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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Optics and Lasers in Engineering 21 (1994), S. 151-164 
    ISSN: 0143-8166
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Research in nondestructive evaluation 10 (1998), S. 63-73 
    ISSN: 1432-2110
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract. A recent advance in the nondestructive inspection of crevice corrosion is reported. Crevice corrosion is one of the most hazardous defects that threaten the integrity of aging aircraft. Two optical techniques, electronic speckle pattern interferometry (ESPI) and digital speckle correlation (DSC), are employed to reveal the existence of crevice corrosion, which is usually undetectable from outside by visual inspection. The ESPI is configured to measure out-of-plane displacement. Both thermal loading and vacuum loading are used. The anomaly of fringe patterns reveals the existence of crevice corrosion hidden between two metallic plates. Not only the location of defects, but also the approximate size can be estimated. The digital speckle correlation technique takes advantage of laser speckle properties. The speckle decorrelation due to out-of-plane displacement in the region with crevice corrosion is larger than the region without defects. This difference is calculated by a digital correlation algorithm, which reveals the crevice corrosion. These two techniques can be used alternatively for field inspection of aircraft. While digital speckle correlation offers a simple, rapid approach to qualitatively detect defects, ESPI can be used as a supplementary tool if a more sensitive and quantitative evaluation is required.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Research in nondestructive evaluation 7 (1996), S. 229-238 
    ISSN: 1432-2110
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fractal geometry is finding its application in the nondestructive evaluation (NDE) of corrosion by characterizing the corrosion surface with fractal dimensions. It was found that corrosion surfaces can be well described by multifractals. Two algorithms were used to obtain the fractal dimensions of a corroded aluminum alloy surface, one being box-counting and another being coherent light scattering. Fractal dimensions were related with the damage caused by corrosion and fatigue.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of nondestructive evaluation 8 (1989), S. 77-95 
    ISSN: 1573-4862
    Keywords: holography ; holographic interferometry ; holospeckle interferometry ; coherent optical methods ; strain measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 14 (1974), S. 347-354 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Experimental and theoretical studies of edge effects in rectangular composite strips under tension are discussed. The objective of the study was to investigate the effect of various parameters, including reinforcement material, fiber orientation and the structure of the reinforcement, on the various quantities which are observed in the vicinity of free edges in multidirectionally reinforced laminates. Of particular interest was the confirmation of theoretical results related to differences in response of graphite- and boron-reinforced laminates. Experiments consisted of moiré measurements of surface-displacement patterns which were compared with theoretical predictions, and examination of failure levels. The experiments were carried out on AVCO 5505 boron and Whitaker 5206 MODMOR II graphite-reinforced angle-ply laminates in which both stacking sequence and fiber orientation were varied parametrically. Moiré techniques were developed which allowed observation of displacements on both the wide surface and along the narrow edge of 1 in.-wide × 16-ply-thick (.085 in.-.105 in.) laminates.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 11 (1971), S. 296-302 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The moiré gap equation originally derived by Sciammarella and Chiang has been generalized to include linear and rotational mismatches. The equation is then applied to the measurement of deflection of beams and plates. The method has the advantages of being simple in comparison with other optical whole-field methods. The application of moiré gap effect to the study of dynamic problems is also discussed.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 31 (1991), S. 197-201 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The relation between the angular distribution of the reflected-plus-scattered light intensity (scattered field) from a metallic surface and the flow stress, plastic strain the material has experienced is experimentally and theoretically investigated. A scattered field, which is obtained by illuminating a specimen surface using a laser beam, carries surface-feature-related information. Experimental evidence suggests that surface correlation length of a material decreases in proportion to the flow stress and plastic strain that the material experiences. A theoretical derivation based on Huygens-Fresnel principle, Fraunhofer approximation, and Wiener-Khintchine theorem shows that the correlation length may be obtained by performing a Fourier transform to the scattered field from the surface. This leads to the development of a noncontact, nondestructive, and remote technique for measuring flow stress and plastic strain.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A novel whole-field residual stress measurement technique is developed using moiré interferometry and Twyman/Green interferometry coupled with thermal annealing. The technique is successfully applied to residual stress measurement in rail. In the measurement, a high temperature resistant 1200-lines/mm cross grating is made on a rail transverse slice surface. The whole-field residual stress relief is achieved by thermal annealing. Moiré interferometry and Twyman/Green interferometry are employed to obtain the in-plane and out-of-plane deformations generated by the residual stress relaxation. The whole-field strain redistribution due to the residual stress relief is calculated, and the whole-field residual stress distribution, including the possible stress concentration, is then obtained. Because of the three-dimensional nature of the residual stress relaxation and the measurement, the three-dimensional residual stress reconstruction sometimes becomes possible based on some plausible assumptions. In this paper, the principle of the experimental theory, technique and procedures are described. Three-dimensional residual stress reconstruction in a rail using a transverse slice is shown. Its comparison to the hole-drilling method with moiré interferometry is also presented.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 42 (1990), S. 371-388 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé En utilisant une technique de mesure optique des déplacements, on obtient les champs régnant à l'estrémité d'une entaille, qui s'experiment par la déformation d'extrémité d'entaille, l'angle d'ouverture de la crique (COA et l'angle d'ouverture de la pointe de la crique (CTOA). On étudie des feuillards présentant différentes configurations de fissures et réalisés en six matériaux élasto-plastiques dont les modules d'écrouissage s'échelonnent de 3 à l'infini. On trouve que la courbe de résistance COA suppose certaines caractéristiques communes à tous les matériaux. Les résultats expérimentaux indiquent que la valeur critique du COA peut être utilisée comme paramètre de ténacité à la rupture pour les matériaux étudiés.
    Notes: Abstract By using optical displacement-measuring techniques we obtain the crack tip fields in terms of crack tip strain, crack opening angle (COA) and crack tip opening angle (CTOA). Thin plates with different crack configurations made of six elastic-plastic materials with strain hardening exponent ranging from 3 to ∞ are studied. We find that the COA resistance curve assumes certain characteristics common to all the materials. The experimental results indicate that the critical value of COA may be used as a fracture toughness parameter for these materials.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 36 (1988), S. 243-257 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé On détermine le champ de déformation des dimensions au voisinage d'une fissure arrondie dans un feuillard d'un matériau à faible consolidation en utilisant un faisceau laser et la technique des moirés. Les résultats des essais sont comparés avec ce que fournit un champ de singularité HRR. On procede à un mapping d'une zone à effets tridimensionnels dominants en amont de l'extrémité de la fissure. Les contours des déformations, la frontière élastique-plastique et les trajectoires de déformations maximum de cisaillement sont également portées en diagramme par un traitement numérique des données expérimentales.
    Notes: Abstract Three-dimensional deformation field in the vicinity of a blunt crack in a sheet of low-hardening material is determined using laser speckle and moiré techniques. Experimental results are compared with the HRR singularity field. A zone of dominant three-dimensional effects is mapped out ahead of the crack tip. Strain contours, elastic-plastic boundary and maximum shear strain trajectories are also plotted by numerically processing the experimental data.
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