SU1460594A1 - Apparatus for measuring deformation in extension testing of materials - Google Patents

Description

The invention relates to measuring technique, namely to means for controlling forces and strains during tensile testing of materials, and can be used to remove the relationship between these values with a continuous increase or decrease in the load on the sample.

The aim of the invention is to expand the functionality of the device by simultaneously measuring the deforming force, which is achieved by introducing a force sensor, an analog-to-digital converter and a digital storage device with a counting input for address generation, by performing a transducer of the angle of rotation of the drum of the strain gauge into an electric signal in the form of kinematically connected with a drum of a coding disk with optical marks and a photoelectric reader, the output of which is connected with a counting input of the storage device, as a result of which, at each increment of deformation by a given Discrete value, the force value is recorded in digital form.

The drawing shows a diagram of a device for measuring strains in testing tensile materials.

The device contains a series-connected force sensor 1 with an analog output, an analog-to-digital converter 2 and a digital storage device 3 with an information input 4 and a counting input 5 for generating an address recorded in this encoded message device, as well as a mechanical tensometer 6 made in the form of a drum with wound on it with a flexible thread and a kinematically connected coding disk with optical marks (strain gauge elements not shown), and a photoelectric reader 7 connected to the even input 5 of the digital storage device 3 and the counter 8.

The device operates as follows.

The strain gauge 6 is installed on the test sample at a given point and connect the end of the flexible thread. With another point on the sample, spaced from the first at a distance equal to the required base of the strain gauge. The force sensor 1 is connected in series with the sample and placed in the grips of the testing machine, after which the continuous loading mode is activated by tensile force or another mode simulating a real load. In the process of sample deformation under this load, a flexible thread is wound from the drum, the drum is rotated by a certain angle, and the coding disk is rotated by a larger angle, the magnitude of which depends on the transmission coefficient of the kinematic connection. As soon as the rotation of the coding disk exceeds the angular pitch between the two optical marks, the photoelectric reader 7 generates an electric pulse, which is a recording command for digital memory 3. When this pulse arrives at the counting input 5 of memory 3, the unit number of the memory cell is increased by one, into which the signal is recorded from the analog-to-digital converter 2, which periodically (or by the same command) interrogates the force sensor 1. As a result, each encoded message from the analog-to-digital converter 2 is recorded in the next memory cell of the storage device 3 at the very moment when the deformation of the sample increased by a fixed increment, which ensures the recording of the relationship between the force and deformation with high accuracy in a digital code. The accumulated strain value is also recorded in counter 8.

Using the proposed device allows registration of both fast-moving processes and processes in which the strain rate of a sample varies over a wide range, without reducing the accuracy of the measurements.

Claims (1)

Claim A device for measuring deformations during testing of materials <tensile, containing a strain gauge with a drum, a flexible thread wound around the drum and a converter for the angle of rotation of the drum into a pulsed electrical signal, and a counter for the number of pulses, characterized in that, in order to expand the functionality of the device due to simultaneous measurement of the deforming force as well; it is equipped with a series-connected force sensor, an analog-to-digital converter and a digital storage device with counting the input input of the address formation, and the angle-to-electric signal converter is made in the form of a kinematically 5 coding disk with optical marks and a photoelectric reader connected to the drum, the output of which is connected to the counting input of the storage device and the pulse number counter.