by the application of the laser speckle technique for the detection of the surface change. This method is based on observation of the changes in a laser speckle pattern depending on the surface roughness and surface property changes of the foil caused by fatigue. The laser speckle pattern can be analysed automatically and quantitatively using an image processing system.
A New Method to determine Triaxial Non‐Uniform Residual Stresses from Measurements using the Hole Drilling Method
Authors: Wern H. , Cavelius R. , Schläfer D.
Published: October 2008

A new integral analysis technique in combination with finite element calibration data is introduced to resolve the triaxial residual stress profiles of measurements performed with the hole drilling or ring core method. The new technique uses an inverse formulation with symmetrised trigonometric basis functions or wavelets.
Residual deformation analysis of an aluminium plate irradiated by CO2 laser
Authors: Huimin Xie , Guotao Wang , Daqing Zou , Fulong Dai , Dietz Peter , Schmidt Axel
Published: October 2008

In this paper, a grid method was used to measure the residual deformation of a loaded aluminium plate irradiated by CO2 Laser. The residual strain fields near the illuminated area at different irradiation times were obtained. The experimental results were discussed in detail.
Towards a device independent digital image processing software for photoelastic analysis
Authors: Ramesh K. , Govindarajan R.
Published: October 2008

The application of digital image processing (DIP) techniques to photoelasticity has greatly simplified data reduction and analysis. The softwares reported so far are hardware dependent and hence not portable. A simple PC based device independent software for collection of photoelastic data from digitised fringe patterns is presented. The software is validated by evaluating the near crack tip stress field parameters for a crack subjected to mode I and mode II loadings.
Measurement techniques for buckling sensitive composite shells
Authors: Esong I. E. , Elghazouli A. Y. , Chryssanthopoulos M. K.
Published: October 2008

This paper describes a measurement system that was developed for an experimental study on buckling of glass reinforced composite cylinders. An automated non‐contact laser device operating inside the test specimen provided a three dimensional scanning system for measuring the deformation of the shell wall. The measurement system was used to obtain the initial geometric imperfections, as well as the deformation under varying control axial displacement. All loading and data acquisition operations were carried out using advanced computer controlled techniques. Due to the large number of measurements undertaken in each test, data collection was followed by processing and reduction techniques, thus delivering the data in a form suitable for finite element analysis and comparative studies. Typical results are presented in order to demonstrate the reliability, accuracy and versatility of the system.
Splice jointing behaviour in glulam portal frames
Authors: Royles R. , Mullen E.J.
Published: October 2008

The need for effective structural connections in glued laminated timber portal frames is discussed and the design of a flitch plate form of joint is outlined. Tests on the connection are described and its performance under flexure and shear is assessed. The influence of glueline thickness on joint performance is examined.
The design of advanced aircraft structures to resist acoustic fatigue; work in progress
Authors: Cunninghamsp P.R. , Xiao Y. , White R.G.
Published: October 2008

Details of the current research activities in the Department of Aeronautics and Astronautics, on the response of advanced aircraft structures to acoustic loading, are presented. Both box type and sandwich structures, employing aluminium alloy, carbon fibre reinforced plastic, and GLARE composite materials, are being investigated. In order to develop design guidelines for these complex structures, it is necessary to combine theoretical predictions, using the finite element method, with experimental measurements of the structural response to random acoustic loading. Both types of structure will be tested in the Progressive Wave Tube facility at Southampton. In addition, it is hoped that a more comprehensive damping guide will be produced for the type of structure used in advanced aircraft design.
Modelling of unbounded media for fluid‐structure interaction applications ‐ a review
Authors: Hamdan Fadi H.
Published: October 2008

Many structures used at sea must be able to withstand the occasional extreme weather conditions and the risk of underwater explosions. This applies not only for military ships and submarines but also for tankers and civil exploration and extraction platforms. An understanding is therefore required of the effects of shock induced water waves and unbounded fluid‐structure interaction on floating and submerged structures. For modelling purposes these structures may be considered as a system of five components: the structure itself, any fluid within it, the surrounding fluid including the effects of cavitation, the farfield fluid medium and the effect of shock waves. The first two are sufficiently well understood, the remaining three are the subject of continuous research. Recent developments have created new possibilities for treating the farfield fluid medium. Hence, this paper which discusses the various methods used in the modelling of this problem.
Symbolism and the bridge
Authors: Royles R.
Published: October 2008

An account is given of the formation of a symbolic figure representing hope for the development of the human race and the ecosystem of which it is a part.
Phase shifting method for retroreflective grating analysis
Authors: Zhang Xianzhu , North Walter P.T.
Published: October 2008

A phase shifted retroreflective grating system has been presented for measuring the derivative and contour of quasi flat specular surfaces. The system has been tested with a small indent of maximum depth less than 10 microns. The experiment shows that the system can tell the defect size, shape and polarity (indent/outdent). The method can be developed for industrial application in nondestructive testing and evaluation(NDTE).
Catalogue of photoelastic fringes for a biaxially loaded infinite plate with a hole
Authors: Cárdenas‐Garcia Jaime F.
Published: October 2008

This paper presents a typical catalogue of “virtual” photoelastic isochromatic fringes around the hole of a biaxially loaded infinite plate for two problems. Problem 1 relates to an infinite plate in which the circular hole is drilled first and then the loads are applied. Problem 2 is the residual stress problem in which the hole is drilled after the biaxial load is applied to the infinite plate. Use of this catalogue allows visualisation of the stress distribution around the hole, and a first approximation to the solution of the inverse problem using photoelasticity.
Stress concentrations in tube intersections
Authors: Allison I.M.
Published: October 2008

A method has been developed for precision casting photoelastic models of tube intersections to the finished shape. Models made in this way have been tested under internal pressure, axial tension and transverse load. These tests illustrate the difficulty of predicting the location and magnitude of the critical stresses at the intersection.
Plasticity Effects in Residual Stress Measurement by the Hole Drilling Method
Authors: Ermini M.
Published: October 2008

Abstract: A recent paper touched on some important aspects of residual stress measurement by the blind hole drilling method in the presence of an intense stress field. This technical note discusses some significant issues raised in that paper, and presents a different viewpoint. The issues concern the problems regarding a yield condition of the material near the drilled hole. In the presence of plasticity effects, we discuss the dependence of the calibration constants A and B on the biaxiality ratio (Ω) between the principal stresses and on the angle (β) between the principal direction of stress and the direction of the strain gauge.
Impact Location and Quantification on a Composite Panel using Neural Networks and a Genetic Algorithm
Authors: Worden K. , Staszewski W.J.
Published: October 2008

Abstract:The problem of impact detection in composite panels using artificial neural networks is addressed in this paper. The data were taken from an experiment in which time dependent strain data were recorded on a network of surface‐mounted piezoceramic sensors when the plate was impacted. Neural networks were trained to locate and quantify the impact event when presented with features extracted from the measured data. An important problem for detection systems like this is that of optimal sensor placement; this is solved here by means of a Genetic Algorithm. The study shows that a relatively small number of sensors can be used to detect reliably impacts on a composite plate.
Static Behaviour of Transversely Loaded CFRP Laminate Panels Subject to In‐Plane Tension
Authors: Mines R.A.W. , Li Q.M.
Published: October 2008

Abstract: Static tests with various in‐plane loads from 0 to 30 kN were conducted, to study in‐ plane load effects on the static behaviour of CFRP laminated composite panels when subjected to transverse load. The panels were 32 ply with the unidirectional carbon epoxy plies in a quasi‐isotropic lay up. It is shown that panel stiffness and maximum load increase with increasing in‐plane load and that a failure mode transition occurs with increasing in‐plane load. It is also shown that the energy absorbed by the panel to failure is approximately constant with respect to in‐plane load. Experimental information on load v deflection histories, surface strain histories and different failure modes together with material properties are presented in the paper, which could be used for analytical and numerical simulations of the problem.
Reliability Analysis of Non‐Parametric Statistical Tests for the Evaluation of Linear Drift in Experimental Data
Authors: Cappa P. , Sciuto S. A. , Silvestri S.
Published: October 2008

Abstract: During usual data gathering, the statistical analysis efficiency strongly depends on the noise level superimposed on the signal. It has been found that some well known statistical tests, commonly utilised in data acquisition in order to detect the presence of drift, can fail under some conditions. Thus, a statistical procedure for the predictive reliability estimation of the utilised statistical method could be useful in the design of experimental analysis. This paper reports the results of a simulation study carried out to evaluate the performance in drift detection of non‐parametric tests such as the Wald‐Wolfowitz run test, in comparison with the Mann‐Whitney, reverse arrangement test. In order to detect the sensitivity of the tests to evaluate a monotonous drift, a simulation program was developed. In the program a Gaussian raw data sequence with a linear pattern of variable slope and with variable variance was simulated and given as the input to the tests. The capability to detect the presence of drift as a function of angular coefficient and variance of the noise superimposed on the signal was verified. The obtained data were synthesised in graphs so that the experimentalist could determine preliminarily the effectiveness of each of the considered statistical methods in terms of percentage of success in detecting the presence of drift phenomena as a function of drift relevance and the noise amplitude. Finally, the graphs permitted the elucidation of the causes of contradictory failing results observed in long term experimental analysis.
Predicting the Number of Defects Remaining In Operational Software
Authors: Hartman P. J.
Published: October 2008

Software is becoming increasingly critical to the Fleet as more and more commercial off‐the‐shelf (COTS) programs are being introduced in operating systems and applications. Program managers need to specify, contract, and manage the development and integration of software for warfare systems, condition based monitoring, propulsion control, parts requisitions, and shipboard administration. The intention here is to describe the state‐of‐the‐art in Software Reliability Engineering (SRE) and defect prediction for commercial and military programs. The information presented here is based on data from the commercial software industry and shipboard program development. The strengths and weaknesses of four failure models are compared using these cases. The Logarithmic Poisson Execution Time (LPET) model best fits the data and satisfied the fundamental principles of reliability theory. The paper presents the procedures for defining software failures, tracking defects, and making spreadsheet predictions of the defects still remaining in the software after it has been deployed. Rules‐of‐thumb for the number of defects in commercial software and the relative expense required to fix these errors are provided for perspective.
Open Systems Architecture C41 Template
Authors: Madaio J. , Hillers B. J. , Vasilakos J.
Published: October 2008

The Affordability Through Commonality Office (PMS 512) of PEO Surface Strike, in order to promote and enable the implementation of Open Systems Architecture (OSA) for Navy systems, established the Total Ship Open Systems Architecture (TOSA) Industry/Navy Integrated Product Team (IPT). TOSA has developed a notional open C4I template which incorporates an OSA. The application of OSA to C4I spaces will increase flexibility, upgradability, scalability, and adaptability and decrease total ownership cost over the lifecycle of the ship. Open systems concepts are well established in the commercial information technology (IT) field as a means to increase competition among vendors (broaden the market applicability and reduce costs). While the benefits of OSA are easily discernable for IT systems, the use of OSA for HM&E ship systems inter‐faces represents a new and unproven application. An important feature of the adaptable ship concept is the Functional Element (FE) zone, which represents physical divisions of a ship with managed functions, configurations, interfaces, and characteristics. This paper describes how the OSA process was applied to develop an example FE Zone template for a specific space, a notional Combat Information Center (CIC) zone. The resulting concept may be used to develop a family of templates to open the remaining Command, Control, Communications, Computing and Intelligence (C4I) zones on a ship.
Naval Research into the New Millennium — Pitfalls, Challenges, and Opportunities
Authors: Sacks S.
Published: October 2008

Naval research will be critical in meeting the challenges of the new millennium. Pitfalls in the process exist. This article discusses how modeling and simulation can lead to incorrect conclusions and how over‐reliance on inclusion of commercial off‐the‐shelf products may not yield what is really needed. The idea that Information Technology may not be the answer to every need, and can actually cause problems, is also discussed. Research opportunities are addressed. The article reviews the issue of whether the new paradigm of a single corporate entity defining a new generation of ships will necessarily bring into the picture research and technology concepts that may derive from a broader team approach.