JP2017173090A - Vibration measuring device for rotary machines, vibration measuring method for rotary machines, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly precise vibration measuring device for rotary machines, vibration measuring method for rotary machines, and program.SOLUTION: A vibration measuring device for rotary machines is equipped with a time difference calculating unit 6 that calculates the time difference ΔT between the passage time of detection of turbine blades 111 by a non-contact sensor 3 and the passage time of the turbine blades 111 in a reference state stored in a memory unit, a vibration amplitude calculating unit 7 that calculates the vibration amplitude Xof the turbine blades 111 on the basis of the peripheral velocity Vof the turbine blades 111, the vibration velocity Vof the non-contact sensor 3 detected by a small sensor 4 and the time difference ΔT calculated by the time difference calculating unit 6, and a vibration calculating unit 8 that calculates the vibration of the turbine blades 111 on the basis of the vibration amplitude Xcalculated by the vibration amplitude calculating unit 7 of the turbine blades 111.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vibration measurement device for a rotary machine, a vibration measurement method for a rotary machine, and a program.

  A rotary machine including a steam turbine and a gas turbine is required to have sufficient vibration strength. Therefore, at the time of design, the vibrations of the turbine blades are measured to verify that the vibration characteristics of the turbine blades are as designed, or changes in the vibration characteristics due to changes in operating conditions are confirmed. As one of the techniques for measuring the vibration of the turbine blade, a non-contact blade vibration measurement technique (BTT: Blade Tip Timing) that measures the vibration of the turbine blade in a non-contact manner is known (for example, see Patent Document 1). In this technique, a sensor for detecting the passage of a turbine blade in a non-contact manner is disposed in the casing of the turbine blade, and the vibration amplitude of the turbine blade is calculated from the time difference between the passage time between when the turbine blade is vibrating and when the turbine blade is not vibrating.

Japanese Patent No. 5293406

  However, in the non-contact blade vibration measurement technique, since the sensor is arranged in the casing, the sensor vibrates when the casing vibrates. Sensor vibrations may affect measurement errors in turbine blade vibration measurement. More specifically, when the vibration amplitude of the turbine blade is sufficiently larger than the vibration amplitude of the sensor, it can be evaluated that the influence of the vibration of the sensor is a negligible level. On the other hand, when the difference between the vibration amplitude of the turbine blade and the vibration amplitude of the sensor is small, the influence of the vibration of the sensor cannot be ignored. For example, since turbine blades used in gas turbines have high rigidity and small vibration amplitude, the influence of sensor vibration cannot be ignored.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vibration measuring device for a rotating machine, a vibration measuring method for a rotating machine, and a program for measuring the vibration of a rotating body with high accuracy. .

  A vibration measuring device for a rotating machine according to the present invention is disposed on a stationary body facing an outer periphery of a rotating body disposed on the rotating machine, and includes a first sensor that detects the passage of the rotating body in a non-contact manner, and the first sensor. A second sensor that detects vibration of the first sensor, a passage time when the rotating body is detected by the first sensor, and a passage time of the rotating body in a reference state stored in a storage unit. Based on the time difference calculation unit for calculating the time difference, the peripheral speed of the rotating body, the vibration speed of the first sensor detected by the second sensor, and the time difference calculated by the time difference calculation unit. A vibration amplitude calculation unit that calculates a vibration amplitude of the body; and a vibration calculation unit that calculates the vibration of the rotating body based on the vibration amplitude of the rotating body calculated by the vibration amplitude calculation unit. To do.

  According to this configuration, the vibration of the rotating body can be measured with high accuracy.

  In the vibration measurement device for a rotating machine according to the present invention, it is preferable that the second sensor measures a tangential component of the vibration of the rotating body with respect to the rotation direction of the rotating body. According to this configuration, the vibration of the rotating body can be measured with high accuracy.

  In the vibration measurement device for a rotary machine according to the present invention, it is preferable that the second sensor is disposed in a tangential direction with respect to a rotation direction of the rotating body on a peripheral surface of the first sensor. According to this configuration, the vibration of the rotating body can be measured with high accuracy.

  In the vibration measurement device for a rotary machine according to the present invention, it is preferable that two of the second sensors are arranged in directions different from the tangential direction with respect to the rotation direction of the rotating body on the circumferential surface of the first sensor. . According to this configuration, the vibration of the rotating body can be measured with high accuracy.

  The vibration measurement method for a rotating machine according to the present invention is a first vibration measuring step of detecting the passage of the rotating body in a non-contact manner with a first sensor arranged on a stationary body facing the outer periphery of the rotating body arranged in the rotating machine. A second vibration measuring step for detecting vibration of the first sensor with a second sensor arranged in the first sensor, a passage time when the rotating body is detected in the first vibration measuring step, and storage A time difference calculating step for calculating a time difference with the passage time of the rotating body in the reference state stored in the unit, a peripheral speed of the rotating body, and a vibration speed of the first sensor detected in the second vibration measuring step. Based on the time difference calculated in the time difference calculation step, a vibration amplitude calculation step for calculating the vibration amplitude of the rotating body, and on the basis of the vibration amplitude of the rotating body calculated in the vibration amplitude calculation step, Vibration of the rotating body Characterized in that it comprises a vibration calculation step of leaving. According to this method, the vibration of the rotating body can be measured with high accuracy.

  The program of the present invention includes a first vibration measuring step for detecting the passage of the rotating body in a non-contact manner with a first sensor disposed on a stationary body facing the outer periphery of the rotating body disposed on the rotating machine, and the first A second sensor arranged in the sensor, a second vibration measuring step for detecting the vibration of the first sensor, a passage time when the rotating body is detected in the first vibration measuring step, and stored in the storage unit A time difference calculating step for calculating a time difference from the passage time of the rotating body in a reference state; a peripheral speed of the rotating body; a vibration speed of the first sensor detected in the second vibration measuring step; and the time difference calculating step. And a vibration amplitude calculating step of calculating a vibration amplitude of the rotating body based on the time difference calculated in step (b), and a vibration of the rotating body based on the vibration amplitude of the rotating body calculated in the vibration amplitude calculating step. Calculate the vibration Characterized in that to execute a step to the computer output. According to this program, the vibration of the rotating body can be measured with high accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the vibration measuring device of the rotating machine which measures the vibration of a rotary body with high precision, the vibration measuring method of a rotating machine, and a program are realizable.

FIG. 1 is a schematic diagram illustrating an example of a configuration of a vibration measuring device for a rotating machine. FIG. 2 is a cross-sectional view showing an example of the configuration of a turbine blade in which a vibration measuring device for a rotary machine is arranged. FIG. 3 is a front view showing an example of a configuration of a turbine blade in which a vibration measuring device for a rotary machine is arranged. FIG. 4 is a schematic diagram showing a detection signal detected by a non-contact sensor of a vibration measuring device for a rotary machine. FIG. 5 is a side view illustrating an outline of an example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. FIG. 6 is a plan view illustrating an outline of an example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. FIG. 7 is a side view showing an outline of another example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. FIG. 8 is a plan view showing an outline of another example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. FIG. 9 is a schematic diagram illustrating the vibration speed in the tangential direction of the turbine blade of the non-contact sensor of the vibration measuring device of the rotary machine. FIG. 10 is a schematic diagram showing the vibration waveform of the turbine blade obtained from the detection signal shown in FIG. FIG. 11 is a flowchart illustrating an example of a processing flow in the vibration measurement device of the rotating machine.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited to each following embodiment, It can implement by changing suitably.

  First, with reference to FIG. 1 thru | or FIG. 3, the outline | summary of the turbine blade 111 as a rotary body arrange | positioned at the steam turbine and gas turbine as a rotary machine is demonstrated, for example. FIG. 1 is a schematic diagram illustrating an example of a configuration of a vibration measuring device for a rotating machine. FIG. 2 is a cross-sectional view showing an example of the configuration of a turbine blade in which a vibration measuring device for a rotary machine is arranged. FIG. 3 is a front view showing an example of a configuration of a turbine blade in which a vibration measuring device for a rotary machine is arranged. 1 to 3 schematically illustrate a plurality of turbine blades 111 and a casing 120.

  The plurality of turbine blades 111 are disposed radially outward from the turbine shaft (rotating shaft) 110. The turbine blade 111 rotates around the turbine shaft 110 when the turbine shaft 110 rotates. The turbine blade 111 is accommodated in the casing 120. The outer periphery of the turbine blade 111 faces the inner periphery of the casing 120. The plurality of turbine blades 111 are arranged at equal intervals in the circumferential direction of the turbine shaft 110.

  Returning to FIG. 1, the vibration measuring device 1 of the rotating machine measures the vibration of the turbine blade 111 in a non-contact manner. The vibration measuring apparatus 1 for a rotating machine includes a rotation speed sensor 2, a non-contact sensor (first sensor) 3, a small sensor (second sensor) 4, and a calculation unit 5. Here, the vibration of the turbine blade 111 means that when the turbine shaft 110 rotates, the relative position of the turbine blade 111 to the turbine shaft 110 is displaced from the relative position of the turbine blade 111 to the turbine shaft 110 when the turbine shaft 110 is stopped. That is.

  The rotation speed sensor 2 detects the rotation speed of the turbine shaft 110. More specifically, the rotation speed sensor 2 detects the rotation speed of the turbine shaft 110 by detecting the reference position K of the turbine shaft 110. When the rotation speed sensor 2 detects the reference position K, the rotation speed sensor 2 outputs the detection signal to the calculation unit 5 as a reference signal. As shown in FIG. 4, the reference signal output from the rotation speed sensor 2 is pulsed. FIG. 4 is a schematic diagram showing a detection signal detected by a non-contact sensor of a vibration measuring device for a rotary machine. The interval between the reference signals is a cycle of one rotation of the turbine shaft 110.

  As shown in FIGS. 2 and 3, the non-contact sensor 3 is disposed in the casing 120. The non-contact sensor 3 detects passage of the turbine blade 111 in a non-contact manner. The non-contact sensor 3 is disposed on the inner peripheral surface of the casing 120 at a position facing the turbine blade 111. The non-contact sensor 3 detects the passage of the turbine blade 111 in a non-contact manner when the turbine shaft 110 rotates. More specifically, when the non-contact sensor 3 detects passage of the turbine blade 111, it outputs a detection signal, which is a pulse signal, to the computing unit 5 as a blade passage signal. As shown in FIG. 4, the non-contact sensor 3 outputs a blade passage signal every time the turbine blade 111 passes. The blade passing signals are output at regular intervals as indicated by a solid line in the reference state where the turbine blade 111 is not vibrating. In the vibration state in which the turbine blade 111 is oscillating, the blade passage signal fluctuates in the interval as shown by the broken line. The non-contact sensor 3 is, for example, an optical sensor, a capacitance sensor, or an overcurrent sensor. In the present embodiment, N non-contact sensors 3 are arranged at equal intervals.

The small sensor 4 is disposed on the non-contact sensor 3 and detects vibration of the non-contact sensor 3. More specifically, the small sensor 4 detects the vibration of the tip (tip portion) of the sensor probe of the non-contact sensor 3. The small sensor 4 is arranged so that a tangential component of the vibration of the turbine blade 111 with respect to the rotation direction of the turbine blade 111 can be measured. The small sensor 4 is, for example, a strain gauge or an acceleration sensor. The small sensor 4 is arranged in the casing of the non-contact sensor 3. The small sensor 4 outputs the detected strain and acceleration to the calculation unit 5. More specifically, the small sensor 4 outputs data including the vibration amplitude (vibration speed) X _S , the frequency F _S , and the vibration direction of the tip of the non-contact sensor 3.

  As shown in FIGS. 5 and 6, the small sensor 4 has two tangential directions with respect to the rotation direction of the turbine blade 111 (hereinafter referred to as “turbine blade tangential direction”) on the circumferential surface of the non-contact sensor 3. One is arranged. FIG. 5 is a side view illustrating an outline of an example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. FIG. 6 is a plan view illustrating an outline of an example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. In the present embodiment, the two small sensors 4 are arranged at 90 ° intervals in the circumferential direction of the casing of the non-contact sensor 3 with the turbine blade tangential direction interposed therebetween. A direction connecting one small sensor 4 and the center of the non-contact sensor 3 is an X direction, and a direction connecting the other small sensor 4 and the center of the non-contact sensor 3 is a Y direction.

  Alternatively, when it is clear from a prior analysis or the like that the vibration direction of the non-contact sensor 3 is the turbine blade tangential direction, the small sensor 4 may be arranged as shown in FIGS. FIG. 7 is a side view showing an outline of another example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. FIG. 8 is a plan view showing an outline of another example of the arrangement of the non-contact sensor and the small sensor of the vibration measuring device of the rotating machine. The small sensor 4 may be arranged in the turbine blade tangential direction on the peripheral surface of the non-contact sensor 3. In the present embodiment, one small sensor 4 is disposed in the turbine blade tangential direction.

  The calculation unit 5 includes a memory and a CPU (Central Processing Unit). The calculation unit 5 may be realized by dedicated hardware, or may be realized by loading a program for realizing the function of the calculation unit 5 into a memory and executing the program. Good. The calculation unit 5 includes a time difference calculation unit 6, a vibration amplitude calculation unit 7, and a vibration calculation unit 8.

  The time difference calculation unit 6 calculates a time difference ΔT between the passage time when the turbine blade 111 is detected by the non-contact sensor 3 and the passage time of the turbine blade 111 in the reference state stored in advance in the storage unit. In the present embodiment, the time difference calculation unit 6 is a time counter that measures the passage time of the blade passage signal, which is the passage time when the turbine blade 111 is detected by the non-contact sensor 3 in the vibration state, and the passage time in the reference state The time difference ΔT is calculated. The time difference ΔT is a difference between the non-vibration state, which is the reference state, and the vibration state in FIG. When the turbine blade 111 is not vibrating, the time difference ΔT calculated by the time difference calculation unit 6 is zero.

The vibration amplitude calculation unit 7 calculates the peripheral speed V _B of the turbine blade 111, the vibration speed V _{S of} the non-contact sensor 3 detected by the small sensor 4, and the time difference ΔT calculated by the time difference calculation unit 6. based on, for calculating the oscillation amplitude _{X B} of the turbine blade 111. More specifically, the vibration amplitude calculation unit 7 uses the circumferential speed V _B of the turbine blade 111, the vibration speed V _{S of} the non-contact sensor 3 in the tangential direction of the turbine blade, and the time difference ΔT, and the turbine blade 111 according to Formula 1 to the calculated vibration amplitude _{X B.}

The vibration speed V _{S in the} tangential direction of the turbine blade included in Equation 1 is based on the vibration amplitude (vibration speed) X _S , the frequency F _S and the vibration direction of the tip of the non-contact sensor 3 output from the small sensor 4. Is calculated by Formula 2.

In the present embodiment, as shown in FIG. 9, the vibration speed V _{S in the} tangential direction of the turbine blade included in Equation 1 is the vibration speed V _{S-X in} the X direction of the non-contact sensor 3 and the Y of the non-contact sensor 3. Using the vibration velocity V _{S-Y in the} direction and the angle θ, the calculation is performed using Equation 2. FIG. 9 is a schematic diagram illustrating the vibration speed in the tangential direction of the turbine blade of the non-contact sensor of the vibration measuring device of the rotary machine.

Vibrating calculating unit 8, based on the vibration amplitude X _B of the turbine blade 111, which is calculated by the vibration amplitude calculating unit 7 calculates the vibration of the turbine blades 111. More specifically, the vibration calculating unit 8, as shown in FIG. 10, the vertical axis of the vibration amplitude X _B of the turbine blade 111, which is calculated by the vibration amplitude calculating unit 7, the time when passing through each of the non-contact sensor 3 A time history vibration waveform of the turbine blade 111 is reproduced on the horizontal axis. FIG. 10 is a schematic diagram showing the vibration waveform of the turbine blade obtained from the detection signal shown in FIG.

  Next, a vibration measurement method for a rotary machine using the rotary machine vibration measurement apparatus 1 having the above-described configuration will be described with reference to FIG. FIG. 11 is a flowchart illustrating an example of a processing flow in the vibration measurement device of the rotating machine. The vibration measurement method for a rotary machine according to the present embodiment includes a first vibration measurement step S1, a second vibration measurement step S2, a time difference calculation step S3, a vibration amplitude calculation step S4, and a vibration calculation step S5.

  First, the vibration measuring device 1 of the rotating machine executes the first vibration measuring step S1. More specifically, the vibration measuring device 1 of the rotating machine causes the non-contact sensor 3 to detect the passage of the turbine blade 111 in a non-contact manner (step S1). The vibration measuring device 1 of the rotating machine causes the calculation unit 5 to output the blade passage signal of the turbine blade 111 detected by the non-contact sensor 3.

  The vibration measuring device 1 of the rotating machine executes the second vibration measuring step S2 together with the first vibration measuring step S1. More specifically, the vibration measuring device 1 of the rotating machine detects the vibration of the non-contact sensor 3 with the small sensor 4 arranged in the non-contact sensor 3 (step S2). The vibration measuring device 1 of the rotating machine outputs the vibration of the non-contact sensor 3 detected by the small sensor 4.

  The vibration measuring device 1 of the rotating machine executes the time difference calculation step S3. More specifically, the vibration measuring device 1 of the rotating machine calculates a time difference ΔT between the passage time when the turbine blade 111 is detected by the non-contact sensor 3 and the passage time in the reference state stored in advance in the storage unit (step). S3).

  The vibration measuring device 1 of the rotary machine executes the vibration amplitude calculating step S4. More specifically, the vibration measuring device 1 of the rotating machine is based on the peripheral speed of the turbine blade 111, the vibration speed of the non-contact sensor 3 detected by the small sensor 4, and the time difference ΔT calculated in the time difference calculation step S3. The vibration amplitude of the turbine blade 111 is calculated by Equation 1 (step S4).

  The vibration measuring device 1 of the rotating machine executes the vibration calculating step S5. More specifically, the vibration measurement device 1 of the rotating machine calculates the vibration of the turbine blade 111 based on the vibration amplitude of the turbine blade 111 calculated in the vibration amplitude calculation step S4 (step S5).

As described above, according to the present embodiment, when calculating the vibration amplitude X _B of the turbine blade 111, and calculates the vibration speed V _S of the turbine blade tangential caused by vibration of the non-contact sensor 3. In the present embodiment, the vibration amplitude calculation unit 7 uses the circumferential speed V _B of the turbine blade 111, the vibration speed V _{S of} the non-contact sensor 3 in the tangential direction of the turbine blade, and the time difference ΔT, using Equation 1. calculating a vibration amplitude _{X B} of the turbine blade 111. In other words, in the present embodiment, the time difference ΔT caused by the vibration speed V _S caused by the vibration of the non-contact sensor 3 is removed, and the vibration amplitude X _B of the turbine blade 111 is calculated. Thus, this embodiment can measure the vibration of the turbine blade 111 with high accuracy.

In contrast, the prior art had to calculate the vibration amplitude X _B of the turbine blade 111 in Equation 3.

Thus, conventionally, the vibration velocity V _S of the turbine blade tangential caused by vibration of the non-contact sensor 3 has been calculated include the peripheral speed V _B of the turbine blade 111. For this reason, the vibration amplitude of the turbine blade 111 is calculated to be larger than the actual vibration, and the calculated vibration of the turbine blade 111 includes a measurement error due to the vibration of the non-contact sensor 3.

  In the present embodiment, even if the difference between the vibration amplitude of the turbine blade 111 and the vibration amplitude of the non-contact sensor 3 is small and the influence of the vibration of the non-contact sensor 3 cannot be ignored, the vibration of the turbine blade 111 is reduced. It can measure with high accuracy. For this reason, for example, it is suitable for vibration measurement of the turbine blade 111 of the gas turbine having high rigidity and small vibration amplitude.

  In this embodiment, it is highly accurate to verify that the vibration characteristics of the turbine blades implemented during the design of rotating machines including steam turbines and gas turbines are as designed, and to confirm changes in vibration characteristics due to changes in operating conditions. Can be implemented.

  Now, the vibration measurement device for a rotary machine, the vibration measurement method for a rotary machine, and a program according to the present embodiment have been described so far. However, the present invention may be implemented in various different forms other than the above-described embodiments.

  The constituent elements of the calculation unit 5 of the illustrated vibration measuring device 1 for a rotary machine are functionally conceptual and may not necessarily be physically configured as illustrated. That is, the specific form of each component is not limited to that shown in the drawing, and all or a part of the component is functionally or physically distributed or arbitrarily distributed in arbitrary units according to the processing load or usage status of each component. You may integrate.

  The configuration of the calculation unit 5 of the vibration measurement device 1 of the rotating machine is realized by, for example, a program loaded in a memory as software. The above embodiment has been described as a functional block realized by cooperation of these hardware or software. That is, these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

DESCRIPTION OF SYMBOLS 1 Vibration measuring device of rotary machine 2 Rotational speed sensor 3 Non-contact sensor (1st sensor)
4 Small sensor (second sensor)
DESCRIPTION OF SYMBOLS 5 Calculation part 6 Time difference calculation part 7 Vibration amplitude calculation part 8 Vibration calculation part 110 Rotating shaft 111 Turbine blade (rotary body)
120 casing (stationary body)

Claims (6)

A first sensor that is disposed on a stationary body facing the outer periphery of the rotating body disposed in the rotating machine and that detects the passage of the rotating body in a non-contact manner;
A second sensor disposed on the first sensor for detecting vibration of the first sensor;
A time difference calculation unit that calculates a time difference between the passage time when the rotating body is detected by the first sensor and the passage time of the rotating body in the reference state stored in the storage unit;
The vibration amplitude for calculating the vibration amplitude of the rotating body based on the peripheral speed of the rotating body, the vibration speed of the first sensor detected by the second sensor, and the time difference calculated by the time difference calculating unit. A calculation unit;
A vibration measuring device for a rotating machine, comprising: a vibration calculating unit that calculates vibration of the rotating body based on the vibration amplitude of the rotating body calculated by the vibration amplitude calculating unit.   2. The vibration measurement device for a rotary machine according to claim 1, wherein the second sensor measures a tangential component of a vibration of the rotating body with respect to a rotation direction of the rotating body.   3. The vibration measurement device for a rotary machine according to claim 2, wherein the second sensor is disposed in a tangential direction with respect to a rotation direction of the rotating body on a circumferential surface of the first sensor.   3. The vibration of the rotating machine according to claim 2, wherein two of the second sensors are arranged in directions different from a tangential direction with respect to a rotation direction of the rotating body on the circumferential surface of the first sensor. Measuring device. A first vibration measuring step of detecting the passage of the rotating body in a non-contact manner with a first sensor arranged on a stationary body facing the outer periphery of the rotating body arranged in the rotating machine;
A second vibration measuring step of detecting vibration of the first sensor with the second sensor disposed in the first sensor;
A time difference calculating step of calculating a time difference between the passing time when the rotating body is detected in the first vibration measuring step and the passing time of the rotating body in the reference state stored in the storage unit;
Based on the peripheral speed of the rotating body, the vibration speed of the first sensor detected in the second vibration measuring step, and the time difference calculated in the time difference calculating step, the vibration amplitude of the rotating body is calculated. A vibration amplitude calculating step;
A vibration calculation step of calculating vibration of the rotating body based on the vibration amplitude of the rotating body calculated in the vibration amplitude calculating step. A first vibration measuring step of detecting the passage of the rotating body in a non-contact manner with a first sensor arranged on a stationary body facing the outer periphery of the rotating body arranged in the rotating machine;
A second vibration measuring step of detecting vibration of the first sensor with the second sensor disposed in the first sensor;
A time difference calculating step of calculating a time difference between the passing time when the rotating body is detected in the first vibration measuring step and the passing time of the rotating body in the reference state stored in the storage unit;
Based on the peripheral speed of the rotating body, the vibration speed of the first sensor detected in the second vibration measuring step, and the time difference calculated in the time difference calculating step, the vibration amplitude of the rotating body is calculated. A vibration amplitude calculating step;
A program for causing a computer to execute a vibration calculation step of calculating vibration of the rotating body based on the vibration amplitude of the rotating body calculated in the vibration amplitude calculating step.

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