Diffraction-grating speckle photography for measuring out-of-plane surface displacement

1995 ◽  
Author(s):  
W. H. Choi ◽  
Jae Heung Jo ◽  
Soo Chang ◽  
J. Y. Myung
Keyword(s):  
Diffraction Grating ◽  
Plane Surface ◽  
Surface Displacement ◽  
Speckle Photography ◽  
Out Of Plane

Identification of Critical Surface Displacement Parameters for Characterization of Subsurface Flaws

2002 ◽  
Author(s):  
Paul D. Herrington ◽  
Paul J. Schilling ◽  
Melody A. Verges ◽  
Prashanth K. Durgam
Keyword(s):  
Plane Surface ◽  
Surface Displacement ◽  
Homogeneous Material ◽  
Critical Surface ◽  
Near Surface ◽  
Surface Displacements ◽  
Measuring Surface ◽  
Out Of Plane ◽  
Subsurface Geometry

Several NDE methods provide accurate techniques for measuring surface displacements. While these techniques have been successful in identification of near-surface embedded flaws, they generally offer little in terms of characterization of the flaws. The ability to characterize embedded flaws from measurements of surface displacements would offer substantial benefits, especially in terms of remaining life predictions. This paper focuses on the identification of critical out-of-plane surface displacement parameters, and assessment of the potential to characterize subsurface flaw geometry based on these parameters. Finite element models of a homogeneous material have been created that vary the embedded flaw size and edge distance. The results suggest that there is potential to characterize the subsurface geometry from the surface displacement parameters.

AE Sensor Calibration for Out-of-Plane and In-Plane Displacement Sensitivity

2006 ◽  
Vol 13-14 ◽  
pp. 91-98 ◽  
Author(s):  
Pete T. Theobald ◽  
F. Dar
Keyword(s):  
Laser Beam ◽  
Plane Surface ◽  
Surface Displacement ◽  
Normal Incidence ◽  
Sensor Calibration ◽  
Wave Source ◽  
Out Of Plane ◽  
Displacement Sensitivity ◽  
Time Waveform ◽  
Plane Displacement

This paper proposes a method for both the out-of-plane and in-plane displacement sensitivity calibration of an acoustic emission (AE) sensor. In the method, a laser homodyne interferometer is used to measure the out-of-plane and in-plane displacement of the surface of a large test block excited by a repeatable source transducer. The out-of-plane displacement is measured by aligning the laser beam perpendicular to the surface with time gating of the receive waveform used to isolate only the direct arrival of the longitudinal wave produced by the piston source transducer. For the in-plane displacement measurement, the laser beam is aligned parallel to the surface to intersect a small optically reflective step with the time waveform being gated to measure only the direct shear arrival produced using a normal incidence shear wave source transducer. In each case, the interferometer measurement is followed by coupling the sensor under test to the measurement surface, which is then exposed to the same acoustic field and the sensor output signal measured. This substitution method allows the sensor sensitivity to be obtained in terms of volts per unit displacement for both the out-of-plane and in-plane surface displacement. The method allows a comprehensive description of an AE sensor response to different planes of displacement and offers the potential for a traceable sensor calibration to units of length.

scholarly journals In-Process Measurement of Three-Dimensional Deformations Based on Speckle Photography

2021 ◽  
Vol 11 (11) ◽  
pp. 4981
Author(s):  
Andreas Tausendfreund ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Evaluation Method ◽  
Process Analysis ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Machining Process ◽  
Image Correlation ◽  
Speckle Photography ◽  
Process Measurement ◽  
Out Of Plane ◽  
Plane Deformations

In the concept of the process signature, the relationship between a material load and the modification remaining in the workpiece is used to better understand and optimize manufacturing processes. The basic prerequisite for this is to be able to measure the loads occurring during the machining process in the form of mechanical deformations. Speckle photography is suitable for this in-process measurement task and is already used in a variety of ways for in-plane deformation measurements. The shortcoming of this fast and robust measurement technique based on image correlation techniques is that out-of-plane deformations in the direction of the measurement system cannot be detected and increases the measurement error of in-plane deformations. In this paper, we investigate a method that infers local out-of-plane motions of the workpiece surface from the decorrelation of speckle patterns and is thus able to reconstruct three-dimensional deformation fields. The implementation of the evaluation method enables a fast reconstruction of 3D deformation fields, so that the in-process capability remains given. First measurements in a deep rolling process show that dynamic deformations underneath the die can be captured and demonstrate the suitability of the speckle method for manufacturing process analysis.

scholarly journals Unlocking surface octahedral tilt in two-dimensional Ruddlesden-Popper perovskites

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yan Shao ◽  
Wei Gao ◽  
Hejin Yan ◽  
Runlai Li ◽  
Ibrahim Abdelwahab ◽  
...  
Keyword(s):  
Density Functional ◽  
Carrier Transport ◽  
Plane Surface ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Spin Splitting ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Out Of Plane ◽  
Inversion Asymmetry

AbstractMolecularly soft organic-inorganic hybrid perovskites are susceptible to dynamic instabilities of the lattice called octahedral tilt, which directly impacts their carrier transport and exciton-phonon coupling. Although the structural phase transitions associated with octahedral tilt has been extensively studied in 3D hybrid halide perovskites, its impact in hybrid 2D perovskites is not well understood. Here, we used scanning tunneling microscopy (STM) to directly visualize surface octahedral tilt in freshly exfoliated 2D Ruddlesden-Popper perovskites (RPPs) across the homologous series, whereby the steric hindrance imposed by long organic cations is unlocked by exfoliation. The experimentally determined octahedral tilts from n = 1 to n = 4 RPPs from STM images are found to agree very well with out-of-plane surface octahedral tilts predicted by density functional theory calculations. The surface-enhanced octahedral tilt is correlated to excitonic redshift observed in photoluminescence (PL), and it enhances inversion asymmetry normal to the direction of quantum well and promotes Rashba spin splitting for n > 1.

A Real-Time DSPI System for Measuring Surface Deformation in Clamped Bolted Joints

2008 ◽  
Author(s):  
Aidong Meng ◽  
Sayed A. Nassar
Keyword(s):  
Real Time ◽  
Vibration Isolation ◽  
Surface Deformation ◽  
Plane Surface ◽  
Speckle Pattern ◽  
The Real ◽  
Time Deformation ◽  
Out Of Plane ◽  
Phase Data ◽  
Set Up

A Digital Speckle Pattern Interferometry (DSPI) system is developed for the real-time measuring and monitoring the out-of-plane surface deformation around tightened threaded fasteners that are used to clamp bolted assemblies. Spatial phase shifting is employed to quantitatively determine the distribution of phase data by introducing a spatial carrier fringe pattern to the speckle interferogram. This is achieved by leading the object and reference beams to two separate apertures. The configuration is also suitable for collecting the real-time deformation during bolt tightening. The experimental DSPI system is set-up with optical components on a vibration-isolation table. A Matlab software is developed for the image acquisition and phase data calculation, which yields the out-of-plane surface deformation caused by the bolt preload. An aluminum joint is used with an M12 steel fastener. For miniature screw application, however, a plastic joint is used for collecting data.

Spectroscopic evaluation of out-of-plane surface vibration bands from surface functionalization of graphite oxide by fluorination

Carbon ◽  
2014 ◽  
Vol 77 ◽  
pp. 577-591 ◽  
Author(s):  
Muge Acik ◽  
Sriram Yagneswaran ◽  
Weina Peng ◽  
Geunsik Lee ◽  
Benjamin R. Lund ◽  
...  
Keyword(s):  
Surface Functionalization ◽  
Graphite Oxide ◽  
Plane Surface ◽  
Surface Vibration ◽  
Out Of Plane
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