SU896498A1 - Device for mechanical testing of specimens under cyclic loads - Google Patents

Description

(54) INSTALLATION FOR MECHANICAL TESTS OF SAMPLES DURING CYCLIC LOADS

I

The invention relates to a test technique, materials for strength, namely to test samples under cyclic loads.

A known apparatus for mechanical testing of samples, comprising a lever-hydraulic loading device with a float placed in a tank of liquid.

The disadvantage of this setup lies in the inadequacy of the loading rate of the sample due to the friction of the float against the tank wall, leading to a change in the direction of the pushing force and a corresponding change in the loading force.

The closest in technical essence to the present invention is an installation for mechanical testing of samples under cyclic loads, comprising a base with a fixed grip and a prismatic support, a double-arm lever mounted on it, a movable grip connected to one of the arms of the lever, a container fixed on the other shoulder lever, constant pressure head fluid communicated with the container through the diaphragm, and

means of measuring the force applied to the sample 2.

A disadvantage of the known installation is the low accuracy of the tests due to the inadequacy of the sample discharge rate, which is determined by a non-linear decrease in the level of the liquid when it is removed from the tank.

The purpose of the invention is to improve the accuracy of the tests.

This goal is achieved by the fact that the installation is equipped with an additional capacity attached to the lever arm with a movable gripper and an additional diaphragm through which the additional capacity communicates with the tank of constant pressure.

15

The drawing shows the installation, general view.

The installation contains a base 1 with a fixed grip 2 and a prismatic support

3 mounted on a support 3 double-shouldered lever

20

Claims (2)

4, a movable gripper 5, connected to the left shoulder of the lever 4 through a dynamometer 6, used as a means of measuring the forces applied to the back 7. a container 8. fixed on the right shoulder of the lever 4, additional capacity 9 fixed on the left shoulder lever 4, tank 10 constant pressure liquid, made in the form of two chambers 1 and 12 with discharge pipes 13 and liquid inlet 14, communicated with capacity 8 through valve 15 and diaphragm 16 and with capacity 9 through valve 17 and additional diaphragm 18, strain gauge 19, which serves to measure the deformation of the sample 7 .. Set Vka works as follows. The fluid through the pipe 14 is fed into the chamber 12 of the tank 10 in an amount greater than its subsequent flow through the diaphragm 16: or 18. Initially, the taps 15 and 17 are closed, the liquid from the chamber 12 enters the chamber 11 and is discharged through the socket 13. The pressure of the liquid in the chamber 12 The tank 10 is kept constant due to its overflow into chamber 11. When the valve 15 is opened, the liquid from chamber 12 flows through diaphragm 16 into capacitance 8. The rate of change of mass of tank 8 and, consequently, the rate of increase of force on sample 7, constant nna since npd is proportional to the area di passage aperture section 16 and the magnitude of fluid pressure in the chamber 12 of the tank 10, which are constant. When a predetermined value is reached, the force of deformation, controlled by diameter 6 and strain gauge 19, closes the valve 15 and simultaneously opens the valve 17. When the liquid arrives, it enters through the diaphragm 18 with a constant flow section into the container 9, the mass of which increases with a constant speed the filling of the container 8. Since the container 9 is fixed on the opposite, relative to the container 8, arm of the lever, the force applied to the sample 7 decreases with constant speed. In order to obtain a variety of load and discharge rates, the diaphragms 16 and 18 are placed with other cross sections. The use of the proposed invention makes it possible to carry out the load and unloading of the sample at constant speeds, the change of which in the process of drinking does not exceed 1%. The magnitudes of the speeds can change 10 times when changing the aphragms. Claims apparatus for mechanical testing of samples under cyclic loads, comprising a base with a fixed grip and a prismatic support, a double-arm lever mounted on it, a movable grip connected to one of the arms of the lever, a container fixed on the other arm of the lever, a tank of constant pressure fluid communicated with the container through the diaphragm, and the means of measuring the forces applied to the sample, is different in that, in order to improve accuracy, it is equipped with an additional capacity attached to the shoulder lever with a movable gripper, and an additional diaphragm, through which the additional capacity is in communication with the tank of constant pressure, Sources of information taken into account in the examination 1. Authors certificate of the USSR N 200264, cl. G 01 N 3/18, 1968 .. 2. Problems of strength, 1974, No. 12, p. 26-30 (prototype). dffa & sf (o, 9 t ffOffffV f