High precision optical strain measurements at high pressures

1987 ◽  
pp. 41-51 ◽  
Author(s):  
Charles Meade ◽  
Raymond Jeanloz
Keyword(s):  
High Precision ◽  
High Pressures ◽  
Strain Measurements ◽  
Optical Strain

scholarly journals Differential Sea-Ice Drift. II. Comparison of Mesoscale Strain Measurements to Linear Drift Theory Predictions

1974 ◽  
Vol 13 (69) ◽  
pp. 457-471 ◽  
Author(s):  
W. D. Hibler
Keyword(s):  
High Pressures ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Local Pressure ◽  
Strain Measurements ◽  
Linear Drift ◽  
Special Cases ◽  
Drift Theory ◽  
Sea Ice Drift ◽  
Frequency Behavior

A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicate that the ice divergence rate and vorticity follow the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds the divergence rate was found to be negative with the vorticity being counter-clockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior was shown to agree with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen (1970) for pack ice. The best least-squares values of the constitutive law parametersηandζwere found to be ≈ 1012kg/s. Using typical divergence rates these values yield compressive stresses of the magnitude of 105N/m which are similar to values suggested by the Parmerter and Coon (1972) ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low-pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer).Calculations were also carried out using a more general linear visco-elastic constitutive law that includes memory effects and which includes a generalized Hooke’s law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates overall a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated “viscosities” similar to the Glen law behavior at temporal frequencies less than ≈ 0.01 h−1.

Optical strain measurements

1970 ◽  
Vol 1 (2) ◽  
pp. 11-11
Author(s):  
E Marom ◽  
R K Mueller
Keyword(s):  
Strain Measurements ◽  
Optical Strain

A Discussion on the measurement and interpretation of changes of strain in the Earth - New Zealand Earth strain measurements

1973 ◽  
Vol 274 (1239) ◽  
pp. 311-321 ◽  
Keyword(s):  
New Zealand ◽  
High Precision ◽  
Heavy Rain ◽  
Great Care ◽  
Strain Measurements ◽  
Exposed Site ◽  
The Earth

Three invar wire lever type Earth strain meters are being operated in geophysically interesting areas in New Zealand. T he oldest has been operational since early 1970. The main object of the work has been to detect possible strain changes occurring before an earthquake. None have been detected, the most likely earthquake to have produced an effect before hand having M s = 5.3 and lying at A = 1° from the nearest strain meter. Strain steps accompanying earthquakes appear to be rather smaller than expected. A great deal of information has been accumulated on strains induced by wind and rain at the most exposed site which is but 10 m below the top of a very exposed 300 m hill. Strain changes produced by several days’ heavy rain can, at this site, be as m uch as 3 x 10-6, and this indicates th at great care m ust be taken in interpreting apparent changes in the length of a baseline m easured by high precision surveying.

Strain Test for Evaluation of Rubber Compounds

1949 ◽  
Vol 22 (1) ◽  
pp. 201-211 ◽  
Author(s):  
Frank L. Roth ◽  
Robert D. Stiehler
Keyword(s):  
High Precision ◽  
Chemical Reaction ◽  
Strain Measurements ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Order Chemical Reaction ◽  
Strain Testing ◽  
Order Of Magnitude ◽  
Single Sheet ◽  
Uniform Treatment

Abstract Measurements of elongation of rubber vulcanizates at a fixed stress have been made with a precision much greater than can be obtained in the usual measurements of stress at a specified elongation. Such measurements form the basis of a strain test developed to characterize rubber vulcanizates in control and research testing. Statistical analyses show that the errors introduced in the actual strain measurements are negligible compared to those introduced by variations during compounding and curing, whereas the errors introduced by the usual measurements of stress at a specified elongation are of the same order of magnitude as those for compounding and curing. The high precision of strain testing has been used to detect variations within a single sheet of vulcanized rubber and variations among sheets cured from the same compounded batch. It has been possible also to determine with a single sheet its change in stiffness or modulus with age. The uniform treatment of specimens in the strain test makes them particularly useful for precise measurements of set. Further, it has been found that the decrease in elongation with time of cure apparently follows the laws of a second-order chemical reaction; consequently it is possible to represent the data by an equation involving three vulcanization parameters.

scholarly journals Borehole multi-functional logger for geophysical high-precision monitoring in Antarctic and Greenland ice sheets and glaciers

2021 ◽  
pp. 1-11
Author(s):  
Aleksey Markov ◽  
Pavel Talalay ◽  
Mikhail Sysoev ◽  
Andrey Miller ◽  
Alexander Cherepakhin
Keyword(s):  
High Precision ◽  
Cross Sections ◽  
Low Temperatures ◽  
High Pressures ◽  
Ice Sheets ◽  
Dome A ◽  
Lake Vostok ◽  
Pressure Axis ◽  
Vostok Station ◽  
Kunlun Station

Abstract This article presents the main aspects of the design solutions (based on the application of sensors MEMS and cantilevers), testing and applying of the multi-functional borehole logger ANTTIC (Antarctic Thermo-barometer, Inclinometer, Caliper) for geophysical high-precision monitoring (when simultaneous registering of temperature, pressure, axis inclination angle and radii of borehole cross-sections at 12 points), which is designed specifically for ultra-low temperatures and ultra-high pressures, and to determine an elliptical borehole shape and registration anisotropy factor in deep ice boreholes in the central region of Eastern Antarctica, in the areas of dome A at the Kunlun station (China) and/or of lake Vostok at the Vostok station (Russia).

Low Cost Dynamic Optical Strain Measurements in Glass Reinforced Polymer

1994 ◽  
Vol 3 (3) ◽  
pp. 096369359400300 ◽  
Author(s):  
G T Reed ◽  
M Hadjiprocopiou ◽  
A Möller ◽  
H Garden ◽  
A Thorne ◽  
...  
Keyword(s):  
Low Cost ◽  
Optical Measurements ◽  
Strain Measurements ◽  
Optical Fibre Sensor ◽  
Reinforced Polymer ◽  
Fibre Sensor ◽  
Optical Strain ◽  
Strain Gauge Measurements ◽  
Cost Components ◽  
Good Agreement

The combination of sensors and structural components to create “Smart Structures” or “Smart Skins” represents a new, fast developing branch of engineering. The monitoring of such systems will require accurate and fast strain measurements. Optical sensing techniques are receiving considerable attention for monitoring of such systems. In this work an optical fibre sensor has been embedded with the protective coating on, in glass reinforced polymer (GRP) coupons, to perform strain measurements. We show that the system can be used for measurements up to 2000με. The sensor was made using only commercially available, low cost components. The optical measurements show good agreement with conventional strain gauge measurements.

scholarly journals A high magnification UV lens for high temperature optical strain measurements

2019 ◽  
Vol 90 (4) ◽  
pp. 045117
Author(s):  
Robert S. Hansen ◽  
Trevor J. Bird ◽  
Ren Voie ◽  
Katharine Z. Burn ◽  
Ryan B. Berke
Keyword(s):  
High Temperature ◽  
High Magnification ◽  
Strain Measurements ◽  
Optical Strain

Evaluation of Bendability of Hot-Rolled S960 Grade Steel Using Optical Strain Measurements and FE-Modelling

2015 ◽  
Vol 651-653 ◽  
pp. 610-616 ◽  
Author(s):  
Anna Maija Arola ◽  
Antti J. Kaijalainen ◽  
Vili Kesti
Keyword(s):  
Damage Model ◽  
Forming Limit ◽  
Forming Process ◽  
Fe Modelling ◽  
Bending Tests ◽  
Strain Measurements ◽  
Air Bending ◽  
Bending Process ◽  
Optical Strain ◽  
Hot Rolled

Bending is an important forming process for ultra-high strength steel (UHSS) because it is cost-effective, fast and in many cases it can be used to replace welding in a part manufacturing processes. One major challenge in air bending of UHSS is to predict the limits for bendability since the traditional methods for failure prediction, such as forming limit diagram (FLD), cannot generally be applied to bending process. In this paper, 3D FE-modelling coupled with a CDM-damage model is used to simulate the air bending process and to determine the bendability limits for a hot-rolled 960MPa grade. Damage parameters for the CDM-model are determined by using optical strain measurements and inverse modelling of the tensile test. Three point bending tests with optical strain measuring were carried out to determine the deformation field of the outer bend in different bending angles and the results of the bending simulation are compared with the strain measurements of the bending tests. The damage model is then calibrated using the experimental results of the bending tests to adjust the crack occurrence in the simulation. A good agreement was found between simulations and experimental measurements.

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