JP2009059094A - Vibration analyzing system and vibration analyzing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for supporting specification of a part effective for improving vibration/noise performance. <P>SOLUTION: A structure is provided with: an input point (a) to which vibration is applied; an evaluation point (b) where a response to the input is evaluated; and a point (c) of interest. A transmission function matrix acquisition part 10 acquires a transmission function matrix including a transmission function Hab between the input point (a) and the evaluation point (b), a transmission function Hac between the input point (a) and the point (c) of interest, a transmission function Hbc between the evaluation point (b) and the point (c) of interest, and a transmission function Hcc between the point (c) of interest and the same point (c) of interest. An operation condition setting part 11 sets operation conditions including vibration to be applied to the input point (a) and a target to be satisfied by the response of the evaluation point (b). A calculation part 12 calculates and outputs a target achievement range on the basis of the transmission function and the operation conditions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for analyzing vibration of a structure.

  When the vibration / noise performance of a structure (for example, an automobile) does not achieve the target, some structural change is required. However, with conventional analysis tools, reference information for finding an approximate guide on where and how to change (for example, resonance frequency, resonance frequency, strain / kinetic energy, stress distribution, sound production, deformation diagram) Etc.). Therefore, the engineer repeats trial and error of the structure change based on the reference information so that the performance target can be achieved.

  Such trial and error improvement work largely depends on the skill of the engineer. For example, the number of repetitions varies greatly depending on how to select a part to be changed. Moreover, even if a means for achieving the performance target is found through this repetition, there is no method for objectively evaluating whether or not it is the optimal solution. In addition, since it is not known whether it is easy, difficult, or impossible to achieve the performance target by changing the structure of the focused part, there is a high possibility that repeated examination will end up with effort. Furthermore, when carrying out repeated examinations, a modification period is required if the examination is based on an actual structure (for example, a prototype), and if a simulation model is used, a model modification and additional simulation (several hours to several days) are required. Both involve scheduling difficulties.

The following techniques are available as techniques for analyzing the vibration of the structure. Japanese Patent Application Laid-Open No. 2003-228561 discloses a method of obtaining a vibration level of a response point of a vehicle body by connecting an element other than the vehicle body to the vehicle body with a dynamic spring and performing frequency analysis on the motion equation of the vehicle body. Patent Document 2 discloses an FEM analysis method for modeling a soundproof material as a spring / mass model. Patent Document 3 discloses an evaluation method for obtaining rigidity from vibration displacement at 0 Hz of an FEM model representing an analysis target part.
JP-A-8-272837 JP 2006-65466 A JP 2007-94567 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for supporting specification of a countermeasure site effective for improving vibration and noise performance.

  In order to achieve the above object, the present invention adopts the following configuration.

  The vibration analysis system according to the present invention includes a first transfer function between the input point and the evaluation point with respect to an input point to which vibration is applied, an evaluation point at which a response is evaluated, and a structure having a point of interest. , A second transfer function between the input point and the point of interest, a third transfer function between the evaluation point and the point of interest, and a fourth between the point of interest and the same point of interest. Transfer function acquiring means for acquiring the transfer function, operating condition setting means for setting an operating condition including a vibration to be applied to the input point and a target to which the response of the evaluation point should be satisfied, and the first to fourth A target achievement range calculating means for calculating a target achievement range that is a range of values that the fourth transfer function should take in order for the response of the evaluation point to satisfy the target based on the transfer function and the operating condition; , The current value of the fourth transfer function and the target achievement range And an output means for outputting.

  Here, the “point of interest” is a candidate for a part to be subjected to structural change. The fourth transfer function represents the vibration characteristic of the point of interest, and if any structural change is made to the point of interest, the value (amplitude, phase) of the fourth transfer function changes.

  When the evaluation point response does not satisfy the target, the current value of the fourth transfer function is out of the target achievement range. At this time, by comparing the current value of the fourth transfer function with the target achievement range, it can be determined whether or not the target can be achieved by changing the structure of the target point, and further whether or not the target can be achieved easily. For example, the smaller the difference between the target achievement range and the current value, that is, the smaller the amount of change in the fourth transfer function, the easier the target is achieved. In addition, it can be said that the achievement of the target is easier as the range of the target achievement range is wider. Conversely, if the target achievement range is far away from the current value or the range of the target achievement range is narrow, it can be seen that it is difficult to achieve the target by changing the structure of the target point. If the target achievement range does not exist or is extremely narrow, it is understood that the target cannot be achieved by changing the structure of the target point. The transfer function may be calculated from the result of a vibration experiment using a real structure or may be calculated by simulation.

  It is preferable that the output means outputs the target achievement range by superimposing the target achievement range on a graph indicating a current value of the fourth transfer function. This is because it becomes easy to compare the current value of the fourth transfer function with the target achievement range.

  The structure preferably includes a plurality of the points of interest, and the target achievement range is calculated for each of the plurality of points of interest. As a result, the possibility and ease of achieving the target can be compared among a plurality of points of interest (candidates), so that it is easy to select a countermeasure site effective for performance improvement.

  For the plurality of points of interest, the amount of change in the fourth transfer function required to achieve the target is calculated based on the current value of the fourth transfer function and the target achievement range. preferable. Further, the output means may rank and output the plurality of points of interest according to the amount of change of the fourth transfer function. This makes it easier to select countermeasure sites effective for performance improvement.

  The present invention can be understood as a vibration analysis system having at least a part of the above means. The present invention can also be understood as a vibration analysis method including at least a part of the above processing, or a program for realizing the method. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

  For example, in the vibration analysis method as one aspect of the present invention, the input point and the evaluation point of the structure having the input point to which the vibration is applied, the evaluation point at which the response is evaluated, and the point of interest are calculated. The first transfer function between the input point and the point of interest, the second transfer function between the input point and the point of interest, the third transfer function between the evaluation point and the point of interest, and the same as the point of interest A process for obtaining a fourth transfer function between the target point, a process for setting an operating condition including a vibration to be applied to the input point and a target to which a response of the evaluation point should be satisfied; A process of calculating a target achievement range that is a range of values that the fourth transfer function should take in order for the response of the evaluation point to satisfy the target based on the transfer function of 4 and the operating condition; Output the current value of the fourth transfer function and the target achievement range And executes processing and, the.

In addition, the vibration analysis program as one aspect of the present invention includes an input point where vibration is applied to a computer, an evaluation point where a response is evaluated, and a structure having a point of interest. The first transfer function between the input point and the point of interest, the second transfer function between the input point and the point of interest, the third transfer function between the evaluation point and the point of interest, and the same as the point of interest A process for obtaining a fourth transfer function between the target point, a process for setting an operating condition including a vibration to be applied to the input point and a target to which a response of the evaluation point should be satisfied; A process of calculating a target achievement range that is a range of values that the fourth transfer function should take in order for the response of the evaluation point to satisfy the target based on the transfer function of 4 and the operating condition; Output the current value of the fourth transfer function and the target achievement range Process and that is intended to run.

  According to the present invention, it becomes easy to identify a countermeasure site effective for improving vibration and noise performance.

  Hereinafter, a preferred embodiment of the present invention will be described by taking a vehicle vibration analysis as an example. However, the scope of application of the present invention is not limited to vehicle vibration analysis, and the present invention is preferably applicable to vibration analysis of any structure in which vibration and noise are problems.

(System overview)
In vehicle development, reduction of vibration and noise is a very important issue, and it is various so that the vibration / noise level of a predetermined performance evaluation point (for example, the driver's ear position, steering, seat, etc.) is below the target value. Measures are taken. However, in the past, since it was impossible to objectively compare and judge which part of the vehicle it was effective to modify the structure, it was inefficient because it had to rely on repeated examinations through trial and error.

  Further, in actual development, there may be a part that is difficult to change the structure (preferably a part where it is desirable to avoid the structure change) due to design, strength, cost, and the like. When there is a vibration factor in such a part, it is desirable that the performance target can be achieved by changing the structure of another part rather than changing the structure of the part. However, conventionally, it has not been possible to determine at which part the target can be achieved (or is it easier).

  Therefore, the vibration analysis system of the present embodiment presents the user with information that can objectively evaluate the possibility and ease of achievement of the performance target by changing the structure of the point of interest, thereby improving the vibration / noise performance. Navigate.

(Calculation method of target achievement range)
First, the basic theory of the method for calculating the target achievement range in the present system will be described with reference to FIG. FIG. 1 shows a theoretical model of the transfer function synthesis method.

  The first term on the left side of FIG. 1 represents the initial state of the structure. This structure has an input point a at which vibration is applied, a performance evaluation point b at which a response (vibration / noise performance) to the input is evaluated, and a point of interest c at which the structure is changed. Let the vibration system of the structure in the initial state be [Hij]. Hij represents a transfer function between the points i and j. In the present embodiment, as the transfer function Hij, a compliance that is a displacement of the point j when the point i is vibrated is used, but the form of the transfer function is not limited to this.

As shown on the left side of FIG. 1, it is assumed that some structural change is applied to the point of interest c in the initial vibration system [Hij], and a new vibration system [Hij] ^* is obtained as shown on the right side of FIG. Possible structural changes include, for example, changing the rigidity and mass of the parts, changing the contact state and coupling state of the parts, attaching additional parts, and attaching dynamic dampers and damping sheets. The These treatments can be expressed by a vibration system of Fc = Q · Xc. Q is determined depending on what kind of treatment is performed. Here, (Equation 1) is obtained by constructing the relational expression of FIG. 1 and eliminating Q by the theory of the transfer function synthesis method.

Hac is a transfer function between the input point a and the point of interest c, Hbc is a transfer function between the performance evaluation point b and the point of interest c, and Hcc is a transfer function between the point of interest c and the same point of interest c ( This is called excitation point compliance at the point of interest c). H ^* cc is the excitation point compliance of the point of interest c after treatment. Hab and H ^* ab are transfer functions representing the response (vibration or noise) of the performance evaluation point b before and after the treatment, respectively.

（Ａ、Ｂは振動系［Ｈｉｊ］により決まる定数である。） Now, we want to know what type of vibration system Q should be given to the point of interest c in order to make the response H ^* ab after treatment less than or equal to the target level R (real number). From such an idea, (Equation 1) can be described as follows.

(A and B are constants determined by the vibration system [Hij].)

From this, H ^* cc is expressed on the complex plane as shown in FIG.

であり、この条件を満足する領域が図２のハッチング部分である。 At this time, since H ^* cc is the excitation point compliance, the phase is -180 to 0 degrees. And the response after treatment of a performance evaluation point should just be below target level R. That is,

The area satisfying this condition is the hatched portion in FIG.

This hatching region represents a range of values (target achievement range) that the excitation point compliance H ^* cc of the target point c should take in order for the response H ^* ab of the performance evaluation point c to satisfy the target R. That is, if the structure is such that H ^* cc falls within this target achievement range, it is a structure that can satisfy the target R.

When the evaluation point response Hab of the initial vibration system [Hij] does not satisfy the target R, the current value Hcc of the excitation point compliance at the point of interest c is out of the target achievement range of FIG. At this time, by comparing Hcc with the target achievement range, it can be determined whether or not the target can be achieved by changing the structure with respect to the target point c, and further whether or not the target can be achieved easily. For example, the smaller the difference between the target achievement range and the current value Hcc, that is, the smaller the change amount of Hcc, the easier the target is achieved. In addition, it can be said that the achievement of the target is easier as the range of the target achievement range is wider. vice versa,
If the target achievement range and the current value Hcc are far apart or the width of the target achievement range is narrow, it can be seen that it is difficult to achieve the target by changing the structure of the target point c. If the target achievement range does not exist or is extremely narrow, it can be seen that there is no solution, that is, it is impossible to achieve the target regardless of any structural change at the point of interest c.

  The transfer functions Hab, Hac, Hbc, and Hcc of the structure may be calculated by (1) simulation or (2) from the result of a vibration experiment using an actual structure. In the case of (1), a vibration / noise simulation using a FEM model of the structure is performed, and a transfer function matrix is calculated. In the case of (2), a vibration / noise transmission measuring device (configuration consisting of a noise meter, accelerometer, signal generator, and vibrator) is attached to the structure, and a vibration experiment is performed. By analyzing, the transfer function matrix of the structure is obtained. It is desirable that the transfer function in the initial state is an ideal value that does not include an error factor. Therefore, average the measurement results from multiple measurements or, if possible, average the measurement results from multiple real structures. Is preferred.

(System configuration)
Next, a specific configuration of the vibration analysis system of this embodiment will be described.

  FIG. 3 is a block diagram showing the configuration of the vibration analysis system. The vibration analysis system 1 includes a transfer function matrix acquisition unit 10, an operation condition setting unit 11, a calculation unit 12, and an output unit 13 as main functions. This system can be configured by a general-purpose computer system including a CPU (Central Processing Unit), a storage device, a display device, an input device, etc. in terms of hardware. Each function described above is stored in the storage device. The program is executed by the CPU.

  The transfer function matrix acquisition unit 10 has a function of acquiring transfer function matrix data of a structure to be analyzed. Here, as shown in FIG. 4, a structure including an input point A, a performance evaluation point B, and a plurality of points of interest C1 to C5 is assumed. However, the number of points of interest can be freely set according to the purpose of analysis and analysis frequency. A plurality of input points and performance evaluation points may be set. It is assumed that the transfer function matrix of this structure is obtained in advance by simulation or experiment as described above.

  The operating condition setting unit 11 is a function for setting operating conditions. As an operation condition, at least a vibration condition that defines a vibration (excitation frequency, excitation force, etc.) applied to the input point A and a target condition that defines a target level that the response of the performance evaluation point B should satisfy are given. .

  First, the calculation unit 12 calculates the current vibration / noise performance of the structure from the transfer function matrix and the operating conditions. The calculation result is output to the display device or the printing device by the output unit 13. FIG. 5 shows an output example of the current performance. The horizontal axis represents frequency [Hz], and the vertical axis represents phase [deg] (upper stage) and sound pressure level [dB] (lower stage). The alternate long and short dash line in the lower graph represents the target level (50 dB). It can be seen that the target is not achieved in some frequency ranges R1 and R2.

  The calculation unit 12 calculates a target achievement range for each point of interest C1 to C5 using (Expression 2) and (Expression 3). The calculation result is output to the display device or the printing device by the output unit 13.

FIG. 6 is an example in which the current vibration characteristics (solid line graph) of a certain point of interest and its target achievement range (gray area) are output in an overlapping manner. Here, the excitation point inertance of the target point is displayed as the vibration characteristic of the target point (the inertance corresponds to the second derivative of compliance). The horizontal axis represents the frequency [Hz], the vertical axis represents the phase [deg] (upper stage) and the inertance level [dB.
] (Bottom). From FIG. 6, it can be seen that in the frequency ranges R1 and R2 where the target has not been achieved (see FIG. 5), the phase and level of the excitation point inertance at the point of interest are out of the target achievement range. Furthermore, in the frequency range R1, the target can be achieved by slightly changing the vibration characteristics of the target point. However, in the frequency range R2 (particularly in a high frequency range), the target achievement range is narrow, so the target is achieved by changing the structure of the target point. It can be seen that is difficult. By obtaining a graph of each point of interest, the possibility and ease of achieving the target can be compared among a plurality of points of interest, so that it is easy to select a countermeasure site effective for performance improvement.

  FIG. 7 is an example in which the necessary change amount of the vibration characteristic at each point of interest is output as a list. When the frequency range of interest is designated as the calculation condition, the calculation unit 12 calculates the average of the difference between the current value (phase and level) of the vibration characteristic and the target achievement range in the designated frequency range for each point of interest. The average of the gaps corresponds to the required change amount. It can be said that the smaller the necessary change amount, the easier it is to achieve the target. When the target achievement range does not exist, the necessary change amount is “NONE” (no solution). As shown in FIG. 7, by selecting and outputting the points of interest in order of increasing required change amount, it becomes easier to select a countermeasure site effective for performance improvement.

  The present system described above has the following advantages.

  According to this system, information that can objectively evaluate the possibility and ease of achievement of performance targets by changing the structure of the point of interest can be obtained, so it is extremely easy to identify countermeasure sites that are effective in improving vibration and noise performance. Therefore, the examination by trial and error as in the past becomes unnecessary.

  Further, the present system has an advantage that the result can be output in a short time of several seconds to several minutes because the influence of each point of interest can be predicted only by the calculation based on the transfer function.

  The above embodiment is merely an example of the present invention. The scope of the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea. For example, in the above embodiment, compliance is used as a transfer function, but other types of transfer functions such as inertance may be used.

FIG. 1 is a diagram illustrating a theoretical model of the transfer function synthesis method. FIG. 2 is a diagram illustrating the relationship between the transfer function and the performance target on the complex plane. FIG. 3 is a block diagram showing the configuration of the vibration analysis system according to the embodiment of the present invention. FIG. 4 is a diagram illustrating an example of a structure. FIG. 5 is a diagram illustrating an output example of the current vibration / noise performance. FIG. 6 is a diagram illustrating an output example of the current vibration characteristic of a certain point of interest and the target achievement range. FIG. 7 is a diagram illustrating an example in which the necessary change amounts of the vibration characteristics of the respective points of interest are output as a list.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibration analysis system 10 Transfer function matrix acquisition part 11 Operation condition setting part 12 Calculation part 13 Output part a, A Input point b, B Performance evaluation point c, C1-C5 Points of interest

Claims (6)

An input point to which vibration is applied, an evaluation point at which response is evaluated, and a structure having a target point, a first transfer function between the input point and the evaluation point, the input point and the target point Transfer function to acquire a second transfer function between the target point and the third transfer function between the evaluation point and the target point, and a fourth transfer function between the target point and the same target point Means,
An operation condition setting means for setting an operation condition including a vibration to be applied to the input point and a target to which a response of the evaluation point should be satisfied;
Based on the first to fourth transfer functions and the operating conditions, a target achievement range that is a range of values that the fourth transfer function should take in order for the response of the evaluation point to satisfy the target is calculated. A target achievement range calculation means to
Output means for outputting a current value of the fourth transfer function and the target achievement range;
A vibration analysis system comprising: 2. The vibration analysis system according to claim 1, wherein the output unit outputs the target achievement range by superimposing the target achievement range on a graph indicating a current value of the fourth transfer function. The structure has a plurality of the points of interest,
The vibration analysis system according to claim 1, wherein the target achievement range is calculated for each of the plurality of points of interest. For the plurality of points of interest, based on the current value of the fourth transfer function and the target achievement range, the amount of change in the fourth transfer function necessary to achieve the target is calculated. The vibration analysis system according to claim 3, wherein The vibration analysis system according to claim 4, wherein the output unit ranks and outputs the plurality of points of interest according to a change amount of the fourth transfer function. Computer
An input point to which vibration is applied, an evaluation point at which response is evaluated, and a structure having a target point, a first transfer function between the input point and the evaluation point, the input point and the target point Obtaining a second transfer function between the target point and the third transfer function between the evaluation point and the target point, and a fourth transfer function between the target point and the same target point;
A process of setting an operating condition including a vibration to be applied to the input point and a target that the response of the evaluation point should satisfy;
Based on the first to fourth transfer functions and the operating conditions, a target achievement range that is a range of values that the fourth transfer function should take in order for the response of the evaluation point to satisfy the target is calculated. Processing to
Processing to output a current value of the fourth transfer function and the target achievement range;
The vibration analysis method characterized by performing.

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