Measuring and testing – Vibration
Patent
1986-04-22
1987-09-22
Ciarlante, Anthony V.
Measuring and testing
Vibration
73778, G01N 2900, G01L 100
Patent
active
046946985
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a method of measuring, by utilizing ultrasound, the factor of stress concentration at the portion of a mechanical member, structural member or the like where stress is concentrated (will be referred to as "stress-concentrated portion" hereinafter).
The stress-concentrated portions of members, to which the present invention is applicable, include structural notched or cut portions such as hole, key way formed in members composing, for example, machineries, structures, etc. in all fields of industry, as well as undercut, blow hole, nest, crack, etc. developed in the manufacturing processes such as welding, forging, molding, etc. Also, they include the portions of materials, like flaw, crack, etc., of which the section varies abruptly.
More particularly, the present invention concerns a method of measuring the factor of stress concentration at the stress-concentrated portion of a member made of a metal or nonmetal (glass, ceramic, synthetic resin, etc.) and through which ultrasound can be propagated.
(b) Description of the prior art
Analysis concerning the stress-concentrated portion of a member, and setting of a factor of stress concentration at such portion, among others, are essential in designing and manufacturing a machine or structure in order to prevent any breakdown or damage of them and also to improve the safety and reliability. In the field of technology to which the present invention belongs, however, the method of measuring the factor of stress concentration of a real object easily, real-time and quantitatively is very important and necessary, but has not yet been established, for analysis of the stress concentration at the portions joined by the welding having been utilized from the old time and of which the application is very wide, and even for analysis of the stress concentration at the structural notched or cut portions of mechanical parts, typically, hole or key way formed by utilizing no welding and of which, it is said, the study has been highly advanced. It is very hard to theoretically analyze the mechanism of stress concentration even in these fields.
To solve the above problem, various methods of measuring the factor of stress concentration have been proposed. However, they include only the experimental methods of measuring using the photo-elasticity. That is, model experiments were made for analysis and study of only the typical models such as those in which circular holes or elliptical cavities were developed inside or on the surface of an elastic object like steel or in which U- or V-shaped notches were found on the surface of such object. These proposed methods were static, qualitative and indirect ones, and they were reported by H. Neuber and R. B. Heywood in 1958.
However, since the notches developed in the surface of bead weld vary in shape from one to another depending upon the method and kind of welding and also the shape of welded joint, the reproducibility can hardly be expected of the conventional method of measuring the factor of stress concentration at the weld zone. Therefore, it is practically impossible to condition any test piece of a weld zone into a predetermined model. In measurement of the factor of stress concentration at the welded portion, even the method of measuring by using the photo-elasticity, namely, a static, qualitative and indirect one, has some problems in applications and it is difficult to employ the method, as will be explained below.
(1) Although it is necessary to prepare a model as test piece, this modeling is impossible in practice for the above reasons.
(2) Even if such model could be prepared, since it is to be made from a material such as high-molecular epoxy resin, diarylphthalate resin or the like, differences in material, dimensions, working precision, etc. from the actual test piece are inevitably encountered which will also affect the fringe order of the stress-concentrated portion, resulting in no stable fringe order.
(3) Because of the material p
REFERENCES:
patent: 4484475 (1984-11-01), Ogura et al.
Ciarlante Anthony V.
Hitachi Construction Machinery Co. Ltd.
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