SU905707A1 - Device for testing material specimens for tension - Google Patents

Description

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The invention relates to a test technique and can be used in testing tensile samples of materials.

A device for testing tensile materials is known, containing a force frame with grippers for fastening the ends of the sample, a loading system installed on the frame, force and strain sensors with amplifiers, and a recording unit 1.

A disadvantage of this device is the inability to control the loading system from the strain sensors.

The closest to the invention in technical essence and the achieved result is a device for testing samples of materials for tension, containing a power frame with grips for fastening the ends of the sample, a loading system installed on the frame, force sensors, deformations and displaced with appropriate amplifiers sequentially electrically interconnected control key with a command setter, a memory circuit, an adder, a signal setter with a controller, associated with a loading system, and a recording unit, one .The inputs of which is coupled to the output of force sensor 2.

The drawback of the device is its low accuracy, since during testing there is no change in the speed of movement of the grips depending on the change in the speed of deformation.

The purpose of the invention is to increase the accuracy of the test.

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The goal is achieved by the fact that the device is equipped with a subtraction unit, the inputs of which are connected to the outputs of the amplifiers of the strain and displacement sensors, and the output - with the key input, and the second input of the recording unit 15 is connected with the output of the adder, the second input of which .

The drawing shows the scheme of the proposed device.20

The device comprises a frame 1 with grippers 2 and 3 for fastening the ends of the specimen, mounted on frame 1, loading system 4 with an accumulator 5, force sensor 6 with amplifier 7, movement sensor 8 with amplifier

9 and strain sensor 10 with amplifier 11, subtraction unit 12, the inputs of which are connected to the outputs of amplifiers 9 and 11 of data points 8 and

10 displacement and deformations that are successively electrically interconnected between a control key 13 and a command setter 14, a memory circuit 15, an adder 16, the second input of which is connected to the output of the amplifier 9, and a signal setpoint adjuster 17 with a regulator 18 associated with the converter 5. In addition, the device contains a recording unit 19 one of the inputs of which is connected to the output

the adder 16, and the second with the output of the amplifier 7 of the force sensor 6.

The device works as follows.

Sample 20 is placed in grippers 2 and 3 and loaded with a tensile force using a loading system 4. When the sample is loaded 20, the signals from sensors 6, 8 and 10 are amplified in the corresponding forces 7, 9 and 11. At this time, the signal from the signal setpoint generator 17 is fed to the input of the regulator 18. As long as there is a difference in the signals that go to the regulator 18 from the signal setpoint generator 17 and from the movement sensor 8 through the adder 16, the controller 18 acts on the converter 5, the cylinder rod of the loading system 4 moves. Signals from force sensor 6 are fed through amplifier 7 to one of the inputs of registering unit 19. Signals from deformation sensor 10 and displacement sensor 8 are sent to subtraction unit 12. A signal equal to the difference of the signals arriving at the block 32 is fed through the key 13 and the memory circuit 15 to the adder 16, where it is added to the signal from the displacement sensor 8 and fed to the second input of the regulator 1 After the linear relationship between the signals of the displacement sensors 8 and 10 deformation; the command setting device 14 locks the output of the difference signals to the adder 16. Thereafter, to the second input of the registering

The block 19 and the controller 18 receive only the signal from the displacement sensor 8. The regulator 18 maintains the constant specified movement speeds from the signal setpoint generator 17.

both in the elastic region and in the event of plastic deformation, and due to the presence of the subtraction unit 12, the relationship between the complete deformation of the entire sample and the deformation of the sample based on the deformation sensor 10, i.e. The effect of material inhomogeneity on the deformation along the length of the sample is taken into account. In addition, a sharp increase in the difference signal indicates the presence of

soldering on the sample.

The device allows to increase the accuracy of testing samples of materials for stretching and to record with high accuracy the value of proportional limits and yield strengths of materials.

Claims (2)

1. Lebedev L.M. Machines and instruments for testing polymers. M., Maapshostroenie, 1967, P.68. 2. USSR author's certificate No. 484440, cl. G 01 N 3/06, 1971 (prototype).