CN116242523A - A piezoresistive high anti-interference shock wave pressure capture method and device - Google Patents

Abstract

The invention discloses a piezoresistive high-anti-interference shock wave pressure capturing method and device. Two groups of shock wave capturing devices consisting of piezoresistors and silicon diaphragms are arranged in the sensor packaging shell, one side of the shock wave capturing devices is completely filled with a hardness material, and the other side of the shock wave capturing devices is provided with a cavity. The key is that the connection of one group of piezoresistor bridge circuit electrode needs to be connected positively, and the other group of electrodes needs to be connected reversely, because the propagation speed of electromagnetic wave is far faster than that of shock wave, the piezoresistor bridge circuit electrode reaches the mounting point of the sensor when being exploded, and the signal of the piezoresistor bridge circuit electrode is directly overlapped on the signal output line of the sensor through an electromagnetic induction way on the sensor transmission cable. Based on the above, the output voltage caused by the micro-variation of the resistance value of the piezoresistor is processed by the signal processing module and then is balanced against each other, so that the aim of eliminating the influence on the accuracy of the final measured pressure value caused by the oscillation of the output pressure curve is fulfilled.

Description

A piezoresistive high anti-interference shock wave pressure capture method and device

technical field

The invention belongs to the field of shock wave pressure testing, and in particular relates to a piezoresistive high anti-interference shock wave pressure capturing method and a device thereof.

Background technique

Shock wave overpressure is an important measurement content in anti-blast experiments of protective engineering structures. At present, in the shock wave pressure test, commonly used pressure sensors are divided into two types, namely piezoelectric pressure sensors and piezoresistive pressure sensors. However, during the pressure measurement process, the two sensors are greatly affected by the optical radiation and electromagnetic radiation produced by the explosion, which ultimately affects the reliability of the shock wave overpressure value.

The piezoresistive sensor has the advantages of very high sensitivity, high resolution, high frequency response, and is not significantly affected by the vibration generated by the explosion, especially its high natural frequency and wide dynamic response range, making it piezoelectric The incomparable advantages of conventional sensors have gradually become an important technical means for shock wave overpressure measurement in explosion fields. Different from piezoelectric sensors, the sensitive parts of commonly used piezoresistive sensors are mostly silicon diaphragms, which are highly sensitive to optical radiation, electromagnetic radiation and thermal shock in the range of infrared to visible light, and are easily affected by electromagnetic radiation generated by explosions. , optical radiation and thermal shock interference.

In the process of explosive explosion and gas explosion, in addition to generating shock waves, electromagnetic radiation, optical radiation, vibration shock and other interference factors are also generated during the detonation process. The optical radiation and electromagnetic radiation generated by the explosion attenuate rapidly with the increase of distance, so when the sensor is installed in a well-protected middle and far field, the electromagnetic wave and optical radiation can be attenuated to a large extent, and generally will not affect the shock wave measurement signal. However, when the pressure sensor is arranged in the near field, the electromagnetic wave and optical radiation signal will be superimposed on the shock wave signal, which will seriously interfere with the measurement of the shock wave pressure, especially when the chemical explosion shock wave overpressure measurement such as gas has a long acting time, the light , heat and other radiation have a greater impact, so the initial signal output by the sensor oscillates at high frequency, causing errors or even distortions in the final measured pressure value, which greatly limits the use scenarios of piezoresistive pressure sensors.

Chinese invention patent 200510037982.2 discloses the device composition and principle of a piezoresistive high-frequency dynamic high-pressure sensor, which is mainly composed of a piezoresistive sensitive component, a sensor base, a transfer circuit and a lead-out cable, which solves the pressure-sensitive diaphragm stress surface. The problem of direct flush packaging realizes the requirement of high dynamic frequency response and extremely small rise time for the sensor during dynamic high voltage measurement. Chinese patent 200510038458.7 The device composition and principle of piezoresistive high-frequency dynamic low-voltage sensor, which is composed of piezoresistive sensitive components, sensor base, transfer circuit and lead-out cable, is a silicon micromachining based on MEMS (MicroElectro Mechanical System) The high-frequency dynamic piezoresistive low-pressure sensor with advanced technology is especially suitable for dynamic pressure measurement in aerodynamic tests (commonly known as wind tunnel tests), water conservancy projects, aerospace, weapon tests, ships, etc., and has good dynamic frequency response performance.

The above two devices and methods weaken the interference and influence of electromagnetic waves and optical radiation effects to a certain extent, but they still cannot eliminate the impact of the interference on the voltage before the explosion shock wave overpressure reaches the piezoresistive sensitive element in the case of sensors arranged in the near field. The impact of the signal (as shown in the curve in the box in Figure 1), for this, the general method is to take the starting point of the overpressure wave caused by the negative pulse residual into the calculation of the overpressure wave, obviously, There are certain errors in this method. The shock wave pressure curve measured by the pressure sensor is shown in Fig. 1.

At present, in order to weaken the influence of electromagnetic waves on the output signal of the sensor, the mainstream methods are roughly divided into two types: one is to add a protective film to the sensor, which will cause the loss of the frequency response of the sensor and the reduction of the dynamic performance; The surface of the force-sensitive area of the sensor is coated with Vaseline, silicone oil, etc., but this method will affect the measurement accuracy of the sensor.

Contents of the invention

In order to solve the technical problems mentioned above in the background technology, the present invention proposes a piezoresistive high anti-interference shock wave pressure capture method and its device.

In order to realize above-mentioned technical purpose, technical scheme of the present invention is:

A piezoresistive high anti-interference shock wave pressure capture device, including a sensor package shell, a signal amplification module, a signal processing module and a power supply module, wherein a shock wave capture device is arranged on the surface of the sensor package shell, and the output end of the shock capture device passes through The sensor packaging shell is connected to the input end of the signal amplification module, and the shock capture device collects electromagnetic wave signals, optical radiation signals, thermal shock signals and shock wave signals and transmits them to the signal amplification module respectively, wherein the shock wave capture device is directly connected to the signal amplification module The collected electromagnetic wave signal, optical radiation signal and thermal shock signal are counteracted in a reverse connection mode, and the output end of the shock wave capture device passes through the part inside the sensor packaging shell to contain the output of part of the shock wave signal by filling the hardness material, and the signal is amplified The output end of the module is connected to the input end of the signal processing module, the shock wave signal is amplified and processed by the signal processing module to output the actual shock wave pressure curve, and the power supply module supplies power for the signal amplification module and the signal processing and output module.

Preferably, the piezoresistive high anti-interference shock wave pressure capture device also includes a silicon diaphragm, the silicon diaphragm is fixed on the surface of the sensor package housing, the shock wave capture device is embedded in the silicon diaphragm, and the lead wires at the two poles of the impact capture device Pass through the sensor packaging shell and connect with the signal amplification module.

Preferably, the shock wave capture device includes two piezoresistors distributed in a mirror image, the first piezoresistor is reversely connected to the signal amplification module, the second piezoresistor is forwardly connected to the signal amplification module, the first signal amplifier and the second piezoresistor The output terminals of the two signal amplifiers are respectively connected to the input terminals of the signal processing module.

Further, the piezoresistor includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 connected in a rhombus connection to form a Wheatstone bridge, wherein the positive pole of the power module is connected to the first resistor The common terminal of R1 and the fourth resistor R4, the negative pole of the power module is connected to the common terminal of the second resistor R2 and the third resistor R3, the common terminal of the first resistor R1 and the second resistor R2 is connected to the third resistor R3 and the fourth resistor R4 The common terminal of the signal amplifier is used as the output terminal to connect to the input terminal of the signal amplifier amplifying module.

Further, the portion inside the sensor package housing through which the lead wire of the output end of the first piezoresistor connected to the signal amplification module passes is filled with a hard material.

A shock wave pressure capture method based on a piezoresistive high anti-interference shock wave pressure capture device, comprising the following steps

S1. The piezoresistive high anti-interference shock wave pressure capture device collects the electromagnetic wave, light radiation, thermal shock forward voltage signal and reverse voltage signal and the forward voltage signal of the shock wave generated by the explosion;

S2. The piezoresistive high anti-interference shock wave pressure capture device amplifies the forward voltage signal and reverse voltage signal of the collected electromagnetic wave, optical radiation and thermal shock signal, and amplifies the amplified electromagnetic wave, optical radiation and thermal shock voltage signal Cancel each other out;

S3. The piezoresistive high anti-interference shock wave pressure capture device amplifies and outputs the forward voltage signal of the shock wave.

Preferably, the first piezoresistor in the piezoresistive high anti-interference shock wave pressure capture device is filled with a hard material, and there is no signal output when collecting the voltage signal of the positive pressure shock wave.

The beneficial effect brought by adopting the above-mentioned technical scheme:

The present invention cleverly designs two sets of piezoresistors to be used at the same time. The key point is that the inside of one of the sensors is completely filled with a hardness material to prevent the piezoresistor from being deformed downward after contact with the shock wave and cause the resistance value to change, but it does not affect the pressure caused by electromagnetic waves and negative pressure. The change of the resistance value caused by the upward deformation of the sensitive resistor; the internal measurement of the sensor on the other side is set as a cavity, and the shock wave signal is received normally. The key is that one group of piezoresistor bridge electrode wiring needs to be connected positively, and the other group of electrodes needs to be connected reversely. Since the electromagnetic wave propagation speed is much faster than the shock wave front propagation speed, it reaches the sensor installation almost at the same time as the detonation. point, and directly superimpose its signal on the signal output line of the sensor through the electromagnetic induction path on the sensor transmission cable. Based on this, the output voltage caused by the slight change in the resistance of the piezoresistor is processed by the signal processing module, and then the positive and negative are offset, so as to eliminate the influence of the output pressure curve on the accuracy of the final measured pressure value.

Description of drawings

Figure 1 is a graph of the shock wave pressure signal measured by a common pressure sensor;

Fig. 2 is a schematic diagram of the internal structure of the piezoresistive high anti-interference shock wave pressure capture device subpackage shell;

Fig. 3 is a schematic diagram of a varistor circuit;

Fig. 4 is a schematic diagram of the module division of the piezoresistive high anti-interference shock wave pressure capture device;

Fig. 5 is a diagram of the shock wave pressure signal measured by the piezoresistive high anti-interference shock wave pressure capture device;

Fig. 6 is a flow chart of signal processing of the piezoresistive high anti-jamming shock wave pressure capture device.

Detailed ways

The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.

The invention discloses a piezoresistive high anti-interference shock wave pressure capturing method and a device thereof.

Taking 2kg TNT explosion as an example, using a piezoresistive high anti-interference shock wave pressure capture device to measure the ground shock wave pressure at a distance of 3m from the detonation point, the sensor parameters are shown in Table 1.

1. Explosives detonate from the detonation point;

2. The initial electromagnetic wave, light radiation and thermal shock generated by the detonation of the explosive act on the force-sensitive area of the sensor. Among them, the force-sensitive area is shown in Figure 2 as varistor 1 and varistor 2, and varistor 1. In the case of no external force, the Wheatstone bridges of piezoresistor 1 and piezoresistor 2 are in a balanced state, as shown in Figure 3, at this time there is no voltage signal output, when the electromagnetic wave and other signals generated by the explosion act on the After the varistor is connected, the resistance value of the resistance forming the Wheatstone bridge changes, and the varistor 1 and varistor 2 bridges are out of balance, outputting a voltage signal;

3. The signal amplifier amplifies the forward and reverse voltage signals received in step 2, as shown in Figure 4, the signal amplifier is connected to the lead-out wire of the sensor package shell, and the inside of the sensor package shell is shown in Figure 2, the pressure sensitive Resistor 1 is filled with a hard material, which will not produce strain when it receives positive pressure, so when piezoresistor 1 receives negative pressure, it will produce strain, and the bridge will lose balance at this time Output voltage signal; voltage The sensitive resistor 2 will generate strain when receiving positive pressure and negative pressure, and output a voltage signal;

4. After the negative pressure caused by the electromagnetic wave, light radiation and thermal shock generated by the explosion acts on the varistor 1 and varistor 2, the two resistors produce the same resistance value change, but due to the output voltage signal Positive and negative, so the positive and negative voltage signals amplified in step 3 are processed by the processor to offset the strong negative pressure signal, so only the micro-oscillation curve will be output at this stage, so the pressure curve will appear before the actual shock wave front reaches the surface of the sensor is no negative pressure signal, as shown in Figure 5;

5. The explosion shock wave reaches the force-sensitive area of the two sets of sensors;

6. Since the inside of the sensor 1 is filled with hard materials, the piezoresistor 1 has no strain after receiving the explosion shock wave signal, that is, the resistance value cannot change, and no voltage signal is output; at the same time, the sensor 2 receives the explosion shock wave signal, and the voltage Sensitive resistor 2 produces strain, the resistance value changes, and outputs a positive voltage signal;

7. The signal amplifier amplifies the voltage signal output by the sensor 2 in step 6;

8. The signal processor processes and outputs the voltage signal in step 7;

9. The signal processor outputs the actual pressure curve of the explosion shock wave. The peak value of the free field shock wave pressure is measured to be 308KPa. As shown in Figure 5, when the shock wave peak value is over, the output pressure signal value shows a tendency to return to zero. The whole action process is shown in Figure 6;

Table 1 Parameters of piezoresistive shock wave pressure sensor

Measuring range 0～15MPa level of accuracy 0.5%FS signal output 0～5V Power supply ±12VDC Compensation temperature range 0℃～60℃ Operating temperature range -40℃～120℃ Zero temperature coefficient 5×10 ⁴ /°C.FS Sensitivity Temperature Coefficient 5×10 ^—4 /°C.FS

Comparative example:

2kg TNT was exploded, and the ground shock wave pressure at a distance of 3m from the detonation point was measured using an ordinary piezoresistive pressure sensor that has not been processed in parallel. The sensor parameters are shown in Table 1.

1. Explosives detonate from the detonation point;

2. The initial electromagnetic wave, light radiation and thermal shock generated by the explosive detonation act on the force-sensitive area of the sensor, causing the piezoresistor to change and output a voltage signal;

3. The signal amplifier amplifies the received forward and reverse voltage signals in step 2;

4. The pressure curve of the amplified voltage signal in step 3 shows an obvious negative pressure signal before the actual shock wave front reaches the surface of the sensor, as shown in Figure 1;

5. The explosion shock wave reaches the force-sensitive area of the two sets of sensors;

6. The sensor receives the explosion shock wave signal, the piezoresistor produces strain, the resistance value changes, and the output voltage signal;

7. The signal amplifier amplifies the voltage signal output by the sensor in step 6;

8. The signal processor processes and outputs the voltage signal in step 7;

9. The signal processor outputs the actual pressure curve of the explosion shock wave. The measured peak value of the free field shock wave pressure is 290KPa. As shown in Figure 1, when the shock wave peak value is over, the output pressure signal value still shows negative pressure.

Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. While preferred embodiments of the present application have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, the appended claims are intended to be construed to cover the preferred embodiment and all changes and modifications which fall within the scope of the application.

Obviously, those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims (7)

1. A piezoresistive high anti-interference shock wave pressure capture device is characterized in that it comprises a sensor package housing, a signal amplification module, a signal processing module and a power supply module, wherein the surface of the sensor package housing is provided with a shock wave capture device, and the shock capture The output end of the device is connected to the input end of the signal amplification module through the sensor packaging shell, and the shock capture device collects electromagnetic wave signals, optical radiation signals, thermal shock signals and shock wave signals and transmits them to the signal amplification module respectively, wherein the shock wave capture device The collected electromagnetic wave signal, optical radiation signal and thermal shock signal are counteracted in a positive and reverse connection with the signal amplification module, and the output end of the shock wave capture device passes through the part inside the sensor package housing to contain part of the shock wave signal by filling the hardness material output, the output end of the signal amplification module is connected to the input end of the signal processing module, the shock wave signal is amplified and processed by the signal processing module to output the actual shock wave pressure curve, and the power module is a signal amplification module and signal processing and output Module power supply. 2. A piezoresistive high anti-interference shock wave pressure capture device according to claim 1, wherein the piezoresistive high anti-interference shock wave pressure capture device also includes a silicon diaphragm, and the silicon diaphragm is fixed on the sensor package On the surface of the shell, the shock wave capture device is embedded in the silicon diaphragm, and the lead wires of the two poles of the shock capture device pass through the sensor packaging shell and are connected to the signal amplification module. 3. A piezoresistive high anti-interference shock wave pressure capture device according to claim 1, wherein the shock wave capture device comprises two piezoresistors distributed in mirror images, and the first piezoresistor is opposite to the signal amplification module. The second varistor is connected to the signal amplification module in the forward direction, and the output terminals of the first signal amplifier and the second signal amplifier are respectively connected to the input terminals of the signal processing module. 4. A piezoresistive high anti-interference shock wave pressure capture device according to claim 3, wherein the piezoresistor comprises a first resistor R ₁ , a second resistor R ₂ , a third resistor R ₃ and a first resistor R 3 . The four resistors _R4 are connected in a rhombus connection to form a Wheatstone bridge, wherein the positive pole of the power module is connected to the common terminal of the first resistor _R1 and the fourth resistor _R4 , and the negative pole of the power module is connected to the second resistor _R2 and the second resistor R2. The common terminal of the three resistors _R3 , the common terminal of the first resistor _R1 and the second resistor _R2 , and the common terminal of the third resistor _R3 and the fourth resistor _R4 are connected to the input terminal of the signal amplifier module as the output terminal. 5. A piezoresistive high anti-interference shock wave pressure capture device according to claim 3, characterized in that, the inside of the sensor package housing is filled with the part where the lead wire of the output end of the first piezoresistor connected to the signal amplification module passes through There are hard materials. 6. A shock wave pressure capture method based on the piezoresistive high anti-interference shock wave pressure capture device according to any one of claims 1-5, characterized in that it comprises the following steps S1. The piezoresistive high anti-interference shock wave pressure capture device collects the electromagnetic wave, light radiation, thermal shock forward voltage signal and reverse voltage signal and the forward voltage signal of the shock wave generated by the explosion; S2. The piezoresistive high anti-interference shock wave pressure capture device amplifies the forward voltage signal and reverse voltage signal of the collected electromagnetic wave, optical radiation and thermal shock signal, and amplifies the amplified electromagnetic wave, optical radiation and thermal shock voltage signal Cancel each other out; S3. The piezoresistive high anti-interference shock wave pressure capture device amplifies and outputs the forward voltage signal of the shock wave. 7. The shock wave pressure capture method according to claim 1, wherein the first piezoresistor in the piezoresistive high anti-interference shock wave pressure capture device is filled with a hardness material, and when collecting the voltage signal of the positive pressure shock wave No signal output.

Images