Measuring and testing – Specimen stress or strain – or testing by stress or strain... – Deformation or change in stress after fracture – cutting – or...
Reexamination Certificate
1999-07-08
2001-01-09
Noori, Max (Department: 2855)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
Deformation or change in stress after fracture, cutting, or...
C073S806000, C073S762000
Reexamination Certificate
active
06170337
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for measuring permanent length deformations of materials, comprising a step of determining a change of the initial distance between two points on the material surface. The invention relates also to a device for carrying out said method, comprising two measuring elements fastened in a mutual distance on the material surface.
DESCRIPTION OF THE PRIOR ART
Measuring of length deformations in solid substances, particularly in metallic and other materials which are, when mechanically stressed, deformed and strained beyond the limit of elasticity and the yield point in tension with increasing deformation up to the final fracture, has been carried out using mechanical or optical extensometers measuring the material stretch between two fixed points on a structure. Said extensometers require, due to their limited accuracy, a larger distance, e.g. about several tens of centimeters, between said two fixed points on the material or the structure. In order to attain greater accuracy when measuring the distance of the reference points from each other, thus enabling the distance between them to be shorter, it can be possible to use measuring microscopes. The basic disadvantage of these apparatuses consists in their large dimensions and thus their considerable weight, which makes these apparatuses not applicable in practice for measuring deformations on erected metallic structures, e.g. bridges, pipings etc., particularly when these pipes are positioned in narrow spaces, e.g. in atomic power plants. A further considerable problem consists in difficult accessibility of the measuring points e.g. on insulated oil pipeline, distributing pipes inside structures, on bridges etc.
It is therefore the object of the invention to provide a method and a device for measuring permanent length deformations of solid substances and materials of structures, which deformations are caused by excessive or long-term loading of the structure, wherein said method should be carried out in conditions enabling to attain the highest possible measuring accuracy, e.g. in laboratories or in equipped measuring stations being situated at a distance from the measured structure.
SUMMARY OF THE INVENTION
In one aspect of the invention said method for measuring permanent length deformations of materials, comprising the step of determining a change of the initial distance between two points on the material surface, is characterized by making impressions of the measuring points which had been formed on the material surface, on a removable impression body and by measuring the exact distance of the identifiable positions of both measuring points on the impressions of said measuring points.
In another aspect of the invention, a first pair of the measuring point impressions is made on said removable impression body prior to the deformation of the material and a second pair of the measuring point impressions is made after the critical loading of the material, and the distances of the first pair of the impressions and of the second pair of the impressions are compared and evaluated.
The device for carrying out said method consists of a fixed portion arranged on the material section being measured and of a portable portion, the fixed portion of the device being provided with two measuring elements having identifiable measuring points disposed at a mutual distance, and the portable portion comprising an impression body with an impression face adapted for making the impressions of the measuring points.
In still another aspect of the invention, the measuring elements are fastened on a common plate which itself is fastened on the surface of the material section being measured. Said measuring elements are formed by the top part of a pyramidal body having always at least one of its side sharp edges parallel with at least one of the side edges of the other pyramidal body of the second measuring element. The fastened plate is preferably surrounded by a guide ring having inner guiding surface for the impression body, said guide ring being fastened to the material section being measured.
The method and the device according to the invention provide a possibility for exact measuring of permanent (nonreversible) deformations of material on short length sections by using very accurate measuring devices, e.g. measuring microscopes. Since this bulky and heavy apparatus is not suitable to be used directly in the terrain, e.g. on a bridge, an oil pipeline, a ship or other structure, where measuring the state of the structure is necessary, e.g. after an earthquake or other excessive loading, it is advantageous to use the device according to the invention which supposes measuring the distance between the measuring elements prior to and after the loading by measuring said distance of the impressions of the measuring points formed on the removable impression body using a measuring microscope.
REFERENCES:
patent: 3594912 (1971-07-01), Sauterel
patent: 4031746 (1977-06-01), Furuta et al.
patent: 4483075 (1984-11-01), Kundin
patent: 4669106 (1987-05-01), Ammerman
patent: 5668324 (1997-09-01), Voss et al.
Noori Max
Notaro & Michalos P.C.
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