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1.
Practical applications in which carrier fringes are used with moiré interferometry for strain measurements are presented.
Examples illustrate how moiré carrier fringes are applied to obtain the desired data in complex laminated composite specimens.
In many cases, carrier fringes permit extraction of much more detailed information, with procedures that are easier and more
accurate than those using loadinduced fringes alone. The fringe vector for carrier fringes is introduced and its application
to the interpretation of fringe patterns is explained. In moiré interferometry, the carrier fringes are produced easily by
adjustments of optical elements that control the virtual reference grating. 相似文献
2.
The theory of an automated fringe-pattern analysis using temporal phase stepping method for moiré interferometry is presented.
The automated method provides a fast and accurate strain measurement for moiré interferometry. Measurements on a tapered composite
specimen with a dropped ply are shown to highlight the capability of this technique to obtain the strain distribution, particularly
around the region with a dropped ply. 相似文献
3.
Moiré interferometry has been a valuable experimental technique for the understanding of the mechanical behavior of materials and structures. Over the last decade less emphasis has been placed on the development of the technique and more towards applications. This paper is a review article on recent applications using moiré interferometry in the fields of microelectronics devices, material characterization, micromechanics, residual stress, composite materials, fracture mechanics, and biomechanics. The general principles of moiré interferometry and advancement of techniques will not be discussed in this text, but references will be provided. 相似文献
4.
Hole-drilling method is one of the most convenient methods for engineering residual stress measurement. Combined with moiré
interferometry to obtain the relaxed whole-field displacement data, hole-drilling technique can be used to solve non-uniform
residual stress problems, both in-depth and in-plane. In this paper, the theory of moiré interferometry and incremental hole-drilling
(MIIHD) for non-uniform residual stress measurement is introduced. Three dimensional finite element model is constructed by
ABAQUS to obtain the coefficients for the residual stress calculation. An experimental system including real-time measurement,
automatic data processing and residual stresses calculation is established. Two applications for non-uniform in-depth residual
stress of surface nanocrystalline material and non-uniform in-plane residual stress of friction stir welding are presented.
Experimental results show that MIIHD is effective for both non-uniform in-depth and in-plane residual stress measurements.
The project supported by the FRAMATOME ANP 相似文献
5.
There is a compelling need to experimentally understand solder joint deformation behavior at high temperatures over an extended
period of time. Accordingly, the deformation behavior of solder joints in a Ceramic Ball Grid Array (CBGA) package mounted
on an organic FR4 board under extended dwell time at a high temperature has been studied using laser moiré interferometry.
The warpage and the in-plane horizontal deformation of the ceramic substrate and the organic board as a function of time were
determined. The variation of the normal strains and shear strains in the solder joints with time were also investigated. It
was found that increased sensitivity was necessary to accurately determine the strains in the small sized solder joints. A
new method utilizing carrier fringes to increase the sensitivity of the moiré interferometry system is proposed and has been
used to determine the strains in the small sized solder joints. Increased sensitivity can be obtained merely by changing the
incident angle of the laser light on the surface of the specimen, thereby making it unnecessary to use expensive phase shifting
apparatus with the traditional laser moiré system. 相似文献
6.
The mechanics of double-lap joints with unidirectional ([016]) and quasi-isotropic ([0/90/?45/45]2S) composite adherends under tensile loading are investigated experimentally using moiré interferometry, numerically with a finite element method and analytically through a one-dimensional closed-form solution. Full-field moiré interferometry was employed to determine in-plane deformations of the edge surface of the joint overlaps. A linear-elastic two-dimensional finite element model was developed for comparison with the experimental results and to provide deformation and stress distributions for the joints. Shear-lag solutions, with and without the inclusion of shear deformations of the adherend, were applied to the prediction of the adhesive shear stress distributions. These stress distributions and mechanics of the joints are discussed in detail using the results obtained from experimental, numerical and theoretical analyses. 相似文献
7.
Surface and interior straini fields in thick specimens of polycarbonate have been measured by an embedded-multiple-grid moiré
method. Interior gratings are photographed through intervening gratings. Coherent optical processing of grating records creates
moiré fringe pattern. A correction procedure was developed to eliminate moiré errors caused by strain-induced gradients of
refractive index. This procedure utilizes the refraction distribution as obtained from observation of a grating from opposite
sides of a specimen. No measurements other than the normal moiré observations are required in order to find actual strains.
The correction technique should be useful in refining the results obtained when other optical methods are used in three-dimensional
situations. The method is utilized to determine strains on the surfaces and at the mid-and quarter-planes of thick compact
tension specimens. Results obtained, after correction, agree with measurements made with embedded strain gages. Maximum tensile
strain occurs on the midplane. The findings are rationalized by consideration of thickness and proximity to the crack tip. 相似文献
8.
The equations prescribing the gradient and inclination of fringes in moiré interferometry are derived from the basic laws
of diffraction and interference. A vectorial representation of three-dimensional diffraction employs incidence and emergence
vectors in the plane of the grating; the representation is especially well suited for this type of analysis. The corresponding
equations for geometrical moiré are derived by a remarkably direct vectorial method. The analyses prove that the patterns
of moiré interferometry and geometrical moiré are governed by identical relationships.
Paper was presented at 1985 SEM Spring Conference on Experimental Mechanics held in Las Vegas, NV on June 9–14, 1985. 相似文献
9.
An experimental study has been undertaken to investigate the shrinkage characteristics of acrylic-based and epoxy-based stereolithography
(SL) photopolymer resin systems after they have been laser cured and post-cured under ultraviolet (UV), and thermal exposure.
The induced residual stresses and strains were determined by the shadow moiré and the hole-drilling strain-gage methods. Out-of-plane
displacements (warpage) of acrylic-based post-cured resin plates were recorded by means of the shadow moiré method and correlated
to the shrinkage strains by theoretical analysis. The induced residual stresses in the epoxy-based cylindrical resin specimens
were determined from strains of three-element strain-gage rosettes of the blind-hole drilling method. Results are presented
for the shrinkage stresses and strains for both material systems as a function of the post-curing process (UV, thermal). It
was found that the shrinkage strains in the acrylic-based photopolymer resin were of considerable magnitude, while thermal
post-curing resulted in higher shrinkage stresses for both material systems. The values of the shrinkage stresses compare
well with those of the existing literature. 相似文献
10.
Harold E. Gascoigne 《Experimental Mechanics》1994,34(1):27-36
Residual (curing) stresses in a cross-ply laminated plate are related to the strains released when individual plies are separated.
Released displacements are determined using high-sensitivity moiré interferometry and linearized strain-displacement equations
are used to determine residual strains. Elastic orthotropic stress-strain relations are used to calculate residual stresses
remote from free-edges of a [9020/020/9020] graphite-epoxy cross-ply panel. The measured strains compare favorably with those predicted by laminated plate theory. In
a second example, the circumferential and radial residual strains and stresses at the end-section of a thick-walled cross-ply
graphite-epoxy cylinder are determined.
Paper was presented at the 1992 SEM Spring Conference on Experimental Mechanics held in Las Vegas NV on June 8–11. 相似文献
11.
Immersion interferometer for microscopic moiré interferometry 总被引:1,自引:0,他引:1
The basic sensitivity of moiré interferometry has been increased beyond the previously conceived theoretical limit. This is
accomplished by creating the virtual reference grating inside a refractive medium instead of air, thus shortening the wavelength
of light. Various optical configurations of moiré interferometry for operation in a refractive medium are introduced and one
of them has been put into current practice. A very compact four-beamimmersion interferometer has been developed for microscopic viewing, which produces a basic sensitivity of 4.8 fringes per μm displacement (contour
interval of 0.208 μm per fringe order), corresponding to moiré with 4800 lines per mm. Its configuration makes it inherently
stable and relatively insensitive to environmental disturbances. An optical microscope is employed to obtain high spatial
resolution. The method is demonstrated for deformation of a thick graphite/epoxy composite at the 0/90-deg ply interface.
Paper was presented at the 1991 SEM Spring Conference on Experimental Mechanics held in Milwaukee, WI on June 9–13, 1991. 相似文献
12.
A new version of a moiré microscope is presented that embodies the theory of optical moiré interferometry. To interrogate
the deformed specimen grating, the device uses a transmission diffraction grating that allows for a simple and quick change
of the virtual reference grating vector without disturbing the optical alignment of the other components in the optical train.
To analyze deformation from the acquired moiré interference fringe patterns, the displacement light-itensity moiré optical
law introduced by Sciammarella is revisited. The analysis of deformation is consistent with the continuum principles of finite
deformation and can readily be used to obtain micro-mechanical quantities of interest such as the local strains, stretches
and rotations. 相似文献
13.
Nano-meter Displacement Measurement by Phase Analysis of Fringe Patterns Obtained by Optical Methods
0Introduction Inordertomonitorthehealthofstructures,straingagesanddisplacementtransducersare usuallyused.Thereasonisthatmanyrulesorcodesforinspectionofstructuresrequiretousestrain gagesanddisplacementtransducers,anditiseasytousethem.However,thesemethodsarebasically one pointmeasurementmethods.Theyareexpensiveandtime consumingfordistributionanalysis.Opticalmethodssuchasgrating projection,geometricmoir啨,moir啨interferometry,holographic interferometryandspeckleinterferometryareusefultomeasuredi… 相似文献
14.
Moiré interferometry is utilized to investigate the time-temperature-dependent deformation of a woven composite substrate
used in multilayer circuit board applications. Creep tests are performed at temperatures ranging from 27 to 70°C, and the
resulting longitudinal and transverse displacement fields are measured via moiré interferometry. Measured displacement fields
reveal the influence of fabric architecture on woven composite response. The deformation fields in the plane of the composite
for loading along both warp and fill directions consist of a periodic arrangement of high-strain and low-strain regions in
accordance to the interlacing bundle architecture. The deformation fields over the cross-section of the composite indicate
that neighboring unit cells are subjected to equal and opposite bending moment even when the composite is loaded in uniaxial
tension. 相似文献
15.
The strains developed in a tube plate by the process of roller expansion of tubes were measured by moiré interferometry. The
maximum strains during the process were recorded by photographing the fringe patterns during rolling at a rate of five frames
per second. The tubes were rolled according to a prearranged pattern, and the deformations over the whole tube-plate element
were recorded between the rolling of successive tubes; by this means, the effect of each tube rolling on the overall strain
pattern was assessed. 相似文献
16.
A method of combining moiré interferometry and the finite-element method to effect localized stress analysis is presented.
The displacement data from local regions of interest in the optical experiment are used as boundary conditions for the finite-element
stress analysis.
The stability of the method is examined with data from simple numerical models one of which corresponded to the stress analysis
of a pin-loaded plate with friction. These studies show that the method requires the sensivity of moiré interferometry for
successful implementation, i.e., displacement data accuracy within 0.1 μm or 4 μin.
This localized hybrid method of stress analysis provides a powerful and efficient method for the reduction of experimental
data. 相似文献
17.
Daniel Post 《Experimental Mechanics》1983,23(2):203-210
A relatively easy technique for producing high-frequency gratings on specimens extends moiré techniques into the high-sensitivity domain. Whole-field patterns of inplane displacement components are obtained with grating frequencies of 1200, 2400 and 4000 l/mm (30,480, 60,960 and 101,600 l/in.). Moiré interferometry is a case of two-beam interference, characterized by extensive range, excellent fringe contrast and fringe localization on the specimen surface. It is a reflection technique, compatible with opaque specimens and live observation of deformation. 相似文献
18.
Electronic-speckle-pattern interferometry and moiré interferometry have been used to calculateK
1 andJ for compact tension specimens. Automated-fringe-pattern analysis enables the full-field of data to be used with the minimum
of operator intervention. Measurements are shown to be accurate to within 10 percent. TheJ-measurement procedure employed could form the basis of an automatic-fault detection system. 相似文献
19.
The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields (u and v) can be obtained to determinate two strain fields and one shearing strain field. In this paper, by means of Moire interferometry and three directions grating (grating rosette) developed by the authors, three displacement fields (u, v and s) are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials. 相似文献
20.
This paper presents the results of an investigation to develop new techniques to enhance the moiré method of mechanical interferometry. The program demonstrated the practicality of developing the use of orthogonal bicolored moiré fringes with the unique capability to selectively display either set of fringes while obscuring the other set. An interpolation method for the determination of fractional fringe orders is also discussed. 相似文献