Showing papers in "Strain in 2001"
TL;DR: Neutron and synchrotron X-ray strain scanning provides the opportunity for mapping residual strain distributions within polychrystalline materials, non-destructively as mentioned in this paper, and the capabilities and complementarity of the two methods are reviewed and contrasted in this paper through a series of case studies.
Abstract: Neutron and synchrotron X-ray strain scanning provide the opportunity for mapping residual strain distributions within polychrystalline materials, non-destructively. the neutron method is now reasonably mature, industrial standards for measurement are being defined and new dedicated neutron strain scanners are being built at ISIS in the Uk and at the ILL, France, as well as in the United States. Synchrotron strain scanning on the other hand is relatively new and is much less well developed but, with penetrations typically hundreds of time greater than most laboratory X-rays and intensities millions of times greater, it can provide maps of near- and sub-surface strain of unparalleled detail and strain resolution. The capabilities and complementarity of the two methods are reviewed and contrasted in this paper through a series of case studies.
94 citations
73 citations
TL;DR: In this paper, a comparison was made between the fatigue lives of welded specimens in the as welded condition and after heat treatment, and after post-weld vibration, and it was found that the fatigue life of the thermally relieved specimens decreased by 43%, while the vibration treated specimens showed an increase of between 17% and 30%.
Abstract: A comparison has been made between the fatigue lives of welded specimens a) in the as welded condition b) after heat treatment, and c) after post-weld vibration. By comparison with the aswelded specimens, the fatigue lives of the thermally relieved specimens were found to decrease by 43%, while the vibration treated specimens showed an increase of between 17% and 30%. While these findings are interesting in that they offer a way of extending the fatigue lives of welded joints, they confirm the view that the mechanism of residual stress relieving in the vibratory stress relief (VSR) method, and its relationship with fatigue life is poorly understood.
45 citations
TL;DR: In this article, a cross grating was used to measure large strain in polymers and latex materials, with a strain accuracy close to 5 times10-4 at minimum gauge lengths of 0.125 mm.
Abstract: Optical methods have been developed to measure large strains. Two alternatives are presented: the first one uses a cross grating, obtained by an innovative manufacturing process and the second one uses a mark-tracking technique. The production of the grating is based on the deposit of a thin film through a master grid under vacuum. This creates small studs independent of each other, on the specimen surface. For the grid interrogation two techniques are discussed, one using the analysis of the optical diffraction figure and the other one the Fast Fourier Transform algorithm. Markers are simply deposited on the studied surface with a pen and strain determination is then obtained by mark-tracking. The experimental validation consists of several simple tensile tests. Experimental results for polymers and latex materials confirm the quality of measurement. Strains are measured for values up to 1,200% without loss of information, with a strain accuracy close to 5times10-4 at minimum gauge lengths of 0.125 mm.
36 citations
31 citations
TL;DR: In this article, an impression creep test was performed for a service-aged 1/2Cr1/2Mo1/4V steel at 565°C, corresponding to uniaxial stresses in the range of 100-150 MPa.
Abstract: Impression creep tests under multi-step load conditions were performed for a service-aged 1/2Cr1/2Mo1/4V steel at 565°C, corresponding to uniaxial stresses in the range of 100–150 MPa. Results of the tests have shown that the minimum creep strain rate data of the material, produced from the creep curves obtained under different load histories, are in good agreement. The results obtained indicate that the results from a multi-step load test of an impression creep specimen, which is particularly useful when the test material is very limited, can be used to obtain the secondary creep properties for a material from a very small test sample.
18 citations
TL;DR: In this paper, a generic approach to simulation of error in digital photoelasticity is presented and the simulation has showed how to associate the errors in the phase map to the misalignment of optical elements.
Abstract: The accuracy of parameter evaluation by automated photoelastic techniques depends on both their theoretical formulation and experimental procedure The sensitivity of techniques such as phase shifting and load stepping to error in optical misalignment and quarter-wave plate mismatch would be of interest A generic approach to simulation of error in digital photoelasticity is presented The simulation has showed how to associate the errors in the phase map to the misalignment of optical elements
11 citations
9 citations
6 citations
4 citations
TL;DR: In this article, an intensity-based image processing method termed the Intensity Integration Technique (IIT) was proposed to obtain the slope and curvature of loaded reflecting plates, which employs divergent beam illumination to cover a large plate area.
Abstract: An intensity-based image processing method termed the Intensity Integration Technique (IIT) is proposed to obtain the slope and curvature of loaded reflecting plates. It employs divergent beam illumination to cover a large plate area. The deformation field is established by applying cumulative (integrated) intensity as the correlation parameter to relate the reflected images from the undeformed and deformed states of the object. The method is suited to modern computing environment and requires a simple experimental set-up. It obtains absolute values of slope and curvature.
TL;DR: In this article, a simulation study was 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-Wkitney, reverse arrangement test.
Abstract: During usual data gathering, the statistical analysis eficiency 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 usefil 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 suck as the Wald-Wolfowitz run test, in comparison with the Mann-Wkitney, 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 coeficient 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 eflectiveness 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 contradictovy failing results observed in long term experimental analysis.
TL;DR: In this article, a general review of the production of high temperature gratings and their application to deformation measurement is given, focusing on in-plane moire and moire interferometry methods.
Abstract: This paper gives a general review of the production of high temperature gratings and their application to deformation measurement. The fabrication techniques for gratings and deformation measurement methods using the gratings are discussed. The review is confined to in-plane moire and moire interferometry methods. Some typical applications in high temperature deformation measurement are briefly discussed.
TL;DR: The hole-drilling and x-ray residual stress measurement techniques used by Corus, Research, Development & Technology for product integrity and development have been reviewed in this paper, where the application of the x ray residual stress method to heat-treated surfaces, stainless steel and bar straightening is described.
Abstract: The hole-drilling and x-ray residual stress measurement techniques used by Corus, Research, Development & Technology for product integrity and development have been reviewed. Calibration of the x-ray technique can be undertaken although comparative measurements are often adequate. The application of the x-ray residual stress measurement method to heat-treated surfaces, stainless steel and bar straightening is described.
TL;DR: In this article, the authors provide confidence in the adequacy of their designs by providing accurate information on the hogging and sagging exteme and fatigue stresses which will be experienced by ships in service.
Abstract: To provide confidence in the adequacy of their designs, naval architects require accurate information on the hogging and sagging exteme and fatigue stresses which will be experienced by ships in service. These should include verticla and lateral bending and the effects of slamming and slam induced whipping.
TL;DR: The sensitivity of the joint's stiffness to changes in certain parameters (geometric and material properties) has been investigated and an understanding of the Joint's behaviour gained from this parametric study is gained.
Abstract: The sensitivity of the joint's stiffness to changes in certain parameters (geometric and material properties) has been investigated and an understanding of the joint's behaviour gained from this parametric study. This insight into simple overlap joint behaviour has been used to fashion some design guidelines aimed at increasing joint stiffness. A representation that can be successfully substituted for certain adhesively bonded overlap joints in finite element (FE) analyses is also suggested.
TL;DR: The atan and atan2 functions are standard features of a high level programming language like Fortran or C, which are used to calculate the inverse tangent functions, and considering that the angle 8 refers to the fast axis of the model produces the following intensity equation.