scholarly journals Two-dimensional surface strain measurement based on a variation of Yamaguchi's laser-speckle strain gauge

1991 ◽  
Author(s):  
John P. Barranger
Keyword(s):  
Strain Gauge ◽  
Strain Measurement ◽  
Laser Speckle ◽  
Surface Strain ◽  
Two Dimensional ◽  
Dimensional Surface

Observation of Heat Cycle Delamination Process with Surface Strain Measurement in Thermal Barrier Coating

2004 ◽  
Vol 261-263 ◽  
pp. 453-458
Author(s):  
Hiroyuki Waki ◽  
Izuru Nishikawa ◽  
K. Ogura
Keyword(s):  
Thermal Expansion ◽  
Strain Measurement ◽  
Laser Speckle ◽  
Surface Strain ◽  
Thermal Barrier ◽  
Heat Cycle ◽  
Bond Coating ◽  
Strain Behavior ◽  
Delamination Life ◽  
Plasma Sprayed

A surface strain measurement approach to understanding of delamination processes of thermal barrier coatings (TBCs) under heat cycle conditions was described in this paper. Heat cycle tests between the high temperature ranged from 1473K to 1073K and the relatively low temperature (573K) was carried out on thermal barrier coated type 304 stainless steel specimens. 8mass%Y2O3- ZrO2 and Al2O3 coatings were used for the TBCs. The surface strain behavior during the heat cycle test was measured using a laser speckle strain/displacement gauge (SSDG). It was found that the thermal expansion of a substrate was almost reflected on a surface strain if a delamination wasn't initiated, while the value of a surface strain decreased to the value of the thermal expansion of a ceramics-coating if the delamination of the ceramics-coating was initiated. The state of a subsurface delamination was able to be nondestructively inferred by the surface strain behavior. The delamination life of a ceramics-coating in the specimen with a low-pressure-plasma-sprayed (LPPS) bond-coating was found to be longer than that with an atmospheric-plasma-sprayed (APS) bond-coating. The large roughness of a bond-coating was also found to be effective in improving the delamination life of a ceramics-coating owing to the restriction of a crack propagation parallel to the interface between the ceramics-coating and the bond-coating.

High resolution imaged laser speckle strain gauge for vascular applications

2000 ◽  
Vol 5 (1) ◽  
pp. 62 ◽  
Author(s):  
Sean J. Kirkpatrick ◽  
Marilyn J. Cipolla
Keyword(s):  
High Resolution ◽  
Strain Gauge ◽  
Laser Speckle

scholarly journals DISCRETE AND CONTINUUM APPROACHES TO THREE-DIMENSIONAL QUANTUM GRAVITY

1991 ◽  
Vol 06 (39) ◽  
pp. 3591-3600 ◽  
Author(s):  
HIROSI OOGURI ◽  
NAOKI SASAKURA
Keyword(s):  
Gauge Theory ◽  
Moduli Space ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Analogue Model ◽  
Gauge Invariant ◽  
Invariant Functions ◽  
Dimensional Lattice ◽  
Chern Simons ◽  
Dimensional Surface

It is shown that, in the three-dimensional lattice gravity defined by Ponzano and Regge, the space of physical states is isomorphic to the space of gauge-invariant functions on the moduli space of flat SU(2) connections over a two-dimensional surface, which gives physical states in the ISO(3) Chern–Simons gauge theory. To prove this, we employ the q-analogue of this model defined by Turaev and Viro as a regularization to sum over states. A recent work by Turaev suggests that the q-analogue model itself may be related to an Euclidean gravity with a cosmological constant proportional to 1/k2, where q=e2πi/(k+2).

Development of a Quick and Easy-to-Install Strain Measurement Tool for Both Bending and Torsional Piping Stress Assessment

2016 ◽  
Author(s):  
Tsunemichi Takahama ◽  
Kazuma Nishimura ◽  
Seiichiro Ninomiya ◽  
Yoshihiro Matsumoto ◽  
Yutaka Harada
Keyword(s):  
Strain Gauge ◽  
Strain Measurement ◽  
Adhesive Bonding ◽  
Working Time ◽  
Measurement Tool ◽  
Stress Assessment ◽  
The Moment ◽  
Time Required ◽  
Longitudinal Strains

To assess the stresses on small-bore piping, we have developed a new tool that can be easily installed on a piping surface without adhesive bonding and that measures strains on piping quickly and accurately. This tool, which we call a “strain gauge holder,” is patented in Japan. As the tool can contain four strain gauge rosettes, with each rosette comprising three elements, the longitudinal strains and sheer strains can be measured synchronously at any four points precisely 90 degrees apart, with one point in each quadrant. By mockup testing, we confirmed that the measured bending and torsional strains by the holder were almost equivalent to the measured strains by the bonded gauges with adhesive, and that the holder made it possible to synchronously measure all of the strains resulting from the moment of force acting in three axes on the piping by measuring the bending and torsional strains in each quadrant. The strain gauge holder is expected to significantly reduce the pre- and post-working time required for strain measurement and stress assessment of piping in real plants.

An electronic speckle pattern interferometer for two-dimensional strain measurement

1996 ◽  
Vol 7 (12) ◽  
pp. 1740-1747 ◽  
Author(s):  
Andrew J Moore ◽  
Margaret Lucas ◽  
John R Tyrer
Keyword(s):  
Strain Measurement ◽  
Speckle Pattern ◽  
Two Dimensional

An investigation of photoresists for use in optical strain analysis

1970 ◽  
Vol 5 (3) ◽  
pp. 162-168 ◽  
Author(s):  
A Luxmoore ◽  
R Hermann
Keyword(s):  
Strain Measurement ◽  
Strain Analysis ◽  
Surface Strain ◽  
High Contrast ◽  
Moire Method ◽  
Optical Strain

Some commercial photoresists have been examined to assess their suitability for use with the moiré method of surface-strain measurement. As most of these materials do not produce a pattern of high contrast directly, some etching and plating procedures are also described. Combined with correct illumination, these processes will produce grids of sufficient contrast for most applications.

The Elastic Moduli of Silver Thin Films Measured with a New Microtensile Tester

1991 ◽  
Vol 239 ◽  
Author(s):  
J. Ruud ◽  
D. Josell ◽  
A. L. Greer ◽  
F. Spaepen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Diffraction Grating ◽  
Strain Measurement ◽  
Elastic Moduli ◽  
Two Dimensional ◽  
Bulk Crystals ◽  
Free Standing ◽  
Tensile Direction ◽  
Silver Thin Films

ABSTRACTA new design for a thin film microtensile tester is presented. The strain is measured directly on the free-standing thin film from the displacement of laser spots diffracted from a thin grating applied to its surface by photolithography. The diffraction grating is two-dimensional, allowing strain measurement both along and transverse to the tensile direction. In principle, both Young's modulus and Poisson's ratio of a thin film can be determined. Ag thin films with strong <111> texture were tested. The measured Young moduli agreed with those measured on bulk crystals, but the measured Poisson ratios were low, most likely due to slight transverse folding of the film that developed during the test.

Asymptotic analysis of some two-dimensional diffusion problems

1995 ◽  
Vol 448 (1933) ◽  
pp. 213-236 ◽  
Keyword(s):  
Linear Problem ◽  
Vacancy Concentration ◽  
Surface Concentration ◽  
Two Dimensional ◽  
Surface Source ◽  
Dimensional Diffusion ◽  
Equilibrium Vacancy ◽  
Equilibrium Vacancy Concentration ◽  
Dimensional Surface ◽  
Diffusion Problems

In this paper we discuss two-dimensional surface source and implant problems for a substitutional-interstitial diffusion model. We present asymptotic solutions in the limit of the surface concentration of impurity (or peak concentration of the implant) being far greater than the equilibrium vacancy concentration. Using leading order composite solutions we plot contours of constant impurity concentration. Some of these contours differ markedly from those of the corresponding linear problem, having the ‘bird’s beak’ shape which is frequently observed in experiments. We also discuss a two-dimensional surface source problem for a va­cancy model.

Anisotropic Coarsening of Two-Dimensional Surface Domains in Copolymer Thin Films

1999 ◽  
Vol 32 (26) ◽  
pp. 9007-9012 ◽  
Author(s):  
Jakob Heier ◽  
Easan Sivaniah ◽  
Edward J. Kramer
Keyword(s):  
Thin Films ◽  
Two Dimensional ◽  
Surface Domains ◽  
Dimensional Surface
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