Holographic Determination Of The Surface Shape By Means Of The Fringe Visibility Method

1986 ◽  
Author(s):  
Marek J. Matczak
Keyword(s):  
Surface Shape ◽  
Fringe Visibility

Determination of Phase Shift by Digital Holography

2019 ◽  
Vol 888 ◽  
pp. 43-46
Author(s):  
Yoshitaka Takahashi ◽  
Masatoshi Saito ◽  
Toru Nakajima ◽  
Masakazu Shingu
Keyword(s):  
Phase Shift ◽  
Noise Reduction ◽  
Digital Holography ◽  
High Accuracy ◽  
Measured Data ◽  
Phase Shifting ◽  
Surface Shape ◽  
Shape Measurement ◽  
Phase Shifting Interferometry

In phase shifting interferometry phase shift is applied by various ways, but applying it with high accuracy, especially by LD current modulation, is not easy. In order to determine the accurate phase shift a new method has been proposed that the value of LD current corresponding to π/2 phase shift can be determined by phase shifting digital holography. The measured data of standard in surface shape measurement were used for calibration, and the obtained value was confirmed to cause noise reduction and improvement of holographic reconstructed images in digital holography.

scholarly journals Determination of surface shape deviation by using force-controlled burnishing

Procedia CIRP ◽  
2020 ◽  
Vol 93 ◽  
pp. 1275-1280
Author(s):  
Marco Posdzich ◽  
Rico Stöckmann ◽  
Marco Witt ◽  
Matthias Putz
Keyword(s):  
Surface Shape ◽  
Shape Deviation

A Numerical Elastoplastic Model for Rough Contact

1995 ◽  
Vol 117 (3) ◽  
pp. 422-429 ◽  
Author(s):  
C. Mayeur ◽  
P. Sainsot ◽  
L. Flamand
Keyword(s):  
Yield Criterion ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Surface Shape ◽  
Real Surface ◽  
Pressure Distributions ◽  
Surface Displacements ◽  
Elastic Shakedown ◽  
Von Mises

Pressure distributions due to surface roughness in contact induce high stresses just beneath the surface. These stresses can bring on crack initiation and micro-pitting. A purely elastic contact model to account for these effects is restrictive because stress fields often exceed the yield strength of the material. Plastic flow occurs and modifies the surface shape and material properties (work hardening). This paper presents a numerical model for elastoplastic rough contact. It allows the determination of real pressures and permanent surface displacements (flattening of asperities) as well as residual stress and plastic strains useful in fatigue analysis). The material is assumed to obey the Von-Mises yield criterion with linear kinematic hardening. Real surface profiles obtained from a measurement can be considered. In addition, simplified methods have been used to treat cyclic loading. Thus the ability of a rough surface to reach an elastic shakedown state can be investigated, even for a three-dimensional contact found, for instance, in roller bearings.

scholarly journals Multi-Variant TLS and SfM Photogrammetric Measurements Affected by Different Factors for Determining the Surface Shape of a Thin-Walled Dome

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7095
Author(s):  
Grzegorz Lenda ◽  
Jakub Siwiec ◽  
Jacek Kudrys
Keyword(s):  
Laser Scanning ◽  
Point Clouds ◽  
Surface Shape ◽  
Structure Changes ◽  
First Case ◽  
Accuracy Of Measurement ◽  
Thin Walled ◽  
Measured Length ◽  
Photogrammetric Measurement

The paper presents a combined analysis of terrestrial laser scanning (TLS) and structure from motion (SfM) photogrammetric measurement to determine an accurate model of the surface shape of a thin-walled dome. The analysis takes into account several factors that may affect the accuracy of measurement. In TLS measurements, these are related to scattering of the beam and its penetration into the structure of objects. Penetration of the beam into a synthetic structure changes the measured length. Shell moisture, caused by rainfall or dew effect, similarly affects the measured length, but the changes are dispersed. In the first case, it will change the size of the object, and in the second one, it generates measurement noise. SfM photogrammetric problems, such as object gloss and ambient reflection, lack of detail, and different results from software creating point clouds were also analyzed. An interesting observation was the significant influence of atmospheric pollution, sedimented on the lower half of the glossy dome, on increasing the accuracy of photogrammetric measurement. The analyses contain a number of cases that take into account the complex problems of obtaining and processing data of such facilities: periodic measurement, TLS and SfM photogrammetric measurement, measurement outside and inside the object, determination of the wall thickness, comparison with the project and free-sphere fitting, and use of dome rotation during TLS.

Nonlinear problem of flat-plate entry into an incompressible liquid

2008 ◽  
Vol 611 ◽  
pp. 151-173 ◽  
Author(s):  
ODD M. FALTINSEN ◽  
YURIY A. SEMENOV
Keyword(s):  
Free Surface ◽  
Flat Plate ◽  
Incompressible Liquid ◽  
Initial Conditions ◽  
Numerical Procedure ◽  
Contact Angles ◽  
Surface Shape ◽  
Surface Pressure Distribution ◽  
Free Surface Shape

The self-similar flow and free-surface shape induced by a flat plate entering an inviscid and incompressible liquid are investigated for arbitrary initial conditions. An analytical solution, which is based on two governing expressions, namely the complex velocity and the derivative of the complex potential, is obtained. These expressions are derived in an auxiliary parameter plane using integral formulae proposed for the determination of an analytical function from its modulus and argument given on the boundary of the parameter region. We derive a system of an integral and an integro-differential equation in terms of the velocity modulus and the velocity angle at the free surface, which are determined by the dynamic and kinematic boundary conditions. A numerical procedure for solving these equations is carefully validated by comparisons with results available in the literature. The results are presented in terms of the free surface shape, the angles at the tip of the splash jet, the contact angles at the intersection with the plate surface, pressure distribution and force coefficients. New features caused by the flow unsteadiness are found and discussed.

Principles of regular-shaped radome antennas study with a spherical scanner

2020 ◽  
pp. 14-21 ◽  
Author(s):  
A. V. Kirpanev ◽  
N. A. Kirpanev
Keyword(s):  
Near Field ◽  
Plane Waves ◽  
Single Layer ◽  
Surface Shape ◽  
Complex Coefficient ◽  
Spherical Waves ◽  
Spatial Frequencies ◽  
Amplitude Spectra ◽  
Homogeneous Plane

The paper  considers  the  characteristics  determination  method  basing  on  amplifasometric  measurements  of  near  field  of the «antenna-radio-transparent radome» system with use of a spherical scanner. The method is based on determination of components of the amplitude spectra of homogeneous plane waves through the amplitudes of vector spherical waves of the tested antenna and the «antenna-radio-transparent radome» system. It is assumed that the radome has a regular surface shape and is a single-layer radome. The proposed method, in addition to determination of radiation characteristics, allows for the given antenna field polarization to determine the complex coefficient of passage thorough the radome as a function of spatial frequencies. It is also shown that it is possible to estimate the complex dielectric permittivity of a single-layer radome, both by calculating the components of uniform plane waves, and directly from the reduced field components on the outer surface of radome. Ways to study the radiophysical characteristics of theradom, are proposed.

Design of Irregular Slider Surface for Satisfying Specified Load Demands

2004 ◽  
Vol 127 (6) ◽  
pp. 1184-1190 ◽  
Author(s):  
Chin-Hsiang Cheng ◽  
Mei-Hsia Chang
Keyword(s):  
Pressure Distribution ◽  
Inverse Method ◽  
Design Method ◽  
Surface Shape ◽  
Problem Solver ◽  
Design Problems ◽  
Geometric Conditions ◽  
Slider Surface ◽  
Air Film

This study is to design the surfaces of sliders to meet the pressure distribution specified by the designers. The slider surfaces, in general, characterize an irregular profile. A direct problem solver, which is able to provide solutions for pressure distribution in the air film between the slider and the moving surface for various geometric conditions, is incorporated with an inverse method for determination of slider surface shape. In this report, a point-by-point design method is developed to improve the polynomial-function approach proposed in an earlier study (Cheng and Chang, 2004, J. of Tribology 126, pp. 519-526.) An exact solution for the two-dimensional design problems has also been developed to partly confirm the present approach. Results obtained from the present approaches are demonstrated by a comparison with the data from the existing method and the exact solutions to display the relative performance of the present method. The desired slider-shape design is a function of the bearing numbers. The slider shapes associated with different combinations of bearing numbers are investigated.

Evaluation of Grinding Wheel Surface Shape on Difference Multiple Helical Dressing Condition

2021 ◽  
Vol 15 (1) ◽  
pp. 57-64
Author(s):  
Gen Uchida ◽  
Takazo Yamada ◽  
Kouichi Ichihara ◽  
Makoto Harada ◽  
Kohichi Miura ◽  
...  
Keyword(s):  
Surface Condition ◽  
Ground Surface ◽  
Surface Characteristics ◽  
Measuring Method ◽  
Surface Shape ◽  
Grinding Wheel ◽  
Wheel Surface ◽  
Dressing Method ◽  
Measurement Results

In the grinding process, a grinding wheel surface is a tool that is directly applied to the workpiece. As the condition of the grinding wheel surface is determined by its dressing conditions, the ability to accurately measure the grinding wheel surface with an applied dressing would enable the prediction of the ground surface characteristics of the workpiece as well as the determination of optimum dressing conditions. Recently, a new dressing method called the multiple helical dressing was proposed, which has led to improvements in the grinding performance. However, there is still no method to quantitatively evaluate the changes in the grinding wheel surface condition caused by multiple helical dressings. In this study, we measured the grinding wheel surface applied with multiple helical dressings using a so-called measured focus position recalculation method to determine whether we can quantitatively evaluate the measured dressing grooves generated on the grinding wheel surface by multiple helical dressings, and the resultant undulated grinding wheel surface shapes. We ground an actual workpiece to demonstrate the effects of changes in the grinding wheel surface shape due to multiple helical dressings on the ground surface of the workpiece. The experimental results show that our proposed measuring method can accurately measure the changes in the grinding wheel surface condition due to multiple helical dressings. We also proposed a method to evaluate the dressing grooves to prove that we can quantitatively evaluate the measurement results of dressing grooves generated by multiple helical dressings. In addition, we evaluated undulated grinding wheel surface shapes as its cylindricities by extracting only the undulation shapes generated by multiple helical dressings. Finally, we performed groove grinding with a grinding wheel applied with multiple helical dressings to reveal the relationship between the ground surface of the workpiece and the grinding wheel surface condition, which demonstrated the effectiveness of multiple helical dressings.

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