JP2012055636A - System and method for designing golf club - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a design system and a design method of golf club by which a change of ball hitting sound when changing the structure of the golf club head can be estimated by simulation and a golf club head generating good ball hitting sound can be efficiently designed.SOLUTION: The design system of golf club includes: an analysis model forming part which can form a golf club head analysis model capable of performing numerical analysis of a golf club head to form a numerical analysis model capable of performing numerical analysis at a position corresponding to a response point away from the golf club head by a prescribed distance; an analysis part which virtually applies exciting force to a face of the golf club head analysis model to acquire a frequency response function of the numerical analysis model to acquire time waveform data of sound pressure upon golf ball hitting in the numerical analysis model using the frequency response function and the exciting force applied to the golf club head upon golf ball hitting; and an evaluation part which evaluates hitting sound upon golf ball hitting using the time waveform data of the sound pressure.

Description

  The present invention relates to a golf club design system and a golf club design method using a golf club head hitting sound obtained by simulation, and more particularly to a change in hitting sound when a golf club head structure is changed by simulation. The present invention relates to a predicted golf club design system and a golf club design method.

In recent years, various golf club heads that can fly golf balls farther and golf club heads that have a large and stable sweet spot have been provided. Such a golf club head has a different structure such as a face portion, a sole portion, a crown portion, and the like. For this reason, the hitting sounds generated when hitting the face surface, that is, the hitting surface are greatly different from each other. For this reason, although the golf ball can actually fly far away, the hitting sound itself makes a dull sound, giving the golfer the impression of a golf club with no flying distance, or giving an unpleasant image Often given. From such a background, it is desired to adjust the sound of hitting a golf ball by a golf club.
In order to adjust the hitting sound at the time of hitting a golf ball, a guideline on how to adjust the characteristics of the hitting sound of the golf club is necessary.

  By the way, in order to manufacture a golf club head that emits a desired hitting sound, it is necessary to actually design the golf club head and make a trial, and then perform a test hit to confirm the hitting sound. The design and prototype cycle is repeated until the desired sound is obtained. However, such a golf club head design method is inefficient and tends to increase the development period and development cost. Therefore, a golf club design method for efficiently producing a golf club head excellent in hitting sound has been proposed (for example, Patent Document 1).

In Patent Document 1, first, a primary design of a golf club head is performed (step S1). Then, mode analysis is performed on the primary designed golf club head by using a computer with analysis application software (step S2). Accordingly, it is possible to grasp the vibration characteristics of the golf club head before actually making a prototype of the golf club head ([0021]).
Next, the primary designed head is actually prototyped, and the hitting sound is collected and evaluated (steps S3 to S5).
In the measurement of the hitting sound of the golf club head, a golf club head is prototyped by mounting a shaft on the prototyped golf club head, and a golf ball hitting test is performed using this golf club. And the sound at the time of impact is sampled with a microphone ([0023]). The microphone is installed at the position of the addressed golfer's ear and the horizontal distance between the golf ball and the ear on the opposite side of the golf ball from the test golfer ([0027]).
The evaluation of the hitting sound (step S5) is performed by, for example, reproducing the recorded hitting sound with a headphone or a speaker via an amplifier and listening to it with an evaluator's ear. Evaluation criteria include “sound pitch”, “reverberation length”, “sound intensity”, “preference”, and the like ([0032]).

If the evaluation result of the hitting sound of the primary designed golf club head is found to be undesirable (N in step S6), an improvement point for improving the hitting sound is identified based on the hitting sound and vibration characteristics. (Step S7). In order to identify the improvement point, first, the frequency band of the sound to be improved is identified from the hitting sound, and the part that causes the sound is estimated from the vibration characteristics obtained by the mode analysis ([0031]).
Then, a head improvement point is specified, and the secondary design of the golf club head is performed by applying this improvement point (step S8). Prior to trial production of the secondary designed golf club head, the secondary designed golf club head is subjected to a mode analysis on a computer to obtain vibration characteristics (step S9).
The improvement of the hitting sound is confirmed by comparing the vibration characteristics before and after the improvement (step S10). When the improvement effect is recognized in the secondary design golf club head (Y in step S11), the process returns to step S3, and the trial production of the secondary design golf club head, sampling of the hitting sound, and evaluation (steps S3 to 5) are performed. Do.

  If the hitting sound of the secondary design golf club head is satisfactory (Y in step S6), a golf club head with good hitting sound is manufactured by the design plan of the secondary design golf club head. Can do. If a satisfactory hitting sound is not obtained even with the golf club head of this secondary design, the above-described step S7 and subsequent steps are repeated again to perform the tertiary design and the like.

Japanese Patent Laying-Open No. 2005-6673

  In Patent Literature 1, mode analysis is performed, the vibration characteristics of the golf club head are grasped, and the vibration characteristics before and after the improvement are compared to confirm the effect of improving the hitting sound. In Patent Document 1, it is necessary to make a prototype golf club head in order to obtain a golf club head with good hitting sound, and it is also necessary to make a trial hit in order to obtain a hitting sound. Thus, even in Patent Document 1, there is a problem that the degree of improvement in efficiency is low and the development period and development cost cannot be shortened.

  The object of the present invention is to solve the problems based on the above prior art, predict a change in hitting sound when the structure of the golf club head is changed by simulation, and efficiently design a golf club head with good hitting sound. An object of the present invention is to provide a golf club design system and a golf club design method that can be performed.

  In order to achieve the above object, the present invention creates a golf club head analysis model that can be numerically analyzed for a golf club head and can perform numerical analysis at a position corresponding to a response point that is a predetermined distance away from the golf club head. An analytical model creation unit for creating a numerical analysis model, and a frequency response function of the numerical analysis model of the response point is obtained by virtually applying a predetermined excitation force to the face surface of the golf club head analysis model, Using the frequency response function and the excitation force applied to the golf club head at the time of hitting the golf ball, an analysis unit for obtaining time waveform data of sound pressure at the time of hitting the golf ball in the numerical analysis model of the response point; And an evaluation unit that evaluates the hitting sound at the time of hitting the golf ball using time waveform data of pressure. It is intended to provide a golf club design system.

In this case, it is preferable that the response point is a position corresponding to the height of a golfer's ear hitting the golf ball.
In addition, the evaluation unit includes a sound pressure parameter that represents the magnitude of the hitting sound when hitting the golf ball, a reverberation parameter that represents the degree of attenuation of the hitting sound, and a high and low parameter that represents the frequency characteristic of the hitting sound. It is preferable to calculate as an evaluation parameter.
For example, the analysis unit calculates the frequency response function using sound field analysis.

  Further, the present invention creates a golf club head analysis model that can be numerically analyzed for a golf club head, and creates a numerical analysis model that can be numerically analyzed at a position corresponding to a response point that is a predetermined distance away from the golf club head. A step of virtually applying a predetermined excitation force to the face surface of the golf club head analysis model to obtain a frequency response function of the numerical analysis model of the response point, and the frequency response function and the golf ball when hitting Using the excitation force applied to the golf club head, obtaining the time waveform data of the sound pressure at the time of hitting the golf ball in the numerical analysis model of the response point, and using the time waveform data of the sound pressure, And a step of evaluating a hitting sound at the time of hitting a golf ball.

In this case, it is preferable that the response point is a position corresponding to the height of a golfer's ear hitting the golf ball.
Further, the step of evaluating the hitting sound represents a sound pressure parameter indicating a magnitude of the hitting sound when hitting the golf ball, a reverberation parameter indicating a degree of attenuation of the hitting sound, and a frequency characteristic of the hitting sound. It is preferable to calculate the elevation parameter as an evaluation parameter.
The frequency response function is calculated using, for example, sound field analysis.

  According to the present invention, it is possible to predict a change in hitting sound when the structure of the golf club head is changed by simulation, and to efficiently design a golf club head with good hitting sound.

It is a mimetic diagram showing a golf club design system of an embodiment of the present invention. It is a flowchart which shows the design method of the golf club of embodiment of this invention. (A) is a typical perspective view which shows the 1st golf club head model used for the design system of the golf club of embodiment of this invention, (b) is a magnitude | size of a 1st golf club head model. FIG. 4C is a cutaway view showing the size of the first golf club head model, and FIG. 4D is used for the golf club design system of the embodiment of the present invention. It is a typical perspective view showing the 2nd golf club head model. It is a typical perspective view which shows the analysis model used for the design method of the golf club of embodiment of this invention. (A)-(c) are the transfer function of the 1st golf club head model calculated | required from the analysis model, and the transfer function of the 1st golf club head model calculated | required with the measuring apparatus shown to Fig.10 (a). It is a graph which shows. (A), (b) is a graph which shows the hit sound of the 1st golf club head model calculated | required from the analysis model, (c), (d) is a measuring apparatus shown in FIG.10 (b). It is a graph which shows the hit sound of the calculated | required 1st golf club head model. (A) is the 1st golf club calculated | required from the sound pressure parameter of the 1st golf club head model and 2nd golf club head model calculated | required with the measuring apparatus shown in FIG.10 (b), and an analysis model. It is a graph which shows the sound pressure parameter of a head model and a 2nd golf club head model, (b) is the 1st golf club head model and 2nd golf which were calculated | required with the measuring apparatus shown in FIG.10 (b). It is a graph which shows the reverberation parameter of a club head model, and the reverberation parameter of the 1st golf club head model and the 2nd golf club head model which were calculated | required from the analysis model, (c) is shown in FIG.10 (b). High and low parameters of the first golf club head model and the second golf club head model obtained by the measuring device, It is a graph showing the height parameter of the first golf club head model and a second golf club head model which is obtained from the analysis model each time. (A)-(c) is the transfer function of the 2nd golf club head model calculated | required from the analysis model, and the transfer function of the 2nd golf club head model calculated | required with the measuring apparatus shown to Fig.10 (a). It is a graph which shows. (A), (b) is a graph which shows the hit sound of the 2nd golf club head model calculated | required from the analysis model, (c), (d) is a measuring apparatus shown in FIG.10 (b). It is a graph which shows the hit sound of the calculated | required 2nd golf club head model. (A) is a schematic diagram which shows the measuring apparatus used for the measurement of the transfer function in the position corresponding to each response point, (b) is the measurement used for the measurement of the hitting sound in the position corresponding to each response point. It is a schematic diagram which shows an apparatus. It is a schematic diagram which shows the measuring apparatus used for the measurement of an exciting force. It is a graph which shows the time waveform of the applied excitation force, and the time waveform of the excitation force calculated | required by calculating backward, taking an output value on a vertical axis | shaft and taking time on a horizontal axis. It is a schematic diagram which shows the drop test apparatus used for the measurement of an exciting force.

Hereinafter, a golf club design system and a golf club design method according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic diagram showing a golf club design system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a golf club design method according to an embodiment of the present invention.

  A golf club design system 10 (hereinafter referred to as a design system 10) of the embodiment shown in FIG. 1 predicts a change in hitting sound when the structure of the golf club head is changed by simulation, and golf with good hitting sound. The club head is designed efficiently. In the design system 10, a frequency response analysis is performed using, for example, the position of the golfer's ear using a golf club head analysis model as a response point. Using this frequency response analysis result and the striking force applied to the golf club head, for example, a complex spectrum at the position (response point) of the golfer's ear is obtained, and by performing inverse FFT (fast Fourier transform) on this complex spectrum, Obtain the time waveform of the response point. Furthermore, the golf club is designed by calculating the evaluation parameter of the hitting sound using the time waveform and evaluating the hitting sound. In addition, by converting the time waveform into audio data such as a WAVE file, it is possible to obtain a hitting sound at the position (response point) of the golfer's ear that can be heard by the golfer, the designer, and the like. Note that the number of response points is not limited to one and may be plural.

  The design system 10 includes a processing device 12, an operation unit 14, and a monitor 16. The operation unit 14 is a keyboard, a mouse, or the like generally used for a PC. The monitor 16 displays various analysis results, analysis models, response point time waveforms, hitting evaluation parameters, and the like calculated by the processing device 12. Various types of monitors 16 that are generally used in personal computers can be used.

  The processing device 12 includes an analysis model creation unit 20, an analysis unit 22, a hitting sound evaluation parameter calculation unit 24, a memory 26, and a CPU 28. The CPU 28 controls the analysis model creation unit 20, the analysis unit 22, and the hitting sound evaluation parameter calculation unit 24, and the analysis model creation unit 20, the analysis unit 22, the hitting sound evaluation parameter calculation unit 24, and the memory 26. The movement of data between them is also controlled, and the data is stored in the memory 26. The memory 26 stores three-dimensional CAD data of the golf club head model.

The analysis model creation unit 20 converts the golf club head model represented by the three-dimensional CAD data into mesh data that can be subjected to numerical analysis such as finite element analysis for sound field analysis by numerical analysis (simulation) described later. Then, a mesh model (golf club head analysis model) is created. In addition to the golf club head, mesh data that can be subjected to numerical analysis such as finite element analysis for a position corresponding to a response point set at a predetermined distance from the golf club head, for example, the position of the golfer's ear To create an observation mesh mesh model (numerical analysis model). An analysis model used for numerical analysis (simulation) described later is configured by the mesh model of the golf club head model and the mesh model of the region corresponding to the response point. A known method used for numerical analysis (simulation) such as a finite element method can be used to create these mesh models.
For example, the analysis model creation unit 20 can be replaced with software and the CPU 28 can execute the software. In this case, for example, Patran manufactured by MSC can be used as software.

In this embodiment, examples of the golf club head model include a first golf club head model 30 shown in FIGS. 3A to 3C and a second golf club head model 30a shown in FIG. Used.
A first golf club head model 30 shown in FIG. 3A is obtained by modeling a golf club head by paying attention to a face portion and a sole portion. The first golf club head model 30 includes a face portion 32 corresponding to the face portion, a sole portion 34 corresponding to the sole portion, and a hosel portion 38 corresponding to the hosel portion. The surface 32a of the face portion 32 corresponds to the face surface.
In the first golf club head model 30, substantially triangular ribs 36 that reach the sole portion 34 from the back surface 32 b are provided on both sides of the face portion 32. One rib 36 is provided with a hosel portion 38. The hosel portion 38 has a mounting hole 39 for mounting a golf club shaft.
The magnitude | size of the 1st golf club head model 30 is a magnitude | size shown to FIG.3 (b), (c), for example.

In addition, the second golf club head model 30a shown in FIG. 3D has two ribs 35 extending in the lateral direction of the face portion 32 on the sole portion 34 as compared with the first golf club head model 30. The other configurations are the same as those of the first golf club head model 30 except for the configuration. The rib 35 has a square cross section, a height of 5.5 mm, and a width of 3.0 mm.
The first golf club head model 30 and the second golf club head model 30 a are both represented by three-dimensional CAD data and are stored in the memory 26. Since the first golf club head model 30 and the second golf club head model 30a are represented by three-dimensional CAD data, a real material can be easily manufactured by processing a metal material using a machine tool. Can do.

The analysis unit 22 performs sound field analysis by numerical analysis (simulation) and creation of a hitting sound by numerical analysis (simulation). For the sound field analysis, a frequency response analysis is performed when a predetermined excitation force is applied to the center of the face surface of the golf club head model, for example, in the form of a sine wave. The response at the observation mesh provided at a position away from the position, for example, a position corresponding to the position of the golfer's ear is obtained by numerical analysis. That is, the frequency response function in the observation mesh is obtained. In this sound field analysis, the fluid around the golf club head is, for example, air. As the material of the golf club head, for example, information on material characteristics of 6-4 titanium (Ti-6Al-4V) is used. In addition, the analysis is performed at a frequency range of 2 kHz to 10 kHz, for example, every 3 Hz or every 50 Hz.
In addition, since it is known that the golf club shaft has a small influence on the hitting sound, in the analysis model, the fixing condition of the golf club shaft may not be particularly defined. Further, one or more response points may be used.

For example, the analysis unit 22 stores the calculated transfer function (frequency response function) of the response point in the memory 26.
The analysis unit 22 virtually calculates a complex spectrum of the response point when an excitation force spectrum is applied to the center of the face surface of the golf club head model. The analysis unit 22 performs inverse FFT on the complex spectrum of the response point to obtain time waveform data of the sound pressure level at the response point by numerical analysis (simulation), that is, sound pressure waveform data. The obtained time waveform of the sound pressure level is stored in the memory 26, for example.

  Here, the frequency response function (transfer function) is expressed by the ratio of the input Fourier spectrum and the output Fourier spectrum. The Fourier spectrum of the input is the Fourier spectrum (complex spectrum (imaginary part and real part of spectrum)) of the excitation force signal on the face surface. The Fourier spectrum of the output is the response point, that is, the Fourier spectrum of the sound pressure signal at the observation mesh. Here, when the frequency response function is G, the frequency response function G is expressed by the following Equation 1.

  G = X (f) / Fa (f) (1)

  In Equation 1, Fa (f) is the complex Fourier spectrum of the excitation force signal on the face surface, and X (f) is the complex Fourier spectrum of the sound pressure signal in the observation mesh. As described above, the sound pressure in the observation mesh is obtained by using the frequency response function (transfer function) calculated by the analysis unit 22 and the complex Fourier spectrum of the excitation force signal generated when the golf ball is hit. The complex Fourier spectrum of the signal can be determined. The complex Fourier spectrum of the sound pressure signal in this observation mesh is subjected to inverse FFT to obtain inverse Fourier transform data. Thereby, time waveform data of the hitting sound generated when the golf ball is hit can be obtained.

Further, the analysis unit 22 can convert the time waveform data of the hitting sound into voice file data, for example, a WAVE file, and create a hitting sound that can be heard by golfers, designers, and the like.
As described above, the analysis unit 22 performs sound field analysis and sound generation by numerical analysis (simulation), and has both functions of sound field analysis software and an FFT analyzer. For this reason, the analysis unit 22 can be replaced by sound field analysis software and an FFT analyzer. As the sound field analysis software, for example, VA One (trade name) manufactured by Nippon SII Co., Ltd. can be used.

  The hitting sound evaluation parameter calculation unit 24 uses the time waveform data of the sound pressure level obtained by the analysis unit 22 to represent, for example, a sound pressure parameter indicating the size of the hitting sound and a degree of attenuation of the hitting sound. The reverberation parameter and the height parameter representing the frequency characteristic of the hitting sound are calculated as evaluation parameters. For example, a method disclosed in Japanese Patent Application Laid-Open No. 2008-132262 is used to calculate the sound pressure parameter, the reverberation parameter, and the height parameter.

  As the sound pressure parameter, a known loudness level (unit: phon) value obtained by logarithmically expressing the loudness (unit: one) defined in the ISO 532B standard is used. Specifically, the entire sound pressure waveform data (16384) used for evaluation of the hitting sound is subjected to frequency analysis by FFT to obtain a spectrum waveform, and by applying a loudness curve in the ISO 532B standard, the loudness ( Unit) and a value of the loudness level (unit: phon) obtained by logarithmically expressing the loudness. The calculated sound pressure parameter value is stored in the memory 26 of the processing device 12.

As the reverberation parameter, the sound pressure waveform data is set to the first sample data (start point data) on the time axis as a reference number, and the sound pressure waveform is sequentially divided from this number by a predetermined number of samples, for example, 100 samples The obtained block group α is created. Then, a block A _k square sum of the sound pressure waveform level for each of the blocks alpha, logarithm (hereinafter referred to as block value) of the sum of squares for each block obtained. Then, the maximum sound pressure block having the maximum block value is extracted from each block of the block group α as a starting block. Then, a value lower than the block value of the maximum sound pressure block by a predetermined value (30 dB in the present embodiment) is set as an end point block value, and in a plurality of blocks after the start point block, the block value is initially equal to or less than the end point block value. Extract the end point block. Then, the time width between the earliest sample data on the time axis of each of the start block and the end block is used as a reverberation parameter.

More specifically, assuming that a sound pressure waveform signal sampled at a sampling frequency of 44.1 kHz is y (i) (i = 1 to 16384 natural number), the number of blocks A divided into 100 samples according to the following equation 2. _For each _k , a relative sound pressure level value E (k) (K is 1 to 16285) is calculated, for example, 16285 E (k) are obtained, and E (k) that is the maximum among them is determined as the maximum sound. Extract as a pressure block. In the processing device 12, the obtained reverberation parameter value is stored in the memory 26 of the processing device 12.

  As the high and low parameters, the sound pressure waveform data obtained is a sound pressure waveform data excluding a predetermined number of samples (1,500 in this embodiment) on the time axis on the time axis. Frequency analysis is performed on the data (8192 data in this embodiment) to obtain a spectrum waveform. Then, the energy weighted average frequency of the vibration waveform in a predetermined frequency range (1 kHz to 20 kHz in the present embodiment) excluding the low frequency component using the spectrum value of the spectrum waveform as a weighting coefficient is set as a high and low parameter. The obtained value of the height parameter is stored in the memory 26 of the processing device 12.

  The above-mentioned energy weighted average frequency is obtained according to the following formula 3. In Expression 3, f is the frequency, L is the sound pressure level (dB value) of the vibration waveform at the frequency f obtained from the spectrum value at the frequency f in the spectrum waveform. An energy weighted average frequency is obtained in a frequency range (1 kHz to 20 kHz). Such an energy weighted average frequency is obtained using vibration waveform data that has passed a certain time after the impact, so that the problem of deterioration of accuracy as a parameter and reproducibility is solved. In addition, for example, since the energy weighted average frequency is obtained in a frequency range excluding low frequency components whose frequency is less than 1 kHz, the influence of DC (direct current) components generated when frequency analysis is performed on the vibration waveform can be eliminated. Further, the problem that accuracy as a parameter and further reproducibility deteriorate is further solved.

Next, a golf club design method will be described.
In the golf club designing method of the present embodiment, first, the first golf club head model 30 is designed so that sound field analysis can be performed on the first golf club head model 30 represented by three-dimensional CAD data. The three-dimensional CAD data is called from the memory 26 to the analysis model creation unit 20, and the analysis model creation unit 20 converts the first golf club head model 30 into mesh data that can be subjected to numerical analysis such as finite element analysis. A mesh model (golf club head analysis model) of the golf club head model 30 is created (step S10). Further, the region including the response point is also converted into mesh data that can be subjected to finite element analysis, and a mesh model (numerical analysis model) of the observation mesh is created (step S10). For example, the response points are set at three points including a golfer's ear position at a predetermined distance from the face surface. Thereby, for example, the analysis model 40 shown in FIG. 4 is obtained and displayed on the monitor 16.
The analysis model 40 shown in FIG. 4 is different from the mesh model 42 of the first golf club head model 30 in that the mesh model 44 for the first observation mesh, the mesh model 46 for the second observation mesh, The observation mesh mesh model 48 is virtually arranged with a predetermined distance from the face surface.

  In the analysis model 40, the material characteristics of the first golf club head model 30 and the second golf club head model 30a are 6-4 titanium (Ti-6Al-4V) having the material characteristics shown in Table 1 below. The fluid around the golf club head is air having the characteristics shown in Table 2 below.

Next, the analysis unit 22 performs sound field analysis on the analysis model 40, and calculates the frequency response functions (transfer functions) of the mesh models 44 to 48 corresponding to the response points (step S12).
For calculating the frequency response function (transfer function), for example, in the mesh model 44 to 48 when the excitation force is applied to the position corresponding to the center of the face surface of the mesh model 42 in a sine wave form at 1N. The frequency response analysis is performed at a frequency range of 2 kHz to 10 kHz, for example, every 3 Hz.
The results of the frequency response analysis (frequency response function (transfer function)) of the first golf club head model 30 are shown in FIGS. Further, in FIGS. 5A to 5C, for comparison, the first golf club head model 30 is actually manufactured, and each measurement device 100a shown in FIG. The result of obtaining the frequency response function (transfer function) at the position corresponding to the response point is also shown. Note that β shown in FIGS. 5A to 5C is a frequency response function (transfer function) obtained by numerical analysis (simulation), and γ is what is actually produced. The frequency response function (transfer function) obtained using the measuring apparatus 100a shown in FIG. The first golf club head model 30 was made of 6-4 titanium (Ti-6Al-4V).

Next, in the analysis model 40, a complex spectrum (hitting sound spectrum (spectrum of spectrum)) at each response point when an excitation force spectrum is applied to the center position of the face surface of the mesh model 42 of the first golf club head model 30. The imaginary part and the real part)) are calculated by the analysis unit 22 and the complex spectrum at each response point is stored in the memory 26.
Next, inverse FFT is performed on the complex spectrum at each response point. Thereby, sound pressure waveform data (sound pressure level time waveform data) at each response point is obtained (step S14). The sound pressure waveform data at each response point indicates the hitting sound created by the simulation. Sound pressure waveform data at each response point is stored in the memory 26.

  With respect to the first golf club head model 30, FIG. 6A shows the time waveform of the hitting sound created by the simulation of the position of the mesh model 44 of the first observation mesh, and FIG. The time waveform of the hitting sound created by the simulation of the position of the mesh model 46 of the observation mesh is shown. For comparison, with respect to the first golf club head model 30, FIG. 6C shows the time waveform of the hitting sound measured at the same position as the mesh model 44 of the first observation mesh. d) shows the time waveform of the hitting sound measured at the same position as the mesh model 46 of the second observation mesh. In addition, the time waveform of the hitting sound shown in FIGS. 6C and 6D is measured using a measuring apparatus 100b shown in FIG. 10B described later.

  Next, the analysis unit 22 converts the time waveform data of the sound pressure level at each response point into sound data, for example, a WAVE file. Then, the WAVE file at each response point is stored in the memory 26. By converting into voice data in this way, a golfer, a designer, etc. can hear the hitting sound at each response point created by simulation.

Next, the time waveform of the sound pressure level at each response point is called from the memory 26 to the evaluation parameter calculation unit 24 for the hitting sound. Next, using the time waveform of the sound pressure level at each response point, the sound pressure evaluation parameter calculation unit 24 calculates the sound pressure parameter, the reverberation parameter, and the height parameter (step S16). The results of the sound pressure parameter, reverberation parameter, and high / low parameter are stored in the memory 26.
FIG. 7A shows the result of the sound pressure parameter, FIG. 7B shows the result of the reverberation parameter, and FIG. 7C shows the result of the high and low parameter.
As shown in FIGS. 7A to 7C, the hitting sound can be evaluated using the hitting sound created by the simulation without making a prototype.

7A to 7C, P ₁ indicates the result at the position of the mesh model 44 of the first observation mesh, and P ₂ indicates the mesh of the second observation mesh. and shows the results at the location of the model 46, P ₃ shows the result of the position of the third observation mesh of the mesh model 48. For comparison, FIGS. 7A to 7C show the results of sound pressure parameters obtained by actually producing the first golf club head model 30 in FIG. 7 (b) shows the result of the reverberation parameter, and FIG. 7 (c) also shows the result of the high / low parameter. 7A to 7C, D ₁ indicates a result at a position corresponding to the mesh model 44 of the first observation mesh, and D ₂ indicates the mesh of the second observation mesh. and shows the results at the location corresponding to the model 46, D ₃ shows the results at the location corresponding to the mesh model 48 of the third observation mesh. D _{1 to} D ₃ shown in FIGS. 7A to 7C are obtained using a measuring apparatus 100b shown in FIG. 10B described later.

Next, with respect to the first golf club head model 30, the second golf club head 30a whose structure is changed is evaluated in the same manner as the first golf club head model 30.
In this case, the analysis model creation unit 20 converts the second golf club head model 30a into mesh data, and the response points also include the first observation mesh to the third observation mesh mesh models 44 to 48. To create an analysis model (step S10). Next, the analysis unit 22 performs sound field analysis on the analysis model, and calculates a frequency response function (transfer function) of the mesh model corresponding to each response point (step S12). The results are shown in FIGS. 8 (a) to (c).
Further, in FIGS. 8A to 8C, for comparison, the second golf club head model 30a is actually manufactured, and each measurement device 100a shown in FIG. The result of obtaining the frequency response function (transfer function) at the position corresponding to the response point is also shown. Note that β shown in FIGS. 8A to 8C is a frequency response function (transfer function) obtained by numerical analysis (simulation), and γ is what is actually produced, which will be described later with reference to FIG. The frequency response function (transfer function) obtained using the measuring apparatus 100a shown in FIG. The second golf club head model 30a was made of 6-4 titanium (Ti-6Al-4V).

Next, in the analysis model 40, a complex spectrum (hitting sound spectrum (imaginary spectrum) at each response point when the excitation force spectrum is applied to the center position of the face surface of the mesh model of the second golf club head model 30a. Part and real part)) are calculated by the analysis unit 22, and the complex spectrum at each response point is stored in the memory 26.
Next, inverse FFT is performed on the complex spectrum at each response point. Thereby, sound pressure waveform data at each response point is obtained (step S14). Sound pressure waveform data at each response point is stored in the memory 26. The sound pressure waveform data at each response point is shown in FIGS. 9 (a) and 9 (b). FIG. 9A shows the time waveform of the hitting sound created by the simulation of the position of the mesh model 44 of the first observation mesh, and FIG. 9B shows the mesh model 46 of the second observation mesh. The time waveform of the hitting sound created by the simulation of the position of is shown. For comparison, FIG. 9 (c) shows a time waveform of the hitting sound measured at the same position as the mesh model 44 of the first observation mesh, and FIG. 9 (d) shows the second observation mesh. The time waveform of the hitting sound measured at the same position as the mesh model 46 is shown. In addition, the time waveform of the hitting sound shown in FIGS. 9C and 9D is measured using a measuring apparatus 100b shown in FIG. 10B described later.

  Next, the analysis unit 22 converts the time waveform data of the sound pressure level at each response point into sound data, for example, a WAVE file. Then, the WAVE file at each response point is stored in the memory 26. By converting into voice data in this way, a golfer, a designer, etc. can hear the hitting sound at each response point created by simulation.

Next, the time waveform data of the sound pressure level at each response point is called from the memory 26 to the evaluation parameter calculation unit 24 for the hitting sound. Next, using the time waveform of the sound pressure level at each response point, the sound pressure evaluation parameter calculation unit 24 calculates the sound pressure parameter, the reverberation parameter, and the height parameter (step S16). The results of the sound pressure parameter, reverberation parameter, and high / low parameter are stored in the memory 26.
FIG. 7A shows the result of the sound pressure parameter, FIG. 7B shows the result of the reverberation parameter, and FIG. 7C shows the result of the high and low parameter. As shown in FIGS. 7A to 7C, in the second golf club head model 30a, the hitting sound can be evaluated using the hitting sound created by the simulation without making a prototype.

As shown in FIGS. 7A to 7C, the first golf club head model 30 and the second golf club head model 30a have different sound pressure parameters, reverberation parameters, and height parameter results. This difference is due to the rib provided on the sole portion. In addition, the difference in each evaluation parameter due to the provision of the ribs can be obtained in the same tendency even when compared with the first golf club head model 30 and the second golf club head model 30a that were prototyped.
Even when the hitting sound is created by simulation as in this embodiment, changes in the sound pressure parameter, the reverberation parameter, and the height parameter based on the difference in the structure of the golf club head can be reproduced. For this reason, when designing a golf club head, it is possible to know by simulation without making a trial change of the hitting sound based on the configuration of the golf club head. It is known from sensory tests that the higher the sound and the greater the reverberation, the better. For this reason, when changing the structure, whether or not the arrangement of the members such as the ribs is appropriate can be confirmed depending on whether the sound is higher and the reverberation is higher than before the structure change.

Hereinafter, a measuring apparatus 100a used for measuring a transfer function at a position corresponding to each response point and a measuring apparatus 100b used for measuring a hitting sound at a position corresponding to each response point will be described.
The measurement apparatus 100a shown in FIG. 10A has predetermined vibrations applied to the first microphone 102a to the third microphone 102c, the FFT analyzer 104, the PC 106, the monitor 108, and the first golf club head model 30. And an impulse hammer 122 for applying a force.

  The first microphone 102 a to the third microphone 102 c measure the hitting sound generated when the first golf club head model 30 is hit with the impulse hammer 122, and the first golf club head model 30. The face portion 32 is disposed at a predetermined interval from the surface 32a. The first microphone 102a to the third microphone 102c are located at positions corresponding to the mesh model 44 of the first observation mesh, the mesh model 46 of the second observation mesh, and the mesh model 48 of the third observation mesh. Is provided. Output signals of the hit sounds of the first microphone 102 a to the third microphone 102 c are output to the FFT analyzer 104.

  The impulse hammer 122 is a vibration hammer having a built-in force sensor for measuring the natural frequency of the structure and performing modal analysis. For example, when the impulse hammer 122 strikes the surface 32 a of the face portion 32 of the first golf club head model 30, an excitation force signal is output from the built-in force sensor to the FFT analyzer 104. With this impulse hammer 122, a known excitation force can be applied to the first golf club head model 30.

The FFT analyzer 104 takes in the sound pressure signals of the hit sounds measured by the first microphone 102a to the third microphone 102c in time series, converts them into digital signals, and converts the sound pressure signals of the hit sounds to time series data ( Time-series data (time waveform) of the excitation force by the impulse hammer 122 is obtained in a time series and is converted into a digital signal. Get.
Further, the FFT analyzer 104 includes time-series data of sound pressure signals of the sound hit by the first microphone 102 a to the third microphone 102 c (time waveform data of the hit sound) and time-series data of the excitation force from the impulse hammer 122. It has a function of obtaining a frequency response function based on (time waveform). In addition, the FFT analyzer 104 has a function included in a general FFT analyzer.
Time series data of the sound pressure signal of the hitting sound acquired by the FFT analyzer 104, time series data (time waveform) of the excitation force by the impulse hammer 122, and the result of the frequency response function (transfer function) obtained by the FFT analyzer 104 Is output to the PC 106.

The PC 106 is a processing device and has a configuration similar to that of a general personal computer. The PC 106 includes a CPU (not shown) and a memory (not shown) and is used for computer input such as a keyboard and a mouse. An input unit (not shown), and a monitor 108 such as an LCD for displaying input information from the input unit and information processed by the CPU.
In the measuring apparatus 100a, the impulse hammer 122 measures the hitting sound generated when the surface 32a of the face portion 32 of the first golf club head model 30 is hit with the first microphone 102a to the third microphone 102c. The FFT analyzer 104 obtains time waveform data of the hitting sound and time series data (time waveform) of the excitation force by the impulse hammer 122. Further, the FFT analyzer 104 obtains a frequency response function (transfer function) f based on these.

A measuring apparatus 100b shown in FIG. 10B has the same configuration as the measuring apparatus 100a shown in FIG. 10A except that a cylinder 110 is provided instead of the impulse hammer 122.
The cylinder 110 has an inner diameter through which the golf ball 112 can pass. The cylinder 110 has an opening 110a facing the first golf club head model 30, and the axis of the cylinder 110 is provided perpendicular to the horizontal plane.
The golf ball 112 is dropped from the opening 110 b above the cylinder 110, passes through the inside of the cylinder 110, and collides with the surface 32 a of the face portion 32 of the first golf club head model 30. The hitting sound generated by the fall of the golf ball 112 is measured by the first microphone 102a to the third microphone 102c.

  In the measuring apparatus 100b, the hitting sound generated when the golf ball 112 is dropped and passes through the inside of the cylinder 110 and collides with the surface 32a of the face portion 32 of the first golf club head model 30 is the first microphones 102a to 102b. The time waveform data of the hitting sound is obtained by the FFT analyzer 104 and measured by the third microphone 102c, and the frequency response function (transfer function) f is obtained.

  Further, the excitation force applied to the mesh model 42 of the analysis model 40 in order to obtain a hitting sound is preferably an excitation force generated by a golfer's swing in order to approximate the actual hitting sound. Furthermore, as shown in Japanese Patent Application No. 2009-204505, specifically, an excitation force measured as shown below can be used.

A measuring device 120 that measures the excitation force applied by the golf ball or the like to the golf club head 130 shown in FIG. 11 is used.
11 includes an impulse hammer 122 that applies a predetermined excitation force to the golf club head 130, an FFT analyzer 124, an acceleration sensor 126, an amplifier 128, and a computer (hereinafter referred to as a PC) 129. Have.
The acceleration sensor 126 is connected to the FFT analyzer 124 via the amplifier 128, and the impulse hammer 122 is connected to the FFT analyzer 124.

  Since the impulse hammer 122 is the same as the measurement apparatus 100a described above, a detailed description thereof is omitted. For example, when the impulse hammer 122 hits the face surface 132 of the golf club head 130, an excitation force signal is output from the built-in force sensor to the FFT analyzer 124. With this impulse hammer 122, a known excitation force can be applied to the golf club head 130.

The acceleration sensor 126 measures the acceleration generated in the golf club head 130 when an excitation force is applied to the face surface 132 of the golf club head 130.
The acceleration sensor 126 is attached below the hosel part 134 of the golf club head 130, for example. The position where the acceleration sensor 126 is attached is referred to as an attachment position d.
For the acceleration sensor 126, for example, a lightweight acceleration pickup is used. The acceleration pickup is preferably an ultralight one. For example, a material having a mass of 0.6 g may be used. This is because the influence on the vibration of the face surface 132 is increased when the mass is large.

  The amplifier 128 is connected to the acceleration sensor 126. An acceleration signal obtained by the acceleration sensor 126 is input to the amplifier 128 in the form of electric charges, for example. The amplifier 128 converts the acceleration signal input in the form of the electric charge into a voltage, amplifies it, and outputs it to the FFT analyzer 124 as an acceleration signal.

  The FFT analyzer 124 takes the acceleration signal from the acceleration sensor 126 output in the form of voltage from the amplifier 128 and the excitation force signal output from the impulse hammer 122 in time series, and further obtains a frequency response function as described later. Is.

In the FFT analyzer 124, for example, the acceleration signal from the acceleration sensor 126 and the excitation force signal from the impulse hammer 122 are struck, and then, for example, 0 at a sampling period of 20 microseconds (0.35 seconds / 16384). Capture for 35 seconds (sampling time). At the time of capture, the sampling frequency is 48 kHz, and the number of captured data is 16384.
The FFT analyzer 124 acquires time series data (time waveform) of acceleration by the acceleration sensor 126 and time series data (time waveform) of excitation force by the impulse hammer 122.

The FFT analyzer 124 has a function of performing FFT on time series data (time waveform) of acceleration by the acceleration sensor 126 and time series data (time waveform) of excitation force by the impulse hammer 122.
Further, the FFT analyzer 124 has a function of obtaining a frequency response function based on time series data (time waveform) of acceleration by the acceleration sensor 126 and time series data (time waveform) of excitation force by the impulse hammer 122. In addition, the FFT analyzer 124 has a function included in a general FFT analyzer.

The time series data (time waveform) of acceleration obtained by the acceleration sensor 126 and the time series data (time waveform) of the excitation force obtained by the impulse hammer 122 acquired by the FFT analyzer 124 are output to the PC 129.
Further, the result of the FFT performed by the FFT analyzer 124 and the obtained frequency response function are also output to the PC 129.

  The sampling period for the acceleration signal and the excitation force signal by the FFT analyzer 124 is not limited to 20 microseconds, and can be changed as appropriate according to the required measurement accuracy of vibration. Furthermore, the acquisition time (sampling time) for the acceleration signal and the excitation force signal by the FFT analyzer 124 is not limited to 0.35 seconds, and the characteristics of the golf club head 130 and the required measurement accuracy are not limited. It can be changed as appropriate.

The PC 129 and the monitor 129a have the same configuration as the PC 106 and the monitor 108 of the measurement apparatus 100a shown in FIG.
The PC 129 receives time series data (time waveform) of the acceleration signal from the acceleration sensor 126 from the FFT analyzer 124 and time series data (time waveform) of the excitation force signal of the impulse hammer 122, for example, a memory, a hard disk ( (Not shown) and the like, and has a function of displaying the monitor 129a in the form of a graph, a numerical value, or the like.

Next, a method for measuring the excitation force of the golf club head 130 will be described. An acceleration sensor 126 is attached to the attachment position d of the golf club head 130.
First, the impulse hammer 122 strikes the center point P of the face surface 132 of the golf club head 130. At the time of hitting, an excitation force signal is output from the impulse hammer 122 to the FFT analyzer 124. The acceleration (first response signal) generated in the golf club head 130 by the hit is measured by the acceleration sensor 126, and the acceleration signal of the acceleration is output to the FFT analyzer 124 via the amplifier 128.

  In the FFT analyzer 124, for example, the acceleration signal from the acceleration sensor 126 and the excitation force signal of the impulse hammer 122 are captured for 0.35 seconds (sampling time) at a sampling period of 20 microseconds (0.35 seconds / 16384). The time series data of the acceleration of the golf club head and the time series data of the excitation force by the impulse hammer 122 are acquired.

Next, a frequency response function at the center point P is calculated by the FFT analyzer 124 based on the time series data of acceleration and the time series data of the excitation force by the impulse hammer 122.
The time series data of acceleration of these golf club heads, the time series data of the excitation force by the impulse hammer 122, and the frequency response function are output to the PC 129 and stored in the memory of the PC 129, the hard disk, and the like.

  The frequency response function is represented by a ratio of an input Fourier spectrum and an output Fourier spectrum. The input Fourier spectrum is the Fourier spectrum of the excitation force signal of the impulse hammer 122. The output Fourier spectrum is the Fourier spectrum of the acceleration signal of the golf club head. Here, when the frequency response function is H, the frequency response function H is expressed by the following Equation 4.

  H = A (f) / F (f) (4)

In Formula 4, F (f) is a complex Fourier spectrum of the excitation force signal of the impulse hammer 122, and A (f) is a complex Fourier spectrum of the acceleration of the golf club head.
Further, for example, the complex Fourier spectrum of the excitation force signal generated when the golf ball 112 is caused to collide with the center point P of the face surface 132 is F1 (f). When the complex Fourier spectrum of the acceleration signal of the acceleration generated in the golf club head 130 when colliding with the center point P of the face surface 132 is A1 (f), the complex Fourier spectrum F1 (f) of this excitation force signal. Can be obtained by the following formula 5.

  F1 (f) = A1 (f) / H (5)

  When obtaining the frequency response function H, first, FFT (Fast Fourier Transform) is performed on the time series data of the acceleration of the golf club head and the time series data of the excitation force by the impulse hammer 122 by the FFT analyzer 124. Thereby, the complex Fourier spectrum about the acceleration of the golf club head, that is, A (f) is obtained. Furthermore, a complex Fourier spectrum for the excitation force by the impulse hammer 122, that is, F (f) is obtained.

Next, the frequency response function H is calculated by the FFT analyzer 124 using the complex Fourier spectrum A (f) of acceleration and the complex Fourier spectrum F (f) of excitation force. Thereby, the frequency response function H is obtained, and the frequency response function H is output to the PC 129 and stored.
Next, the golf ball 112 is caused to collide with the golf club head 130 on which the frequency response function H is measured, at a predetermined speed, for example, at the center point P hit with the impulse hammer 122. At this time, the acceleration generated in the golf club head 130 by the acceleration sensor 126 is measured and output to the FFT analyzer 124 via the amplifier 128. The FFT analyzer 124 acquires time series data of the acceleration of the golf club head 130.

Next, the time series data of the acceleration of the golf club head 130 is fast Fourier transformed by the FFT analyzer 124 to obtain the Fourier transform data of the acceleration of the golf club head 130. Thereby, the complex Fourier spectrum A1 (f) of the acceleration generated in the golf club head 130 when the golf ball 112 is collided is obtained.
Next, the frequency response function H stored in the PC 129 and the complex Fourier spectrum A1 (f) of acceleration are output to the FFT analyzer 124. The FFT analyzer 124 uses the above equation 2 to make the golf ball 112 collide. Then, a complex Fourier spectrum F1 (f) of the excitation force generated in the golf club head 130 is obtained.

Next, the FFT analyzer 124 performs inverse FFT (inverse fast Fourier transform) on the complex Fourier spectrum F1 (f) of the obtained excitation force to obtain inverse Fourier transform data. Thereby, time series data of the excitation force at the time of collision of the golf ball 112 is obtained.
The FFT analyzer 124 extracts the maximum value of the excitation force in the time series data of the excitation force obtained by the inverse Fourier transform. The maximum value of the excitation force is output from the FFT analyzer 124 to the PC 129 as the excitation force F1 when the golf ball 112 collides with the face surface, and stored in the PC 129. In this way, the excitation force generated in the golf club head 130 when the golf ball 112 collides can be obtained.

In the present embodiment, the complex Fourier spectrum F (f) of the excitation force is obtained from the excitation force by the impulse hammer 122 based on the obtained acceleration signal and the frequency response function using Equation 3. . The complex Fourier spectrum F (f) was subjected to inverse FFT transform to obtain time series data of the excitation force signal.
As a result, as shown in a graph 140 in FIG. 12, a curve 142 indicating time series data of the excitation signal of the impulse hammer 122 obtained by calculation, and a curve 144 indicating time series data of the excitation signal of the impulse hammer 122 are obtained. Then, the peak values almost coincided. As described above, when the impulse response is obtained by using the impulse hammer 122 so that the excitation force can be understood, the acceleration at the time of applying the excitation force such as when the golf ball 112 is collided is obtained. The excitation force can be obtained from the series data.

Next, the excitation force obtained by the above-described excitation force measurement method will be verified.
FIG. 13 is a schematic diagram showing a drop test apparatus used for measuring the excitation force.
A drop test apparatus (hereinafter simply referred to as a test apparatus) 150 shown in FIG. 13 includes a load cell 152, a cylinder 110, an amplifier 128a, an FFT analyzer 124, a PC 129, and a monitor 129a.
The load cell 152 measures the excitation force by the golf ball 112 and is placed on the horizontal plane B. The load cell 152 is connected to the amplifier 128a. The amplifier 128a amplifies the output signal generated in the load cell 152 by a predetermined factor according to the excitation force. This amplified output signal is output to the FFT analyzer 124.

  The FFT analyzer 124, the PC 129, and the monitor 129a have the same configuration as the FFT analyzer 124, the PC 129, and the monitor 129a of the measurement apparatus 120 shown in FIG.

Since the cylinder 110 has the same configuration as the cylinder 110 of the measuring apparatus 100b shown in FIG. 10B, a detailed description thereof is omitted. The cylinder 110 is provided with its opening 110 a facing the load cell 152 and the axis of the cylinder 110 perpendicular to the horizontal plane B.
The golf ball 112 is dropped from the opening 110 b above the cylinder 110, passes through the inside of the cylinder 110, and collides with the load cell 152. The excitation force generated in the load cell 152 due to the fall of the golf ball 112 is measured.

Moreover, in this test apparatus 150, it replaced with the load cell 152 and used the 1st golf club head model 30 shown to Fig.3 (a)-(c). The excitation force applied to the first golf club head model 30 is measured.
An acceleration sensor 126 a can be attached to the back surface 32 b of the face portion 32. For this reason, when the golf ball 112 is caused to collide with the center point on the surface 32a of the face portion 32, the excitation force at the center point can be measured. Accordingly, it is possible to apply an excitation force to the first golf club head model 30 and to measure the excitation force under the same conditions as when the golf ball 112 collides with the load cell 152.

  The acceleration sensor 126a is the same as the acceleration sensor 126 used in the measurement apparatus 120 shown in FIG. For this reason, the detailed description is abbreviate | omitted. The acceleration sensor 126a is connected to the amplifier 128a, and an acceleration signal is input to the FFT analyzer 124.

In the test apparatus 150 shown in FIG. 13, a drop test was performed on the load cell 152 using three types of golf balls 1 to 3. The excitation force at this time was measured.
Further, in the test apparatus 150 shown in FIG. 13, the first golf club head model 30 is arranged in place of the load cell 152. At this time, the height of the surface 32a of the face portion 32 of the first golf club head model 30 is set to the same height as the portion of the load cell 152 where the golf ball collides. Similar to the load cell 152, a drop test was performed using three types of golf balls, balls 1 to 3. The excitation force at this time was measured.
The test conditions in the drop test are the same for the load cell and the first golf club head model 30, and the contact time between the golf ball and the vibrating portion at the time of the collision of the golf ball is about the same.

  In addition, since the measuring method of an exciting force is a well-known measuring method using a load cell, an acceleration sensor, and an FFT analyzer, the detailed description is abbreviate | omitted. The measurement results of the measured excitation force are shown in Table 1 below.

  In Table 3 below, normalization is performed based on the excitation force of the first golf club head model 30 obtained with the ball 1. In the load cell column, the numerical values shown in parentheses are normalized based on the excitation force of the load cell obtained with the ball 1 in the drop test using the load cell.

  As shown in Table 3 above, the difference in excitation force depending on the type of ball is the same between the load cell and the first golf club head model 30. Further, the load cell and the first golf club head model 30 have different excitation forces even when the same golf ball is used. This is affected by the difference in the rigidity of the colliding portion between the thin hollow structure such as a golf club head and the load cell placed directly on the horizontal plane B. As described above, the test conditions are the same for both the load cell and the first golf club head model 30. From these facts, it can be said that the value of the excitation force obtained for the first golf club head model 30 is a highly accurate value.

  Thus, if the frequency response function is obtained in advance, the excitation force when the golf ball is collided can be obtained with high accuracy. Thereby, for example, when performing FEM analysis about a golf club head, since the exciting force which actually acts can be used, analysis accuracy can be made high.

Further, in the present embodiment, the frequency response function H is defined as the above Equation 4, but the present invention is not limited to this. For example, a frequency response function H1 represented by the following formula 6 may be used. This frequency response function H1 is the reciprocal of the frequency response function H.
In this case, the complex Fourier spectrum F1 (f) of the excitation force signal generated in the golf club head 130 when the golf ball 112 is caused to collide can be obtained by the following formula 7. Even when this frequency response function H1 is used, if the frequency response function H1 is obtained in advance for the golf club head 130, the excitation force when the golf ball 112 is caused to collide can be obtained accurately as described above. it can. In this way, since the excitation force that actually acts can be obtained, the analysis accuracy can be increased when performing numerical analysis.

  H1 = F (f) / A (f) (6)

  F1 (f) = H1 × A (f) (7)

  The present invention is basically configured as described above. The golf club design system and golf club design method of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiment, and various improvements or modifications can be made without departing from the spirit of the present invention. Of course.

10 Golf club design system (design system)
DESCRIPTION OF SYMBOLS 12 Processing apparatus 14 Operation part 16 Monitor 20 Analysis model production part 22 Analysis part 24 Evaluation parameter calculation part 26 of impact sound 26 Memory 28 CPU
30 First golf club head model 30a Second golf club head model 40 Analytical model 42 Mesh model 44 Mesh model of first observation mesh 46 Mesh model of second observation mesh 48 Third mesh of observation 48 Mesh model

Claims (6)

An analysis model creation unit for creating a golf club head analysis model capable of numerical analysis with respect to the golf club head and creating a numerical analysis model capable of numerical analysis at a position corresponding to a response point that is a predetermined distance away from the golf club head; ,
A predetermined excitation force is virtually applied to the face surface of the golf club head analysis model to obtain a frequency response function of the numerical analysis model of the response point, and the frequency response function and the golf club head at the time of golf ball hitting are obtained. An analysis unit for obtaining time waveform data of sound pressure at the time of hitting the golf ball in the numerical analysis model of the response point using an applied excitation force;
A golf club design system comprising: an evaluation unit that evaluates a hitting sound when the golf ball is hit using the time waveform data of the sound pressure.   The golf club design system according to claim 1, wherein the response point is a position corresponding to a height of a golfer's ear hitting the golf ball.   The evaluation unit evaluates a sound pressure parameter representing the magnitude of the hitting sound when hitting the golf ball, a reverberation parameter representing the degree of attenuation of the hitting sound, and an elevation parameter representing the frequency characteristic of the hitting sound. The golf club design system according to claim 1, wherein the system is calculated as follows. Creating a golf club head analysis model capable of numerical analysis for the golf club head, and creating a numerical analysis model capable of numerical analysis at a position corresponding to a response point a predetermined distance away from the golf club head;
A step of virtually applying a predetermined excitation force to the face surface of the golf club head analysis model to obtain a frequency response function of the numerical analysis model of the response point;
Using the frequency response function and the excitation force applied to the golf club head when hitting a golf ball, obtaining time waveform data of sound pressure at the time of hitting the golf ball in the numerical analysis model of the response point;
And a step of evaluating a hitting sound when the golf ball is hit using the time waveform data of the sound pressure.   The golf club design method according to claim 4, wherein the response point is a position corresponding to a height of a golfer's ear hitting the golf ball.   The step of evaluating the hitting sound includes a sound pressure parameter that represents the magnitude of the hitting sound when hitting the golf ball, a reverberation parameter that represents the degree of attenuation of the hitting sound, and an elevation parameter that represents the frequency characteristic of the hitting sound. The golf club design method according to claim 4, wherein the evaluation parameter is calculated as an evaluation parameter.