CN105258784B - A kind of autompulse excitation Modal Parameters Identification and device - Google Patents

Abstract

The invention relates to an automatic pulse excitation modal parameter identification method and device, belonging to the field of vibration testing instruments. In this method, an automatic pulse excitation device is used to automatically excite the tested part, and modules such as a controller, a power amplifier and a multi-function data acquisition card are supplemented to realize the control of the excitation force and the acquisition of the measured signal. The device mainly includes an impact head, a force sensor, a cover, a spring support assembly, a mandrel, a yoke, an excitation coil, an iron core and a base. After the coil is energized, it can drive the iron core to push out to generate an exciting force on the tested object. The force sensor can feedback the excitation force received by the tested part, and the adjustment of the excitation force can be realized by adjusting the amplitude and width of the pulse signal. The invention solves the problems of continuous strike, overload and poor repeatability caused by human factors in the traditional hand-held vibrating hammer. It has compact structure, small volume, high degree of automation, strong repeatability, easy operation, and can improve accuracy and efficiency.

Description

A method and device for automatic pulse excitation modal parameter identification

technical field

The invention relates to an automatic pulse excitation modal parameter identification method and device, belonging to the field of vibration testing instruments.

Background technique

Modal testing is a common method to obtain the dynamic characteristics of the system, and it is widely used in the field of engineering vibration. One of its key issues is to obtain accurate frequency response function data, only on this basis can the modal parameters be accurately identified.

In the traditional mechanical system frequency response function test, the pulse excitation device is a hand-held vibrating hammer. Since the impact force of the hammer striking the specimen is determined by the mass of the hammer head and the movement speed when striking, the hammering method is easy. Affected by human factors, the applied force is not easy to control. If the applied force is too large, it is easy to cause overload; if the applied force is too small, the various modes cannot be excited. During the tapping process, due to the poor grasp of the pulse duration, double-clicking is prone to occur, and repeated tapping is required. Moreover, during the testing process, it cannot be guaranteed that the strength and direction of each tap are completely consistent, so the repeatability is poor. These disadvantages have resulted in the low efficiency and difficult to guarantee the accuracy of the existing modal experiments.

Contents of the invention

The purpose of the present invention is to overcome the deficiency of traditional artificial excitation and solve the problem of unreliable data caused by human factors. Provided is an electromagnetic pulse excitation device which can automatically control the amplitude of the excitation force and realize the automatic excitation operation. And based on this device, an automatic pulse excitation modal parameter identification method is proposed to realize the automation, digitization and high efficiency of modal testing.

Technical scheme of the present invention is as follows:

An automatic pulse excitation modal parameter identification device, driven by a signal generator and a power amplifier, mainly includes an impact head 1, a force sensor 2, a cover body 3, a spring support assembly 4, a push rod 5, a yoke 6, and an excitation coil 7 , Iron core 8 and base 9, as shown in Figure 1. The impact head 1, the force sensor 2, the ejector rod 5 and the iron core 8 are connected to each other and installed on the yoke 6 via the spring support assembly 4, the yoke 6 is installed on the base, and the cover body 3 is installed on one side of the yoke 6. The excitation coil 7 is fixed inside the yoke 6, and the yoke 6 is an all-inclusive structure; after the iron core 8 is fixedly connected with the ejector rod 5, it is supported by the spring support assembly 4 between the center holes of the yoke iron 6, and one end of the ejector rod 5 Protrude from the through hole opened on the top of the cover body 3, and connect the force sensor 2 and the impact head 1 through screws; one end of the iron core 8 goes deep into the vibrator.

The structure of the exciter with the iron core 8 deep into the end has dense leakage flux, and the magnetic field is radial relative to the coil, so the excitation coil 7 will receive axial electromagnetic force after being energized. Since the excitation coil 7 is fixed Therefore, the iron core 8 will be subjected to the electromagnetic force in the opposite direction to generate an exciting force on the tested object. Wherein the spring supporting assembly 4 plays a supporting and rebounding role, and is light in weight and good in toughness.

An automatic pulse excitation modal parameter identification method. The automatic pulse excitation device realizes the automatic excitation of the tested part, and is supplemented by a controller, a power amplifier and a multi-function data acquisition card module to realize the control of the excitation force. And the acquisition of the measured signal, the principle block diagram of this method is shown in Figure 2. The pulse signal is sent out by the controller, converted by the multi-function acquisition card DA and output to the power amplifier, and then amplified by the power amplifier and then output to the automatic pulse excitation device. By adjusting the gain of the power amplifier, the amplitude of the pulse signal or the pulse width, it can Control the size of the exciting force to realize the automatic excitation of the DUT. The force signal can be collected and displayed to the controller through the acquisition card to realize the feedback control of the excitation force. Connect the acceleration sensor to the tested part, collect the force signal and acceleration signal into the computer, and obtain the frequency response function and modal parameters of the tested part after further processing.

The control instrument is composed of a computer with Labview, and the control software written with Labview adjusts the size of the exciting force by changing the pulse amplitude and width. The power amplifier adopts silicon crystal high-power amplifying circuit, OCLC output mode, and the low-frequency amplification performance is good. The size of the exciting force can also be changed by adjusting the gain button of the power amplifier.

The present invention uses autonomous excitation instead of human percussion, is simple to operate, easy to use, can be quickly excited and repeated multiple times, replaces humans to complete repetitive excitation, and can control the magnitude of the excitation force to realize the dynamic characteristics of the CNC machine tool spindle system Online automatic testing. The system effectively eliminates the influence of human factors in the measurement process, making the measurement value more accurate, so as to quickly and automatically obtain a reliable frequency response function of the machine tool to complete the test.

Description of drawings:

Figure 1 Schematic diagram of the section of the automatic pulse excitation device

Figure 2 Schematic diagram of the modal test system

In the picture:

1—impact head 4—spring support assembly 7—excitation coil

2—force sensor 5—push rod 8—iron core

3—cover body 6—yoke iron 9—base

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

S1. Fix the base 9 of the electromagnetic exciter on the plane with screws, install the force sensor 2 between the impact head 1 and the exciter, align the impact head and the force sensor with the point to be tested and adjust a reasonable gap .

S2. Connect the controller, multi-function acquisition card, power amplifier, automatic pulse excitation device and force sensor in sequence, then turn on the power supply of the controller and power amplifier, and increase the gain of the power amplifier appropriately. Start the control software, adjust the appropriate pulse width, and then click the shock button on the front panel to realize automatic excitation of the DUT.

S3. After clicking the impact button on the front panel, the power amplifier will output the pulse voltage of the specified amplitude and pulse width to the automatic pulse excitation device, and the automatic pulse excitation device will generate a magnetic field after the drive coil is energized to magnetize the iron core. The iron core is subjected to electromagnetic force to generate an exciting force on the tested object.

S4. The force sensor installed between the impact head and the ejector rod can collect the force signal into the computer through the data acquisition card. According to the size of the collected force, the amplifier gain and pulse width can be further adjusted to realize the impact force amplitude. feedback control.

S5. Connect the acceleration sensor to the tested part, collect the force signal and the acceleration signal into the computer, and obtain the frequency response function and modal parameters of the tested part through further processing.

The above is an embodiment of the present invention, and the implementation of the present invention is not limited thereto.

Claims (2)

1. An automatic pulse excitation modal parameter identification method, the method is realized by a parameter identification device, which is driven by a signal generator and a power amplifier, and mainly includes an impact head (1), a force sensor (2), a cover body (3 ), spring support assembly (4), ejector rod (5), yoke (6), excitation coil (7), iron core (8), base (9); impact head (1), force sensor (2), After the ejector rod (5) and the iron core (8) are connected to each other, they are installed on the yoke (6) through the spring support assembly (4), the yoke (6) is installed on the base, and the cover (3) is installed on the yoke ( 6) one side; the excitation coil (7) is fixed inside the yoke (6), and the yoke (6) is a fully enclosed structure; (4) Supported between the center holes of the yoke (6), one end of the ejector rod (5) protrudes from the through hole opened on the top of the cover body (3), and connects the force sensor (2) and the impact head (1) through screws ; One end of the iron core (8) goes deep into the vibrator; The structure of the exciter with the iron core (8) deep into the end has dense leakage flux, and the magnetic field is radial relative to the coil, so the excitation coil (7) will be subjected to axial electromagnetic force after being energized. The coil (7) is fixed, so the iron core (8) will be subjected to the electromagnetic force in the opposite direction to generate an exciting force on the measured piece; wherein the spring support assembly (4) plays a role of supporting and rebounding; It is characterized in that: the automatic pulse excitation device realizes the automatic vibration excitation of the tested part, supplemented by a controller, a power amplifier and a multi-function data acquisition card module to realize the control of the excitation force and the acquisition of the measured signal ; The pulse signal is sent by the controller, converted by the multi-function acquisition card DA, then analog output to the power amplifier, and then amplified by the power amplifier and then output to the automatic pulse excitation device. By adjusting the gain of the power amplifier, the amplitude of the pulse signal or the pulse width, It can control the size of the exciting force to realize the automatic vibration of the tested part; the force signal can be collected and displayed to the controller through the acquisition card to realize the feedback control of the exciting force; the acceleration sensor is connected to the tested part, The force signal and acceleration signal are collected into the computer, and the frequency response function and modal parameters of the tested part are obtained after further processing; the controller is composed of a computer with Labview, and the control software written in Labview changes the pulse amplitude and width Adjust the size of the excitation force; the power amplifier adopts a silicon crystal high-power amplifier circuit, OCLC output mode, and the low-frequency amplification performance is good; the size of the excitation force can also be changed by adjusting the gain button of the power amplifier. 2. A kind of automatic pulse excitation modal parameter identification method according to claim 1, is characterized in that: S1. Fix the electromagnetic exciter base (9) on the plane with screws, install the force sensor (2) between the impact head (1) and the exciter, and the impact head and force sensor are connected to the point to be tested Align and adjust a reasonable gap; S2. Connect the controller, multi-function acquisition card, power amplifier, automatic pulse excitation device and force sensor in sequence, then connect the power supply of the controller and power amplifier, and increase the gain of the power amplifier appropriately; start the control software, adjust the pulse width, Then click the shock button on the front panel to realize the automatic excitation of the DUT; S3. After clicking the impact button on the front panel, the power amplifier will output the pulse voltage of the specified amplitude and pulse width to the automatic pulse excitation device, and the automatic pulse excitation device will generate a magnetic field after the drive coil is energized to magnetize the iron core. The iron core is subjected to electromagnetic force to generate an exciting force on the tested part; S4. The force sensor installed between the impact head and the ejector rod can collect the force signal into the computer through the data acquisition card. According to the size of the collected force, the amplifier gain and pulse width can be further adjusted to realize the impact force amplitude. feedback control; S5. Connect the acceleration sensor to the tested part, collect the force signal and the acceleration signal into the computer, and obtain the frequency response function and modal parameters of the tested part through further processing.