CN115711694A - Method and device for measuring surface cavitation impact load of solid propellant in cavitation field - Google Patents
Method and device for measuring surface cavitation impact load of solid propellant in cavitation field Download PDFInfo
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Abstract
The invention relates to a method and a device for measuring surface cavitation impact load of a solid propellant in a cavitation field, and particularly relates to the technical field of cavitation impact load. The device comprises a base and a sensor; the sensor comprises a PVDF piezoelectric film, a first conductive electrode, a second conductive electrode and a wafer; the PVDF piezoelectric film is arranged on the base, and one end of the first conductive electrode and one end of the second conductive electrode are both connected with the PVDF piezoelectric film; the wafer is arranged on a set area of the PVDF piezoelectric film; the material of the wafer is solid propellant; the PVDF piezoelectric film is only plated with a silver layer on the set area; the other end of the first conductive electrode and the other end of the second conductive electrode are connected with an oscilloscope. The invention can realize the measurement of impact load of explosive charge by cavitation in the cavitation field.
Description
Technical Field
The invention relates to the technical field of cavitation impact loads, in particular to a method and a device for measuring the surface cavitation impact load of a solid propellant in a cavitation field.
Background
Cavitation is a very complex hydrodynamic phenomenon, and has long been one of the key and difficult issues in the field of fluid dynamics. Cavitation is in most cases harmful and the creation of cavitation is to be avoided to the utmost, but if the flow system can be designed reasonably, cavitation can be changed from harmful to beneficial for our use, such as cavitation drag reduction, cavitation degradation, cavitation cleaning and cavitation fragmentation, and the like. Particularly, the cavitation effect can be utilized to realize safe and efficient crushing and cleaning of solid explosive in waste ammunition, and the hydraulic cavitation technology is applied to treat more sensitive explosive charges such as trinitrotoluene, high polymer bonded explosives, solid propellants and the like. The research on treating the dull black aluminum charge by cavitation water jet is also carried out by the national institute of chemistry and modern society of Western's society. The cavitation jet flow has wide development prospect in the aspect of crushing waste ammunition, explosive and explosive.
Whether harmful cavitation or beneficial cavitation, the action mechanism is consistent, the high-frequency impact of impact waves and micro-jet generated by continuous collapse of cavitation bubbles formed by fluid cavitation on the surface of a material is a mechanical process of high-frequency impact load with extremely short duration and extremely small action area generated by continuous collapse of single cavitation bubbles or cavitation bubble groups. Therefore, the measurement of the impact load of the high-frequency cavitation is always one of the key and difficult problems in the field of cavitation research. The existing high-frequency cavitation impact load measuring technology mainly comprises two types, namely, a sensor made of piezoelectric ceramics or a PVDF piezoelectric film is used for directly measuring a voltage signal generated by cavitation impact in a cavitation field; secondly, a specially-made metal thin rod is arranged on the piezoelectric ceramic or the piezoelectric film, cavitation impact in the cavitation field generates impact on the free end face of the metal rod to form stress waves, and the stress waves are transmitted to the piezoelectric material to generate voltage signals.
The prior art has the following defects: in the first type of technology, the surface of a sensor made of piezoelectric ceramics is made of stainless steel or other special materials, the surface of a sensor made of a PVDF piezoelectric film is made of a polyimide adhesive tape, and signals acquired by the sensors reflect the mechanical response of cavitation impact to the stainless steel, the polyimide or other special materials, namely, the technology cannot measure the impact load of cavitation in a cavitation field to other metal materials such as copper and aluminum and other non-metal materials except the polyimide; in the second type of technology, although the impact load of cavitation field cavitation on different metal materials can be measured by replacing metal rods made of different materials, the measurement technology is difficult to realize for explosive charges such as TNT, blunt black aluminum, solid propellant and the like, and no literature reports exist at present for experimental measurement of the impact load of cavitation field cavitation on explosive charges. Therefore, the existing high-frequency cavitation impact load measuring technology cannot realize the measurement of impact load of cavitation field cavitation on explosive charge, and the research progress of the key problems of cavitation jet flow crushing treatment on the explosive charge, such as action mechanism, safety mechanism, treatment efficiency and the like is seriously restricted.
Disclosure of Invention
The invention aims to provide a method and a device for measuring the surface cavitation impact load of a solid propellant in a cavitation field, which can realize the measurement of the cavitation field on the impact load of explosive loading.
In order to achieve the purpose, the invention provides the following scheme:
a device for measuring the surface cavitation impact load of a solid propellant in a cavitation field comprises:
a base and a sensor; the sensor comprises a PVDF piezoelectric film, a first conductive electrode, a second conductive electrode and a wafer;
the PVDF piezoelectric film is arranged on the base, and one end of the first conductive electrode and one end of the second conductive electrode are both connected with the PVDF piezoelectric film; the wafer is arranged on a set area of the PVDF piezoelectric film; the material of the wafer is solid propellant; a silver coating is only coated on the set area on the PVDF piezoelectric film; the other end of the first conductive electrode and the other end of the second conductive electrode are connected with an oscilloscope.
Optionally, the shape of base is the cuboid, and the material is organic glass.
Optionally, the device for measuring the solid propellant surface cavitation impact load in the cavitation field further includes: one surface of the first double-sided tape is stuck to the upper surface of the base; the PVDF piezoelectric film is arranged on the other side of the first double-sided adhesive tape.
Optionally, the device for measuring the solid propellant surface cavitation impact load in the cavitation field further includes: one surface of the second double-sided tape is adhered to the PVDF piezoelectric film, the wafer is arranged on the other surface of the second double-sided tape, and the wafer is aligned with the set area of the PVDF piezoelectric film.
Optionally, the first conductive electrode and the second conductive electrode are both double-sided conductive copper foil tapes.
Optionally, the device for measuring the solid propellant surface cavitation impact load in the cavitation field further includes: the waterproof layer and the 304 stainless steel foil are arranged from bottom to top in sequence; a round hole is formed in the center positions of the waterproof layer and the 304 stainless steel foil and aligned with the wafer; and a closed space is formed between the base and the waterproof layer.
Optionally, the waterproof layer includes first waterproof sticky tape and the second waterproof sticky tape that sets gradually from bottom to top.
A method for measuring the surface cavitation impact load of the solid propellant in the cavitation field is applied to the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field, and the method comprises the following steps:
vertically accelerating a stainless steel shot to obtain the mass of the stainless steel shot, the incident speed of the stainless steel shot, the rebounding speed of the stainless steel shot, the amplitude and the duration of a shot impact signal; the incident speed is the speed when the stainless steel projectile impacts on a wafer in a device for measuring the surface cavitation impact load of the solid propellant in the cavitation field, and the rebound speed is the speed when the stainless steel projectile impacts on the wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field and is rebounded; the shot impact signal amplitude is the signal amplitude of an electric signal generated on a wafer in a measuring device of the solid propellant surface cavitation impact load when the stainless steel shot impacts the cavitation field; the duration is the time from the stainless steel shot impacting on the wafer in the device for measuring the solid propellant surface cavitation impact load in the cavitation field to the time from the stainless steel shot impacting on the wafer in the device for measuring the solid propellant surface cavitation impact load in the cavitation field being rebounded.
Determining the impact load of the stainless steel projectile on the solid propellant according to the mass of the stainless steel projectile, the incident velocity of the stainless steel projectile, the rebound velocity of the stainless steel projectile and the duration;
determining a power constant according to the impact load of the stainless steel projectile on the solid propellant and the projectile impact signal amplitude;
acquiring the amplitude of a cavitation impact signal; the amplitude of the cavitation impact signal is the signal amplitude of an electric signal generated by a wafer in a measuring device of the solid propellant surface cavitation impact load in the cavitation field;
and calculating the surface cavitation impact load of the solid propellant in the cavitation field according to the electric constant and the cavitation impact signal amplitude.
Optionally, the stainless steel projectile is accelerated vertically by an electromagnetic accelerator.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: according to the invention, a solid propellant test piece (wafer) is directly adhered to a sensitive area of a PVDF piezoelectric film, and the acquired voltage signal directly reflects the impact mechanical response of cavitation field cavitation to the surface of the solid propellant, so that the measurement of the cavitation field cavitation to the impact load of explosive charging can be realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic structural diagram of a device for measuring the surface cavitation impact load of a solid propellant in a cavitation field according to an embodiment of the present invention;
FIG. 2 is a perspective view of a device for measuring cavitation impact load on the surface of a solid propellant in a cavitation field;
FIG. 3 is a schematic diagram of a calibration test system;
FIG. 4 is a diagram of a pulse signal collected during calibration;
FIG. 5 is a schematic structural diagram of a cavitation field cavitation impact load test system;
FIG. 6 is a diagram of pulse signals collected during a cavitation field cavitation impact load test.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The embodiment of the invention provides a device for measuring the surface cavitation impact load of a solid propellant in a cavitation field, which is also called as a PVDF piezoelectric film/solid propellant sensor, and relates to the measurement of the high-frequency impact load of the very short duration and the very small action area, generated by cavitation bubble collapse, on the surface of the solid propellant in a hydrodynamic cavitation jet flow field, as shown in fig. 1 and 2, the device comprises:
a base 1 and a sensor; the sensor comprises a PVDF piezoelectric film 3, a first conductive electrode 4.1, a second conductive electrode 4.2 and a wafer 6; the PVDF piezoelectric film 3 is arranged on the base 1, and one end of the first conductive electrode 4.1 and one end of the second conductive electrode 4.2 are both connected with the PVDF piezoelectric film 3; the wafer 6 is arranged on a set area of the PVDF piezoelectric film 3; the material of the wafer 6 is solid propellant; a silver coating is only coated on the set area on the PVDF piezoelectric film 3; the other end of the first conductive electrode 4.1 and the other end of the second conductive electrode 4.2 are connected with an oscilloscope; the other end of the first conductive electrode 4.1 and the other end of the second conductive electrode 4.2 are respectively welded with two electrodes of a coaxial signal line 10 of a BNC interface, and the interface is sealed by a waterproof sealing adhesive tape 11 to realize the connection with an oscilloscope.
In practical application, the base 1 is cuboid and made of organic glass.
In practical application, the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field further comprises: a first double-sided tape 2, one side of the first double-sided tape 2 being attached to the upper surface of the base 1; the PVDF piezoelectric film 3 is arranged on the other side of the first double-sided adhesive tape 2.
In practical application, the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field further comprises: one surface of the second double-sided adhesive tape 5 is adhered to the PVDF piezoelectric film 3, the wafer 6 is arranged on the other surface of the second double-sided adhesive tape 5, and the wafer 6 is vertically aligned with the set area of the PVDF piezoelectric film 3.
In practical application, the first conductive electrode 4.1 and the second conductive electrode 4.2 are both double-sided conductive copper foil tapes.
In practical application, the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field further comprises: the waterproof layer and the 304 stainless steel foil 9 are arranged from bottom to top in sequence; a round hole is formed in the center positions of the waterproof layer and the 304 stainless steel foil 9 and is vertically aligned with the wafer 6; and a closed space is formed between the base 1 and the waterproof layer.
In practical application, the waterproof layer comprises a first waterproof adhesive tape 7 and a second waterproof adhesive tape 8 which are sequentially arranged from bottom to top.
The preparation method of the PVDF piezoelectric film/solid propellant sensor provided by the invention comprises the following steps:
(1) A100X 40X 100mm rectangular PMMA (polymethyl methacrylate) plate is pre-adhered with 1 layer of double-sided adhesive tape on the upper surface of the plate with the thickness of 100X 40 mm.
(2) Cutting the PVDF piezoelectric film with silver plated on both sides into a rectangle of 11 multiplied by 10mm, carefully scraping the peripheral silver plated layer by a blade under the condition of keeping the lead areas of the positive and negative electrodes to enable the sensitive area, namely the set area, to be a circle with the diameter of 8.0mm, leading the positive and negative electrodes by a double-sided conductive copper foil tape, and then directly sticking the double-sided conductive copper foil tape on the double-sided adhesive tape in the step (1) and locating at the center of the upper surface of the PMMA cuboid.
(3) And a layer of double-sided tape is covered and adhered on the PVDF film to play a role in insulation protection.
(4) And (3) cutting the solid propellant into circular sheets with the thickness of 2.0mm and the diameter of 8.0mm (experimental research proves that the mechanical response of the small-scale and larger-scale solid propellant test pieces to the micro-scale dynamic impact is consistent relative to the ultra-micro-scale cavitation impact load), and then adhering an adhesive on the double-sided adhesive tape in the step (3) and aligning the double-sided adhesive tape with the cut PVDF film up and down.
(5) A waterproof tape (with the thickness of 1mm and the diameter of a middle hole of 8.0 mm), a waterproof tape (with the thickness of 1.5mm and the diameter of a middle hole of 7.0 mm) and 304 stainless steel foil (with the thickness of 0.1mm and the diameter of a middle hole of 7.0 mm) are sequentially adhered to the upper surface of the PMMA cuboid from bottom to top.
(6) The positive electrode and the negative electrode led out from the double-sided conductive copper foil adhesive tape are respectively welded with the two electrodes of the coaxial signal line of the BNC interface by soldering tin, and the interface is sealed by a waterproof adhesive tape (with the thickness of 1.5 mm) to play the role of insulation protection.
The embodiment of the invention also provides a method for measuring the surface cavitation impact load of the solid propellant in the cavitation field, which is applied to the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field, and the method comprises the following steps:
vertically accelerating a stainless steel shot to obtain the mass of the stainless steel shot, the incident speed of the stainless steel shot, the rebounding speed of the stainless steel shot, the amplitude and the duration of a shot impact signal; the incident speed is the speed when the stainless steel projectile impacts on a wafer in a device for measuring the surface cavitation impact load of the solid propellant in the cavitation field, and the rebound speed is the speed when the stainless steel projectile impacts on the wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field and is rebounded; the shot impact signal amplitude is the signal amplitude of an electric signal generated on a wafer in a measuring device for the solid propellant surface cavitation impact load when the stainless steel shot impacts in the cavitation field; the duration is the time from the stainless steel shot impacting on a wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field to the stainless steel shot impacting on the wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field being rebounded;
determining the impact load of the stainless steel projectile on the solid propellant according to the mass of the stainless steel projectile, the incident velocity of the stainless steel projectile, the rebound velocity of the stainless steel projectile and the duration;
determining a power constant according to the impact load of the stainless steel projectile on the solid propellant and the projectile impact signal amplitude;
acquiring the amplitude of a cavitation impact signal; the amplitude of the cavitation impact signal is the signal amplitude of an electric signal generated on a wafer in a measuring device of the solid propellant surface cavitation impact load in the cavitation field;
and calculating the surface cavitation impact load of the solid propellant in the cavitation field according to the electric constant and the cavitation impact signal amplitude.
In practical application, a stainless steel projectile is vertically accelerated, the mass of the stainless steel projectile, the incident speed of the stainless steel projectile, the rebounding speed of the stainless steel projectile, the projectile impact signal amplitude and the duration are obtained, and the impact load of the stainless steel projectile on a solid propellant is determined according to the mass of the stainless steel projectile, the incident speed of the stainless steel projectile, the rebounding speed of the stainless steel projectile and the duration; determining dynamic calibration of a power constant, also called PVDF piezoelectric film/solid propellant sensor, according to the impact load of the stainless steel projectile on the solid propellant and the projectile impact signal amplitude, specifically comprising:
(1) the mass m of the stainless steel shot was weighed and recorded.
(2) And (5) installing equipment such as a high-speed camera, an oscilloscope, a projectile accelerator and the like and setting acquisition parameters.
(3) Starting a high-speed camera, an oscilloscope and a projectile accelerator, measuring and calculating the incident velocity v of the projectile through the process that the projectile collected by the high-speed camera impacts the surface of the propellant and then rebounds i And velocity v of rebound r (ii) a Reading the amplitude U and the duration delta t of a projectile impact signal through an electric signal generated when the projectile impacts the surface of the solid propellant and collected by an oscilloscope;
(4) the impact load F of the projectile on the solid propellant is calculated as follows:
(5) the force-electric constant K is calculated from F and U, establishing the equation F = KU.
In practical application, acquiring the amplitude of a cavitation impact signal; the amplitude of the cavitation impact signal is the signal amplitude of an electric signal generated on a wafer in a measuring device of the solid propellant surface cavitation impact load in the cavitation field; calculating the surface cavitation impact load of the solid propellant in the cavitation field according to the electric constant and the cavitation impact signal amplitude, and specifically comprises the following steps:
(1) fixing the prepared PVDF piezoelectric film/solid propellant sensor on a target plate of a cavitation jet device, connecting the sensor to an oscilloscope, and adjusting acquisition parameters of the oscilloscope.
(2) Starting the cavitation jet device and an operation program, and adjusting the jet distance and the jet center offset distance (the distance of the jet center from the center of the sensitive area of the sensor) to set values.
(3) Covering a flow baffle on a sensitive area of the PVDF piezoelectric film/solid propellant sensor, starting a high-pressure pump, and adjusting the working pressure to a set value.
(4) And removing the flow baffle, observing the signal condition of the oscilloscope, immediately stopping the pump after acquiring the cavitation impact signal, and recording and storing data.
(6) And substituting U acquired and recorded by an oscilloscope into the equation F = KU to calculate the cavitation impact load.
The principle of the method for measuring the surface cavitation impact load of the solid propellant in the cavitation field provided by the embodiment of the invention is as follows: a thin-layer solid propellant test piece is pasted on the surface of a sensitive area of the PVDF piezoelectric sensor, and when cavitation impact load acts on the surface of the solid propellant test piece, stress waves are transmitted to the PVDF piezoelectric film through the solid propellant to generate a piezoelectric phenomenon. For a PVDF piezoelectric film, the piezoelectric equation in its thickness direction is: q = d 33 Aσ zz Wherein Q is the amount of charge generated by the piezoelectric film, d 33 The piezoelectric coefficient in the thickness direction of the piezoelectric film is constant, A is the area of action, sigma zz Is the stress perpendicular to the active area a.
And σ zz And F is the impact load acting perpendicularly on the area a. Q = CU ', C is the capacitance of the piezoelectric film, U' is the voltage generated by the piezoelectric film, and C is a constant when the piezoelectric film is constant. Then there are: f = CU'/d 33 The impact load F is in direct proportion to the voltage U 'generated by the piezoelectric film, and the voltage U' generated by the piezoelectric film, namely the amplitude U of a projectile impact signal acquired by an oscilloscope when a lower projectile impacts a propellant on the surface of the sensor, is in direct proportion to the F.
When the sensor is calibrated, the process of the subsequent rebound of the propellant on the surface of the sensor when the shot with the mass m and collected by the high-speed camera impacts the propellant is measured and calculated i And velocity v of rebound r (ii) a Reading the impact signal amplitude U and the duration time delta t of the projectile through electric signals acquired by an oscilloscope, and calculating the impact load F of the projectile on the solid propellant on the surface of the sensor according to the momentum theorem by the following formula:
and based on the basis that F is in direct proportion to U, K is obtained according to U and F, a relation equation F = KU between the impact load F and U is further established according to the calibration of the sensor, and the acquired impact signal amplitude U generated by cavitation impact in the cavitation field is substituted into the equation, so that the cavitation impact load F can be calculated.
The following will describe the preparation process of the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field provided by the above embodiment of the present invention in further detail with reference to the following embodiments.
The PVDF piezoelectric film/HTPB propellant sensor is prepared by the following specific preparation steps:
(1) A3M ScotchBrandTape double-sided tape 1 layer thick 110 μ M and 20mm wide was previously attached to the 100X 40mm upper surface of a 100X 40X 100mm rectangular PMMA plate.
(2) A52-micron-thick double-sided silver-plated PVDF film of PolyK Technologies company is cut into a rectangle of 11 x 10mm, the silver coating on the periphery is scraped off by a blade carefully under the condition of keeping a positive and negative lead area, so that a sensitive area is in a circle with the diameter of 8.0mm, a 60-micron-thick double-sided conductive copper foil tape is used for leading out a positive electrode and a negative electrode, and then the positive electrode and the negative electrode are directly pasted on the 3M double-sided tape in the step (1) and positioned at the center of the upper surface of the PMMA cuboid.
(3) And (2) covering and sticking a layer of the 3M double-sided adhesive tape in the step (1) on the PVDF film.
(4) And (3) cutting the HTPB three-component propellant into round pieces with the thickness of 2.0mm and the diameter of 8.0mm, and then adhering the round pieces on the 3M double-sided adhesive tape in the step (3) by using an AB adhesive of Guangdong Aibida adhesive limited company and aligning the round pieces with the cut PVDF film up and down.
(5) From bottom to top, a Mita Er brand butyl waterproof tape (thickness 1mm, middle hole 8.0 mm), a butyl waterproof tape (thickness 1.5mm, middle hole 7.0 mm) and a 304 stainless steel foil (thickness 0.1mm, middle hole 7.0 mm) of Shanghai Xuan Jia industry Co.
(6) The positive electrode and the negative electrode led out from the Zhongzi double-sided conductive copper foil adhesive tape are respectively welded with the two electrodes of the coaxial signal line of the BNC interface by soldering tin, and the interface is sealed by a Mita' er butyl waterproof adhesive tape (thickness is 1.5 mm) of Shanghai Xuan Jia practical Co.
The invention also provides a calibration test system built based on the device, and as shown in fig. 3, an embodiment of dynamic calibration of the prepared PVDF piezoelectric film/HTPB propellant sensor is provided. The system comprises a Qianyun high-speed camera 12 of Hefenhuang Jundagaokadsuki information technology limited company, a self-assembly electromagnetic type projectile accelerator 13, an MSO-X-3052A type oscilloscope 14 produced by Agilent Technologies company and a measuring device 15 formed by compounding a PVDF piezoelectric film and a solid propellant. Precise bearing steel balls with the material GCr15 and the nominal diameters of 1.5mm, 1.588mm and 2.0mm are used as impact projectiles, the calibration data of the HTPB propellant/PVDF sensor are shown in a table 1, and pulse signals acquired in the serial number 5 calibration process are shown in a table 4.
Electromagnetic projectile accelerator: the accelerating voltage is 200-320V;
high-speed camera setting: frame rate is 5000 frames/second, exposure time is 5 mus, and length is 10000 frames;
the filter is arranged: standard acquisition mode, sample rate 200MSa/s, trigger voltage 500mV.
TABLE 1PVDF piezoelectric film/HTPB sensor calibration data
If the average value of the power coefficient K is 3.52, the power equation is: f =3.52U.
The invention also provides an embodiment of a cavitation field cavitation impact load test system based on the device, the structure is shown in fig. 5, and the cavitation field cavitation impact load test system collects cavitation impact signals borne by the surface of a solid propellant in a cavitation field and calculates impact load. The system comprises an oscilloscope 14 of MSO-X-3052A type produced by Agilent technologies, a measuring device 15 formed by compounding a PVDF piezoelectric film and a solid propellant, a conical cavitation jet spray head 16, an organic glass flooding water tank 17, a high-pressure pump 18 of ANNOVI REVERBERI SXW21.35N model Italy, a three-phase asynchronous motor 19 of YBX-160L-4 type produced by Bei De explosion-proof motor Limited of China and a water storage tank 20.
Working conditions are as follows: the upstream pressure of the cavitation nozzle is 12.54MPa, the downstream pressure is 0.0977MPa, the spraying distance is 54mm, and the jet center-sensor center offset distance is 15mm.
The oscilloscope is set: standard acquisition mode, sample rate 200MSa/s, trigger voltage 1.0V.
The signal recorded by the oscilloscope in the time length of 1ms is shown in fig. 6, and the amplitude voltage U of the pulse signal with the amplitude being equal to or greater than 1.0V and the corresponding impact load F calculated according to the equation F =3.52U are shown in table 2.
TABLE 2 pulse signal amplitude voltage and impact load
| |
1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Amplitude voltage U/V | 2.97 | 4.67 | 1.20 | 1.79 | 1.75 | 3.58 | 1.00 |
| Impact load F/N | 10.45 | 16.44 | 4.22 | 6.30 | 6.16 | 12.60 | 3.52 |
The invention has the following technical effects:
(1) According to the PVDF piezoelectric film/solid propellant sensor, the solid propellant test piece is directly adhered to the sensitive area of the PVDF piezoelectric film, the acquired voltage signal directly reflects the impact mechanical response of cavitation in a cavitation field to the surface of the solid propellant, and the problem that the cavitation impact load borne by the explosive charging surface cannot be measured in the prior art is solved.
(2) The PVDF piezoelectric film/solid propellant sensor dynamic calibration method of the invention uses an electromagnetic accelerator to accelerate a stainless steel projectile and vertically impact the surface of a solid propellant in a sensitive area of the PVDF piezoelectric film/solid propellant sensor, uses an oscilloscope to record a voltage signal generated by the projectile impacting the sensitive area of the sensor, and calculates the impact load of the projectile on the solid propellant according to momentum theorem and by the mass, the incident speed and the rebound speed of the projectile, the signal amplitude and the duration time, thereby establishing the relation between the impact load and the signal amplitude voltage. Compared with the traditional ball falling calibration method, the method has the advantages that the size of the shot is smaller, the impact speed is higher, and the impact action duration is closer to the cavitation impact.
(3) The principle of the method provided by the invention is based on the basic laws of physics such as momentum theorem, piezoelectric equation of PVDF piezoelectric film and the like, is accurate and reliable, the used materials such as PVDF piezoelectric film, double-sided conductive copper foil, double-sided adhesive tape, waterproof adhesive tape and the like, and equipment such as high-speed camera, oscilloscope, electromagnetic accelerator and the like are widely commercialized, and the method is easy to establish.
(4) The invention not only effectively solves the problem that the cavitation impact load on the surface of explosive charge can not be measured in the prior art, but also can be widely popularized and applied to the measurement of the cavitation impact load on the surface of polymer materials such as metal materials, plastic rubber and the like.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A device for measuring the surface cavitation impact load of a solid propellant in a cavitation field is characterized by comprising:
a base and a sensor; the sensor comprises a PVDF piezoelectric film, a first conductive electrode, a second conductive electrode and a wafer;
the PVDF piezoelectric film is arranged on the base, and one end of the first conductive electrode and one end of the second conductive electrode are both connected with the PVDF piezoelectric film; the wafer is arranged on a set area of the PVDF piezoelectric film; the material of the wafer is solid propellant; a silver coating is only coated on the set area on the PVDF piezoelectric film; and the other end of the first conductive electrode and the other end of the second conductive electrode are connected with an oscilloscope.
2. The device for measuring the surface cavitation impact load of the solid propellant in the cavitation field according to claim 1, wherein the base is cuboid and made of organic glass.
3. The apparatus for measuring the surface cavitation impact load of the solid propellant in the cavitation field as claimed in claim 1, further comprising: one surface of the first double-sided tape is stuck to the upper surface of the base; the PVDF piezoelectric film is arranged on the other side of the first double-sided adhesive tape.
4. The apparatus for measuring the surface cavitation impact load of the solid propellant in the cavitation field as claimed in claim 1, further comprising: one surface of the second double-sided tape is adhered to the PVDF piezoelectric film, the wafer is arranged on the other surface of the second double-sided tape, and the wafer is aligned with the set area of the PVDF piezoelectric film.
5. The device for measuring the surface cavitation impact load of the solid propellant in the cavitation field according to claim 1, wherein the first conductive electrode and the second conductive electrode are both double-sided conductive copper foil tapes.
6. The apparatus for measuring the surface cavitation impact load of the solid propellant in the cavitation field as claimed in claim 1, further comprising: the waterproof layer and the 304 stainless steel foil are arranged from bottom to top in sequence; a round hole is formed in the center positions of the waterproof layer and the 304 stainless steel foil and aligned with the wafer; and a closed space is formed between the base and the waterproof layer.
7. The device for measuring the surface cavitation impact load of the solid propellant in the cavitation field according to claim 6, wherein the waterproof layer comprises a first waterproof adhesive tape and a second waterproof adhesive tape which are sequentially arranged from bottom to top.
8. A method for measuring the surface cavitation impact load of the solid propellant in the cavitation field, which is characterized in that the method is applied to a device for measuring the surface cavitation impact load of the solid propellant in the cavitation field according to any one of the claims 1 to 7, and the method comprises the following steps:
vertically accelerating a stainless steel shot to obtain the mass of the stainless steel shot, the incident speed of the stainless steel shot, the rebounding speed of the stainless steel shot, and the amplitude and the duration of a shot impact signal; the incident speed is the speed when the stainless steel projectile impacts on a wafer in a device for measuring the surface cavitation impact load of the solid propellant in the cavitation field, and the rebound speed is the speed when the stainless steel projectile impacts on the wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field and is rebounded; the shot impact signal amplitude is the signal amplitude of an electric signal generated on a wafer in a measuring device of the solid propellant surface cavitation impact load when the stainless steel shot impacts the cavitation field; the duration is the time from the stainless steel shot impacting on a wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field to the stainless steel shot impacting on the wafer in the device for measuring the surface cavitation impact load of the solid propellant in the cavitation field being rebounded;
determining the impact load of the stainless steel projectile on the solid propellant according to the mass of the stainless steel projectile, the incident velocity of the stainless steel projectile, the rebound velocity of the stainless steel projectile and the duration;
determining a power constant according to the impact load of the stainless steel projectile on the solid propellant and the projectile impact signal amplitude;
acquiring the amplitude of a cavitation impact signal; the amplitude of the cavitation impact signal is the signal amplitude of an electric signal generated on a wafer in a measuring device of the solid propellant surface cavitation impact load in the cavitation field;
and calculating the surface cavitation impact load of the solid propellant in the cavitation field according to the electric constant and the cavitation impact signal amplitude.
9. The method for measuring the surface cavitation impact load of the solid propellant in the cavitation field according to claim 8, wherein the stainless steel projectile is vertically accelerated by an electromagnetic accelerator.
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