CN113155335B - Two-stage type micro-flying piece impact stress testing device and testing method - Google Patents

Abstract

The invention discloses a two-stage micro-flyer impact stress test device and a test method. The two-stage micro-flyer impact stress test device includes a fixed base, an ignition device is installed on one side of the fixed base, and an ignition device is installed on the fixed base in sequence. There are excitation device, flyer target, front-stage piezoelectric sensing unit, acceleration chamber and rear-stage piezoelectric sensing unit, and a charge conversion unit is installed on one side of the fixed base, and both the front-stage piezoelectric sensing unit and the rear-stage piezoelectric sensing unit are Communicatively connected to the charge conversion unit. When the micro-flyer is perforated, the electric signal formed by the depolarization effect of the sensing layer of the front-stage piezoelectric film can be used to accurately obtain the equivalent area of the micro-flyer, which is convenient for evaluating the shape of the micro-flyer under the excitation of the transducer element At the same time, it is beneficial to accurately measure the impact stress of the micro-flyer; the equivalent conversion of the contact area of the micro-flyer by adding the front-stage piezoelectric film sensing layer will significantly increase the measurement accuracy of the subsequent piezoelectric film sensing layer.

Description

Two-stage microflyer impact stress testing device and testing method

Technical Field

The invention belongs to the field of explosion and impact testing, and in particular relates to a two-stage micro-flyer impact stress testing device and a testing method.

Background Art

Impact piece detonators do not contain sensitive explosives, and have the advantages of high safety, high reliability and anti-electromagnetic interference. They can be widely used in many fields such as intelligent weapons and civilian blasting. In the design and manufacturing process of impact piece detonators, measuring the impact stress obtained by the microfly sheet under the excitation of transducers such as electric explosion foil is one of the key parameters for evaluating its detonation performance. At present, the measurement of impact stress is mainly obtained by real-time acquisition of the charge output signal of the highly sensitive piezoelectric film under the accelerated impact of the microfly sheet. This method has the advantages of low testing cost and applicability to a variety of different measurement occasions. In the specific test, the magnitude of the impact stress is determined by the piezoelectric charge output and the impact area of the fly sheet. Obviously, the shape and size of the microfly sheet and the area of action when it impacts the piezoelectric film are the key to measuring stress. However, in actual measurement, since it is impossible to accurately determine the size of the microfly sheet generated by the electric explosion, the sensitive area of the piezoelectric film is often used as an equivalent substitute, resulting in a large error in the impact stress of the microfly sheet measured, which cannot meet actual needs.

Summary of the invention

The main purpose of the present invention is to provide a two-stage micro-flyer impact stress testing device and testing method, so as to overcome the problem of large error in the existing piezoelectric film micro-flyer impact stress testing.

In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a two-stage micro-flyer impact stress testing device is provided, comprising a fixed base, an ignition device is installed on one side of the fixed base, an excitation device, a flying chip target, a front-stage piezoelectric sensing unit, an acceleration chamber and a rear-stage piezoelectric sensing unit are sequentially installed on the fixed base, a charge conversion unit is installed on the other side of the fixed base, the front-stage piezoelectric sensing unit and the rear-stage piezoelectric sensing unit are both communicatively connected with the charge conversion unit, the charge conversion unit is communicatively connected with a charge amplification unit, a multi-channel data acquisition unit and a data information storage unit in sequence, and the charge signals from the front-stage piezoelectric sensing unit and the rear-stage piezoelectric sensing unit are stored in the data information storage unit.

In the above structure, the front-stage piezoelectric sensing unit has a front-stage piezoelectric film sensing layer, which is integrated on the back side of the flying chip target through multiple solution spin coating to form a whole with the flying chip target, and the front-stage piezoelectric film sensing layer is arranged parallel to the front end face of the acceleration chamber.

In the above structure, the front piezoelectric film sensing layer includes a front upper electrode layer, a front piezoelectric film layer and a front lower electrode layer integrated into one by a high-speed spin coating process, and the front upper electrode layer and the front lower electrode layer are both spin-coated with non-metallic conductive ink.

In the above structure, the rear-stage piezoelectric sensing unit has a rear-stage piezoelectric film sensing layer, and the rear-stage piezoelectric film sensing layer is arranged in parallel to the rear end surface of the acceleration chamber.

In the above structure, the rear-stage piezoelectric film sensing layer includes a rear-stage upper packaging layer, a rear-stage upper electrode layer, a rear-stage piezoelectric film layer, a rear-stage lower electrode layer and a rear-stage flexible substrate layer which are arranged in sequence, the rear-stage upper packaging layer and the rear-stage flexible substrate layer are both made of thin and flexible polymer film materials, the rear-stage upper electrode layer and the rear-stage lower electrode layer are both formed by sputtering metal with good conductivity, and the rear-stage piezoelectric film layer is made of flexible polymer piezoelectric film material.

In the above structure, the charge conversion unit includes an external capacitor and an external resistor. The charge conversion unit is connected to the front-stage piezoelectric film sensing layer using a front-stage cable. The charge conversion unit is connected to the rear-stage piezoelectric film sensing layer using a rear-stage cable. The resistance value of the external resistor is equal to the equivalent resistance of the front-stage cable, and the resistance value of the external resistor is equal to the equivalent resistance of the rear-stage cable.

In order to achieve the above object, according to another aspect of the present invention, a two-stage microflyer impact stress testing method comprises:

a. Start the ignition device;

b. Record the peak value V _1max of the charge signal output by the front-stage piezoelectric film sensing layer, and record the rise time t _s1 of the charge signal. According to the sensing characteristics of the piezoelectric film, the actual effective area A ₁ of the sheared microfly can be calculated, as follows:

Where _K1 is the polarization strength of the front-stage piezoelectric film sensing layer;

c. Record the peak value V _2max of another charge signal output by the subsequent piezoelectric film sensing layer, and record the rise time t _s2 of the charge signal;

The average velocity v of the microfly in the acceleration chamber can be calculated using formula (2);

The peak value P _max of the impact stress of the microfly can be calculated as follows:

Where, _K2 is the sensitivity coefficient of the subsequent piezoelectric film sensing layer; _K2 is dynamically calibrated by the Hopkinson bar pressure device;

Substituting equation (1) into equation (3), we can obtain the peak impact stress of the microfly:

Compared with the prior art, the present invention has the following beneficial effects:

1. When the microflyer is perforated, the electrical signal formed by the depolarization effect of the front-stage piezoelectric film sensing layer can accurately obtain the equivalent area of the microflyer, which is convenient for evaluating the morphology of the microflyer under the excitation of the transducer, and is also conducive to accurately measuring the impact stress of the microflyer;

2. Using the rise time difference obtained by the charge signal of the front-stage piezoelectric film sensing layer and the charge signal of the rear-stage piezoelectric film sensing layer, combined with the acceleration chamber size, the average speed of the micro-flyer in the acceleration chamber can be obtained while measuring the impact stress of the micro-flyer;

3. For the front-stage piezoelectric film sensing layer, using non-metallic conductive ink as the upper electrode layer and the lower electrode layer can greatly reduce the mechanical influence of the front-stage piezoelectric film sensing layer on the micro-flyer sheet during perforation.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

FIG1 is a schematic diagram of a two-stage microflyer impact stress testing device according to the present invention;

Figure 2 shows the structure of the front-stage piezoelectric film sensing layer;

Figure 3 shows the structure of the subsequent piezoelectric film sensing layer;

FIG4 is a schematic diagram of the structure of a charge conversion circuit;

FIG5 is a table of impact stress and charge surface density.

DETAILED DESCRIPTION

It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiment of the present application will be clearly and completely described below in combination with the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

As shown in Figures 1-4, a two-stage micro-flyer impact stress testing device includes a fixed base 1, an ignition device 2 is installed on one side of the fixed base 1, an excitation device 3, a flying chip target 4, a front-stage piezoelectric sensing unit 5, an acceleration chamber 6 and a rear-stage piezoelectric sensing unit 7 are installed on the fixed base 1 in sequence, and a charge conversion unit 8 is installed on the other side of the fixed base 1, the front-stage piezoelectric sensing unit 5 and the rear-stage piezoelectric sensing unit 7 are both communicatively connected to the charge conversion unit 8, and the charge conversion unit 8 is communicatively connected to a charge amplification unit 9, a multi-channel data acquisition unit 10 and a data information storage unit 11 in sequence, and the charge signals from the front-stage piezoelectric sensing unit 5 and the rear-stage piezoelectric sensing unit 7 are stored in the data information storage unit 11.

The front-stage piezoelectric sensing unit 5 has a front-stage piezoelectric thin film sensing layer, which is integrated on the back side of the flying chip target 4 through multiple solution spin coating to form a whole with the flying chip target 4, and the front-stage piezoelectric thin film sensing layer is arranged in parallel to the front end surface of the acceleration chamber 6.

The front-stage piezoelectric film sensing layer includes a front-stage upper electrode layer 501, a front-stage piezoelectric film layer 502 and a front-stage lower electrode layer 503 which are integrated into one by a high-speed spin coating process. The front-stage upper electrode layer 501 and the front-stage lower electrode layer 503 are both spin-coated with non-metallic conductive ink.

The rear-stage piezoelectric sensing unit 7 has a rear-stage piezoelectric film sensing layer, and the rear-stage piezoelectric film sensing layer is arranged in parallel to the rear end surface of the acceleration chamber 6 .

The rear-stage piezoelectric film sensing layer includes a rear-stage upper packaging layer 704, a rear-stage upper electrode layer 701, a rear-stage piezoelectric film layer 702, a rear-stage lower electrode layer 703 and a rear-stage flexible substrate layer 705 which are arranged in sequence. The rear-stage upper packaging layer 704 and the rear-stage flexible substrate layer 705 are both made of thin and flexible polymer film materials, the rear-stage upper electrode layer 701 and the rear-stage lower electrode layer 703 are both made of well-conductive metal sputtering, and the rear-stage piezoelectric film layer 702 is made of flexible polymer piezoelectric film material.

The charge conversion unit 8 includes an external capacitor 801 and an external resistor 802. The charge conversion unit is connected to the front-stage piezoelectric film sensing layer using a front-stage cable. The charge conversion unit is connected to the rear-stage piezoelectric film sensing layer using a rear-stage cable. The resistance value of the external resistor 802 is equal to the equivalent resistance of the front-stage cable, and the resistance value of the external resistor 802 is equal to the equivalent resistance of the rear-stage cable.

As shown in FIG1 , a two-stage micro-flyer impact stress test method is specifically described in combination with the working principle, including:

a. Start the ignition device, and the electric explosion foil will produce impact force;

b. The impact force generates shear force through the excitation device, and the shear force shears and destroys the target material to form micro-flying pieces of a certain size;

c. The micro-flying sheet perforates the front-stage piezoelectric film sensing layer;

d. The front-stage piezoelectric film sensing layer outputs a certain charge signal with a peak value of V _1max . At the same time, the rise time t _s1 of the charge signal is recorded. According to the sensing characteristics of the piezoelectric film, the actual effective area A ₁ of the sheared micro-flyer can be calculated, as follows:

Where _K1 is the polarization strength of the front-stage piezoelectric film sensing layer;

e. After the micro-flyer perforates the front-stage piezoelectric film sensing layer, it passes through the acceleration chamber of length L, and its kinetic energy is further increased, and it inertially impacts the rear-stage piezoelectric film sensing layer located at the rear end surface of the acceleration chamber. Accordingly, the rear-stage piezoelectric film sensing layer outputs another charge signal. At the same time, the peak value V _2max of the charge signal and the rise time t _s2 of the charge signal are recorded;

At this time, the average velocity v of the microfly in the acceleration chamber can be calculated using formula (2);

The peak value P _max of the impact stress of the microfly can be calculated as follows:

Where, _K2 is the sensitivity coefficient of the subsequent piezoelectric film sensing layer; _K2 is dynamically calibrated by the Hopkinson bar pressure device;

Substituting equation (1) into equation (3), we can obtain the peak impact stress of the microfly:

In fact, the area of the perforation formed by the microflyer impacting the front-stage piezoelectric film is comparable to the size of the microflyer.

As can be seen from Figure 5, the charge surface density output of the subsequent piezoelectric film sensing layer is proportional to the loading pressure, so the impact stress of the microfly can be measured. At the same time, the charge surface density is closely related to the contact area between the load and the subsequent piezoelectric film sensing layer in the calibration experiment.

Table 1 Statistical values of sensitivity coefficients of piezoelectric sensing layers with different contact areas

Area ratio Sensitivity coefficient (μC/N) 1 7.107 0.6 5.835 0.36 2.814

Combined with Table 1, it can be seen that when the contact area with the load is significantly smaller than the sensitive area of the subsequent piezoelectric film sensing layer, that is, when the area ratio is less than 1, the sensitivity _K2 will also drop rapidly. By adding the front-stage piezoelectric film sensing layer to convert the contact area of the micro-flyer into an equivalent, the measurement accuracy of the subsequent piezoelectric film sensing layer will be significantly increased.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, component splitting or combination, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (5)

1. A two-stage micro-flyer impact stress testing device, characterized in that it comprises a fixed base, an ignition device is installed on one side of the fixed base, an excitation device, a flying chip target, a front-stage piezoelectric sensing unit, an acceleration chamber and a rear-stage piezoelectric sensing unit are sequentially installed on the fixed base, a charge conversion unit is installed on the other side of the fixed base, the front-stage piezoelectric sensing unit and the rear-stage piezoelectric sensing unit are both communicatively connected with the charge conversion unit, the charge conversion unit is communicatively connected with a charge amplification unit, a multi-channel data acquisition unit and a data information storage unit in sequence, and the charge signals from the front-stage piezoelectric sensing unit and the rear-stage piezoelectric sensing unit are stored in the data information storage unit; The front-stage piezoelectric sensing unit has a front-stage piezoelectric film sensing layer, which is integrated on the back side of the flying sheet target by multiple solution spin coating to form a whole with the flying sheet target, and the front-stage piezoelectric film sensing layer is arranged in parallel to the front end face of the acceleration chamber; the front-stage piezoelectric film sensing layer includes a front-stage upper electrode layer, a front-stage piezoelectric film layer and a front-stage lower electrode layer which are integrated into one by a high-speed spin coating process, and the front-stage upper electrode layer and the front-stage lower electrode layer are both formed by spin coating with non-metallic conductive ink. 2. A two-stage micro-flyer impact stress testing device according to claim 1, characterized in that the rear-stage piezoelectric sensing unit has a rear-stage piezoelectric film sensing layer, and the rear-stage piezoelectric film sensing layer is arranged in parallel to the rear end surface of the acceleration chamber. 3. A two-stage micro-flyer impact stress testing device according to claim 2, characterized in that the rear-stage piezoelectric film sensing layer includes a rear-stage upper packaging layer, a rear-stage upper electrode layer, a rear-stage piezoelectric film layer, a rear-stage lower electrode layer and a rear-stage flexible substrate layer arranged in sequence, the rear-stage upper packaging layer and the rear-stage flexible substrate layer are both made of thin and flexible polymer film materials, the rear-stage upper electrode layer and the rear-stage lower electrode layer are both formed by sputtering metal with good conductivity, and the rear-stage piezoelectric film layer is made of flexible polymer piezoelectric film material. 4. A two-stage micro-flyer impact stress testing device according to claim 2, characterized in that the charge conversion unit includes an external capacitor and an external resistor, the charge conversion unit is connected to the front-stage piezoelectric film sensing layer using a front-stage cable, and the charge conversion unit is connected to the rear-stage piezoelectric film sensing layer using a rear-stage cable, the resistance value of the external resistor is equal to the equivalent resistance of the front-stage cable, and the resistance value of the external resistor is equal to the equivalent resistance of the rear-stage cable. 5. A two-stage microflyer impact stress testing method, characterized by using the testing device according to any one of claims 1 to 4, comprising: a. Start the ignition device; b. Record the peak value V _1max of the charge signal output by the front-stage piezoelectric film sensing layer, and record the rise time t _s1 of the charge signal. According to the sensing characteristics of the piezoelectric film, the actual effective area A ₁ of the sheared microfly can be calculated, as follows:

Where _K1 is the polarization strength of the front-stage piezoelectric film sensing layer; c. Record the peak value V _2max of another charge signal output by the subsequent piezoelectric film sensing layer, and record the rise time t _s2 of the charge signal; The average velocity v of the microfly in the acceleration chamber can be calculated using formula (2);

Where L is the length of the acceleration chamber; The peak value P _max of the impact stress of the microfly can be calculated as follows:

Where, _K2 is the sensitivity coefficient of the subsequent piezoelectric film sensing layer; _K2 is dynamically calibrated by the Hopkinson bar pressure device; Substituting equation (1) into equation (3), we can obtain the peak impact stress of the microfly:

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