Search

Spheroidal graphite cast iron is often used for machine parts that require high strength. A shrinkage cavity may be generated inside the cast iron during the manufacturing process. If there is a shrinkage cavity in the cast iron, the strength of the cast iron is significantly reduced. In this article, a non-destructive testing method for detection of shrinkage cavity inside the cast iron by constant frequency vibration measurement using electromagnetic force excitation at low frequency is proposed. In this method, the electromagnetic force vibration is generated inside the cast iron from the static magnetic field by a permanent magnet and the eddy current by an alternating exciting coil. Then, the vibration is measured by an accelerometer that is in contact with the surface of the cast iron material. If there is a shrinkage cavity inside the cast iron, since the vibration intensity is changed, the shrinkage cavity is estimated by the vibration measurement. In this method, the shrinkage cavities inside cast iron can be inspected at high speed with an inexpensive device. In this article, the electromagnetic force vibration is calculated using the 3-D nonlinear electromagnetic finite element method (FEM) analysis. The displacement due to vibration in the cast iron is calculated by the 3-D displacement FEM analysis. The phenomenon of electromagnetic force excitation is clarified using these FEM analysis methods. Then, the effectiveness of the proposed inspection method is investigated by comparing the results of the verification experiment and analysis. [ABSTRACT FROM AUTHOR]

Steel tubes are used in the heat exchanger in the petrochemical plant. Since these steel tubes in the heat exchanger are stored as a bundle, it is necessary to inspect the defects of these tubes from the inside of tube. In this paper, problems in applying the alternating flux leakage testing method for the inspection of the outer side defect on steel tube are examined using 3-D finite element method. The features of detecting property of outer side defect using an inner coil at low-frequency are investigated by analyzing the flux and current distribution. It is shown that the inspection of the outer side defect on a steel tube with cooling aluminum fin is possible using the proposed method. Index Terms--Alternating flux leakage testing method, eddy current, nondestructive inspection, nonniformity of permeability and conductivity, outer side defect.

It is known that the detection of cracks on the outer side of steel plate is possible using the dc flux leakage testing. If the examined steel plate is thin, the outer side crack may be detected by alternating flux leakage testing. The merit of the alternating flux leakage testing method is that a cheap coil is used for detecting the leakage flux from the crack. In this paper, the inspection method of outer side crack of the steel plate using the alternating flux leakage testing is proposed. The component [Bx] of the leakage flux parallel to the surface of steel is utilized for detecting the crack. The behavior of leakage flux is examined using a three-dimensional edge-based hexahedral FEM (finite element method). It is shown that the outer side crack can be inspected by detecting the parallel (x-) component of leakage flux. Index Terms--Alternating magnetic flux leakage testing, finite element method (FEM), outer side crack, three-dimensional (3-D) non-destructive inspection.

A new process, the Non Anchor Coating Extrusion Laminating Process for producing an extrusion laminated film without any chemical primer, was investigated. Good adhesive properties were obtained by combining an ozone treatment of a molten polyethylene (LDPE) web and an activation treatment of the polyamide (ONy) substrate film. The adhesion mechanism induced by the new process was studied by FT-IR, ESCA and extraction of unreacted polyamide from the laminated samples. The peel strength between the ONy and LDPE laminated films produced with this process was greater than that for laminated film made with a conventional lamination process using anchor coating agents. A model of the adhesive mechanism is proposed. Hydrogen and covalent bonds through oxygenated functional groups are responsible for the enhanced adhesion., INTRODUCTION Low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) are widely used in various packaging and extrusion laminating applications. In an extrusion laminating process, LDPE is generally melt-extruded [...]