A method of measuring impact acceleration

Abstract

The application provides an impact acceleration measurement method based on an impact acceleration measurement device, which comprises an impact wave generating device, a piezoelectric pressure sensor, a test block, a charge amplifier, a dynamic signal test collector, a microcomputer and a MATLAB simulation environment, and the measurement method comprises the following steps: step 1, determining the measurement point position of the measured equipment, and selecting the piezoelectric pressure sensor and the test block to be installed; step 2, applying impact charge to the measured equipment by using the impact wave generating device, testing, and collecting force signals; and step 3, calculating the time-domain acceleration according to the collected force signals, so that the application has the advantages of providing a device with simple structure, convenient operation and accurate impact acceleration measurement, and providing a measurement impact acceleration method with the advantages of eliminating low-frequency zero drift, not being controlled by frequency size and high testing precision.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of impact acceleration measurement, and particularly relates to an impact acceleration measurement method. BACKGROUND

[0002] At present, acceleration is one of the main physical quantities in vibration and impact measurement and analysis. In the impact resistance test of gas turbines and key components, a direct measurement method is often used, that is, an acceleration sensor is used to measure the impact acceleration of the whole machine and key components. However, in the measurement and data processing of impact acceleration, the output baseline often deviates from zero, that is, the zero drift phenomenon occurs, so that the measurement data cannot reflect the true impact state at low frequency, and the test result is inaccurate. Therefore, it is necessary to suppress and reduce the low-frequency zero drift to ensure the accuracy of measurement.

[0003] The main reasons for causing the zero drift phenomenon are: one is the influence of the piezoelectric material and manufacturing process of the sensor itself, and the other is the influence of external factors such as cable noise, charge amplifier and post-processing conditioning circuit. At present, the commonly used methods to solve the zero drift are: mechanical filtering method, improved wavelet correction method, Fourier transform-spring oscillator correction method, wavelet transform-spring oscillator correction method, selection of sensors with high value, high frequency response characteristics and external design improvement, etc. Research shows that taking the above reasonable measures has a certain effect on reducing and suppressing the zero drift phenomenon. The piezoelectric pressure sensor has the advantages of good frequency response characteristics, large range, high sensitivity, simple structure, etc., and can be used to solve the problem of poor low-frequency characteristics of the acceleration sensor in combination with the FFT technology. SUMMARY

[0004] The present application provides an impact acceleration measurement method, which provides a device with simple structure, convenient operation and accurate measurement of impact acceleration, and also provides a method for measuring impact acceleration with elimination of low-frequency zero drift, without frequency size control and high test precision.

[0005] The technical scheme of the present application is implemented as follows: an impact acceleration measurement device, comprising an impact wave generating device, a piezoelectric pressure sensor, a test block, a charge amplifier, a dynamic signal test and collection instrument, a microcomputer and a MATLAB simulation environment, wherein the impact wave generating device is connected to one side of the measured equipment, the piezoelectric pressure sensor is arranged at the measurement point of the measured equipment, the test block is arranged on the upper surface of the piezoelectric pressure sensor, and the piezoelectric pressure sensor, the charge amplifier, the dynamic signal test and collection instrument, the microcomputer and the MATLAB simulation environment are sequentially connected and arranged.

[0006] A measurement method using the impact acceleration measurement device according to claim 1, comprising the following steps:

[0007] Step 1, determine the measuring point position of the device under test, and select piezoelectric pressure sensor and test block for installation;

[0008] Step 2, use the shock wave generating device to apply shock charge to the device under test, test, and complete the collection of force signals;

[0009] Step 3, calculate the time domain acceleration according to the collected force signals.

[0010] As a preferred embodiment, the piezoelectric pressure sensor in step 1 has an acceleration compensation structure, and the mass of the test block is 1-2 kg.

[0011] As a preferred embodiment, the measuring point position in step 1 is the horizontal direction of the device under test.

[0012] As a preferred embodiment, the shock load in step 2 is a positive and negative half-sine wave generated by a 5000 kg transverse impact machine.

[0013] As a preferred embodiment, the collection method of force signals in step 2 is that the detection signal of the piezoelectric pressure sensor is amplified by a charge amplifier and then input into a dynamic signal test collection instrument, and after the microcomputer processes and stores the data of the dynamic signal test collection instrument, the collection of the force signals is completed.

[0014] As a preferred embodiment, the method for calculating the time domain acceleration according to the collected force signals in step 3 is that the frequency spectrum F(k) of the force signal f(t) is obtained, and then the amplitude A fx , circular frequency ω k and initial phase angle of each harmonic component of the force signal are obtained, according to the mechanical principle, the amplitude A ak and initial phase angle of each harmonic component of the acceleration are obtained, the acceleration frequency spectrum A(k) is obtained, and then the time domain acceleration a(t) is obtained.

[0015] As a preferred embodiment, the force signal f(t) is a polyharmonic force discrete signal, and its expression is:

[0016]

[0017] According to the fast Fourier transform FFT technique, the frequency spectrum F(k) is obtained, and its expression is:

[0018]

[0019] wherein,

[0020]

[0021] wherein, respectively are the amplitude, circular frequency and initial phase angle of each harmonic component; respectively are the real part and imaginary part of the complex number obtained by Fourier transform of each harmonic component; T is the sample length, and N is the number of collected data within time T.

[0022] As a preferred embodiment, the acceleration of the point to be measured is obtained according to the relationship between force and acceleration as follows:

[0023]

[0024] wherein,

[0025]

[0026] wherein, m is the mass of the test block, respectively are the amplitude and initial phase angle of the acceleration generated by each harmonic component. Through calculation, the real part and imaginary part of each harmonic component in the frequency domain are respectively:

[0027]

[0028] Further, the acceleration frequency spectrum A(k) is obtained, and the expression thereof is as follows:

[0029]

[0030] As a preferred embodiment, according to the acceleration frequency spectrum A(k), the method for obtaining the time-domain acceleration a(t) is as follows: inverse fast Fourier transform (IFFT) is performed on the acceleration frequency spectrum A(k), and the obtained time-domain acceleration a(t) is obtained.

[0031] After the above technical solution is adopted, the application has the following advantages:

[0032] 1. The piezoelectric pressure sensor has the advantages of good frequency response characteristics, wide frequency range, high sensitivity, simple structure, etc., and can realize more range measurement of low frequency and high frequency, and has high test precision. In addition, the piezoelectric pressure sensor with acceleration compensation is selected, which can greatly weaken the influence of the acceleration signal caused by mechanical vibration on the actual measured pressure signal, so that the measurement result is accurate and reliable.

[0033] 2. The piezoelectric pressure sensor is used for measuring impact acceleration, and the instruments involved are some commonly used test equipment, without the need for additional investment, and easy to operate, saving a lot of manpower, material resources and financial resources.

[0034] 3. The FFT and IFFT technologies are adopted, and the programming is simple, the calculation precision is high, and the speed is fast.

[0035] 4. The device can effectively measure low-frequency acceleration, suppress zero drift phenomenon, and has high engineering practical value. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Fig. 1 The flow chart of the present application;

[0038] Fig. 2 The structural schematic diagram of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] According to Figs. 1-2 As shown in the figure, an impact acceleration measuring device includes an impact wave generating device, a piezoelectric pressure sensor, a test block, a charge amplifier, a dynamic signal test and collection instrument, a microcomputer and a MATLAB simulation environment. The impact wave generating device is connected to one side of the measured equipment. The piezoelectric pressure sensor is arranged at the measuring point of the measured equipment. The test block is arranged on the upper surface of the piezoelectric pressure sensor. The piezoelectric pressure sensor, the charge amplifier, the dynamic signal test and collection instrument, the microcomputer and the MATLAB simulation environment are sequentially connected.

[0041] The impact wave generating device applies impact load to the measured equipment. The detection signal of the piezoelectric pressure sensor is amplified by the charge amplifier and then input to the dynamic signal test and collection instrument. The microcomputer processes and stores the data of the dynamic signal test and collection instrument to complete the collection of force signals. In the MATLAB simulation environment, the FFT and IFFT technologies are used to obtain the time-domain acceleration signal. The device has simple structure, convenient operation and can effectively measure low-frequency acceleration.

[0042] A measurement method using the impact acceleration measuring device according to claim 1, comprising the following steps:

[0043] Step 1, determine the measuring point position of the device under test, and select piezoelectric pressure sensor and test block for installation;

[0044] Step 2, use the shock wave generating device to apply shock charge to the device under test, test, and complete the collection of force signals;

[0045] Step 3, calculate the time domain acceleration according to the collected force signals.

[0046] The piezoelectric pressure sensor in step 1 has an acceleration compensation structure, and the mass of the test block is 1-2 kg.

[0047] In this embodiment, the method of determining the measuring point position of the device under test and selecting piezoelectric pressure sensor and test block is a common technical means, so it will not be described in detail here. In this embodiment, the piezoelectric pressure sensor and test block with appropriate range and sensitivity are selected to achieve low-frequency and high-frequency measurement with a larger range and high test accuracy. In addition, the piezoelectric pressure sensor with acceleration compensation can greatly weaken the influence of acceleration signals caused by mechanical vibration on the actual measured pressure signals, making the measurement results accurate and reliable.

[0048] The piezoelectric pressure sensor with acceleration compensation structure in this embodiment is also a common technical means in the prior art, so it will not be described in detail here.

[0049] The measuring point position in step 1 is the horizontal direction of the device under test.

[0050] The impact load in step 2 is a positive and negative half-sine wave generated by a 5000 kg transverse impact machine.

[0051] In step 2, the detection signal of the piezoelectric pressure sensor is amplified by a charge amplifier and input to a dynamic signal test acquisition instrument. After the microcomputer processes and stores the data of the dynamic signal test acquisition instrument, the collection of the force signal is completed.

[0052] In step 3, the method for calculating the time domain acceleration according to the collected force signals is as follows: according to the force signal f(t), its frequency spectrum F(k) is obtained, and then the amplitude A fx , circular frequency ω k and initial phase angle of each harmonic component of the force signal are obtained. According to the mechanical principle, the amplitude A ak and initial phase angle of each harmonic component of the acceleration are obtained, the acceleration frequency spectrum A(k) is obtained, and then the time domain acceleration a(t) is obtained.

[0053] The force signal f(t) is a polyharmonic force discrete signal, and its expression is:

[0054]

[0055] According to the fast Fourier transform FFT technique, the frequency spectrum F(k) thereof is obtained, and the expression thereof is as follows:

[0056]

[0057] wherein,

[0058]

[0059] wherein, are respectively the amplitude, the circular frequency and the initial phase angle of each harmonic component; are respectively the real part and the imaginary part of the complex number obtained by Fourier transform of each harmonic component; T is the sample length, and N is the number of collected data within the time T.

[0060] According to the relationship between force and acceleration, the acceleration of the point to be measured is obtained as follows:

[0061]

[0062] wherein,

[0063]

[0064] wherein, m is the mass of the test block, are respectively the acceleration amplitude and the initial phase angle generated by each harmonic component. Through calculation, the real part and the imaginary part of each harmonic component in the frequency domain are as follows:

[0065]

[0066] Further, the acceleration frequency spectrum A(k) is obtained, and the expression thereof is as follows:

[0067]

[0068] According to the acceleration frequency spectrum A(k), the method for obtaining the time-domain acceleration a(t) is as follows: the inverse fast Fourier transform IFFT is performed on the acceleration frequency spectrum A(k), and the obtained time-domain acceleration a(t) is obtained.

[0069] By using the piezoelectric pressure sensor with the acceleration compensation structure, and combining the FFT and IFFT techniques to measure the impact acceleration, on the one hand, the influence of the acceleration signal caused by mechanical vibration on the measured pressure signal is greatly weakened, so that the measurement result is accurate and reliable; on the other hand, the effective measurement of low-frequency acceleration can be realized, the zero drift phenomenon is suppressed, and the method has high engineering practical value.

[0070] In the description of the application, it is to be understood by the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In the description of the application, unless otherwise specified and limited, it is to be noted that the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be mechanical connection or electrical connection, it can be the communication between the two elements inside, it can be directly connected, or indirectly connected through intermediate medium, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0071] The above is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A shock acceleration measurement method characterized by, The method is based on an impact acceleration measuring device, wherein the impact acceleration measuring device comprises an impact wave generating device, a piezoelectric pressure sensor, a test block, a charge amplifier, a dynamic signal test collector, a microcomputer and a MATLAB simulation environment, wherein the impact wave generating device is connected to one side of the measured equipment, the piezoelectric pressure sensor is arranged at the measuring point of the measured equipment, the test block is arranged on the upper surface of the piezoelectric pressure sensor, and the piezoelectric pressure sensor, the charge amplifier, the dynamic signal test collector, the microcomputer and the MATLAB simulation environment are sequentially connected. The measurement method of the impact acceleration measuring device comprises the following steps: Step 1, determining the measuring point position of the measured equipment, and selecting a piezoelectric pressure sensor and a test block for installation; Step 2, using the impact wave generating device to apply an impact charge to the measured equipment for testing and completing the collection of force signals; Step 3, calculating the time-domain acceleration according to the collected force signals; The method for calculating time-domain acceleration according to the collected force signal in step 3 is to obtain the spectrum F(k) of the force signal f(t), and then obtain the amplitude A of each harmonic component of the force signal fx , circular frequency ω k and initial phase angle According to the mechanical principle, the amplitude A ak and initial phase angle of each harmonic component of the acceleration are obtained, the acceleration spectrum A(k) is obtained, and then the time-domain acceleration a(t) is obtained; The force signal f(t) is a multi-harmonic force discrete signal, and its expression is: According to the fast Fourier transform FFT technology, the frequency spectrum F(k) is obtained, and its expression is: Wherein, wherein, are the amplitude, circular frequency and initial phase angle of each harmonic component, respectively; are the real and imaginary parts of the complex number obtained by Fourier transform of each harmonic component, respectively; T is the sample length, and N is the number of collected data within the time T. The relationship between the force and the acceleration is that the acceleration of the measuring point is: Wherein, wherein m is the mass of the test block, The acceleration amplitude and initial phase angle of each harmonic component are calculated, and the real part and the imaginary part of each harmonic component in the frequency domain are calculated, respectively. Further, the acceleration frequency spectrum A(k) is obtained, and its expression is: 。 2. A method of impact acceleration measurement according to claim 1, wherein The piezoelectric pressure sensor in step 1 has an acceleration compensation structure, and the mass of the test block is 1-2 kg.

3. A method of impact acceleration measurement according to claim 1, wherein The measuring point position in step 1 is the horizontal direction of the measured equipment.

4. A method of impact acceleration measurement according to claim 1, wherein The impact load in step 2 is a positive and negative half-sine wave generated by a 5000kg transverse impact machine.

5. A method of impact acceleration measurement according to claim 1, wherein The force signal collection method in step 2 is that the detection signal of the piezoelectric pressure sensor is amplified by the charge amplifier and then input into the dynamic signal test collector, and the microcomputer processes and stores the data of the dynamic signal test collector, thereby completing the collection of the force signal.

6. A method of impact acceleration measurement according to claim 1, wherein According to the acceleration frequency spectrum A(k), the method for obtaining the time-domain acceleration a(t) is that the inverse fast Fourier transform IFFT of the acceleration frequency spectrum A(k) is performed, and the obtained time-domain acceleration a(t) is obtained.

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