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

Abstract

The application discloses a kind of piezoresistive high anti-interference shock wave pressure capture method and device, by sensor package body, signal amplification module, signal processing module and power module composition.The sensor package shell is arranged two groups by piezoresistance, silicon diaphragm and is composed of shock wave capture device, one side in it is filled with hardness material completely, and the other side is cavity.Key lies in one group piezoresistance bridge road electrode wiring needs positive connection, and the other group electrode needs reverse connection, since electromagnetic wave propagation speed is much faster than shock wave propagation speed, thus it reaches the installation point of sensor at the same time when detonation, and is directly superimposed on its signal on the signal output line of sensor on sensor transmission cable by electromagnetic induction approach.The output voltage caused by piezoresistance resistance value micro change is handled after signal processing module, and positive and negative phase is offset, to achieve the purpose of eliminating the influence of final measured pressure value accuracy due to output pressure curve oscillation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of shock wave pressure test, and particularly relates to a piezoresistive high anti-interference shock wave pressure capturing method and device. BACKGROUND

[0002] Shock wave overpressure is an important measurement content of blast-resistant engineering structure blast experiment. At present, the commonly used pressure sensors in shock wave pressure test are divided into two types, namely piezoelectric pressure sensor and piezoresistive pressure sensor. However, the two types of sensors are greatly affected by light radiation, electromagnetic radiation and other factors generated by explosion in the pressure measurement process, which finally affects the reliability of the shock wave overpressure value.

[0003] The piezoresistive sensor has the advantages of very high sensitivity, high resolution, high frequency response and little influence of vibration generated by explosion, and particularly has the incomparable advantages of piezoelectric sensor, such as very high natural frequency and very wide dynamic response range, so it gradually becomes an important technical means for measuring shock wave overpressure in explosion field. Unlike piezoelectric sensors, the commonly used piezoresistive sensors have silicon diaphragms as sensitive parts, which have strong sensitivity to light radiation, electromagnetic radiation and thermal shock in the infrared to visible light range, and are easily disturbed by electromagnetic radiation, light radiation and thermal shock generated by explosion.

[0004] In the process of explosive explosion, gas explosion and other processes, in addition to the generation of shock wave, electromagnetic radiation, light radiation, vibration impact and other interference factors are also generated in the initiation process. The light radiation and electromagnetic radiation generated by explosion rapidly attenuate with the increase of distance, so when the sensor is arranged and installed in the well-protected middle and far field, the electromagnetic wave and light radiation can be greatly attenuated, and generally will not affect the measurement signal of the shock wave. However, in the case of near-field arrangement of the pressure sensor, the electromagnetic wave and light radiation signal will be superimposed on the shock wave signal, thereby seriously interfering with the measurement of the shock wave pressure, especially in the measurement of the shock wave overpressure of chemical explosion such as fuel gas with a long acting time, the influence of light and heat radiation is greater, so the initial signal output by the sensor occurs high-frequency oscillation, causing the measured pressure value to produce error or even distortion, greatly limiting the use scene of the piezoresistive pressure sensor.

[0005] Chinese invention patent 200510037982.2 discloses a device composition and principle of piezoresistive high-frequency dynamic high-pressure sensor, mainly composed of piezoresistive sensitive component, sensor base, switching circuit and lead-out cable, solves the problem of direct flush packaging of pressure sensitive diaphragm stress surface, realizes the requirement of high dynamic frequency response and extremely small rise time of sensor in dynamic high-pressure measurement. Chinese patent 200510038458.7 piezoresistive high-frequency dynamic low-pressure sensor device composition and principle, composed of piezoresistive sensitive component, sensor base, switching circuit and lead-out cable, is a high-frequency dynamic piezoresistive low-pressure sensor based on MEMS (Micro Electro Mechanical System) silicon body micro-machining technology, especially suitable for dynamic pressure measurement of aerodynamics test (commonly known as wind tunnel test), water conservancy engineering, aerospace, weapon test, ship, etc., with good dynamic frequency response performance.

[0006] The above two devices and methods weaken the interference and influence of electromagnetic wave and light radiation to a certain extent, but still cannot eliminate the influence of the voltage signal caused by the interference before the explosion shock wave overpressure reaches the piezoresistive sensitive element (such as Figure 1 the curve in the block), for this, the general method is to change the overpressure wave starting point caused by the baseline drop of the negative pulse residue, consider it in the calculation of overpressure wave, obviously, this method has certain error. The measured shock wave pressure curve of the pressure sensor is shown in Figure 1 .

[0007] At present, in order to weaken the influence of electromagnetic wave and the like on the output signal of the sensor, the mainstream methods are roughly divided into two kinds: one is to add a protective film to the sensor, which will cause the loss of frequency response and the reduction of dynamic performance of the sensor; the other method is to smear vaseline, silicon oil and the like on the surface of the force sensitive area of the sensor, but this method will affect the measurement accuracy of the sensor. SUMMARY

[0008] In order to solve the technical problems mentioned in the above background art, the present application proposes a piezoresistive high anti-interference shock wave pressure capturing method and device.

[0009] In order to achieve the above technical purpose, the technical scheme of the present application is:

[0010] The piezoresistive high anti-interference shock wave pressure capturing device comprises a sensor packaging shell, a signal amplification module, a signal processing module and a power module, wherein the surface of the sensor packaging shell is provided with a shock wave capturing device, the output end of the shock capturing device is connected with the input end of the signal amplification module through the sensor packaging shell, the shock capturing device collects electromagnetic wave signals, light radiation signals, thermal shock signals and shock wave signals and transmits them to the signal amplification module, wherein the shock wave capturing device offsets the collected electromagnetic wave signals, light radiation signals and thermal shock signals through positive and negative connection with the signal amplification module, the output end of the shock wave capturing device is filled with a hardness material to suppress the output of part of the shock wave signals in the inside of the sensor packaging shell, the output end of the signal amplification module is connected with the input end of the signal processing module, the shock wave signals are amplified and then output actual shock wave pressure curves after being processed by the signal processing module, and the power module supplies power for the signal amplification module and the signal processing and output module.

[0011] Preferably, the piezoresistive high anti-interference shock wave pressure capturing device further comprises a silicon diaphragm fixed to the surface of the sensor packaging shell, and the shock wave capturing device is embedded in the silicon diaphragm, and the lead wires of the two poles of the shock capturing device are connected with the signal amplification module through the sensor packaging shell.

[0012] Preferably, the shock wave capturing device comprises two mirror-distributed piezoresistors, the first piezoresistor is reversely connected with the signal amplification module, the second piezoresistor is positively connected with the signal amplification module, and the output ends of the first signal amplifier and the second signal amplifier are respectively connected with the input ends of the signal processing module.

[0013] Further, the piezoresistor comprises a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 which are connected in a rhombus connection mode to form a Wheatstone bridge, wherein the positive pole of the power module is connected with the common end of the first resistor R1 and the fourth resistor R4, the negative pole of the power module is connected with the common end of the second resistor R2 and the third resistor R3, and the common end of the first resistor R1 and the second resistor R2 and the common end of the third resistor R3 and the fourth resistor R4 are connected with the input end of the signal amplifier amplification module as the output end.

[0014] Further, the inside of the sensor packaging shell is filled with a hardness material through which the output end lead wire of the first piezoresistor connected with the signal amplification module passes.

[0015] A shock wave pressure capturing method based on the piezoresistive high anti-interference shock wave pressure capturing device, comprising the following steps

[0016] S1, the piezoresistive high anti-interference shock wave pressure capturing device collects electromagnetic waves, light radiation, thermal shock positive voltage signals and reverse voltage signals and shock wave positive voltage signals generated by explosion;

[0017] S2, the piezoresistive high anti-interference shock wave pressure capturing device amplifies the positive voltage signal and the reverse voltage signal of the collected electromagnetic wave, light radiation and thermal shock signal, and offsets the voltage signals of the amplified electromagnetic wave, light radiation and thermal shock from each other;

[0018] S3, the piezoresistive high anti-interference shock wave pressure capturing device amplifies the positive voltage signal of the shock wave and outputs.

[0019] Preferably, the first piezoresistor in the piezoresistive high anti-interference shock wave pressure capturing device is filled with a hardness material inside, and there is no signal output when collecting the voltage signal of the positive pressure shock wave.

[0020] The beneficial effects brought by the above technical scheme are:

[0021] The present application cleverly designs two groups of piezoresistors to be used at the same time, and the key is that the inside of one sensor is completely filled with a hardness material to prevent the piezoresistor from deforming downward after being contacted by the shock wave, thereby causing the resistance value to change, but it does not affect the upward deformation of the piezoresistor caused by the electromagnetic wave and negative pressure, thereby causing the resistance value to change; the inside of the other sensor is a hollow cavity, which normally receives the shock wave signal. The key is that one group of piezoresistor bridge electrodes needs to be connected in positive, and the other group of electrodes needs to be connected in reverse. Since the electromagnetic wave propagates much faster than the shock wave wavefront propagation speed, it reaches the installation point of the sensor almost at the same time as the explosion, and it directly superimposes its signal on the signal output line of the sensor through electromagnetic induction on the sensor transmission cable. Based on this, the output voltage caused by the slight change of the piezoresistor resistance value is processed by the signal processing module, and the positive and negative phases are offset, thereby achieving the purpose of eliminating the influence of the final measured pressure value accuracy caused by the oscillation of the output pressure curve. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a measured shock wave pressure signal diagram of a common pressure sensor;

[0023] Figure 2 is a schematic diagram of the internal structure of the piezoresistive high anti-interference shock wave pressure capturing device;

[0024] Figure 3 is a piezoresistor circuit schematic diagram;

[0025] Figure 4 is a module division schematic diagram of the piezoresistive high anti-interference shock wave pressure capturing device;

[0026] Figure 5 is a measured shock wave pressure signal diagram of the piezoresistive high anti-interference shock wave pressure capturing device;

[0027] Figure 6It is a signal processing flow chart of a piezoresistive high anti-interference shock wave pressure capturing device. DETAILED DESCRIPTION

[0028] The technical solutions of the application will be described in detail below with reference to the drawings.

[0029] The application discloses a piezoresistive high anti-interference shock wave pressure capturing method and device.

[0030] Taking the explosion of 2 kg of TNT as an example, the piezoresistive high anti-interference shock wave pressure capturing device is used to measure the ground shock wave pressure at a distance of 3 m from the explosion point, and the sensor parameters are shown in Table 1.

[0031] 1. The explosive is exploded from the explosion point;

[0032] 2. The explosion of the explosive generates an initial electromagnetic wave, light radiation, heat shock and the like to act on the force-sensitive area of the sensor, wherein the force-sensitive area is shown in the pressure-sensitive resistor 1 and the pressure-sensitive resistor 2, the pressure-sensitive resistor 1. Figure 2 In the absence of external force, the Wheatstone bridge circuit of the pressure-sensitive resistor 1 and the pressure-sensitive resistor 2 is in a balanced state, as shown in the figure, at this time, no voltage signal is output, when the electromagnetic wave and the like generated by the explosion act on the pressure-sensitive resistor, the resistance value of the resistor forming the Wheatstone bridge circuit changes, the pressure-sensitive resistor 1 and the pressure-sensitive resistor 2 bridge lose balance, and output a voltage signal. Figure 3

[0033] 3. The signal amplifier amplifies the positive and negative voltage signals received in step 2, as shown in the figure, the signal amplifier is connected with the lead-out wire of the sensor packaging shell, and the inside of the sensor packaging shell is shown in the figure. Figure 4 Figure 2 The pressure-sensitive resistor 1 is filled with a hardness material, and will not produce strain in the case of receiving positive pressure, so strain will be produced in the case of receiving negative pressure, at this time, the bridge loses balance and outputs a voltage signal; the pressure-sensitive resistor 2 will produce strain in the case of receiving positive pressure and negative pressure, and output a voltage signal.

[0034] 4. After the negative pressure caused by the electromagnetic wave, light radiation, heat shock and the like generated by the explosion acts on the pressure-sensitive resistor 1 and the pressure-sensitive resistor 2, the two resistors produce the same resistance value change, but the output voltage signals are 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, therefore, only a microseismic oscillation curve will be output in this stage, so before the actual shock wave wavefront reaches the surface of the sensor, the pressure curve shows no negative pressure signal, as shown in the figure. Figure 5

[0035] 5. The explosion shock wave reaches the force-sensitive areas of the two groups of sensors.

[0036] ​​​6. Since the interior of sensor 1 is filled with hard material, varistor 1 does not generate strain after receiving the explosion shock wave signal, that is, no resistance change occurs, and no voltage signal is output; at the same time, sensor 2 receives the explosion shock wave signal, varistor 2 generates strain, the resistance value changes, and a positive voltage signal is output;

[0037] 7. The signal amplifier amplifies the voltage signal output by the sensor 2 in step 6;

[0038] 8. The signal processor processes and outputs the voltage signal in step 7;

[0039] 9. The signal processor outputs the actual pressure curve of the explosion shock wave, and the peak pressure of the free field shock wave is measured to be 308KPa. Figure 5 As shown in Figure 1, when the peak value of the shock wave ends, the output pressure signal value shows a trend of returning to zero. Figure 6 As shown;

[0040] Table 1 Parameters of piezoresistive shock wave pressure sensor

[0041] Measuring range 0~15MPa Accuracy level 0.5% FS Signal output 0～5V Power supply mode ±12VDC Compensated temperature range 0℃～60℃ Operating temperature range -40℃～120℃ Zero temperature coefficient 5x10 4 / °C. FS Sensitivity temperature coefficient 5 x 10 —4 / °C. FS

[0042] Comparative Examples:

[0043] A 2kg TNT explosion was used to measure the ground shock wave pressure at a distance of 3m from the detonation point using a standard piezoresistive pressure sensor without parallel connection. The sensor parameters are shown in Table 1.

[0044] 1. The explosive detonates from the detonation point;

[0045] 2. The initial electromagnetic waves, light radiation and thermal shock generated by the detonation of explosives act on the force-sensitive area of ​​the sensor, causing the piezoresistor to change and output a voltage signal;

[0046] 3. The signal amplifier amplifies the positive and reverse voltage signals received in step 2;

[0047] 4. The pressure curve of the voltage signal amplified in step 3 shows an obvious negative pressure signal before the actual shock wave front reaches the sensor surface, such as Figure 1 As shown;

[0048] 5. The explosion shock wave reaches the force-sensitive areas of the two sets of sensors;

[0049] 6. The sensor receives the explosion shock wave signal, the piezoresistor generates strain, the resistance value changes, and the output voltage signal;

[0050] 7. The signal amplifier amplifies the voltage signal output by the sensor in step 6;

[0051] 8. The signal processor processes the voltage signal in step 7 and outputs;

[0052] 9. The signal processor outputs the actual pressure curve of the explosion shock wave, and the measured free field shock wave pressure peak value is 290 KPa, as shown in Figure 1 The output pressure signal value still shows negative pressure after the end of the shock wave peak value action.

[0053] Those skilled in the art will appreciate that embodiments of the application can be provided as methods, systems, or computer program products. Accordingly, the application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Although the preferred embodiments of the application have been described, those skilled in the art will appreciate that modifications and variations to the preferred embodiments can be made without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims encompass all such modifications and variations as fall within the scope of the application.

[0054] Obviously, various modifications and changes can be made to the application without departing from the spirit and scope of the application. Accordingly, it is intended that the application embrace all such modifications and changes as fall within the scope of the claims and their equivalents.

Claims

1. A piezoresistive high-jamming-impact shock wave pressure capturing device, characterized in that, The sensor packaging shell is provided with an impact wave capturing device on the surface, the output end of the impact capturing device is connected with the input end of the signal amplification module through the sensor packaging shell, the impact capturing device collects electromagnetic wave signals, light radiation signals, thermal impact signals and shock wave signals and transmits them to the signal amplification module, wherein the impact wave capturing device offsets the collected electromagnetic wave signals, light radiation signals and thermal impact signals through positive and negative connection with the signal amplification module, the output end of the impact wave capturing device is partially filled with a hardness material to suppress the output of part of the shock wave signals inside the sensor packaging shell, the output end of the signal amplification module is connected to the input end of the signal processing module, the shock wave signals are amplified and then processed by the signal processing module to output the actual shock wave pressure curve, and the power module supplies power to the signal amplification module and the signal processing and output module; the impact wave capturing device comprises two mirror image distributed piezoresistors, the first piezoresistor is reversely connected with the signal amplification module, the second piezoresistor is positively connected with the signal amplification module, the output ends of the first signal amplifier and the second signal amplifier are respectively connected to the input end of the signal processing module, and the part of the sensor packaging shell inside which the output end lead wire of the first piezoresistor connected with the signal amplification module passes is filled with a hardness material.

2. The piezoresistive high anti-interference shock wave pressure capturing device according to claim 1, wherein, The piezoresistive high anti-interference shock wave pressure capturing device further comprises a silicon diaphragm fixed to the surface of the sensor packaging shell, and the impact wave capturing device is embedded in the silicon diaphragm, and the lead wires of the two poles of the impact capturing device are connected with the signal amplification module through the sensor packaging shell.

3. The piezoresistive high-jamming-impact shock wave pressure trap device according to claim 2, wherein, The piezoresistor comprises a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 which are connected in a rhombus connection mode to form a Wheatstone bridge, wherein the positive electrode of the power module is connected to the common end of the first resistor R1 and the fourth resistor R4, the negative electrode of the power module is connected to the common end of the second resistor R2 and the third resistor R3, and the common end of the first resistor R1 and the second resistor R2 and the common end of the third resistor R3 and the fourth resistor R4 are connected to the input end of the signal amplifier amplification module as the output end.

4. A shock wave pressure capturing method based on the piezoresistive high- interference-impulse wave pressure capturing device according to any one of claims 1 to 3, characterized in that, The piezoresistive high anti-interference shock wave pressure capturing device comprises the following steps: S1, the piezoresistive high anti-interference shock wave pressure capturing device collects electromagnetic waves, light radiation, thermal impact positive voltage signals and reverse voltage signals and shock wave positive voltage signals generated by explosion; S2, the piezoresistive high anti-interference shock wave pressure capturing device amplifies the positive voltage signals and reverse voltage signals of the collected electromagnetic wave signals, light radiation signals and thermal impact signals, and offsets the voltage signals of the amplified electromagnetic wave signals, light radiation signals and thermal impact signals; S3, the piezoresistive high anti-interference shock wave pressure capturing device amplifies and outputs the positive voltage signals of the shock wave.

5. The shockwave pressure capture method of claim 4, wherein, The first piezoresistor in the piezoresistive high anti-interference shock wave pressure capturing device is filled with a hardness material, and no signal is output when collecting the voltage signals of the positive pressure shock wave.

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