DETERMINATION OF LIGHT SHEET THICKNESS IN PIV

1995 ◽  
Vol 2 (3) ◽  
pp. 259-266 ◽  
Author(s):  
Mahmoud F. Maghrebi ◽  
Kiyosi Kawanisi ◽  
Shoitiro Yokosi
Keyword(s):  
Sheet Thickness ◽  
Light Sheet

CHARACTERIZATION OF FLOW CURVES FOR ULTRA-THIN STEEL SHEETS WITH THE IN-PLANE TORSION TEST

2021 ◽  
pp. 1-25
Author(s):  
Fabian Stiebert ◽  
Heinrich Traphöner ◽  
Rickmer Meya ◽  
A. Erman Tekkaya
Keyword(s):  
Sheet Thickness ◽  
High Strength ◽  
Torsion Test ◽  
New Method ◽  
Bulge Test ◽  
Thin Sheets ◽  
Flow Curves ◽  
Steel Sheets

Abstract The in-plane torsion test is a shear test that has already been successfully used to determine flow curves up to high strains for thin sheets with thicknesses between 0.5 mm and 3.0 mm. In the same way as with other shear tests, the formation of wrinkles is a major challenge in determining flow curves with the in-plane torsion test, especially when testing ultra-thin sheets with a thickness between 0.1 mm and 0.5 mm. A new method for suppressing wrinkling is introduced, in which the formation of wrinkles is avoided by arranging and gluing single sheets to multi-layered specimens. The influence of the used adhesive on the determination of flow curves is negligible. The proposed method is used to identify flow curves for two materials, the high strength steel TH620 and the soft steel TS230, used in the packaging industry. The Materials are tested in sheet thicknesses between 0.17 mm and 0.6 mm. The determined equivalent plastic strains for the TH620 with a sheet thickness of 0.20 mm, could be increased from 0.38 (bulge-test) to over 0.8 with the new method by using four-layered specimens.

Determination of the third velocity component with PTA using an intensity graded light sheet

1992 ◽  
Vol 13 (5) ◽  
pp. 357-359 ◽  
Author(s):  
F. Dinkelacker ◽  
M. Schäfer ◽  
W. Ketterle ◽  
J. Wolfrum ◽  
W. Stolz ◽  
...  
Keyword(s):  
Velocity Component ◽  
Light Sheet ◽  
The Third

scholarly journals Investigation of Relative Importance of Some Error Sources in Particle Image Velocimetry

2012 ◽  
Author(s):  
Jeff Harris ◽  
Barton L. Smith ◽  
Brandon Wilson
Keyword(s):  
Particle Image ◽  
Sheet Thickness ◽  
Light Sheet ◽  
Velocity Measurements ◽  
Calibration Target ◽  
Error Sources ◽  
Noise Floor ◽  
Correlation Algorithm ◽  
Calibration Uncertainty ◽  
Image Velocimetry

Several error sources are analyzed for 2-component PIV, including: calibration, magnification variation, perspective, resolution, and the correlation algorithm noise floor. Several of these error sources are compared with previously published estimates. New experimental data and methods for measuring the contribution of each source to velocity uncertainty are presented. The calibration uncertainty on the velocity measurement was found to be small (so long as reasonable care is taken in the calibration) and independent of the calibration target for a 2-component PIV setup. The perspective error and magnification variation were both calculated and experimentally found to be small. The light sheet thickness only has an effect when the thickness is greater than 1% of the distance from the light sheet to the camera lens plane. The spatial resolution may be so coarse as to not capture the smaller eddies in the flow, thus attenuating the measured fluctuations. The noise floor was found to contribute significantly to the uncertainty in the velocity measurements in sub-pixel displacement.

Three-Dimensional Particle Tracking Velocimetry With Laser-Light Sheet Scannings

1996 ◽  
Vol 118 (2) ◽  
pp. 352-357 ◽  
Author(s):  
Satoru Ushijima ◽  
Nobukazu Tanaka
Keyword(s):  
Particle Tracking ◽  
High Speed ◽  
Particle Tracking Velocimetry ◽  
Laser Light ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Light Sheet ◽  
Optical Scanners ◽  
Particle Images

This paper describes three-dimensional particle tracking velocimetry (3D PTV), which enables us to obtain remarkably larger number of velocity vectors than previous techniques. Instead of the usual stereoscopic image recordings, the present 3D PTV visualizes an entire three-dimensional flow with the scanning laser-light sheets generated from a pair of optical scanners and the images are taken by a high-speed video system synchronized with the scannings. The digital image analyses to derive velocity components are based on the numerical procedure (Ushijima and Tanaka, 1994), in which several improvements have been made on the extraction of particle images, the determination of their positions, the derivation of velocity components and others. The present 3D PTV was applied to the rotating fluids, accompanied by Ekman boundary layers, and their complicated secondary flow patterns, as well as the primary circulations, are quantitatively captured.

Forming Limit Diagram Determination of Al 3105 Sheets and Al 3105/Polypropylene/Al 3105 Sandwich Sheets Using Numerical Calculations and Experimental Investigations

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
M. H. Parsa ◽  
M. Ettehad ◽  
P. H. Matin
Keyword(s):  
Damage Model ◽  
Sheet Thickness ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Experimental Investigations ◽  
Element Analysis ◽  
Gtn Damage Model ◽  
Core Thickness ◽  
Sandwich Sheets

Sandwich sheet structures are gaining a wide array of applications in the aeronautical, marine, automotive, and civil engineering fields. Since such sheets can be subjected to forming/stamping processes, it is crucial to characterize their limiting amount of deformation before trying out any forming/stamping process. To achieve this goal, sandwich sheets of Al 3105/polymer/Al 3105 were prepared using thin film hot melt adheres. Through an experimental effort, forming limit diagrams (FLDs) of the prepared sandwich sheets were evaluated. In addition, simulation efforts were conducted to predict the FLDs of the sandwich sheets using finite element analysis (FEA) by considering the Gurson–Tvergaard–Needleman (GTN) damage model. The agreement among the experimental results and simulated predictions was promising. The effects of different parameters such as polymer core thickness, aluminum face sheet thickness, and shape constraints were investigated on the FLDs.

scholarly journals A method for determining ice-thickness change at remote locations using GPS

1994 ◽  
Vol 20 ◽  
pp. 263-268 ◽  
Author(s):  
Christina L. Hulbe ◽  
Ian M. Whillans
Keyword(s):  
Accumulation Rate ◽  
Sheet Thickness ◽  
Ice Thickness ◽  
Pilot Studies ◽  
Thickness Change ◽  
Remote Locations ◽  
Remote Sites ◽  
Different Depths ◽  
The Difference

Ice-thickness changes at remote locations on ice sheets can be determined by means of precise Global Positioning System (GPS) surveys with interferometric solutions. Remote sites are precisely surveyed relative to GPS receivers on rock. Repeat observations of the position of a remote site provide its vertical velocity. The difference between this velocity and accumulation rate is an indicator of change in ice-sheet thickness. Allowance must be made for the movement of survey markers due to firn compaction and down-slope ice motion, To allow for firn compaction, very long- poles arc placed to a sufficient depth in the firn that the densification rate can be considered steady. This assumption may be tested by measurements with poles set to different depths. An analysis of errors in pilot studies indicates that the limit to precision is the determination of accumulation rate.

scholarly journals How to define and optimize axial resolution in light-sheet microscopy: a simulation-based approach

2019 ◽  
Author(s):  
Elena Remacha ◽  
Lars Friedrich ◽  
Julien Vermot ◽  
Florian O. Fahrbach
Keyword(s):  
Sheet Thickness ◽  
Light Sheet ◽  
Image Contrast ◽  
Axial Resolution ◽  
Light Sheet Microscopy ◽  
3D Data ◽  
Simulation Based ◽  
Different Types ◽  
The Many ◽  
The Relationship

Abstract“How thick is your light sheet?” is a question that has been asked frequently after talks showing impressive renderings of 3D data acquired by a light-sheet microscope. This question is motivated by the fact that most of the time the thickness of the light-sheet is uniquely associated to the axial resolution of the microscope. However, the link between light-sheet thickness and axial resolution has never been systematically assessed and it is still unclear how both are connected. The question is not trivial because commonly employed measures cannot readily be applied or do not lead to easily interpretable results for the many different types of light sheet. Here, by using simulation data we introduce a set of intuitive measures that helps to define the relationship between light sheet thickness and axial resolution. Unexpectedly, our analysis revealed a trade-off between better axial resolution and thinner light-sheet thickness. Our results are surprising because thicker light-sheets that provide lower image contrast have previously not been associated with better axial resolution. We conclude that classical Gaussian illumination beams should be used when image contrast is most important, and more advanced types of illumination represent a way to optimize axial resolution at the expense of image contrast.

scholarly journals A shape-switch-block method for confocal light-sheet microscopy with sectioned Bessel beams and stimulated emission depletion

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Luis Köbele ◽  
Alexander Rohrbach
Keyword(s):  
Continuous Wave ◽  
Imaging Techniques ◽  
Optical Resolution ◽  
Sheet Thickness ◽  
Light Sheet ◽  
Stimulated Emission ◽  
Bessel Beams ◽  
Isotropic Resolution ◽  
Light Sheet Microscopy ◽  
Stimulated Emission Depletion

Abstract Microscopy seeks to simultaneously maximize optical resolution, contrast, speed, volume size, and probe tolerability, which is possible by combining different complementary imaging techniques with their specific strengths. Here, we show how to combine three physical concepts to increase resolution and contrast in light-sheet microscopy by making the effective light-sheet thinner through phase shaping, fluorophores-switching, and dynamic blocking of fluorescence. This shape-switch-block principle is realized by illumination with two holographically shaped, sectioned Bessel beams. Second, by switching off fluorophores in the proximity of the excitation center using continuous-wave stimulated emission depletion (STED). And third, by blocking fluorescence outside the switching region by confocal line detection. Thereby, we reduce the light-sheet thickness by 35%, achieving an isotropic resolution with beads in a 300 × 70 × 50 µm³ volume. Without STED, we obtain 0.37 µm resolution in cell clusters at improved sectioning and penetration depth. The shape-switch-block concept promises high potential, also for other microscopy techniques.

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