SU851193A1 - Device for measuring solid material viscoelastic characteristics - Google Patents

Description

(54) DEVICE FOR DETERMINATION OF VISCOELASTIC CHARACTERISTICS OF SOLID MATERIALS

I

The invention relates to a measurement technique and can be used to determine the viscoelastic characteristics of materials, in particular, the elastic modulus, as well as the loss tangent of the viscoelastic material.

A device comprising a system that introduces a pulsed perturbation and a system for measuring and recording the deformation of a sample is known. The sample is made in the form of a biplastin of the material and metal under study. The frequency and the logarithmic decrement of the oscillations are determined from the record of damped oscillations of the deformation of the sample, and then the elastic modulus and the loss tangent of the material 1 are determined using the formulas.

However, this device has the disadvantage of having difficulty making accurate measurements on one sample in a wide frequency range and the impossibility of taking measurements on a sample in a stressed state.

Closest to the present invention is a device comprising a unit for fastening the sample under test, a system for exciting periodic oscillations of a liquid in a sample, made in the form of a pulsed pulsator with a drive, a system for registering oscillations in a sample, and a system for registering the stroke of a pulsator. Samples made in the form of a pipe section with hermetic stoppers are examined. In the elastic characteristics of the material

 are determined by the frequency characteristics of a sample filled with liquid 2. The drawbacks of this device are the complexity of the equipment to excite periodic oscillations of a liquid in a wide Q range of frequencies and the complexity of processing the frequency characteristics obtained at the facility, which in turn leads to a decrease in the measurement accuracy .

The purpose of the invention is to increase the accuracy of measurements in the elastic characteristics

15 solid materials.

This goal is achieved by the fact that the device containing the assembly for fastening the test sample, made in the form of a pipe section with hermetic plugs, the excitation system and the system for registering oscillations in the sample, is additionally equipped with a movable support made with the possibility of sliding in vertical guides, and a shock plate , and

The test specimen is placed on a movable support, and the vertical guides are rigidly fixed on the impact plate.

The drawing schematically shows the proposed device.

The device includes a pressure gauge 1, a compressor 2 pressurization, an upper stopper 3, guides 4, a level gauge 5, a pipe section 6 of the material under study, a strain gauge 7, a dynamic pressure sensor 8, a system 9 for detecting variable deformation of the pipe wall, a system 10 for registering variable pressure, movable bearing 11, line 12 filling the pipe with liquid, shock plate 13, the bottom cap 14, the latch 15, the valve 16 of the level gauge and the filling valve 17.

The device works as follows.

A section of pipe 6 made of the material under study, which is plugged at both ends, with a dynamic pressure sensor 8 or a strain gauge 7 connected at the bottom, is mounted on a movable support 11, which is lifted above the impact plate 13 and fixed above it with a clamp 15. Then the pipe is filled with water, the level of which in the pipeline, the gauge 5 is measured, and the taps 16 and 17 are closed. Through shtutser 2 pressurization located in the upper plug 3, the pipeline is pressurized with gas to the required pressure fixed by pressure gauge 1. Then retainer 15 is removed and the pipe on the movable support, it moves under the force of gravity along the guides 4 downwards against the stop into the shock plate 13. At the moment of stopping, a hydraulic shock occurs in the pipe, causing the fluid in the pipeline to experience free damped oscillations, which are recorded using a dynamic pressure sensor 8 or a strain gauge 7 variable pipe strain detection system 9; or variable pressure detection system 10. By recording the damped oscillations, the natural oscillation frequency, the logarithmic decrement, the elastic modulus, and the loss tangent of the material are determined.

To obtain the dependence of viscoelastic characteristics on the frequency, the tests are carried out at different levels of pipe filling.

water, while the natural frequency of the pipe varies. To obtain the dependence of viscoelastic characteristics on the stress state of the material, the tests are carried out at different pressures of the pipeline.

The proposed device has better technical characteristics in comparison with the known devices, high measurement accuracy and a wider field of application with simpler instrumentation.

Claims (2)

Invention Formula A device for determining the viscoelastic characteristics of solid materials, comprising a node for fixing a test specimen made in the form of a pipe section with hermetic plugs, an excitation system and a system for registering oscillations in a specimen, characterized in that, in order to improve the measurement accuracy, it is additionally equipped with a movable support , made with the possibility of sliding in vertical guides, and a shock plate, and the sample under study is placed on a movable support, and the vertical guides are rigidly fixed replenished on a shock plate. Sources of information taken into account in the examination 1. Ferry J. In the elastic elastic properties of polymers. M., Publishing House of Foreign Literature, 1963, p. 155-156. 2. USSR author's certificate in application number 2742398 / 18-25, cl. G 01 N 11/16, 979. S