RU2338169C1 - Method for high-intensity impact tests for instruments and equipment - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: high-intensity impact effect test method for instruments and equipment by impact spectre method involves impact load of test object by pyrotechnical devices with given impact acceleration spectres, and acceleration registration in control points. Tests are performed in series in the same test object setting: first impact and vibration load modes are formed separately by dividing frequency band into two areas. Vibration test mode is formed in low frequency area to sustain given impact spectre, while pyrotechnical devices form impact test mode in high-frequency spectre band. Then required vibration loading sources and pyrotechnic devices, test series of vibration and impact effect are performed, acceleration measurement results at which impact acceleration spectres are obtained in the same control points are used to combine obtained impact spectres. If obtained impact spectres differ from given impact acceleration specters, relevant vibration and impact load modes are corrected by changing frequency bands and sources of vibration and impact load.

EFFECT: enhanced accuracy of impact effect measurement.

5 dwg

Description

This invention relates to shock impact testing methods and can be used in tests for high-intensity shock impacts of various technical systems consisting of various, functionally connected devices, autonomous testing of each of which is insufficient (for example, functional relationships between the instruments remain unexplored during impacts )

Currently, the most widely used methods of testing the impact spectrum of accelerations, when the effect itself is not important, but the reaction that this effect causes in the construction is important (book 2, “Testing technique”, book 1. - M., Mechanical Engineering, 1982, pg. 334-335).

There are quite a lot of shock testing methods: the impact is set by the simplest form of a shock pulse and is realized using vibrating electrodynamic stands, stands with falling tables. Such tests make it possible to create well shock spectra of accelerations only in a narrow zone of the low-frequency spectrum. The best results when tested in the frequency range above 1 kHz can be obtained if pyrotechnic devices are used as a source of impact, for example, RF patents No. 2085889, No. 2171974.

The closest is the test method according to the patent of Russian Federation No. 2262679. The method of impact tests of high intensity instruments and equipment by the method of impact spectra, which consists in the impact loading of extended systems with pyrotechnic devices with a predetermined impact acceleration spectrum - adopted as a prototype.

The disadvantages of this method include the great difficulty in creating the necessary shock spectrum of accelerations in the low-frequency region (frequency range up to 500 Hz). To create an impact, a pyrotechnic device is used, the impact spectrum of the accelerations of which should overlap the required one, which allows creating an impact not only in a small area around the point of application of the impact, but also at a certain distance from it. At the same time, it is quite difficult to provide the necessary (predetermined) shock spectrum of accelerations in the entire frequency range (the response time, for example, of an 8X54 bolt, is about 0.2 ms and consists of two peaks with a duration of ~ 0.1 ms). Therefore, the low-frequency region of the shock spectrum of accelerations must be "covered" in some other way.

It is also not possible to use vibration stands, because their control system (even the most modern vibration stands) does not allow creating a combined signal in the form of a sum of signals with a small amplitude of 20-30 g, a duration of 5-10 ms and an amplitude of 5-10 thousand g and a duration of 0.1-0.2 ms to obtain the necessary shock spectrum of accelerations.

The task to be solved by the claimed invention is directed is the elimination of these drawbacks, which will allow higher quality impact testing of high intensity impacts. The solution to this problem is achieved by the fact that the tests are carried out sequentially with the same installation of the test object: first, shock and vibration loading modes are separately formed, dividing the frequency range into two sections, in the low-frequency region of which the vibration test mode is formed to ensure a predetermined shock spectrum, and in the high-frequency region of the spectrum, the shock test mode is formed by pyrotechnic devices. Then select the necessary sources of vibration loading and pyrotechnic devices, conduct sequential tests for vibration and shock effects, according to the results of measurements of accelerations at which they obtain shock spectra of accelerations at the same control points, combine the obtained shock spectra and if the received shock spectra differ from the predetermined ones shock acceleration spectra specify the necessary modes of vibration and shock loading, changing the frequency ranges, sources of vibration and shock loading, repeat the test stage, after which the pyrotechnic devices are activated during vibration loading of the test object, shock acceleration spectra are obtained at the above control points, compared with the predetermined shock acceleration spectra, and when the received and specified shock acceleration spectra differ by a large than the test error, specify the necessary loading modes according to the above procedure, and the test procedure is continued until the received blow matches acceleration spectra with predetermined ones.

The essence of the decision can be explained as follows. Let us consider the formation of shock acceleration spectra by the example of testing the apparatus and equipment of a spacecraft (SC) in the event of separation of the upper stage (SC) from the SC from the launch vehicle (LV). When the shock effect is created by the same physical nature of the device as during operation, the quality of equipment development improves. When impact loading using pyrotechnic devices, this condition is met. Such effects close the components represented in the necessary impact spectrum of accelerations by impacts from the pyrotechnic devices of the RB / LV separation system, but at this moment the low-frequency components from the launch vehicle also act: separation of sufficiently large masses of the RB and the last stage of the LV. This is a transient process associated with low-frequency damped oscillations at frequencies below 100 Hz. Thus, we will divide the general frequency range in which the required acceleration shock spectrum of accelerations (USE) is set into two parts and close the low-frequency part with vibration tests, and the high-frequency part of the spectrum with pyrotechnic devices. The partitioning of the frequency range should be carried out, first of all, based on the physics of real spacecraft loading. The procedure for generating vibration test modes can be performed, for example, according to the patent of the Russian Federation No. 2234690, and shock - according to the patent of the Russian Federation No. 2262679. Since the control system is a nonlinear function, the summation of the control system, as well as the selection of the necessary tools and loading modes are not a trivial procedure. But these procedures relate to the "know-how" of the invention and are not considered in this application. You can only notice that the effects determined by any methodology should overlap the amplitude-frequency ranges of the USU intended for them. In addition, in the zone of overlapping frequencies, a significant increase in the impact is possible, and therefore the process of the formation of vibration and shock modes is iterative. Undermining the pyrotechnic devices is carried out during vibration loading, since the attenuation time of the pyrotechnic shock is 1-2 ms, and the maximum vibration lasts only a few seconds, even for a damping transient. At the same time, there are no technical problems preventing the blasting of the pyrotechnic device with an accuracy of less than 1 ms.

The essence of the claimed solution is illustrated by drawings, in which Fig. 1 shows a diagram for simultaneously conducting shock and vibration tests, in Fig. 2 is a horizontal section A-A, in Fig. 3 is a vertical section B-B, in Fig. 4 are shock spectra accelerations: the required shock spectrum, from pyrotechnic devices and from vibration effects, and in Fig.5 - graphs of the required shock spectrum and shock spectra at the control point under joint loading by shock and vibration effects.

The test bench consists of a conical shell 1, a flange 2 for attaching the test object, a honeycomb panel 3 with equipment blocks 4 (test object) of control sensors 5, flexible cables for weightless test object 6, an adapter 7 for attaching damping rods to flange 2, shock absorbing rods with a pyrodevice for creating shock effects 8, a flange 9 for attaching a vibration stand 10, a threaded hole 11 with a bolt 12, and also a profiled groove 13, the curvature of which coincides with the curvature of the flange 2.

The honeycomb panel 3 with devices 4 is attached to the flange 2 of the conical shell without interfering with the docking of the damping rods 8 with the bursting bolts. Another flange 9 of the conical shell 1 easily allows you to attach a vibration stand 10. Existing vibration stands, as a rule, allow rotations of 90-180 degrees relative to the attachment points, which allows testing in three mutually perpendicular directions.

The implementation of the test method is carried out as follows.

Let it be necessary to create, on the honeycomb panel 3 with devices 4, the control unit shown in Fig. 4, graph 1. After the test circuit shown in Fig. 1 is assembled, the vibrostand 10 is turned on and when it reaches a predetermined mode, the test object is loaded in the low-frequency region (figure 4, graph 3 - USU from the vibration stand.). At this moment, the pyrotechnic devices are blown up and the high-frequency region of the required shock spectrum of accelerations is loaded (Fig. 4, graph 2 - USM from the pyrodevice). The necessary loading modes for pyrodevices and vibrostand are obtained in advance. As a result of such combined loading, it is possible to realize the required test mode (in Fig. 5, graph 1 is the required loading mode, 2 is the result of the combined effect).

Thus, the present invention allows for testing of shock loading in a wide amplitude-frequency range using standard equipment, which improves the quality of testing instruments and equipment and brings the test procedure closer to real processes during operation.

The procedure for selecting pyrotechnic devices, cushioning rods and vibration test modes relates to the "know-how" of the invention and is not considered in this application.

Practical example

Figure 1 (pos. 4) shows a repeater unit used on one of the spacecraft developed by NPO PM.

The qualification requirements for impact loads for this block in the form of a shock spectrum of accelerations (for each of three mutually perpendicular directions) are given in the table.

frequency Hz Amplitude of the shock spectrum of accelerations, g one hundred 25 1000 500 4000 500

Since the mass of the repeater unit together with the technological plate was more than 250 kg, the tests were carried out using pyrotechnic devices. The damping bolts were fitted with 8X54 explosive bolts. Each core consisted of layers of the following materials: textolite-textolite-aluminum-steel-aluminum-textolite-textolite. Fluoroplastic ring washers were installed between the layers. However, when selecting influences and conducting tests using pyrotechnic devices only, it was not possible to provide the required control system in the frequency range 150-600 Hz, therefore, the tests were carried out according to the scheme shown in Figs. 1-3. By vibration tests, it was necessary to close the range of 150-600 Hz.

A damping signal of the form

where δ = ln2 is the logarithmic decrement;

π = 3.14 ...;

τ = 2 ms;

ω is the circular frequency;

α is the attenuation coefficient;

t is time.

Such a signal is simply reproduced by modern control systems of vibration stands.

For vibration tests, the walls of the VEDS 10000 were used.

The operation of the bursting bolts was carried out approximately 2 ms after reaching the vibration stand mode. 6 ms after the detonation of the explosive bolts, the vibration stand was turned off.

Figure 4 shows the shock spectra of accelerations: the required shock spectrum - 1 (see table), from pyrotechnic devices - 2 and from vibration effects - 3.

In figure 5, the number 1 denotes the graphs of the required shock spectrum, and the number 2 denotes the obtained shock spectra at the control point. As can be seen from the drawing, the required USU was provided in the entire frequency range.

From the above practical example, it can be seen that the required impact tests were carried out using standard equipment with minimal manufacturing of new elements. The test design is simple and does not cause playback problems. In addition, as can be seen from the diagram (figure 1), the tests were carried out in three directions. In the example, only the vertical direction is considered. In other areas, when conducting tests according to the above methodology, the required control system was fulfilled.

Of the sources of information and patent materials known to the authors, the totality of features similar to the totality of features of the claimed objects is not known.

Claims (1)

The method of testing for high-impact impacts of instruments and equipment according to the method of shock spectra, which consists in shock loading the test object with pyrotechnic devices with predetermined shock spectra of accelerations, and recording accelerations at control points, characterized in that the tests are carried out sequentially with the same installation of the object test: at first, separately form shock and vibration loading modes, dividing the frequency range into two sections, in the low-frequency region In order to ensure a predetermined shock spectrum in advance, a vibration test mode is formed, and in the high-frequency region of the spectrum, the shock test mode is formed by pyrotechnic devices, then the necessary sources of vibration loading and pyrotechnic devices are selected, and the vibration and shock effects are tested sequentially, according to the results of acceleration measurements, in which receive shock acceleration spectra at the same control points, combine the obtained shock spectra and with excellent and the obtained shock spectra from the predetermined shock acceleration spectra, specify the necessary modes of vibration and shock loading, changing the frequency ranges, sources of vibration and shock loading, repeat the test phase, after which the pyrotechnic devices are triggered during vibration loading of the test object, shock acceleration spectra are obtained in the above control points are compared with the predetermined shock spectra of accelerations, and when the received and given shock are different acceleration spectra by an amount greater than the test error, specify the necessary loading modes according to the above procedure, and the test procedure is continued until the obtained shock acceleration spectra coincide with the predetermined ones.

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