RU2793603C1 - Method for static testing of ceramic fairings - Google Patents

Abstract

FIELD: ground testing of aircraft elements.

SUBSTANCE: invention relates to the technique of ground testing of aircraft elements, and in particular to the reproduction of thermal and power modes of the rocket warhead (fairing) in ground conditions. The method includes heating the surface of the fairing and applying a force load to it. In the process of force and thermal loading of the fairing, the deflection of the nose relative to its end is estimated using an intermediate elastic element made in the form of a thin rod. The upper end of the rod abuts against the inner nose of the fairing, and the lower end is rigidly connected to the strain gauge, registering mechanical deformation in the rod deflection plane. At the same time, the upper part of the strain gauge is equipped with a device for setting the measurement range of the deviation of the upper end of the rod.

EFFECT: possibility of controlling the deflection of the toe during static and heat-strength tests on full-scale fairings.

4 cl, 1 dwg

Description

The invention relates to the technique of ground testing of elements of aircraft (hereinafter referred to as LA), namely, to reproduce the thermal and power modes of the head part (fairing) of a rocket in ground conditions.

It is known that the weak point of the ceramic fairing is the adhesive joint of the metal frame with the ceramic shell.

During thermal tests, the ceramic shell can be destroyed from the force interaction with the metal frame due to the difference in the temperature coefficients of linear expansion (hereinafter referred to as TCLE) of the metal and ceramics. In addition, the fairing may be destroyed due to defects that may be formed during the production of the fairing. For example, with complete machining of the outer surface of the ceramic shell with a cutting tool (diamond wheels), the resulting longitudinal scratch with a glass cutter reduces its strength by almost two times. This increases the requirements for controlling the reaction of the fairing during thermal and force loading.

Known methods of static and thermal testing of ceramic rocket fairings, which make it possible to evaluate the strength of the fairing structure (RF patent No. 2571442, IPC G01N25/72, G01M9/04, publ. 12/20/2015; RF patent No. 2534362, IPC G01M9/04, publ. November 27, 2014; RF patent No. 2517790, IPC G01M9/04, G01N25/72 published on May 27, 2014).

The disadvantage of these methods is that the assessment of the strength of the fairing during the test is practically not carried out, therefore, the assessment is mainly carried out on a two-point system: collapsed during the reproduction of the test mode or not. This is due to the lack of reliable technical methods for assessing the reaction of the fairing structure during loading.

The closest in technical essence is the method of thermal testing of ceramic rocket fairings , which includes heating and applying a power load (RF patent No. 2637176, IPC G01N 3/18, publ. 11/30/2017).

The disadvantage, as with analogues, is the lack of technical means for assessing the response of the entire structure to thermal and force effects.

The technical result of the claimed invention is to control the deviation of the toe in the process of static and thermal tests on full-scale fairings

The specified technical result is achieved by the fact that a method for static testing of ceramic fairings is proposed, including heating the surface of the fairing and applying a force load to it, characterized in that in the process of force and thermal loading of the fairing, the deflection of the nose relative to its end is estimated using an intermediate elastic element made in in the form of a thin rod, the upper end of which abuts against the inner nose of the fairing, and the lower end is rigidly connected to the strain gauge, which registers mechanical deformation in the rod deflection plane, and the upper part of the strain gauge is equipped with a device for setting the deflection measurement range of the upper end of the rod.

The method is illustrated by the diagram shown in the figure.

In the diagram, the number 1 indicates the strain gauge, which is mounted in the plane of the end face of the fairing 5 on the crosspiece 3. An elastic rod 2 is mounted in the strain gauge 1, so that when the upper end of the rod abuts against the inner nose of the fairing 5, the lower end is rigidly connected to the strain gauge 1 by fasteners 4, so that the axis of symmetry of strain gauge element 1 coincides with the axis of the fairing under test 5 when the transverse force load on it is zero. In the figure, the number 6 indicates the metal frame and the adhesive connection 7 of the frame 6 with the shell of the fairing 5. When a force load is applied to the tested fairing 5, the place where the upper end of the rod 2 touches the wall of the fairing 5 moves. In this case, the signal D appears at the output of strain gauge 1,

proportional to the deviation of the upper end of the rod 2.

вытекает из системы зависимостей:In fact, the dependence of the signal level D at the output of strain gauge 1 on the deviation of the upper end of the elastic rod

follows from the dependency system:

,

- коэффициенты пропорциональности;

- величина силы, с которой стенка керамической оболочки в зоне носка давит на верхний конец упругой штанги 2.Where

,

- coefficients of proportionality;

- the magnitude of the force with which the wall of the ceramic shell in the toe area presses on the upper end of the elastic rod 2.

From (1) and (2) we find that the signal levelDat the outlet of the strain gauge is directly proportional to the deviation of the upper end of the elastic rod when it rests against the fairing wall near its toe (see Figure 1), i.e.

The results of studies on full-scale fairings for various purposes confirm the possibility of using the proposed method to control the deflection of the toe during static and thermal strength tests.

The method has been experimentally developed and is used to control the reaction of full-scale ceramic fairings in the process of ground static tests.

Claims (4)

1. A method for static testing of ceramic fairings, including heating the surface of the fairing and applying a force load to it, characterized in that in the process of force and thermal loading of the fairing, the deflection of the nose relative to its end is estimated using an intermediate elastic element made in the form of a thin rod, the upper end which rests against the inner nose of the fairing, and the lower end is rigidly connected to the strain gauge, which registers mechanical deformation in the plane of the deflection of the rod, and the upper part of the strain gauge is equipped with a device for setting the range for measuring the deviation of the upper end of the rod. 2. The method of static testing of ceramic fairings according to claim 1, characterized in that the strain gauge element can be equipped with a water or air cooling system. 3. The method of static testing of ceramic fairings according to claim 1, characterized in that the strain gauge element can be placed in a heat-insulating chamber. 4. The method of static testing of ceramic fairings according to claim 1, characterized in that the strain gauge can be equipped with a fiberglass housing to protect against mechanical damage.

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