RU2542639C2 - Lever unit for static and dynamic testing of materials under conditions of uniaxial compression - Google Patents

Abstract

FIELD: testing technology.

SUBSTANCE: invention relates to the testing technology and is designed for silent testing of samples of rocks for compression in vitro both in the creeping condition, and with the controlled rate of loading. The lever unit comprises the load frame, the upper and lower beams, the power rods, the forcemeter consisting of a membrane and an induction sensor of linear motion, which are integrated in a spinning plate to set the samples of materials. The load frame is equipped with the three arm system that is the power-transmitting node from the fluid reservoir in which fluid flows through the control system of fluid leakage rate on the sample.

EFFECT: creating the unit for long-term (creeping) and dynamic (controlled rate of increase in load) testing of rock samples, providing silent experiments on mechanical uniaxial compression.

3 dwg

Description

FIELD OF THE INVENTION

The invention relates to testing equipment and is intended for silent compression testing of rock samples in laboratory conditions both in a creep state and with a controlled loading rate.

State of the art

In studies of samples of materials under uniaxial compression with the registration of acoustic emission radiation, difficulties arise in performing the power part of the press in such a way that the volume of recorded technological acoustic vibrations (not related to crack formation of the sample) when the load changes is minimal.

A well-known installation of long-term testing of rock samples for compression UDI [1], which allows to develop a maximum force of 100 tons. The constancy of the specified load is provided by the elastic energy of the pack of compressed disk springs. A sample (or a high-pressure chamber with a sample) is mounted on a table located on a movable traverse. The force is created with the help of a hydraulic jack and is transmitted through a screw to a packet of Belleville springs and then through a crosshead to a sample. The magnitude of the load is monitored by means of a permanently installed indicator device that measures the arrow of deflection of the spring package both during loading and during creep. After the load has reached its designated level, the nut on the screw is brought to the stop in the yoke. In this case, the jack is disconnected, and the load is closed by columns between the upper and lower traverses. The maximum deflection of the spring pack is 100 mm. A significant drawback of this installation is the drop in the level of loading force when testing samples with large longitudinal deformation, which occurs due to partial unloading of the spring. In this case, the test conditions can only partially be considered close to the creep state. The installation does not provide for other loading conditions. Another drawback is the creation of noise in metal structures when working with a manual jack and tightening with a fixing nut. Installations for dynamic tests with preset parameters for changing the force or deformation [2] are equipped with servo-controlled hydraulic loading systems [3] and also create additional acoustic noise and, partly, vibration, which is a significant drawback in “silent” experiments. The closest analogue (prototype) can still be considered a spring unit for compressing UDI [1], since it, in comparison with other machines, provides a minimum noise level.

The purpose of the invention is the creation of an installation for long-term (creep) and dynamic (controlled rate of increase in load) tests of rock samples, providing silent experiments on mechanical uniaxial compression.

This goal is achieved by the fact that the lever system of three levers is used as the power unit, which transfers the force from the point mass (load) applied to the last lever (due to gravitational forces) to the first lever (transmission coefficient depends on the size of the levers). The use of three levers instead of one significantly increases the transmission force, which is equal to 30 tons. To change the level of load transmitted to the sample, a load made in the form of a reservoir for liquid (water) is connected to the end of the third lever, into which it enters through the leakage rate control system. The technical result is achieved in that, the change in load can occur at any speed and as silently as possible. The technical result is achieved by the fact that when the sample is deformed and the working space is reduced in the compression direction, the lower pressure heel is fed after the sample under the action of gravitational force exerting pressure on the lever system. This allows experiments to be carried out on samples in a creep state, while maintaining the force on the sample with high accuracy.

In FIG. 1 shows a side view of a part of a lever installation for static and dynamic testing of materials under uniaxial compression conditions, FIG. 2 is a vertical sectional view of a portion of a linkage assembly showing the connection of a lever and a power rod; FIG. 3 - frontal projection of the installation.

The lever installation for static and dynamic testing of materials under uniaxial compression conditions contains: a power frame 14; a lever system of three levers 12, 18 mounted on a power frame; nodes of the levers 17; a system for controlling the rate of leakage of liquid 20 and cargo 19 (see Fig. 1); upper 2 and lower 9 traverses, support posts 1, as well as 10 fixing nuts for changing the working volume of the lever installation; a dynamometer consisting of a membrane 4 and an induction linear displacement sensor 5, which are built into the pressure heel on a spherical joint 6, 7; power rods 8, 11 for transmitting force from the lever to the sample and stroke limiters 10 (according to Figs. 2, 3).

Installation works as follows. Test specimen 3 is installed between the upper crosshead 2 and pressure heel 6. After setting the water supply speed, checking the filter, etc. in the system for controlling the rate of leakage of liquid 20 and turning on the supply, the liquid begins to flow into the reservoir 19, thereby changing the mass at the end of the last lever 18. Sinking down, it transfers force to the lever 12, which rises and presses the sample through the power rods 8 and 11 In this case, the stroke limiters 10 are installed with a gap of 1-2 mm to prevent impact after the destruction of the sample. The level of the compressive load is transmitted from the dynamometer built into the pressure heel 6, 7, which operates on the principle of measuring the deflection of the membrane 4 by the linear displacement sensor 5. The system has a feedback, so that with small deformations of the sample 3 in the axial direction, the power rod 8, 11 rises, and followed by a lever 12, after which the remaining levers begin to work. Thus, the load retains the current value.

Sources of literature

1. A.N. Stavrogin, B.G. Tarasov. Experimental physics and rock mechanics. SPb .: Science. 2001.343 s., (Prototype).

2. Copyright certificate of the USSR No. 911208, cl. G01N 3/08, 1982.

3. Copyright certificate of the USSR No. 1651144, cl. G01N 3/10, 1991.

Claims (1)

A lever installation for static and dynamic tests of materials under uniaxial compression, containing a power frame, upper and lower traverses, power rods, a dynamometer consisting of a membrane and an induction linear displacement sensor that are built into the pressure heel for installing material samples, and characterized in that that the power frame is equipped with a system of three levers, which are a power transmitting unit from the fluid reservoir, into which the fluid enters through the fluid leakage control system to the sample.

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