A Study of Mechanism of Bi-Directional Measurement Influenced by Material on Dimensional Measurement Using X-Ray CT

2017 ◽  
Vol 11 (5) ◽  
pp. 707-715 ◽  
Author(s):  
Kazuya Matsuzaki ◽  
◽  
Osamu Sato ◽  
Hiroyuki Fujimoto ◽  
Makoto Abe ◽  
...  
Keyword(s):  
Measurement Error ◽  
Manufacturing Industry ◽  
State Of The Art ◽  
Length Measurement ◽  
Beam Hardening ◽  
Error Sources ◽  
X Ray ◽  
Dimensional Measurement ◽  
X Ray Computed ◽  
Small Feature

X-ray computed tomography systems (X-ray CT) designed for metrological use are frequently used in the manufacturing industry. This is because X-ray CT is able to measure not only outer geometry but also inner geometry nondestructively and relatively quickly. However, X-ray CT in the state of the art is not always able to demonstrate its measurement performance and traceability to SI. One of problems is that it is hard to evaluate error sources unique to X-ray CT, such as scattering and beam hardening, called as “material influence.” The hypothesis to the mechanism of Bi-directional length measurement error from the material influence is proposed. The hypothesis is that Bi-directional length measurement error is mainly caused by the form measurement error of a small feature on the gauge. The form measurement error of a small feature on the gauge is dominantly influenced by beam hardening. The hypothesis is validated through actual experiments and simulations. The results of the experiments and corresponding simulations lead us to the conclusion that the magnitude of the form measurement error of a small feature on a rotational asymmetric gauge is clearly correlated with a location of the small feature on the gauge.

scholarly journals Enhanced dimensional measurement by fast determination and compensation of geometrical misalignments of X-ray computed tomography instruments

CIRP Annals ◽  
2018 ◽  
Vol 67 (1) ◽  
pp. 523-526 ◽  
Author(s):  
Wim Dewulf ◽  
Massimiliano Ferrucci ◽  
Evelina Ametova ◽  
Petr Heřmánek ◽  
Gabriel Probst ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Fast Determination ◽  
X Ray ◽  
Dimensional Measurement ◽  
X Ray Computed

scholarly journals The use of sodium polytungstate as an X-ray contrast agent to reduce the beam hardening artifact in hydrological laboratory experiments

2013 ◽  
Vol 61 (4) ◽  
pp. 347-352 ◽  
Author(s):  
Yoshito Nakashima
Keyword(s):  
Contrast Agent ◽  
Laboratory Experiments ◽  
Source Spectrum ◽  
Ct Scanner ◽  
Beam Hardening ◽  
Two Phase ◽  
X Ray ◽  
X Ray Computed ◽  
Element Bearing ◽  
Sodium Polytungstate

Abstract Iodine is conventionally used as a contrast agent in hydrological laboratory experiments using polychromatic X-ray computed tomography (CT) to monitor two-phase Darcy flow in porous geological media. Undesirable beam hardening artifacts, however, render the quantitative analysis of the obtained CT images difficult. CT imaging of porous sand/bead packs saturated with iodine and tungsten-bearing aqueous solutions, respectively, was performed using a medical CT scanner. We found that sodium polytungstate (Na6H2W12O40) significantly reduced the beam hardening compared with potassium iodide (KI). This result is attributable to the location of the K absorption edge of tungsten, which is nearer to the peak of the polychromatic X-ray source spectrum than that of iodine. As sodium polytungstate is chemically stable and less toxic than other heavy element bearing compounds, we recommend it as a promising contrast agent for hydrological CT experiments.

scholarly journals An Improved Algorithm in Porosity Characteristics Analysis for Rock and Soil Aggregate

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Yanfang Wu ◽  
Xiao Li ◽  
Yu Wang ◽  
Bo Zhang
Keyword(s):  
Compressive Loading ◽  
Soil Aggregate ◽  
Gray Level ◽  
Beam Hardening ◽  
X Ray ◽  
Porosity Evolution ◽  
Evolution Characteristics ◽  
Characteristics Analysis ◽  
X Ray Computed ◽  
Rock And Soil

The rock and soil aggregate (RSA) is a special inhomogeneous multiphase geomaterial. It is crucial for stability of engineering by study of RSA mesodamage characteristic. This paper aims at investigating the porosity evolution characteristics of RSA by X-ray computed tomography (CT) under uniaxial compressive loading. X-ray tomography images were used to extract defects of RSA specimen under different compressive loading. In this paper, we proposed an improved Ostu method to calibrate the beam hardening phenomenon which is caused by X-ray. Also, based on this Ostu method, the outline of rock blocks in RSA is extracted, and the double gray level threshold of soil and rock block is obtained to ensure the reliability of the porosity calculation. We can conclude that the main reason of RSA cracking is the elasticity mismatch between rock blocks and soil, and the porosity evolution of RSA can be divided into four typical stages. These results may be useful to reveal the mesoscopic cracking mechanism and establish mesodamage evolution equation and constitutive relation for RSA.

scholarly journals OBSERVATIONS ON THE PERFORMANCE OF X-RAY COMPUTED TOMOGRAPHY FOR DIMENSIONAL METROLOGY

2016 ◽  
Vol XLI-B5 ◽  
pp. 25-31
Author(s):  
H. C. Corcoran ◽  
S. B. Brown ◽  
S. Robson ◽  
R. D. Speller ◽  
M. B. McCarthy
Keyword(s):  
Computed Tomography ◽  
Reverse Engineering ◽  
X Rays ◽  
Dimensional Metrology ◽  
Beam Hardening ◽  
X Ray ◽  
Accuracy And Precision ◽  
Dimensional Measurements ◽  
X Ray Computed

X-ray computed tomography (XCT) is a rising technology within many industries and sectors with a demand for dimensional metrology, defect, void analysis and reverse engineering. There are many variables that can affect the dimensional metrology of objects imaged using XCT, this paper focusses on the effects of beam hardening due to the orientation of the workpiece, in this case a holeplate, and the volume of material the X-rays travel through. Measurements discussed include unidirectional and bidirectional dimensions, radii of cylinders, fit point deviations of the fitted shapes and cylindricity. Results indicate that accuracy and precision of these dimensional measurements are affected in varying amounts, both by the amount of material the X-rays have travelled through and the orientation of the object.

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