Vibration analysis device and vibration analysis method

Abstract

A vibration analysis device for a structure in which a structural body is joined at fastening sections, the vibration analysis device having: a vibration force application unit that generates an excitation force or excitation moment (excitation force, etc.); a force measurement unit that measures the excitation force, etc.; a fastening section load estimation unit that estimates the central load of the fastening section to which the excitation force, etc. is applied; and a structure analysis unit that analyzes the vibration characteristics of the structure. The fastening section load estimation unit performs vibration analysis of the vibration force application unit and the force measurement unit by using the measurement results of the force measurement unit and a first vibration measurement unit in a first measurement state where the end of the force measurement unit is fixed to a surface plate and the first vibration measurement unit is installed on the vibration force application unit, and finds the response ratio of the central load of the fastening section to the excitation force, etc. The structure analysis unit analyzes the vibration characteristics of the structure by using the response ratio and the measurement results of the force measurement unit and a second vibration measurement unit in a second measurement state where the end of the force measurement unit is fixed to the fastening section and the second vibration measurement unit is installed on the structure. As a result, accurate estimation becomes possible even in cases where the load applied to the object of vibration analysis cannot be directly measured.

Description

Vibration analysis device and vibration analysis method

[0001] The present invention relates to a vibration analysis device and a vibration analysis method.

[0002] A technique is known in which a transfer function is calculated for an object to be subjected to vibration analysis after the object has been vibrated by a vibration excitation device, thereby determining the vibration characteristics of the object. For example, Patent Document 1 discloses such a technique.

[0003] In Patent Document 1, paragraph 0018 and Figure 2 state that "A flange 18 that protrudes radially outward is formed on the upper side of the bearing housing 17, and a measuring device 20 that measures the characteristics of the tire T is provided between this flange 18 and the upper part of the spindle base 16." Paragraph 0020 also states that "A vibration device 50 that forcibly vibrates the spindle shaft 3 by varying the position of the spindle shaft 3 with respect to the magnetic bearing 23 is provided on the upper side of the spindle shaft 3, i.e., on the end side of the spindle shaft 3 on which the rim is attached."

[0004] In paragraph 0026 of Patent Document 1, it states, "A signal generator 42 generates an output signal S1 of a predetermined frequency, and the spindle shaft 3 is vibrated at the predetermined frequency. Then, the radial load of the tire T while the spindle shaft 3 is vibrating in the radial direction is measured by the measuring device 20. The measurement value measured by the measuring device 20 while the spindle shaft 3 is vibrating is defined as a response value. The excitation force applied to the spindle shaft 3 is defined as a reference value." Furthermore, in paragraph 0028, it states, "As shown in FIG. 5, the horizontal axis represents the vibration frequency when the spindle shaft 3 is vibrated, and the vertical axis represents the value obtained by dividing the radial load (response value) for each vibration frequency by the reference value (amplitude of the transfer function). Each data measured by the measuring device 20 is plotted to create a frequency response curve (transfer function). At the same time, the same data may be used to create a curve of the time delay of the radial load measured by the measuring device 20 in the frequency response, as shown in FIG. 6. In this case, the vertical axis of the figure represents a value indicating the time delay (phase of the transfer function)."

[0005] Japanese Patent Application Laid-Open No. 2007-121042

[0006] As in Patent Document 1, when the load acting on the object of vibration analysis (a tire in this case) can be measured directly, i.e., when the measurement value of the load measuring device can be regarded as the load, the transfer function can be calculated with high accuracy from the measurement value. On the other hand, when the load acting on the object of vibration analysis cannot be measured directly, i.e., when there is a discrepancy between the measurement value of the load measuring device and the actual load acting on the object, calculating the transfer function by regarding the measurement value of the load measuring device as the load acting on the object will result in poor accuracy of the transfer function.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vibration analysis device and a vibration analysis method that can accurately estimate the load acting on an object to be analyzed even when the load cannot be measured directly.

[0008] In order to solve the above problems, the vibration analysis device of the present invention is, for example, a vibration analysis device that performs vibration analysis of a structure in which structural members are connected to each other by fastening parts, and includes an excitation force application unit that generates an excitation force or an excitation moment that is the moment of the excitation force, a force measurement unit that is installed on the excitation force application unit and measures the excitation force or the excitation moment, a fastening part load estimation unit that estimates a load that acts on the center of the fastening part when the excitation force or the excitation moment is applied to the fastening part by the excitation force application unit, and a structure analysis unit that analyzes the vibration characteristics of the structure, and the fastening part load estimation unit is configured such that an end of the force measurement unit is fixed to a surface plate and Using the measurement results of the force measuring unit and the first vibration measuring unit in a first measurement state in which a first vibration measuring unit that measures the vibration of the vibration force applying unit is installed on the vibration force applying unit, a vibration analysis of the vibration force applying unit and the force measuring unit is performed to determine the response magnification of the load applied to the center of the fastening part with respect to the vibration force or the vibration moment generated by the vibration force applying unit, and the structure analysis unit analyzes the vibration characteristics of the structure using the measurement results and the response magnification of the force measuring unit and the second vibration measuring unit in a second measurement state in which an end of the force measuring unit is fixed to the fastening part and a second vibration measuring unit that measures the vibration of the structure is installed on the structure.

[0009] Furthermore, the vibration analysis method of the present invention is, for example, a vibration analysis method for performing vibration analysis of a structure in which structural components are connected to each other by fastening parts, and includes a first excitation force application step of causing the excitation force application part to generate an excitation force or an excitation moment which is a moment of the excitation force in a first measurement state in which an end of a force measuring part installed on the excitation force application part is fixed to a surface plate, a first force measurement step of measuring the excitation force or the excitation moment generated in the first excitation force application step, a first vibration measurement step of measuring vibration of the excitation force application part, and performing vibration analysis on the excitation force application part and the force measurement part using measurement results in the first force measurement step and the first vibration measurement step, and determining the excitation force or The method includes a fastening part load estimation step of calculating a response magnification of a load acting on the center of the fastening part relative to the exciting force or the exciting moment when the exciting moment is applied to the fastening part; a second exciting force application step of generating the exciting force or the exciting moment by the exciting force application unit in a second measurement state in which an end of the force measurement unit is fixed to the fastening part; a second force measurement step of measuring the exciting force or the exciting moment generated in the second exciting force application step; a second vibration measurement step of measuring the vibration of the structure; and a structure analysis step of analyzing the vibration characteristics of the structure using the measurement results of the second force measurement step and the second vibration measurement step and the response magnification.

[0010] According to the present invention, it is possible to provide a vibration analysis device and a vibration analysis method that can accurately estimate the load acting on an object to be analyzed even when the load cannot be directly measured. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0011] FIG. 3 is a diagram illustrating an example of a vibration analysis device in a state where an end of a force measuring unit is fixed to a surface plate. FIG. 4 is a diagram illustrating an example of a flowchart of a load estimation process by the vibration analysis device 10. FIG. 5 is a diagram illustrating an example of a response magnification table obtained in step S104. FIG. 6 is a diagram illustrating an example of a vibration analysis device in a state where the force measuring unit is fixed by a fastening part of a structure. FIG. 7 is a diagram illustrating modeling of the structure shown in FIG.

[0012] The present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described below. These embodiments are merely examples, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, in the drawings used in the following description, the same devices and equipment are designated by the same reference numerals, and descriptions of devices, equipment, and operations that have already been described may be omitted.

[0013] FIG. 1 shows an example of a vibration analysis device 10 in which an end of a force measuring unit 12 is fixed to a surface plate 20. The vibration analysis device 10 primarily comprises an excitation force application unit 11, a force measuring unit 12, a vibration measuring unit, and a processing unit 14. The excitation force generated by the excitation force application unit 11 is applied as a load to a structure by bringing the end of the force measuring unit 12 into contact with the structure. The excitation force generated by the excitation force application unit 11 involves vibration with multiple degrees of freedom, making it difficult to directly measure the load applied to the structure. For this reason, the vibration analysis device 10 has a function of measuring the force measured by the force measuring unit 12 and the vibration measured by a vibration measuring unit disposed in a measurement system, and estimating the load applied to the structure. In the example shown in FIG. 1, a first vibration measuring unit 13 is provided in the excitation force application unit 11 as the vibration measuring unit, and a fastening load estimating unit 14A is provided as a functional unit for estimating the load applied to the structure.

[0014] The arithmetic processing device 14 is, for example, a computer equipped with a processor and a memory, and the processor functions as a functional unit that provides a predetermined function by executing processing in accordance with a program loaded into the memory. In the case of Figure 1, the arithmetic processing device 14 functions as a fastening part load estimation unit 14A by executing a fastening part load estimation program.

[0015] In the following description, when describing processing by a program, the program, functional units, etc. may be described as the main components, but the main hardware components are a processor or an arithmetic processing device (computer) configured to include the processor. The arithmetic processing device executes processing according to a program read into memory using resources such as memory and communication interfaces as appropriate. The processor may be a central processing unit (CPU) or a graphical processing unit (GPU). Furthermore, processing to realize a function is not limited to software program processing, and can also be implemented using a dedicated circuit. Examples of the dedicated circuit include a field programmable gate array (FPGA) and an application specific integrated circuit (ASIC).

[0016] 1 , the end of the force measuring unit 12 is fixed to the surface plate 20, thereby fixing the excitation force application unit 11 to the surface plate 20, and the first vibration measuring unit 13 is installed on the excitation force application unit 11. This state is called the first measurement state. The first measurement state is a state when the vibration analysis device 10 performs measurements to estimate what kind of load is actually applied to the structure due to the excitation force generated by the excitation force application unit 11. For this reason, the end of the force measuring unit 12 is in contact with the surface plate 20, not with the structure to be analyzed.

[0017] The excitation force application unit 11 has a vibration exciter 11A and a moment generator 11B. The vibration exciter 11A generates an excitation force. The moment generator 11B converts the excitation force from the vibration force application unit 11 into an excitation moment (moment of the excitation force) based on the coordinate difference between the force point to which the excitation force from the vibration exciter 11A is applied and the point of action at which the excitation force or excitation moment from the moment generator 11B is applied to the structure (the surface plate 20 in the example of FIG. 1 ). With this configuration, it is possible to convert the simple vibration generated by the vibration exciter 11A into a complex vibration with multiple degrees of freedom.

[0018] The moment generator 11B can be configured as a columnar member, and its side surface is provided with fixing portions such as screw holes for connecting the oscillator 11A, and the oscillator 11A is fixed to the fixing portions with screws. The fixing portions are provided on different surfaces of the moment generator 11B, and by fixing the oscillator 11A to different sides of the moment generator 11B, the excitation force from the oscillator 11A can act on the moment generator 11B at six or more points. FIG. 1 shows an example in which the moment generator 11B is a columnar member extending in the X-axis direction. In this case, if the oscillator 11A generates vibration that displaces in one axial direction, when an excitation force in the X-axis direction is applied to the moment generator 11B, the excitation force acts directly in the X-axis direction at the point of application, whereas when an excitation force in a direction other than the X-axis direction is applied, the excitation force is converted into an excitation moment and acts on the point of application. 1, the excitation force from the vibrator 11A is applied in the Z-axis direction, and the converted excitation moment is applied to the point of action. Note that it is desirable for the moment generator 11B to be highly rigid and have no resonant frequencies in the frequency band of the excitation force, but several resonant frequencies may be present.

[0019] The force measuring unit 12 includes a force sensor 12A and an adapter 12B. The force sensor 12A measures the excitation force and excitation moment generated by the excitation force application unit 11. The force sensor 12A includes, for example, a strain gauge and a deformable body. When the excitation force or excitation moment is applied, the strain gauge is distorted by the deformation of the deformable body. The relationship between the strain of the strain gauge and the force in each direction is calibrated and determined in advance. The force sensor 12A includes a calculation circuit that performs calculation processing and outputs each component of force from the measured strain of the strain gauge based on the relationship. Note that the force sensor 12A outputs the strain of the strain gauge, and the calculation process for determining the force from the strain may be performed by a device external to the force sensor 12A, such as a fastening portion load estimation unit 14A. Note that the configuration of the force sensor 12A is not limited to a configuration using a strain gauge. Any device capable of measuring not only the excitation force that displaces in a linear direction but also the excitation moment that displaces in a rotational direction is sufficient. The adapter 12B is used to fix the end to an object, for example, the surface plate 20 or a fastening portion 22 (see FIG. 3 ) of a structure 21 described later. If the force measuring unit 12 can be directly fixed to the surface plate 20 or the fastening portion 22, the adapter 12B can be omitted from the force measuring unit 12.

[0020] The first vibration measurement unit 13 measures the vibration of the excitation force application unit 11. The first vibration measurement unit 13 can be a six-axis sensor (e.g., a MEMS (Micro Electro Mechanical Systems) type sensor) that can measure acceleration in the X-axis, Y-axis, and Z-axis (hereinafter referred to as "three axes") directions and angular velocity around the three axes, or two sensors that are installed on two orthogonal planes and can measure vibrations around the three axes. In the latter case, the angular velocity around the three axes is estimated from the vibrations measured by each of the two sensors.

[0021] The fastening portion load estimation unit 14A performs vibration analysis on the excitation force application unit 11 and the force measurement unit 12 using the measurement results of the force measurement unit 12 and the first vibration measurement unit 13 in the first measurement state, and estimates the load acting on the center 22a of the fastening portion when an excitation force or excitation moment is applied to the fastening portion 22 shown in Figure 3 described below.

[0022] FIG. 2A is an example of a flowchart of a load estimation process performed by the vibration analysis device 10.

[0023] In step S101, in the first measurement state, the excitation force application unit 11 generates an excitation force or excitation moment, and the force measurement unit 12 and the first vibration measurement unit 13 perform measurements. At this time, the fixed portion of the moment generating body 11B to which the oscillator 11A is connected is changed to generate an excitation force or excitation moment, and measurements are performed for each. In the first measurement state, the end of the force measurement unit 12 is fixed to the surface plate 20, so that the force measurement unit 12 is not vibrating. Therefore, it is desirable that the surface plate 20 have high rigidity so as not to affect the vibration characteristics of the force measurement unit 12 and the first vibration measurement unit 13.

[0024] In step S102, the fastening portion load estimator 14A calculates accelerance by performing FFT processing on the measurement results of the force measuring unit 12 and the first vibration measuring unit 13 in the first measurement state, i.e., the excitation force and excitation moment measured by the force measuring unit 12 in the first measurement state and the acceleration measured by the first vibration measuring unit 13 in the first measurement state. Commonly used methods are used for the FFT processing and the method of deriving accelerance. Then, using the calculated accelerance, the eigenmodes of the excitation force applying unit 11 and the force measuring unit 12 and the modal damping ratio of each eigenmode are calculated by curve fitting processing. A commonly used method is used for the curve fitting processing.

[0025] In step S103, the fastening portion load estimating unit 14A performs a vibration analysis simulation by setting the calculated modal damping ratio for a model representing the excitation force applying unit 11 and the force measuring unit 12 in the first measurement state, thereby calculating the load acting on the end of the force measuring unit 12.

[0026] In step S104, the fastening portion load estimation unit 14A calculates the response magnification of the load applied to the end of the force measurement unit 12 relative to the measurement result of the force measurement unit 12 as the response magnification of the load applied to the center 22a of the fastening portion 22 (see FIG. 3) relative to the measurement result of the force measurement unit 12. Here, the response magnification of the load applied to the end of the force measurement unit 12 relative to the measurement result of the force measurement unit 12 is calculated by dividing the load applied to the end of the force measurement unit 12 by the measurement result (excitation force or excitation moment) of the force measurement unit 12 for each frequency, and is complex data having amplitude (magnification) and phase. An example of the response magnification table obtained in step S104 is shown in FIG. 2B. Excitation force F and excitation moment F in different directions are calculated as follows: Ｍ The response magnification factor and phase (a, θ) are registered for each frequency f. The response magnification factor table is registered in the storage unit of the arithmetic processing unit.

[0027] By multiplying the response magnification calculated in this manner by the measurement result of the force measuring unit 12, it becomes possible to determine the load acting on the center 22a of the fastening portion 22 (see FIG. 3).

[0028] FIG. 3 is a diagram showing an example of a vibration analysis device 10 in which the force measurement unit 12 is fixed by a fastening portion 22 of a structure 21. The structure 21 is the target of vibration analysis and has a structure in which a structure 25A and a structure 25B are connected by the fastening portion 22. In the vibration analysis device 10 shown in FIG. 3, the end of the force measurement unit 12 is fixed to the fastening portion 22, thereby fixing the excitation force application unit 11 to the structure 21, and a second vibration measurement unit 15 is installed on a structure 25A of the structure 21. This state is called the second measurement state. The fastening portion 22 refers to the portion where the structures 25 are fastened together by a bolt or the like. The center 22a of the fastening portion 22 is on the central axis of the bolt and on the boundary plane between the structures 25.

[0029] In the second measurement state, the vibration analysis device 10 has a second vibration measurement unit 15 provided in the structure 21 (structure 25A in the example of Figure 3) as a vibration measurement unit, and the calculation processing device 14 has a structure analysis unit 14B which is a functional unit that performs vibration analysis of the structure 21.

[0030] The second vibration measuring unit 15 measures vibrations of the structure 21 caused by the application of an excitation force or excitation moment from the excitation force application unit 11 to the fastening unit 22. The second vibration measuring unit 15 can use a sensor similar to that of the first vibration measuring unit 13. The installation position of the second vibration measuring unit 15 on the structure 25A is not limited, but it is desirable to install it in a position where the natural mode shape (combination of nodes and antinodes) of the structure 21 can be determined.

[0031] The structure analysis unit 14B analyzes the vibration characteristics of the structure using the measurement results of the force measurement unit 12 and the second vibration measurement unit 15 in the second measurement state. That is, the structure analysis unit 14B receives the measurement result (excitation force or excitation moment) of the force measurement unit 12 in the second measurement state as an input and outputs the measurement result of the second vibration measurement unit 15 in the second measurement state to calculate a transfer function, thereby analyzing the vibration characteristics of the structure 21. At this time, the structure analysis unit 14B applies a response magnification table to the measurement result of the force measurement unit 12 to calculate a transfer function between the load applied to the center 22a of the fastening part 22 and the vibration measured by the second vibration measurement unit 15.

[0032] As described above, according to this embodiment, even when the load acting on the object of vibration analysis cannot be measured directly, the transfer function can be calculated with high accuracy.

[0033] Machines and other structures often have structures that are joined together by bolts or the like. When a structure has a vibration generating source such as a motor, it is possible to optimize the design by modeling how vibrations generated in one structure are transmitted to other structures joined by fastening parts. Therefore, the calculation processing device 14 may have a functional unit that uses the above vibration analysis to generate a model of the structure 21 that represents the vibration characteristics of the structure.

[0034] FIG. 4 is a diagram illustrating modeling of the structure 21 shown in FIG. 3 . For example, as shown in FIG. 4 , the arithmetic processing device 14 represents a model of the structure 25A using a fastening center point P0, a vibration measurement point P1, and a transfer function TF1 from the fastening center point P0 to the vibration measurement point P1. The arithmetic processing device 14 represents a model of the structure 25B using a fastening center point P0, a vibration measurement point P2, and a transfer function TF2 from the fastening center point P0 to the vibration measurement point P2. The vibration measurement point P1 is the portion where the second vibration measurement unit 15 is installed, and the transfer function TF1 is calculated by the structure analysis unit 14B. The transfer function TF2 represents the vibration characteristics of the structure 25B, which are similarly analyzed by the structure analysis unit 14B when the second vibration measurement unit 15 is installed at the position of the vibration measurement point P2 of the structure 25B.

[0035] By generating such a model, it is possible to visualize the vibration characteristics of the structure 21, and for example, when vibration measurement point P1 of the structure 25A is excited, it is possible to understand the vibration transmitted to vibration measurement point P2 of the structure 25B via the fastening part 22. Note that the model generation may be performed by a device separate from the arithmetic processing device 14.

[0036] DESCRIPTION OF SYMBOLS 10: Vibration analysis device 11: Excitation force application unit 11A: Vibrator 11B: Moment generator 12: Force measurement unit 12A: Force sensor 12B: Adapter 13: First vibration measurement unit 14: Processing device 14A: Fastening part load estimation unit 14B: Structure analysis unit 15: Second vibration measurement unit 20: Surface plate 21: Structure 22: Fastening part 22a: Center of fastening part 25: Structure

Claims

1. A vibration analysis device for performing vibration analysis of a structure in which structural members are connected to each other by fastening parts, comprising: an excitation force application unit that generates an excitation force or an excitation moment which is the moment of the excitation force; a force measurement unit that is installed on the excitation force application unit and measures the excitation force or the excitation moment; a fastening part load estimation unit that estimates the load applied to the center of the fastening part when the excitation force or the excitation moment is applied to the fastening part by the excitation force application unit; and a structure analysis unit that analyzes vibration characteristics of the structure, wherein the fastening part load estimation unit performs vibration analysis on the excitation force application unit and the force measurement unit using measurement results of the force measurement unit and the first vibration measurement unit in a first measurement state in which an end of the force measurement unit is fixed to a base plate and a first vibration measurement unit that measures the vibration of the excitation force application unit is installed on the excitation force application unit, and determines a response magnification of the load applied to the center of the fastening part with respect to the excitation force or the excitation moment generated by the excitation force application unit, the structure analysis unit analyzes the vibration characteristics of the structure using the measurement results of the force measuring unit and the second vibration measuring unit in a second measurement state in which an end of the force measuring unit is fixed to the fastening unit and a second vibration measuring unit that measures the vibration of the structure is installed on the structure, and the response magnification.

2. A vibration analysis device as described in claim 1, wherein the fastening part load estimation unit calculates a modal damping ratio of the excitation force application unit and the force measurement unit based on the measurement results of the force measurement unit and the first vibration measurement unit in the first measurement state, calculates the load applied to the end of the force measurement unit in the first measurement state by setting the modal damping ratio for a model representing the excitation force application unit and the force measurement unit in the first measurement state and simulating the vibration analysis, and calculates a response magnification of the load applied to the end of the force measurement unit relative to the measurement results of the force measurement unit as a response magnification of the load applied to the center of the fastening part relative to the excitation force or excitation moment generated by the excitation force application unit.

3. A vibration analysis method for performing vibration analysis of a structure in which structural components are connected to each other by fastening parts, comprising: a first excitation force application step for generating an excitation force or an excitation moment which is the moment of the excitation force by the excitation force application part in a first measurement state in which an end of a force measuring part installed on the excitation force application part is fixed to a base; a first force measurement step for measuring the excitation force or the excitation moment generated in the first excitation force application step; a first vibration measurement step for measuring the vibration of the excitation force application part; and a fastening part load estimation step for performing vibration analysis on the excitation force application part and the force measurement part using the measurement results in the first force measurement step and the first vibration measurement step, and determining a response magnification of the load acting on the center of the fastening part relative to the excitation force or the excitation moment when the excitation force or the excitation moment is applied to the fastening part; a second excitation force application step of generating the excitation force or the excitation moment by the excitation force application unit in a second measurement state in which an end of the force measuring unit is fixed to the fastening portion; a second force measurement step of measuring the excitation force or the excitation moment generated in the second excitation force application step; a second vibration measurement step of measuring the vibration of the structure; and a structure analysis step of analyzing vibration characteristics of the structure using measurement results of the second force measurement step and the second vibration measurement step and the response magnification.

4. A vibration analysis method as claimed in claim 3, characterized in that in the fastening part load estimation step, a modal damping ratio of the excitation force application unit and the force measurement unit is calculated based on the measurement results of the first force measurement step and the first vibration measurement step, the modal damping ratio is set for a model representing the excitation force application unit and the force measurement unit in the first measurement state and the vibration analysis is simulated to calculate the load applied to the end of the force measurement unit, and a response magnification of the load applied to the end of the force measurement unit relative to the measurement result of the first force measurement step is calculated as a response magnification of the load applied to the center of the fastening part relative to the excitation force or excitation moment generated by the excitation force application unit.

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