CS241421B1 - Device for measuring the change of body circumference during force loading - Google Patents

Abstract

The device for measuring the change in the circumference of bodies consists of contacts /2/, a chain of rigid yokes /4/, with a displacement sensor /5/ and a spring /6/ connected between the first and last yoke /4/. The contacts /2/ are rotatably mounted on pins /3/ and adjacent contacts /2/ are interconnected by rigid yokes /4/.

Description

The invention relates to a device for measuring the circumference of bodies under static loading with a convex shape circumferential curve, i.e. to measure the average transverse deformation of these bodies, and solves the problem of accurately determining uneven body circumference changes in a simple device construction.

The prior art devices for measuring transverse deformation, e.g. of rock clamps, utilize displacement sensors generally arranged in two mutually perpendicular directions in a plane perpendicular to the axis of the specimen, since the deformations in the individual directions are generally unequal. Each measuring point or pair of measuring points in one direction has one sensor. The average transverse deformation is obtained from the sensor data. The accuracy of the average transverse deformation determination depends primarily on the number of measured points, but this is limited by the dimensions of the sensors. The measurement accuracy _# and thus the sensitivity of the sensors must be high, as these are usually very small displacements.

[0008] The apparatus for measuring the change in circumference of the bodies under load according to the invention is characterized by the fact that it consists of at least three contacts, each contact is rotatably supported on a pin and adjacent contacts are interconnected by rigid brackets enclosing the test body. is less than the number of contacts, with a displacement sensor and a spring urging the contacts on the test body between the first and last yokes.

By using the device according to the invention, a direct measurement of an uneven circumferential change and thus an average transverse deformation is achieved

241 421

- 2 ce, the device being equipped with only one displacement sensor. Measurement accuracy is optional and depends on the number of touches of a particular embodiment.

The attached drawing schematically shows a top view of the device according to the invention. The invention is not limited to the illustrated embodiment.

The device for measuring the circumference of the bodies according to the invention, as shown schematically in the drawing, forms contacts, the adjacent contacts 2 being interconnected by rigid yokes λ in a chain surrounding the test body J along the circumference. A displacement transducer 5 and a spring 6 are provided between the end contacts 2 and provide a pressure of the contacts 2 to the surface of the test body.

The function of the device according to the invention is as follows: During changes in the circumference of the specimen J caused by static loads, the contact 2 follows the surface of the specimen J. Since the length of the yoke chain is constant, 5. Since in practice, these are small displacements, a linear approximation with sufficient accuracy is sufficient to measure this segment of the curve. The average transverse deformation, or average variation of the specimen width, is given by the displacement sensor reading multiplied by the sensor constant.

The device according to the invention can be used to measure changes in convex shape, especially in those bodies where an uneven development of circumferential change along the circumferential curve under static loading can be expected.

For example, the device is suitable for measuring transverse deformation of rock test specimens of approximately cylindrical shape under axial stress.

Claims (4)

Device for measuring the circumference of a body under load by means of a body, spring and sensor encircling device, characterized in that it consists of at least three contacts (2), each contact being rotatably supported on the pin (3) and adjacent contacts (2) ) are connected by rigid brackets (4), enclosing the test specimen (1) the number of which is less than the number of contacts (2), Device according to claim 1, characterized in that the contact (2) is provided with a rotating surface at least in the part contacting the test body (1). Device according to Claims 1 and 2, characterized in that the contacts (2) are equidistant from one another. Device according to claim 1, characterized in that the contacts (2) are cylindrical in shape.