RU1778615C - Method for loading structure by external pressure - Google Patents

Abstract

The invention relates to test equipment and allows to simplify the method of loading the structure. Pressure is applied to a toroidal elastic element having an inner diameter smaller than the outer diameter of the load structure, the element being inflated, its inner diameter increasing, and the load structure being introduced into it. The pressure in the element is relieved, its internal diameter is reduced, and it loads the structure with external pressure distributed over the surface. The load is determined by the elastic properties of the element and the pressure in its cavity. 3 sludge.

Description

The invention relates to a test technique, and in particular to methods for loading cylindrical and weakly conical shells and half-shells by external pressure.

A known test method is implemented in a hydrostatic pressure testing apparatus, in which the test structure is loaded by the pressure of a fluid placed between the test structure and the power frame located equidistant to the surface of the test structure. There is also a known method of loading structures, in which an elastic force-transmitting element is stretched, the structure is placed in it and the structure is loaded by changing the element while reducing the tensile force on it.

A known method of loading the structure with external pressure by placing

them in a toroidal elastic element and shaping it by increasing pressure.

The implementation of the known method involves the use of an external power cage in the device for testing, restricting the movement of the force transmitting element. The presence of this frame leads to an increase in the duration of installation of the testing device and restricts access to the test structure, which makes it difficult to install measuring equipment and power circuits under multiparameter loading on the test structure. These reasons lead to more complicated tests when implementing the known method.

The aim of the invention is to simplify the loading of the structure.

For this, in a known method of loading structures with external pressure by

h

4 00

(L

placing them in a mountain elastic element and shaping it by increasing the pressure, use an elastic element with an inner diameter less than the external diameter of the structure when there is no pressure in it, increase the pressure before placing the structure until the internal diameter of the elastic element exceeds the external diameter of the structure, and loading is carried out by reducing the pressure in the element.

Figs. 1 and 2 show the test structure before loading; in FIG. 3 - the same at the moment of loading.

The device for carrying out the method comprises a toroidal elastic shell 1 provided with a cavity 2, which is in communication with a pressure source 3. The inner diameter DBH of the toroidal shell 1 in the unloaded state (FIG. 1) is smaller than the diameter D of the test structure 4, The pressure is applied to the cavity 2 through the shutoff valve 5, and the pressure relief through the shutoff valve 6. The pressure in the cavity 2 is controlled by gauge 7, about

To place the test structure 4 in the toroidal shell 1 into the cavity 2, the pressure from the pressure source 3 is supplied through the shutoff valve 5. Under pressure, the inner diameter of the toroidal shell increases from DBH to D + Ad. To load the test structure 4, pressure is released from the cavity 2 through shut-off valve 6. In this case, the inner diameter of the toroidal shell decreases and the toroidal shell begins to enclose the test structure 4, loading the latter with an external pressure distributed over the surface. The structural load is determined by the elastic properties of the toroidal shell material and the pressure in the cavity. To regulate the load, the pressure in the cavity 2 is changed by depressurizing through shut-off valve b (thereby increasing the load on the test structure) or by applying pressure through the valve 5 (thereby reducing the load). To determine the actual value of the load, a calibration test is sufficient.

The change in the inner diameter of the toroidal shell DBH depends both on the deformation of the ring as a whole (which increases

distinguishes DBH), as well as from the deformation of the cavity of the ring (which reduces 0Bv). Since the deformation of the ring as a whole depends on

a, the deformation of the cavity depends on g,

and the ratio of the parameters of the shell during the tests is determined by the dependence a d, the inner diameter of the ring will increase when the cavity of the latter is loaded with internal pressure. This is confirmed by the ratios below.

The stress-strain state of a hollow ring is described by the following relationships:

ring voltage O2

 R g

longitudinal stresses a-

 -fЈ. Where

p is the pressure in the cavity 2.

Deformation of the cavity of the ring and the ring as a whole according to Hooke's law

b ± -J $ - r.b.

WG

g

Deformation (moving point B):

As can be seen from the expression for D, already at

s

Claims (1)

- 2, the inner diameter of the ring will increase when loading its cavity with pressure, and decrease when it is depressurized. This will allow the operation to place the test structure in an elastic element, followed by controlled loading of the structure. SUMMARY OF THE INVENTION A method for loading structures with external pressure by placing them in a toroidal elastic element and shaping it with a pressure increase, characterized in that, for the sake of simplification, an elastic element with an internal diameter less than the external diameter of the structure is used in the absence of pressure, the pressure is increased before placement of the structure until the internal diameter of the elastic element exceeds the external diameter of the structure, and loading is carried out by reducing the pressure in the element. fug .; FIG 2 Fig.Z /