RU2428669C1 - Strength test method for articles with open configuration - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: load is provided on the article under test in form of pressure fall by pumping the working medium from the formed closed cavity using a vacuum system. Test results determine whether the article satisfies required technical conditions. Vacuum pumping is carried out based on the function of the change in leakage of the object under test, as well as based on the function of the change in gas release from the walls of the object through programmed control of the flow rate of the pumped working medium.

EFFECT: possibility of testing while meeting a given schedule or program of changing the load on the object under test, which is as much close as possible to that during real operation, which is made possible due to that a closed cavity is formed by joining the article under test with an element which closes the said cavity, while ensuring inlet and outlet of the working medium from the obtained closed cavity.

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Description

The invention relates to the field of testing products of open configuration, in particular, to testing the head fairings of launch vehicles for strength and bearing capacity.

From the patent literature there is known a method for testing products such as open shells, for example, hollow open enclosures in the form of a body of revolution, described in ed. St. USSR No. 1185175, MKI G01 3/12, 3/02, 1982 and consisting in the fact that they form a closed cavity by connecting to the test product a structural element that closes this previously not closed cavity, with the organization of the input-output of the worker body into the obtained closed cavity, provide a load on the test product in the form of a pressure drop on the test product and the result of the test judge the compliance of the test product with the necessary technical conditions.

However, in this method, the pressure drop is created due to excess pressure in the created closed cavity, which makes it difficult to obtain reliable information about the strength of the product, because the actual operating conditions of the product are not fully taken into account.

Also known from the patent literature is a method of testing products of an open configuration for strength, which consists in forming a closed cavity by attaching to the test product a structural element that closes this previously leaky cavity, with the organization of the input and output of the working fluid into the resulting closed cavity, provide the load on the test product in the form of a differential pressure by pumping the working fluid from the formed inner closed cavity using a vacuum pumping system and the result The tests are judged on the compliance of the test product with the necessary technical conditions (see, for example, description to the author's certificate. USSR No. 1840411, MKI G01M 3/08, 1990)

The disadvantage of these known methods is that they do not use a predetermined schedule or program for changing the load on the test object, affecting the product during its operation, which does not give a complete picture of the conformity of the tested product to the specified technical conditions, ensuring its reliability during operation.

The objective of the invention is to provide a method for testing products of open configuration for strength and / or bearing capacity with the achievement of a technical result in the form of verification or testing with a given schedule or program to change the load on the test object, as close as possible to that which the product is subjected to during actual operation , as well as expanding the arsenal of technical means while ensuring the normal operation of products of this type.

This problem is solved in such a way that in the method of testing products of an open configuration for strength, which consists in the fact that they form a closed cavity by connecting to the test product a structural element that closes this previously open cavity, provide a load on the test product in the form of a differential pressure by pumping the working fluid out of the formed closed cavity with the help of a vacuum pumping system and the test result judges the compliance of the test product with the necessary technical characteristics. In accordance with the invention, vacuum pumping is carried out both taking into account the function of changing the leakage of the test object, and taking into account the function of changing gas evolution from the walls of the object by means of programmed control of the flow rate of the pumped working fluid.

Further, the invention is explained in more detail using graphic materials.

Figure 1 shows the device and hardware used in the implementation of the claimed method.

Figure 2 shows a graph of the load on the test product during its operation.

The device or hardware (figure 1) used to implement the claimed method, contains the following elements:

rigging or bench equipment 1 on which the test item 2 (test object) is installed, a structural element that closes the test product, for example, in our case, this structural element is a cover 3 that covers the open part of the test product, in our case, the nose cone 2 of the rocket -carrier. Cover 3 (either first one or already assembled with a fairing 2 form) is installed on snap 1.

To the assembly is a nose fairing 2 and a cover 3 having a closed (not necessarily completely tight) cavity, a pipeline 4 of the evacuation vacuum system is connected. Inductors 5, 6, 7 are mounted on the pipeline 4, which allows changing the characteristics of the pumping vacuum system, in particular, productivity.

The number of chokes depends on the test program adopted,

The method is implemented as follows.

Having formed a closed cavity on the test bench, the pipeline of the pumping vacuum system with a group of chokes is connected to the input-output. Then, vacuum pumping is performed, taking into account the function of changing the leakage of the test object (nose fairing), and taking into account the function of changing the gas evolution of the walls of the test object (walls of the head fairing) by means of programmed control of the flow rate of the pumped working fluid (air). The main task in this case is to reproduce the graph (function) of the force impact (differential pressure) acting during the operation of the product.

Consider a graph of the change in the load of the following form (figure 2).

To solve the problem of reproducing this dependence, it is necessary to constantly solve the problem of joint performance of the following functions:

- a given schedule of load changes;

- changes in the process of pumping leakage of an object with a snap;

- if there is a gas evolution of the object - accounting for the changing gas evolution of the object;

- characteristics of the pumping system.

For simplicity, we consider an object in which gas evolution is absent.

To implement the given load (differential) law, we consider two functions:

- the function of the pumping system;

- leakage function.

The change in pressure inside the fairing obeys the following dependence:

where So is the main characteristic of the pumping system, which remains constant over a fairly wide pressure range;

P is the pressure inside the cowl that changes during pumping (pressure drops).

Thus, the So Pdt characteristic will be falling if its parameters are not artificially changed.

Q _Σ is the leakage rate of the object (fairing), which increases over time due to the fact that the difference between the external environment and inside the fairing increases, since the pressure inside the fairing drops during pumping.

V is the volume of the pumped cavity.

Thus, it is possible to influence the shape of the graph of the change in the given load by changing the So Pdt complex and, in particular, changing So by changing the conductivity of the pumping system by blocking the chokes 5, 6, 7.

The accuracy of the reproduction of the load function (see Fig. 2) will depend on the characteristics of the pumping system, the leakage of the object, the accuracy requirements for reproducing the given load function, as well as on the number of chokes 5, 6, 7, etc. pumping systems and schedules for their shutdown.

In the process of reproducing the load (differential pressure), the stability and strength of the test object are evaluated, in particular, according to load cells and displacement sensors, both in real time and according to the results of analysis and external inspection of the product (fairing) after the tests.

The test is considered successful if the fairing has retained its integrity and bearing capacity.

Claims (1)

A method for testing products of open configuration for strength, which consists in forming a closed cavity by attaching to the test product a structural element that closes this previously open cavity, with the organization of the input-output of the working fluid in the resulting closed cavity, provide a load on the test product in the form differential pressure by pumping the working fluid from the formed inner closed cavity using a vacuum pumping system and according to the test result judge compliance with the test of the product with the necessary technical conditions, characterized in that the vacuum pumping is carried out both taking into account the function of changing the leakage of the test object, and taking into account the function of changing the gas evolution from the walls of the object by means of programmed control of the flow rate of the pumped working fluid.

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