RU2493538C1 - Method to test fragmentation ammunition with axisymmetric field of fragment emission and bench for its realisation - Google Patents

Abstract

FIELD: weapons and ammunition.

SUBSTANCE: method includes blasting of ammunition installed into the specified position in the centre of a profiled target wall marked into zones corresponding to directions of fragment emission in the accepted system of coordinates, registration of hits, capturing and count of fragments getting into each area, measurement of dimensions and area of holes. Evaluation of qualitative and quantitative characteristics of the fragmentation field by weights, speeds, shape and size of fragments is realised by means of registration, recording and further processing of signals from electret sensors placed in appropriate zones of the target wall and equal to them in dimensions. The bench for realisation of the method comprises a profiled target wall made as capable of adjustment of curve radius. The wall lining is made in the form of a set of electret sensors, separately electrically connected with a computerised system of registration and recording. Sensor electrodes are made from mechanically fine-dispersed metal particles.

EFFECT: increased accuracy of measurements.

10 cl, 15 dwg

Description

The invention relates to methods for testing fragmentation munitions of natural and predetermined crushing with axisymmetric fields.

To assess the effectiveness of the fragmentation of ammunition for various purposes, it is necessary to know the distribution by the number of fragments, their masses and initial velocities in a given target destruction space.

A known method of testing ammunition by detonating in a shield target environment, made in the form of a semi-cylindrical vertical target wall, sheathed with sheet material (plywood, cardboard, ruberoid), when penetrated by a fragment of a hole with a clear outline / 1 /. On the inner surface of the skin, the projection contours of a part of the sphere bounded by two meridian sections with an angle Δθ between them, as well as the boundary lines of the angular sectors with a step Δφ are plotted. Explosive ammunition is installed in the center of the half-cylinder in a horizontal position, on a rack with a height equal to half the height of the wall, and the axis of the projectile coincides with a straight line connecting the vertical ends of the wall. After blasting, holes in each lining sector are visually counted, sizes and areas of holes are measured, they are recalculated to the mass of the fragment and, thus, the distribution of the fragments by scattering angles is determined.

The main disadvantage of this method is its low accuracy in determining the mass of a fragment by the area of the hole, the impossibility of separating the fields formed by various striking elements of fragmentation munitions having several types of shells, the inability to fix the moment of impact of the fragment on the skin due to the absence of a light flash at the time of impact, which makes it difficult to measure the time between explosion and collision of a fragment with a skin, and, consequently, the determination of its speed. In addition, it is also possible that the results of the test evaluation are distorted due to splinters ricocheting from the soil entering the lining of the semicylindrical wall.

Closest to the proposed invention in technical essence and the achieved result is a method for testing fragmentation ammunition with a circular field for the expansion of fragments and a stand for its implementation / 2 /, including detonation of the ammunition in a horizontal position in the center of a vertical semi-cylindrical target wall, marked into zones corresponding to the corner zones the expansion of fragments in the equatorial and meridional planes, counting the number of fragments feeding into each zone, measuring the size and area of holes, different t m, which catch debris catcher arranged on the wall are extracted from the catcher ingress latching place and sorted within each angular zone of massive groups.

The test bench for fragmentation munition designed to implement the specified method, contains a vertical target wall made in the form of a half cylinder and sheathed with metal sheet material with zones deposited on it, corresponding to the angular zones of the expansion of fragments in the equatorial and meridian planes, a trap placed between the casing and the wall, a rack located in the center of the half-cylinder, for installation on it in a horizontal position of ammunition along the line connecting the midpoints of the ends of the half-cylinder and, as well as the electrical system and undermining the registration and no-rebound semi-cylindrical wall.

In addition, the description of the prototype method provides for sheet sheathing of individual panels corresponding to the trap cells, and the panels can be made up of two parts, isolated from each other and electrically connected to the undermining and registration system. Parts of the panel form some capacity With _about . When a group of fragments enters the near zone of the panels, the capacitance changes, which is recorded by a recording device.

There is also a method of metrological detection of shells or fragments in the target area / 3 /, which provides for the placement on the target wall of flat capacitors made in the classical design - two layers of metal (aluminum) foil separated by a film or paper insulator. Registration of the destruction of the target and speed characteristics of the fragment is carried out by measuring the short circuit current between the two capacitor plates.

The above method of testing fragmentation ammunition / 2 /, selected as the prototype method, is not without some drawbacks:

- the implementation of the method requires a lot of labor;

- performing many operations that require the presence of a human factor - such as measuring the size and area of holes, counting and sorting the number of fragments that fall into each zone of the target shield, entails a greater likelihood of measurement errors;

- the execution of the target shield in the form of a semi-cylindrical wall does not always correspond to the front of the expansion of fragments in a given space of destruction of the target, especially when the horizontal axis of the munition axis described in the prototype.

In the description of the stand for implementing the method / 2 / there are references to the use of capacitor sensors for detecting damage to the target wall, however, their specific design shown in the illustration has an extremely low capacity, which will require extremely sensitive measuring means to ensure operability and allowance for the useful signal, in turn in need of enhanced protection against interference from uncontrolled external electromagnetic fields. In addition, the capacitance of such a capacitor system will vary greatly depending on external atmospheric conditions - temperature, humidity and dustiness of the surrounding air, as well as the possible presence of biogenic factors, such as insects, in the sensor’s area.

The disadvantage of the sensor for registering fragments by the method / 3 / is its actual disposability. The capacitor of the proposed design when the plates are closed by a passing fragment is completely discharged, and thus will be unsuitable for further work. It will take time to recharge, during which at least one more fragment can get into the sensor, which will not be properly registered. Finally, due to the small thickness of the proposed capacitor sensor and the execution of the foil plates, by definition a plastic material, there is a high probability of the plates closing when they are plastic drawn in contact with the penetrating body. In this case, recharging the capacitor is not possible.

The technical task of the invention is to reduce labor costs while improving the accuracy of measurements in order to create automated systems for collecting and processing information about fragmentation damage fields of the tested ammunition.

The solution to the problem is achieved by the fact that in the known method for testing fragmentation munitions with an axisymmetric expansion field for fragments, including detonating an ammunition installed in a predetermined position in the center of a profiled target wall, marked out into zones corresponding to the directions of expansion of fragments in the adopted coordinate system, recording hits, collecting and counting the number of fragments falling into each zone, measuring the size and area of holes, in accordance with the invention, an assessment of the qualitative and quantitative characteristics The stick of the fragmentation field in terms of mass, speed, shape and size of the fragments is carried out by recording, recording and subsequent processing of signals from electret sensors located in the corresponding zones of the target wall and equal in size to them.

The implementation of the proposed method, in turn, is achieved by the fact that in the known test bench for fragmentation munitions with an axisymmetric field for the expansion of fragments, containing a profiled target wall sheathed with sheet material with zones deposited on it, corresponding to the directions for the expansion of fragments in the adopted coordinate system, in accordance with the invention, the target wall is made with the possibility of adjusting the radius of curvature, and its sheathing is made in the form of a set of electret sensors, individually electrically connected associated with a computerized recording and recording system, while the sensor electrodes are made of mechanically loosely coupled finely divided metal particles.

The most important requirement for automating the collection and processing of information about fragmentation lesions of the tested ammunition is the presence of the corresponding characteristics of the primary transducer-impact sensor that generates an electrical signal when interacting with a moving striking element (PE).

The collision sensor should have a number of specific features: have an unambiguous relationship between the useful signal and the characteristics of the PE (speed, size), sufficient noise immunity, remain operational after being exposed to several PEs, etc.

The above features have an electret sensor, which is a flat capacitor whose dielectric is a pre-charged electret. The capacitor plates are connected through the load resistance R. In order to increase the noise immunity, the front, relative to the missile PE, the sensor plate is grounded.

When the PE interacts with the sensor, the electret is depolarized in the affected area of the target wall, as a result of which a current pulse flows through the load resistance, which is detected by the corresponding recording devices. Because the electret is depolarized (discharged) locally; the sensor maintains its operability for recording subsequent PEs entering it.

The implementation of the target wall with the ability to adjust the radius of curvature will allow you to more accurately set its configuration in accordance with the projected front of the expansion of the PE munition in a given target destruction space, which will lead to a more accurate assessment of the fragmentation field characteristics.

The target wall can be made in the form of a lattice frame structure, with lattice elements in the form of a set of closed convex geometric shapes - triangles, rectangles, etc., equipped with articulated elements in the corner coupling nodes, which enable rotation about two mutually perpendicular axes.

Also, the target wall can be made in the form of a grid of their flexible rod materials, while wall profiling along the given radii is carried out by bending the grid rods in the required places.

Another embodiment of the target wall may be a prefabricated structure of forming a lattice of tubular elements connected by crosses of flexible material.

The experiments showed that vinyl plastic is a quite acceptable electret characteristic - a fairly widespread and cheap thermoplastic polymer material. Therefore, the electret base of the sensor can be made of vinyl plastic.

In view of, by definition, the small thickness of the electret sensor and the good technological properties of thermoplastics, in the manufacturing process it can be profiled in the form of a surface with given radii of curvature in a given coordinate system.

The performance of the sensor electrodes made of mechanically weakly bound finely divided metal particles will provide a thin locally brittle coating, which, unlike the foil, can hardly stretch during interaction with PE and create electrical contact with the penetrating body.

In particular, the sensor electrodes can be applied to the electret substrate using galvanic methods, for example, electrochemical plating.

Also, thin metallized polymer films glued onto an electret substrate can be used for electrodes.

The invention is illustrated by the following graphic information.

Figure 1 shows a diagram of experiments to determine the characteristics of the electret sensor.

Figure 2 presents typical waveforms of signals from an electret sensor when it is punched with a steel ball.

Figure 3 shows the dependence of the maximum amplitude of the signal on the speed of PE.

Figure 4 - dependence of the specific charge (referred to the unit area of the sensor) on the speed of PE for various diameters of the balls.

Figure 5 - dependence of the signal duration on the speed of PE.

In Fig.6, 7 - the shape and geometric dimensions of model PE.

On Fig, 9 - waveforms of electrical signals from the sensor when shooting by a cone and a stepped cylinder, respectively.

Figure 10 is a graph of the relationship of the amplitude of the signal to the diameter of the PE on the speed of the meeting with the sensor.

11 is a diagram for determining the response of a sensor to a cumulative jet.

On Fig - waveform of the signal from the cumulative jet.

On Fig-15 diagrams of embodiments of the supporting metal structure of the target wall.

A set of experimental studies was carried out to determine the characteristics and confirm the operability of the sensor. The experimental design is shown in FIG. The value of the maximum amplitude of the signal and its duration at various PE velocities, the value of the specific charge per unit area for various PE velocities were determined.

In the course of the experiment, sensor 2, which served as a target, was punched by steel balls with a diameter of 4, 6, and 8 mm, thrown from a powder gun with a caliber of 15.2 mm. The throwing of PE into each sensor was carried out until it was completely destroyed. The signal amplitude remained almost constant for balls of the same diameter, which had the same speed, with a distance of 1 ... 2 mm between the edges of adjacent holes.

The speed of the PE meeting the target and the trigger synchronization of the oscilloscope were measured by the photoelectric velocity measurement system and trigger synchronization 1.

The determination of the maximum amplitude of the signal and the magnitude of the charge released into the load (from the output of the integrator 3) was carried out by two pulse voltmeters 4 of type B4-17. The waveform was controlled by a double-beam oscilloscope 5 type OK-33.

Typical waveforms of the signals from the electret sensor when breaking through it with a steel ball are presented in figure 2. The orientation of the electret is such that the direction of the polarization vector is opposite to the direction of motion of the PE. In this case, the signal has a positive polarity. When measuring the orientation of the electret, the polarity of the signal is reversed, and the amplitude remains unchanged.

The experimental dependence of the maximum amplitude of the signal on the speed of PE is shown in Fig.3. The graph shows that at speeds above 0.3 km / s the signal amplitude exceeds 0.1 V, and is sufficient for reliable registration. The magnitude of the signal depends on the size of the PE. The larger the diameter of the ball, the greater the signal (the lower curve is the diameter of the ball 4 mm, the middle - 6 mm, the upper - 8 mm).

The experimental dependence of the specific charge (referred to the unit area of the sensor) on the PE velocity for various ball diameters (ball diameter: + - 4 mm; ♦ - 6 mm; ▲ - 8 mm), presented in Fig. 4, shows that at speeds higher 0.8 km / s the magnitude of the specific charge depends little on the speed of collision. This indicates an almost complete depolarization of the electret in the affected area during interaction with PE. The observed slight excess of the specific charge for balls with a diameter of 4 mm compared to balls with a diameter of 6 and 8 mm can be explained by the fact that the size of the depolarization region slightly exceeds the size of the ball. This relative charge increase plays a role for a ball with a diameter of 4 mm, but is not significant for balls with a diameter of 6 and 8 mm.

Thus, the size of the emitted charge with a sufficient degree of accuracy can be determined by the size of the cross section of PE.

The interaction time between the PE and the target was calculated by the dependence

$$\tau \approx \frac{R+\delta }{W}$$

where R is the radius of the ball;

δ is the thickness of the sensor;

W is the speed of PE.

As can be seen from the graph of Fig. 5, the calculated value of τ in the speed range above 0.4 km / s agrees quite well with the experimental data (the dashed lines show theoretical curves for balls of different diameters: lower - 4 mm, middle - 6 mm, upper - 8 mm). This allows us to determine the time of interaction of the PE with the obstacle from the signal duration and to associate this time with the dimensions of the real PE.

To study the dependence of the electric signal of the sensors on the geometric characteristics of PE, they were shot through by cone-shaped bodies, as well as by cylinders with stepwise changes in diameter. These elements well imitate PE of unintended crushing, from the point of view of the possibility of their shorting the sensor electrodes at the time of penetration. The shape, geometric dimensions of the bodies are shown in Fig.6 and 7.

Oscillograms of electrical signals from the sensor when shooting by a cone and a stepped cylinder, respectively, shown in Figs. 8 and 9 confirm the absence of shorting of the electrodes.

The waveform assumes that the sensor allows you to determine the instantaneous speed of bodies having a stepwise change in cross-sectional area in the direction of movement (for example, the speed of shells having a shell).

From the experiments it follows that the signal from the sensor is functionally related to the size, shape and speed of the PE, which will allow, when determining the characteristics of the fragmentation field of destruction of real ammunition, to exclude, if necessary, signals from inefficient fragments (low speed and mass) from consideration.

It was also found that a punched sensor remains operational, except, of course, when PE enters an existing hole.

Along with the above, studies of electret sensors were carried out to analyze the signals received during collision with a sensor of hypersonic PE. The experiments were carried out in a wide range of speeds. Spherical steel PEs with a diameter of 9.6 and 13.6 mm were thrown by a powder gun in the speed range from 0.5 to 1.8 km / s and a two-stage light-gas gun in the speed range from 2.0 to 3.5 km / s. The speed of PE was measured using non-contact induction sensors, while braking of PE in air was taken into account. The electrical signals generated by the sensor were applied to a S8-13 oscilloscope having an input impedance of 50 Ohms through a matched cable line.

From the graph presented in figure 10, it can be seen that the amplitude of the signal, referred to the diameter of the PE, grows with speed, and for an approximate estimate, we can take the growth linear.

Based on the analysis of experimental data, as well as from solving the problem of the electrical response of the electret sensor at an arbitrary active load, it was concluded that the released specific charge at a speed of encounter of a spherical PE with a sensor over 1.5 km / s is about 0.25 ÷ 0, 30 μC / cm ² and is practically independent of speed, i.e. in this case, complete instantaneous depolarization of the electret in the collision zone occurs. In the speed range of PE up to 3.4 km / s, there are no signs of the influence of the conductivity of the sensor material on the electrical response. The indicated conclusion can be adopted for an approximate assessment of the behavior of the sensor at hypersonic speeds of PE.

To assess the operability of the sensor at higher PE speeds, a cumulative charge was used, which ensured the head fragment velocity of the jet 6.5 ... 7.5 km / s, with the measurement circuit shown in Fig. 11.

An oscillogram of a signal with a sweep length of 100 μs from the cumulative jet (Fig. 12) shows a voltage pulse of positive polarity with an amplitude of 4.8 V, as well as subsequent voltage peaks obtained from other fragments of the jet.

The experiments confirmed the operability of the sensor when exposed to PE at speeds of up to 7.5 km / s. No sensor short circuits in the indicated range of PE velocities characteristic of the warheads of ammunition with a circular expansion field of hypersonic PE were found.

The dependence of the area of the hole on the characteristics of the barrier and PE, has the form:

$$\frac{SPP}{So}-\mathrm{one}=A{\left(\frac{h}{\sqrt{S_0}}\right)}^n\left(V-\mathrm{one}\right)$$

where A is a coefficient taking into account the characteristics of the barrier;

V is the speed at which a PE encounters an obstacle, km / s;

h is the thickness of the barrier, cm;

S _o - the mid-sectional area of PE, cm ² ;

S _ex - area of the hole, in clearance, cm ² .

From the given dependence it follows that the area of the hole is proportional to the value (V-1), and therefore, the charge emitted by the sensor, which in turn is proportional to the area of the hole (or collision with PE), will also increase in the case of complete depolarization in the collision area.

In the case of conventional warheads of ammunition with ready-made PEs, as a rule, the areas of holes from normal PEs are close to each other, so the release of approximately the same charges should be expected. Then, when using an analog-digital multilevel system for recording signals, it is possible to judge the number of normal PEs by the amount of charges allocated by the sensor.

As shown by numerous experiments, the most adequate results of the sensor, allowing to establish reliable correlation dependences of the signal on the characteristics of the PE, are obtained in the case of normal (or close to it) collision of the PE with an obstacle.

On Fig schematically presents a fragment of the target wall, with the possibility of adjusting the radius of curvature in two mutually perpendicular planes, which will allow you to more accurately set its configuration in accordance with the predicted expansion front of the PE munition in a given target destruction space. The wall is shown in the form of a lattice frame structure, with lattice elements in the form of a set of rectangles 6, equipped at the corner mating nodes with hinged elements 7, which enable rotation about two mutually perpendicular axes. Due to the presence of articulated elements, the wall can be set to the corresponding radii of curvature, - in the vertical plane Rв, in the horizontal - Rг. Moreover, depending on the predicted front of the PE expansion, these radii can be set as functions of the corresponding coordinates, for example, the height for Rв and the distance from the tested ammunition for Rг. Thus, the wall will have the form of a concave spatial surface; when sensors are placed on it, PEs will interact with them on trajectories as close to normal as possible at the point of injury, which will increase the accuracy of the results.

14 schematically shows an example of the target wall in the form of a grid of their flexible rods 8, with nodes 9. The wall profiling carried out by bending the rods of the grid is shown with the current values of the bending radii in the respective planes - Rg _t and RB _T , set functionally or pattern.

15 illustrates another possible assembly of the target wall. Here, the lattice is recruited from tubular elements 10 connected by crosses of flexible material 11. The required radius of the spatial profile of the wall is set by bending the bars of the cross relative to the corresponding axes.

The proposed method for testing fragmentation ordnance with an axisymmetric field for fragmentation of fragments and a bench for its implementation using an analog-digital multi-level system for recording signals from electret sensors will accelerate, as statistics are being collected, the creation of automated systems for collecting and processing information about fragmentation damage fields. Such systems will have a number of obvious advantages over the current testing methodology, based on high-speed filming and many "non-instrument" measurements.

Information sources

1. Aircraft ammunition. Ed. V.A. Kuznetsova, Moscow: Publishing House. VVIA them. Zhukovsky, 1968, p. 303.

2. RF patent No. 2131583, F42B 35/00, 1996, Test method for fragmentation munitions with a circular field for the expansion of fragments and a stand for its implementation.

3. German patent No. 3702428, F42B 35/00, 1987, Verfahren und Vorrichtung zum meβtechnischen Erfassen eines Projektils oder Teilen hiervon.

Claims (10)

1. A method of testing fragmentation munitions with an axisymmetric field of fragmentation of the fragments, comprising detonating the munition set to a predetermined position in the center of the profiled target wall, marked into zones corresponding to the directions of the expansion of fragments in the adopted coordinate system, recording hits, trapping and counting the number of fragments that fall into each zone, measuring the size and area of holes, characterized in that the assessment of the qualitative and quantitative characteristics of the fragmentation field by mass, speed, shape and size The fragments of fragments are carried out by recording, recording and subsequent processing of signals from electret sensors placed in the corresponding zones of the target wall and equal in size to them. 2. A test bench for fragmentation munitions with an axisymmetric field for the expansion of fragments, containing a profiled target wall sheathed with sheet material with the zones deposited on it, corresponding to the directions for the expansion of fragments in the adopted coordinate system, characterized in that the target wall is configured to adjust the radius of curvature, and its skin is made in the form of a set of electret sensors, individually electrically connected to a computerized recording and recording system, while the sensor electrodes olneny from mechanically weakly fine metal particles. 3. The stand according to claim 2, characterized in that the target wall is made in the form of a lattice frame structure with lattice elements in the form of a set of closed convex geometric figures equipped with articulated elements at the corner coupling nodes that enable rotation about two mutually perpendicular axes. 4. The stand according to claim 2, characterized in that the target wall is made in the form of a grid of flexible rod materials, while the profiling of the wall along the given radii is carried out by bending the grid rods in the necessary places. 5. The stand according to claim 2, characterized in that the target wall is made in the form of a prefabricated structure of tubular elements forming a lattice connected by means of cross pieces made of flexible material. 6. The stand according to claim 2, characterized in that the electret base of the sensor is made of thermoplastic polymer material. 7. The stand according to claim 2, characterized in that the electret base of the sensor is made of vinyl plastic. 8. The stand according to claim 2, characterized in that the electret sensor is profiled in the form of a plate with predetermined radii of curvature in the adopted coordinate system of the wall marking. 9. The stand according to claim 2, characterized in that the sensor electrodes are made by applying a layer of metal particles to the electret substrate using galvanic methods, for example, electrochemical copper plating. 10. The stand according to claim 2, characterized in that the sensor electrodes are made of thin metallized polymer films glued to an electret substrate.

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