SU1569867A1 - Training aid on structural mechanics - Google Patents

Abstract

The invention relates to demonstration devices for structural mechanics and materials resistance and allows investigating the effect of local dynamic loads on shell stability. The device contains a rack 2 and a ball bearing 3, in which the lower 4 and upper 5 clamping devices are installed. The loading means consists of a lever 6 with a load 7 and a counterweight 29 connected by a ball support 8 with an upper clamping device, and a limiter 9 of movements of the lever. The device also has a shell 10, a pusher 11, a pressure source 12 with a vacuum pump connected by lines 14 to the shell cavity. The shell is installed in ball bearings and an axial compressive force is applied to it by means of a load. Then act on the shell of the external (internal) overpressure. After that, the pusher rod is moved to contact with the casing and a static local load is created on it and, when the specified pressure is reached, the electropneumatic valve is closed. To create a local dynamic load, a pressure source 15 is connected to an electropneumatic valve and is opened, as a result of which pressure, impulsively acting on the piston of the pusher with the rod, creates a dynamic impulse to the shell. By varying the magnitude of the axial load of the shell, the excess pressure, as well as the magnitude and point of application of the local dynamic load, various cases of buckling of the shell are investigated. 3 il.

Description

The invention relates to demonstration devices and can be used, for example, when studying structural mechanics and resistance materials of materials in the course of rotation shells under the influence of external forces.

The purpose of the invention is to expand the diagonal of the problems to be solved by demonstrating the influence of local dynamic loads on the stability of the shell.

Figure 1 is a device, a general view; Fig. 2 shows the node I in Fig. 1. Fig. 3 shows the control panel diagram.

The device contains a rack 2 placed on the base 1 and a ball support 3 in which the lower atomic h is installed, the device 4, the upper clamping device 5, the loading means consisting of the lever 6 mounted on the rack 2 with the load 7, st - j L -iHoro ball bearing 8 with upper button. device 5, and placed - on the basis of 1 limiter 9 of movement of the lever 6, a deformable object in the form of a cover of rotation H placed between the clamping devices, a pusher 11 mounted on a rack 2 with the possibility of movement, a source 12 of pressure with a vacuum pump and a console 13 controls connected by lines 14 to the inner cavity of the shell Yu, and an additional source 15 of pressure with electropneumatic valve 16 connected to the console 13 of the control and the pusher 11.

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The pusher 11 consists of a hollow body 17 and a piston 18 located therein and a rod 19 in contact with the side surface of the shell 10. The control panel 13 consists of a power supply 20, keys 21 and 22, valves 23 and 24, three-position valves 25 and 26, a vacuum gauge 27 and a pressure gauge 28. In addition, a counterweight 29 is mounted on the lever 6, and the movement and fixation of the pusher 11 on the stoic 2 is carried out by means of the suspension 30 and the locking 31 nuts.

The device works as follows. Before the start of the experiment, the shell 10 is fixed in the clamping devices 4 and 5 and installed in the ball bearings 3 and 8, thereby ensuring that only the axial load is transferred to the shell 10. Then set the height of the limiter 9 such that the load 7 acts on the shell 10 only until the shell loses its stability, balance the lever 6 with the counterweight 29 and set the level of axial compression of the shell 10 by installing it on the lever 6 of the corresponding load 7. After that, the shell 10 is acted upon by an external overpressure, which is created by lowering the pressure in the cavity of the shell by pumping air out of it by a vacuum-nose through line 14, while the voltage on the vacuum pump is supplied from the control panel 13 t of power supply 20 via key 21. Then turn off the vacuum pump and, opening valve 23, interconnect the pressure source 12 and the internal cavity of the shell

10, controlling the pressure while using the gauge 27. Then the pusher 11 is set at a predetermined height, pushing the rod 19, for example, by hand, until it contacts the side surface of the casing 10. By applying pressure from the additional source 15 to the pressure of the pusher cavity

11, move the rod 19 to contact

with a shell 10 and create a static local load on the shell 10, the level of which is controlled by the pressure gauge 28, while the pressure source 15 is connected to the cavity of the pusher 11 via a valve 26, a valve 24 and an open electropneumatic valve 16. The area is controlled by legal pressure 18 ps The pressure gauge 28 determines the magnitude of the local force acting on the side surface of the shell 10. When the pusher reaches a predetermined static pressure in the cavity, electropneumatic valve 16 is closed with a key 22.

To create a local dynamic load, the valve 24 is opened, thereby connecting the pressure source 15 to the electropneumatic valve 16. Then the key 22 opens the electropneumatic valve 16, as a result of which the pressure from the pressure source 15 flows in the form of a pulse into the pusher cavity 11 and impulsively affects the piston 18 from rod 19, creates a power (dynamic) pulse on the shell 10. Repeatedly pulsing the source 15 of the pressure into the pusher 11, the buckling of the shell 10 is achieved.

Changing the value of the axial load of the shell 10 by installing various loads 7, the external (internal) overpressure by pumping (supplying) air from the shell, as well as the magnitude and point of application of the local dynamic load by creating different power pulses from the pressure source 15 and moving the pushers 11 the height of the rack 2, investigate various cases of loss of stability of the shell from external factors acting on it. The application of the invention allows in lecture demonstrations to explore the effect of local dynamic loads on the stability of the shell.

Claims (1)

5 Formula of invent and A training device on structural mechanics, containing a lower clamping device and a rack, an upper clamping device, loading means, consisting of a lever mounted on a rack with a load associated with an upper clamping device, and placing on the basis of a lever movement limiter, deformable object in the form of a sheath of rotation placed between the clamping devices, a pusher mounted on a stand 0 with the possibility of movement, and a pressure source with a control panel, Connected by highways to the internal cavity of the shell, characterized in that, in order to expand the range of tasks to be performed by demonstrating the effect of local dynamic loads on the stability of the shell, it is equipped with ball bearings placed between an upper clamping device and a lever and between the lower clamping device and the base, an additional pressure source with an electropneumatic valve connected to the control panel nor a pusher, which consists of a hollow body and a piston located in it and a rod in contact with the lateral surface of the shell. five 0 g l bokun-suck "21 / f.} 22 | 21 23 20 -G Ik I MX3% fr 0 $ 25 JftI -w I . 21 20 -G 23 Ik to the atmosphere Fig.E