SU1401260A1 - Device for determining internal strains in objects - Google Patents

Abstract

The invention relates to a measurement technique, to devices for determining stresses within hardening materials. The purpose of the shadow inventive is to increase accuracy and reliability. In the device, the elastic element 1 is made in the form of a plate with strain gauges located along the entire plate, and the contact elements are made with an arcuate cross section and a length equal to the length of the plate. The cutouts on the contact element contribute to less distortion of the state of concrete and better adhesion of the device and concrete. 2 Il.

Description

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The invention relates to a measuring technique and can be used to measure deformations inside structures made of hardening materials, such as concrete.

The aim of the invention is to improve accuracy and reliability by choosing the shape of contact elements in combination with the shape of an elastic element,

Fig, 1 shows the device, a general view; 2, a device located inside the object, section

The device consists of an elastic element 1 in the form of a rectilinear plate, along the long edges of which the contact elements 2 of the same section are fixed. The contact element has, along the device axis, cuts with constant pitch, symmetrical with respect to the communication line of the plate 1 with contact elements 2, Na

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The surfaces of the elastic element are glued at equal distances from each other by strain gauges 3, The thickness of the contact elements and the plate is chosen from the word equality of stiffness characteristics for a distance of compression and bending of the concrete and the sensor.

The device works as follows.

The tested structure 4 selects the concrete by drilling a hole 1 mm in diameter larger than the meter of the sensor. The device is installed in the hole, gluing the contact elements 2 with epoxy composition 5 to the concrete of construction 4, with the longitudinal axis of the sensor perpendicular to the axis along which the deformations are measured. During deformation of the bondless structure 4 at the interface between the concrete and concrete, contact tangential and normal stresses occur, one acts on the contact elements 2, the tangential stresses are self-balanced, and the deformation of the elastic element 1 is not affected. Normal stresses due to the compatibility of deforming elements 2 and 1 are transferred directly to elastic element 1. Moreover, the execution of contact elements 2 of an arched form is convex

reducing the concentration of normal stresses by distorting more than 25%, distorting the true strain of concrete. The elastic element I works only in compression (stretching) with a bend. The deformations of this element are measured by working strain gauges 3, which are located at equal distances from each other, the longitudinal axes of which coincide with the direction of the deformations sought. At the same time, the implementation of element 1 with a linear length equal to the width of the cross section under study ensures a minimum of distortions, introducing 1x into the strain field of concrete, when several strain gauges are installed, ranging from 5 to 20% C depending on the distance between the sensors and their dimensions) and also eliminates the non-linearity of the nature of the deformation of the elastic element, as a result of which the error can reach 50%. To do this, so that the flexural deformations of elements 1 and 2 do not distort the true deformations in the concrete surrounding the sensor, the contact elements 2 are made of duralumin with cuts along the sensor, and the element 1 is made of steel, which, together with a specially selected thickness, provides the minimum divergence of the flexural rigidity of the sensor and concrete.

Claims (1)

Invention Formula A device for determining internal deformations in objects, containing an elastic element with strain gauges and rigidly connected with opposite sides of an elastic element. Contact elements with arcuate cross section, facing a sensitive element with a concave surface, characterized in that, in order to improve accuracy and reliability, the elastic element is made in the form of a plate, each contact element is made of a length equal to the length of the plate, and with cuts arranged in constant pitch along the entire contact element with mmetrichno relative link plates with the engaging member. , ABOUT- . “O%; ° o-o / -o- .o; .o G .O. z oo /. o. |: ooo about. about . o /. ° o- .o Vu-i.l