JP2005181195A - Vibration test method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration test method capable of evaluating accurate vibration durability, in conformity with practical transportation environments. <P>SOLUTION: This vibration test method concerned in the present invention is provided with a first step of calculating accumulated fatigue generated in a transported object P under a transportation condition in practical transportation as a theoretical accumulated fatigue; a second step for arranging the transported object P on a vibration table 1 to vibrate the vibration table 1 for a prescribed time at a vibration acceleration in the transportation condition; a third step for measuring the vibration acceleration generated in the transported object P and for calculating the accumulated fatigue received by the transported object P within the prescribed time as the practical accumulated fatigue, based on the vibration acceleration; a fourth step for increasing the vibration acceleration of the vibration table 1 to vibrate the vibration table 1 for a prescribed time at the the vibration acceleration; a fifth step for measuring the vibration acceleration generated in the transported object P, and for calculating the practical accumulated fatigue received by the transported object P within the prescribed time, based on the vibration acceleration; and a sixth step for repeating the fourth and fifth steps, until the sum of the practical accumulated fatigues reaches to the theoretical accumulated fatigue. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vibration test method for evaluating durability against a vibration of a transported article loaded on a transportation means such as a cargo vehicle.

Conventionally, the durability of goods to be transported such as cargo, equipment, etc. loaded on transportation means such as vehicles, railways, and aircraft has been generally evaluated by conducting a vibration test in advance. It has been broken. Such a transported product is actually damaged by receiving low acceleration vibration for a long time during transport. On the other hand, in the vibration test, it is inspected whether damage has occurred by applying high acceleration vibration for a short time, for example, about 1 hour, and this is caused on the load during actual transportation. Predicting damage. An example of such a vibration test is disclosed in Patent Document 1.
JP-A-9-327498

  By the way, the test conditions used in the vibration test as described above are based on the assumption that the vibration transmission is linear, and are determined based on the fatigue SN curve. That is, there are many types of goods to be transported, and there are as many vibration response characteristics as there are, but the test conditions are uniformly defined.

  However, goods to be transported such as cargo are often supported by cushioning materials that generate non-linear vibrations such as foamed materials, paper, wood, etc., so large geometric deformations were associated with vibrations exceeding a predetermined value. Large response vibrations may appear, and these large vibrations may damage the goods to be transported. In spite of this reality, the vibration test conditions are uniform as described above. For example, when vibration acceleration smaller than the predetermined value is given as the test condition, the test is performed without generating large vibrations. Was done. On the contrary, there may be a case where the test is performed under conditions that are stricter than the actual test conditions, that is, under conditions larger than the predetermined value. As described above, the conventional test method cannot accurately reproduce the actual vibration state and has a problem that the evaluation accuracy of the vibration durability is low.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vibration test method capable of accurately evaluating vibration durability in accordance with an actual transportation environment.

  A first vibration test method according to the present invention includes a first step of oscillating the vibration table with vibration acceleration under transportation conditions of actual transportation after placing the article to be transported on the vibration table; The vibration acceleration generated in the transported goods is measured, the accumulated fatigue in the whole process of actual transportation is calculated from the vibration acceleration, and this is used as the theoretical accumulated fatigue, and the vibration acceleration in the transportation conditions of the actual transportation, or A third step of vibrating the shaking table for a predetermined time with a smaller vibration acceleration, and an accumulation received by the transported product within the predetermined time based on the vibration acceleration after measuring the vibration acceleration generated in the transported product A fourth step of calculating fatigue and setting this as actual accumulated fatigue; a fifth step of increasing the vibration acceleration of the shaking table and causing the shaking table to vibrate at the vibration acceleration for a predetermined time; After measuring the vibration acceleration generated in the transported product, the accumulated fatigue experienced by the transported product within the predetermined time is calculated based on the vibration acceleration, and this is used as the actual accumulated fatigue. And a seventh step that repeats the fifth and sixth steps until the sum of fatigue reaches the theoretical accumulated fatigue.

  In addition, the article to be transported here means an article that is assumed to be damaged by vibration, such as a device that is mounted on a vehicle or the like, in addition to a product that is transported by a transportation means such as a vehicle or a railroad. Further, the transportation conditions correspond to, for example, vibration acceleration, transportation time, vibration frequency, and the like generated by transportation means such as a vehicle during actual transportation. In addition, in the case of a vehicle-mounted device, it refers to conditions such as vibration acceleration received when the product is used.

  The second vibration test method according to the present invention includes a first step of measuring a power spectrum density of vibration generated in a transported product in actual transport, and the transported product is placed on a shaking table and measured. A second step of measuring the power spectral density of the vibration generated in the transported product by oscillating the shaking table with vibration having a predetermined power spectral density, dividing the measured power spectral density into predetermined frequency intervals, and After deriving a vibration waveform by Fourier transform, based on this vibration waveform, the accumulated fatigue of the whole process in the actual transport is calculated for each frequency interval, and this is the theoretical accumulated fatigue. The product is placed on a shaking table, and the shaking table is vibrated for a predetermined time by the vibration having the power spectral density measured in the actual transportation to generate the product to be transported. A fourth step of measuring the power spectral density of the vibration, and a cumulative fatigue within a predetermined time is calculated from the power spectral density measured in the fourth step in the same manner as the third step. A fifth step of increasing the power spectral density of vibration in the shaking table, vibrating the shaking table for a predetermined time with the vibration having the power spectral density, and measuring the power spectral density of the vibration generated in the transported product Sixth step, a seventh step of calculating accumulated fatigue within a predetermined time from the power spectral density measured in the sixth step in the same manner as the third step, and setting this as actual accumulated fatigue, and the actual accumulated And an eighth step of repeating the sixth and seventh steps until the sum of fatigue reaches the theoretical accumulated fatigue.

  It is preferable that the theoretical accumulated fatigue and the actual accumulated fatigue are calculated based on an SN curve.

  The total time for vibrating the shaking table is more preferably 20 minutes to 8 hours.

  According to the present invention, accurate vibration durability can be evaluated in accordance with the actual transportation environment.

(First embodiment)
Hereinafter, a vibration test method according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a vibration test apparatus used in the test method according to the present embodiment.

  This vibration test apparatus is for predicting the presence or absence of damage to a transported object loaded on a transportation means such as a vehicle or a railway due to vibration during transportation. The transported object corresponds to, for example, a precision instrument, and such a transported article is usually transported in a state of being stored in a container such as a box together with a cushioning material. The cushioning material is formed of foam material, paper, wood, etc., and is disposed between the inner surface of the container and the transported object.

  As shown in FIG. 1, this apparatus includes a vibration table 1 capable of generating vibrations with a predetermined acceleration, and the transported object P is supported on a buffer material 3 on the vibration table 1. It is arranged in the state. A vibration generator 5 that generates vibration with a predetermined acceleration is attached to the vibration table 1. First and second acceleration sensors 7 and 9 for detecting these vibration accelerations are respectively attached to the vibration table 1 and the transported object P, and these acceleration sensors 7 and 9 are connected to a measuring device 11. ing. The measuring device 11 is connected to an analyzing device 13 that analyzes the measured vibration acceleration. The analysis device 13 includes a database 13 a in which various transportation conditions in actual transportation are stored in advance, a calculation unit 13 b that calculates accumulated fatigue generated in the transported product P, and a control that controls the operation of the vibration generator 5. Part 13c. The transportation conditions stored in the database 13a include, for example, vibration acceleration, transportation time, vibration frequency, etc. generated by transportation means such as a vehicle during actual transportation. A calculation formula used for calculating fatigue is also stored. Various calculation formulas can be used. For example, the accumulated fatigue β of the article to be transported P can be expressed by the following formula using a fatigue SN curve.

ここで、ｎ：振動回数、Ａ：振動加速度、α：被輸送品に固有の値、β：蓄積疲労である。

Here, n is the number of vibrations, A is the vibration acceleration, α is a value specific to the transported product, and β is accumulated fatigue.

  By using the above equation (1), the accumulated fatigue experienced by the transported product is calculated. Further, the control unit 13c performs control such as change and adjustment of vibration acceleration generated by the vibration generator 5.

Next, the vibration test method will be described with reference to the flowchart of FIG. Here, as an example, assuming that a precision instrument is transported as a transported product, the transport conditions are vibration acceleration of 0.5 G (4.9 m / s ² ), transport time of 10 hours, vibration frequency of 10 Hz, α = 4. Test for the case of. Under this condition, the number of vibrations in the entire transportation process is 3.6 × 10 ⁵ . First, the transportation conditions of the actual transportation environment to be tested are accumulated in the database 13a (step S1), and the shaking table 1 is vibrated under the transportation conditions selected from here (step S2). On the vibration table 1, a transported product P supported by the cushioning material 3 is disposed. And the vibration acceleration which arises in the to-be-transported object P is measured, and the accumulation fatigue which the to-be-transported goods P receives in the whole process of an actual transport is calculated from said Formula (1) based on this vibration acceleration (step S3). The accumulated fatigue in the whole process of actual transportation calculated in this way is referred to as theoretical accumulated fatigue. At this time, in addition to selecting the transportation condition from the database 13a, the theoretical accumulated fatigue can be calculated by inputting a new transportation condition into the analysis device 13. The theoretical accumulated fatigue under this transport condition is calculated as 22500 from the above formula (1).

Subsequently, the vibration table 1 is vibrated under the above-described transportation conditions, that is, 0.5 G (step S4), and the second acceleration sensor 9 measures the vibration acceleration of the article P to be transported. The vibration acceleration measured here was the same as that of the vibration table 1 and was 0.5 G. When the vibration table 1 is vibrated for 5 minutes at this vibration acceleration (the number of vibrations is 3 × 10 ³ ), accumulated fatigue is calculated as 188 from the equation (1) (step S5). Hereinafter, the fatigue that the transported object P receives as a result of vibration within a predetermined time will be referred to as actual accumulated fatigue. Since the actual accumulated fatigue at this time does not reach the theoretical accumulated fatigue, it is necessary to further apply vibration.

  Therefore, the vibration acceleration of the vibration table 1 is increased (step S6). At this time, the vibration acceleration of the vibration table 1 is set so that the vibration acceleration detected by the first acceleration sensor 7 becomes the vibration acceleration to be set while the vibration acceleration of the vibration table 1 is increased by the control unit 13c of the analysis device 13. Is adjusted. Here, as an example, the vibration acceleration is increased from 0.5 G to 0.75 G. When the vibration acceleration generated in the article to be transported P due to the vibration of the shaking table 1 was measured, it was 0.75 G. When the transported product P is vibrated, for example, for 5 minutes at a vibration acceleration of 0.75 G, the actual accumulated fatigue of the transported product P in this 5 minutes is represented by Equation (1) to 949 (step S7). At this time, the total of the actual accumulated fatigue at 0.5G is 1137, but it is not yet reached the theoretical accumulated fatigue as compared with the theoretical accumulated fatigue (step S8). Therefore, the vibration acceleration applied to the vibration table 1 is further increased (NO in step S8).

Here, for example, when the vibration acceleration is changed from 0.75 G to 1.0 G, the vibration acceleration measured by the transported product P is 10 G, and the actual accumulated fatigue for 5 minutes is 3 × 10 ⁷ from the equation (1). It becomes. That is, the theoretical accumulated fatigue is exceeded. As described above, if the actual accumulated fatigue in a short-time vibration exceeds the theoretical accumulated fatigue, accurate evaluation cannot be performed. Therefore, 1.0G is not appropriate as the vibration to be applied. Therefore, the vibration acceleration is set to 0.8 G which is a slightly small value. At this time, the vibration acceleration of the transported object P is the same 0.8G. So far, the vibration of 0.5G is performed for 5 minutes, and the vibration of 0.75G is performed for 5 minutes. Therefore, when the transported object is vibrated at a vibration acceleration of 0.8G, it is calculated backward from the equation (1). The total actual accumulated fatigue reaches theoretical accumulated fatigue with a vibration of 87 minutes (YES in step S8). Therefore, the shaking table 1 is vibrated for 87 minutes from here, and after shaking the shaking table 1 for a total of 97 minutes, it is stopped (step S9), and it is inspected whether the transported object P is damaged (step S10). . The adjustment of the vibration acceleration as described above is performed by the calculation unit 13b of the analysis device 13.

  As described above, according to the present embodiment, vibration during actual transportation is applied to the transported product P, and vibrations generated from the transported product P are measured. Therefore, the accuracy of the test can be improved as compared with the conventional test method performed under uniform conditions. Since the vibration is gradually increased from the vibration during actual transportation and the test is performed until the sum of the actual accumulated vibrations reaches the theoretical accumulated fatigue, it is compared with the case where the test is performed with a single vibration acceleration. Testing time can be greatly reduced. At this time, since the vibration is gradually increased by changing the vibration, it is possible to perform an evaluation in consideration of the nonlinear vibration that greatly changes the output vibration with respect to the input vibration. As a result, the test accuracy can be greatly improved.

  In addition, although the time for vibrating the vibration stand 1 by the time it complete | finishes a test is so good that it is short, when there is too short, there exists a problem that a test precision falls. From such a viewpoint, the vibration time is preferably 5 minutes or more and 8 hours or less, and more preferably 20 minutes or more and 1 hour or less. Further, it is preferable that the vibration table 1 is vibrated at each vibration acceleration for a short time, and the vibration acceleration is controlled by the accumulated fatigue rate.

  In the database 13a, the relationship between the vibration applied to the vibration table 1 and the vibration generated in the transported product P can be stored in advance. By doing so, the step of measuring the vibration acceleration generated in the transported product P can be omitted, and the test can be performed efficiently.

(Second Embodiment)
Next, a second embodiment of the vibration test method according to the present invention will be described. In the first embodiment, the test was performed by vibrating the vibration table at the same frequency and vibration acceleration. In the second embodiment, the test was performed by applying irregular vibration to the vibration table. Hereinafter, this will be described in detail with reference to the flowchart shown in FIG. In this embodiment, the same apparatus as that shown in FIG. 1 is used.

  As shown in FIG. 3, first, a power spectral density (PSD: Power Spectral Density) of vibration generated in a product during actual transportation is measured in advance (step S11). For example, when a transported product P is loaded on a truck and transported, a recorder for recording the vibration is arranged on the truck bed and the vibration generated in the truck is recorded in advance. And after arrange | positioning the to-be-transported goods P supported by the shock absorbing material 3 on the vibration stand 1, the vibration stand 1 is vibrated by the same vibration as the recorded vibration (step S12), and the vibration generate | occur | produced in the to-be-transported goods P Measure PSD. In addition to recording the vibration of the loading platform as described above, the vibration of the transported product P arranged on the loading platform may be measured. In this case, the PSD is derived from the recorded data. An example of the PSD of the transported product obtained as described above is shown in FIG. In this example, a PSD larger than the PSD of vibration generated in the cargo bed is generated in the transported product P.

  Next, as shown in FIG. 5, the entire frequency range of the PSD is divided into a predetermined number of divisions, for example, a logarithm. Subsequently, the decomposed PSD is subjected to inverse Fourier transform for each frequency interval to derive the vibration waveform shown in FIG. Subsequently, the accumulated fatigue generated in the transported product P is calculated for each divided frequency interval (step S13). At this time, the accumulated fatigue is calculated using the following equation (2), and the calculated accumulated fatigue is defined as theoretical accumulated fatigue.

なお、αは被輸送品固有の値、βは蓄積疲労、ｆ_Oは期待振動数、σは振動加速度の瞬時値に関する確率密度関数の標準偏差、Ｔは実輸送時間、Γはガンマ関数を示している。

Where α is a value specific to the product to be transported, β is accumulated fatigue, f _O is the expected frequency, σ is the standard deviation of the probability density function related to the instantaneous value of vibration acceleration, T is the actual transport time, and Γ is the gamma function. ing.

  Subsequently, after the vibration having the PSD in the actual transportation as described above is applied to the shaking table 1 for a predetermined time (step S14), the accumulated fatigue for each frequency interval occurring within this time is calculated using the equation (2). This is regarded as actual accumulated fatigue (step S15). When the actual accumulated fatigue calculated at this time is compared with the theoretical accumulated fatigue, for example, FIG. 7 is obtained. This figure shows that the actual accumulated fatigue has not yet reached the theoretical accumulated fatigue.

  Next, the vibration PSD is increased by a predetermined amount, the vibration having the PSD is applied to the vibration table 1 for a predetermined time (step S16), and the actual accumulated fatigue within this time is calculated in the same manner as described above (step S17). Then, the sum of the actual accumulated fatigue for each PSD obtained so far is calculated and compared with the theoretical accumulated fatigue (step S18). At this time, as shown in FIG. 8, if the sum of the actual accumulated fatigue does not reach the theoretical accumulated fatigue (NO in step S18), the PSD is further increased and the test is continued (step S16). Thus, the actual accumulated fatigue is measured while increasing the PSD, and when the sum of the actual accumulated fatigue for each PSD reaches the theoretical accumulated fatigue (YES in step S18), the vibration of the shaking table 1 is stopped (step S19). The damage status of the transported product P is inspected (step S20).

  As described above, according to this embodiment, the vibration generated in the article to be transported P is measured by applying the irregular vibration generated in the actual transportation to the vibration table 1. Therefore, since the test can be performed in an environment closer to actual transportation, the test accuracy can be further improved. Similarly to the first embodiment, since the test is performed until the sum of the actual accumulated fatigue reaches the theoretical accumulated fatigue while gradually increasing the vibration level, that is, PSD, when applying a single vibration Compared to the actual transportation environment, the test time can be greatly shortened.

  As mentioned above, although embodiment of this invention was shown, this invention is not limited to this, The change is possible unless it deviates from the meaning. For example, in the above-described embodiment, the accumulated fatigue is calculated by the formula (1) or the formula (2). However, this is an example, and there is no particular limitation as long as it is a calculation formula for calculating the accumulated fatigue. In the above description, the article to be transported is supported on the vibration table while being supported by the cushioning material. However, the goods to be transported can be arranged on the vibration table as they are, and the vibration can be measured.

  In the first embodiment, when the actual accumulated fatigue is measured, the vibration of the shaking table is started and gradually increased with the vibration acceleration at the time of actual transportation, but the vibration is started from a vibration acceleration smaller than this. You may start.

It is a schematic block diagram of the vibration test apparatus which enforces the vibration test method which concerns on this invention. It is a flowchart which shows 1st Embodiment of the vibration test method which concerns on this invention. It is a flowchart which shows 2nd Embodiment of the vibration test method which concerns on this invention. It is a graph which shows the relationship between the vibration conditions of actual transportation, and the vibration frequency of the vibration which arose in the to-be-transported goods, and PSD. It is an example which divided | segmented the graph of FIG. 4 into the predetermined frequency interval. 6 is a vibration waveform generated from the graph of FIG. 5. It is a figure which shows the relationship between the real accumulation fatigue and the theoretical accumulation fatigue at the time of the end of the first vibration. It is a figure which shows the relationship between the real accumulation fatigue and the theoretical accumulation fatigue at the time of finishing the second vibration.

Explanation of symbols

1 Shaking table 7, 9 Acceleration sensor P

Claims (4)

A first step of oscillating the vibration table with vibration acceleration under actual transportation conditions after placing the article to be transported on the vibration table;
A second step of measuring the vibration acceleration generated in the article to be transported on the shaking table, calculating the accumulated fatigue in the whole process of actual transportation from the vibration acceleration, and setting this as the theoretical accumulated fatigue;
A third step of vibrating the shaking table for a predetermined time at a vibration acceleration under the transportation conditions of the actual transportation or a vibration acceleration smaller than the vibration acceleration;
After measuring the vibration acceleration generated in the transported article, calculate the accumulated fatigue experienced by the transported article within the predetermined time based on the vibration acceleration, and set this as the actual accumulated fatigue,
A fifth step of increasing the vibration acceleration of the vibration table and vibrating the vibration table for a predetermined time at the vibration acceleration;
After measuring vibration acceleration generated in the transported product, calculating accumulated fatigue that the transported product is subjected to within the predetermined time based on the vibration acceleration;
And a seventh step of repeating the fifth and sixth steps until the sum of the actual accumulated fatigue becomes the theoretical accumulated fatigue. A first step of measuring a power spectral density of vibration generated in a transported product in actual transportation;
A second step of placing the transported article on a shaking table, vibrating the shaking table with vibration having the measured power spectral density, and measuring a power spectral density of vibration generated in the transported article;
After dividing the measured power spectral density into predetermined frequency intervals and deriving the vibration waveform by inverse Fourier transform, the accumulated fatigue of the whole process in the actual transport is calculated for each frequency interval based on this vibration waveform. , The third step to make this theoretically accumulated fatigue,
The transported product is placed on a vibration table, and the vibration table is vibrated for a predetermined time by vibration having the power spectrum density measured in the actual transportation, and the power spectrum density of the vibration generated in the transported product is measured. 4 steps,
A fifth step of calculating accumulated fatigue within a predetermined time from the power spectral density measured in the fourth step in the same manner as the third step, and setting this as actual accumulated fatigue;
A sixth step of increasing the power spectral density of vibration in the shaking table, vibrating the shaking table for a predetermined time with the vibration having the power spectral density, and measuring the power spectrum density of the vibration generated in the transported product;
Calculating accumulated fatigue within a predetermined time from the power spectral density measured in the sixth step in the same manner as the third step, and setting this as actual accumulated fatigue;
And an eighth step of repeating the sixth and seventh steps until the sum of the actual accumulated fatigue becomes the theoretical accumulated fatigue.   The vibration test method according to claim 1, wherein the theoretical accumulated fatigue and the actual accumulated fatigue are calculated based on an SN curve.   The vibration test method according to claim 1, wherein a total time for vibrating the shaking table is 20 minutes to 8 hours.

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