Measuring and testing – Vibration – By mechanical waves
Patent
1987-02-11
1988-11-22
Noland, Tom
Measuring and testing
Vibration
By mechanical waves
73620, G01N 2904
Patent
active
047856670
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of measuring the inclining angle of a planar defect in various solid materials by utilizing ultrasonic waves.
The planar defect in a solid material in this specification means a flat surface-state defect and hence a planar defect having an area, generated, for example, on a part or component, or a member which constructs an apparatus such as an electric apparatus, a mechanical apparatus or a chemical apparatus in various industrial fields, and involves the state wherein the planar defect is opened on the surface as well as the state wherein the defect is partly opened on the surface, but the state irrespective of the length of the planar defect and the magnitude of the width of the opening. The solid material in this invention involves metal and nonmetal (glass, ceramics, concrete, synthetic resin, rubber and/or wood) and hence a physical body in which ultrasonic waves can be propagated.
Further, the inclining angle of the planar defect in the solid material in this specification means the angle formed between the planar defect in the solid material and the surface or plane of the part or member in which the planar defect is generated.
2. Description of the Prior Art
In the technical field relating to this invention, it is a necessary and important matter to examine the presence or absence of a defect in a part or component, or a member of an apparatus and to know, in the case where the defect exists, the position, shape, type and size of the defect. If there is a planar defect like a crack as type of the defect, in not only the part or member but also destructive dynamics and proposal of countermeasures involving the strength analysis and the lifetime calculation of the entire apparatus, it is important and indispensable to know the type of the planar defect and the inclining angle thereof. There are a number of types of planar defects such as a flat surface defect caused, for example, by improper fusion during the course of welding; a cleavage generated near the surface of a member caused by the fatigue of the member, a thermal stress or a transformation stress upon quenching or tempering or remaining stress during ambient temperature release of the member having the remaining stress; or a crack due to stress corrosion cracking or grain boundary corrosion feasibly generated in a coating material or a heavy metal casing of an atomic reactor fuel used in a corrosive environment or a large-sized storage tank for LPG or gaseous fuel due to tensile stress of a material such as stainless steel or Zr-alloy steel having high tensile strength, toughness and corrosion resistance. The known methods of non-destructively detecting the position and approximate size of a planar defect include detecting the defects by utilizing radiation transmission of X-rays or gamma-rays, of physical energy such as penetration of supersonic waves, magnetic or electric induction, or impregnation with a solution, which are used distinctly according to the types of defects to be detected, i.e., predetermined correlative size. However, there are no known methods of measuring the including angle of the planar defect at present, and the only practical method of measuring a planar defect itself being by taking a photograph of the defect. However, since the result of the test is affected by the results of the taken photograph in this method, it is necessary to provide for selection of film sensitivity and a series of photograph forming steps to the formation of a print, to provide for the shape and the size of an element to be detected in a photographing state, to form a print of high resolution, as well as providing a detecting apparatus having a large scale in consideration the attenuation or scattering of radioactive ray energy due to the material and the size of the element to be detected. In addition, there are special problems with regard to safety during exposure of radioactive rays, thereby resulting in a number of conditions in the measurements
REFERENCES:
patent: 4299128 (1981-11-01), Gruber
patent: 4524622 (1985-06-01), Susuki et al.
patent: 4531409 (1985-07-01), Koch et al.
Miyajima Takeshi
Oshiro Takayuki
Arana Louis M.
Hitachi Construction Machinery Co. Ltd.
Noland Tom
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