JPS6385421A - Test waveform generating device - Google Patents

Abstract

PURPOSE:To reduce storage capacity by developing the power spectrum of a stored waveform to be generated into a Fourier spectrum, performing inverse Fourier transform, and generating a random waveform from found time-series data. CONSTITUTION:A waveform generator 1 generates a preset waveform which is displaced corresponding to displacement data outputted by a computer 2 every time the displacement data arrives and then supplies it to a material testing machine 3. At this time, when the displacement data is determined by the computer 2, a power spectrum G(omega) is led out of a memory 4 while the number of displacement times is denoted as N to find the complex Fourier spectrum F of the spectrum G(omega), and this spectrum F is processed by inverse Fourier transform to obtain the time-series displacement data O. Here, the displacement data is generated until the number of data O reaches N to generate an infinite number of waveforms.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a test waveform generator that is used in a material testing machine and generates various test waveforms.

[Prior Art] For example, when testing materials for aircraft or ships, it is necessary to conduct the test in a manner that matches the load conditions on the test object to the actual environment. Therefore, we use a test waveform generator that reflects the load amount, its probability of occurrence, and the load frequency distribution in the test.

[Problems to be solved by the invention] However, in the conventional test waveform generator, it is necessary to input the load amount into the storage device for each load wave to be generated, Since the number of waves generated in the test is enormous, there is a problem in that it requires an enormous storage capacity and a great deal of effort to memorize it.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a test waveform generation device that can simulate a real environment while having an extremely small storage capacity.

[Means for Solving the Problems] In order to solve the above problems, the present invention has the following configuration. That is, the test waveform generator according to the first invention includes a power spectrum storage means for storing a power spectrum obtained by actually measuring a waveform to be generated in advance and analyzing the measured data; Random wave generation means for expanding a spectrum into a Fourier spectrum and performing inverse Fourier transform to generate a random wave; and waveform generation means for generating a test waveform based on time series data output from the random wave generation means. Become.

Further, the apparatus according to the second invention includes a storage means for actually measuring a waveform to be generated in advance and storing a power spectrum obtained by analyzing the obtained data, and a Fourier method for storing the power spectrum stored in the storage means. Random wave generation means for generating a random wave by expanding it into a spectrum and performing inverse Fourier transform; and waveform generation means for generating a test waveform based on time series data output from the random wave generation means.
a data collection means for collecting response data output by the waveform generation means and actually loaded on the specimen; and a calculation means for Fourier transforming the data collected by the data collection means to obtain a Fourier spectrum and further obtaining a power spectrum. a comparison determination means for comparing the power spectrum obtained by the calculation means with the power spectrum stored in the storage means and determining whether or not the power spectrum is within a preset tolerance range; and the comparison determination means If it is determined that is not within the allowable error range, the transfer function of the load system is determined from the respective Fourier spectra of the waveform to be loaded and the response waveform, and the Fourier spectrum of the waveform to be generated is corrected using this transfer function. and a correction calculation means.

[Function] In the first invention, the power spectrum storage means stores the power spectrum of the waveform to be generated,
The random wave generation means uses a power spectrum as data of only amplitude without a phase component, expands it into a Fourier spectrum, performs inverse Fourier transform, and outputs time series data. The waveform generating means generates a random waveform having the displacement of the data and a preset shape based on the time series data.

Further, in the test waveform generator according to the second invention, the response data outputted from the waveform generation means and loaded on the specimen is collected, the power spectrum of the response waveform is determined, and the deviation from the power spectrum of the original waveform is determined. is not within the tolerance, the load system transfer function is determined from the Fourier spectra of both waveforms, and the Fourier spectrum of the waveform to be loaded is corrected by this transfer function. A test wave faithful to the desired waveform is supplied.

[Embodiment] FIG. 1 is a block diagram showing the configuration of a test waveform generator that is an embodiment of the first invention. In the embodiment, an example will be described in which force waves are generated when a random load having a preset power spectrum is applied to a specimen using a material testing machine. In the embodiment, displacement is used as the physical quantity related to the waveform.

In FIG. 1, every time displacement data output from a computer 2 arrives, a waveform generator 1 generates a waveform having the displacement and a preset shape and supplies it to a material testing machine 3.

The computer 2 stores the memory 4 in accordance with the processing procedure described below.
Displacement data to be supplied to the waveform generator l is determined using the stored contents of the waveform generator l. The power spectrum of the amount of load to be applied to the specimen is stored in the memory 4 in advance. In other words, the frequency-power spectrum distribution as shown in Figure 2
Let me remember it.

Determination of displacement data in the computer is performed according to the flowchart shown in FIG.

When the start of the test is commanded, the power spectrum G(ω) shown in FIG. 2 is retrieved from the memory 4 with the number of displacement points being N, and the complex Fourier spectrum F(ω) of the power spectrum G(ω) is determined. If the power spectrum given here is 1Zt2, then the Fourier spectrum becomes Z=r(cosφ+1sinφ) (r: absolute value, φ: argument, -π×φ≦π), and by arbitrarily giving the value of φ, Randomness is guaranteed. The developed complex Fourier spectrum F(ω) is inversely Fourier transformed to obtain time-series displacement data O(D. Here, until the number of displacement data reaches N, that is, the number of waveform occurrences j reaches N. By generating displacement data one after another, an infinite number of waveforms can be generated.

FIG. 4 is a block diagram showing the configuration of a test waveform generator according to the second invention, and the same reference numerals in the figure indicate the same components as those shown in FIG. 1. The structure of the embodiment of the present invention is basically the same as the embodiment shown in FIG. However, waveform generator 1
A data collection device 5 is provided to collect the response displacement from the testing machine 3 due to the load waveform supplied to the material testing machine 3, and a computer 2 based on the data collected by the data collection device 5 is provided. The data processing is different from the above embodiment.

That is, the computer 2 calculates the power spectrum G(ω) of the response waveform with respect to the power spectrum G(ω) of the waveform to be loaded shown in FIG. A normal load is applied to the specimen.

The data processing procedure of the computer 2 will be explained according to the flowchart shown in FIG. When you command the start of the test,
First, the number of displacement points is N, and the tolerance error of the power spectrum is δ.
, the power spectrum G(ω) of the waveform to be loaded is taken out from the 10th-order memory 4 where variable j is set to O, and the normalization constant C is determined. And the power spectrum G
The complex Fourier spectrum F(ω) of (ω) is calculated,
F(ω) is inversely Fourier transformed to obtain time series displacement data 0(
j) is obtained. Based on the N pieces of displacement data thus obtained, test waveforms are sequentially generated by the waveform generator 1 and supplied to the testing machine 3. At the same time, the response displacement I (j) from the test machine 3 is collected by the data collection device 5.

The response displacement I (j) is Fourier transformed to obtain a Fourier spectrum F/(ω), and further a power spectrum G'(ω). The power spectrum G'(ω) of this response displacement is normalized by a constant C similar to G(ω), and the residual ΔG between G(ω) and G/(ω) is set in advance at each point of the frequency ω. It is determined whether or not the error is within the tolerance range δ.

If the residual ΔG is within the tolerance range, time-series displacement data is calculated from the power spectrum G(ω) of the waveform to be loaded. If ΔG is outside the tolerance range, the following correction is performed. It will be done. In other words, the transfer function H(ω) of this load system is obtained from the Fourier spectrum F(ω) obtained from the response type input IN) and the Fourier spectrum F(ω) obtained from the power spectrum of the displacement to be applied. , F(ω) is corrected using this H(ω). This correction is performed one after another as long as ΔG is outside the allowable range. By adopting the new F(ω) obtained by this correction as the input Fourier spectrum for creating displacement data O(j), a load faithful to the power spectrum G(ω) is applied to the specimen. That will happen.

In the above two embodiments of the invention, displacement is used as the physical quantity related to the waveform, but if you want to randomly change other physical quantities such as velocity and acceleration, the power spectrum can be stored in a similar manner. This can be achieved by Further, hardware dedicated to numerical processing can be used instead of a computer.

[Effects of the Invention] As is clear from the above description, the test waveform generator according to the first invention generates waveforms having physical quantities such as random displacements one after another simply by storing the power spectrum of the physical quantity in the memory. There is no need to allocate and store the generation order for each wave as in the past, and the storage capacity can now be extremely reduced. Moreover, it becomes possible to simulate a real environment with complete randomness guaranteed. Further, according to the test waveform generator according to the second invention, the waveform is corrected using the transfer function of the load system, and it is now possible to apply a load that is faithful to the power spectrum to the specimen. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the first invention,
Figure 2 is a diagram showing the power spectrum of the waveform to be loaded.
Fig. 3 is a flowchart showing the processing procedure in the computer, Fig. 4 is a blow diagram showing the configuration of the embodiment of the second invention, and Fig. 5 shows the power spectrum of the waveform to be loaded and the power spectrum of the response waveform. The figure shown in FIG. 6 is a flowchart showing the processing procedure in the computer. l...Waveform generator 2...Computer 3...Material testing machine 4...
Memory 5...Data collection device

Claims (2)

[Claims] (1) A power spectrum storage means that stores the power spectrum obtained by actually measuring the waveform to be generated in advance and analyzing the obtained data, and developing the power spectrum stored in the storage means into a Fourier spectrum and Fourier inversion. A test waveform generation device comprising a random wave generation means for converting and generating a random wave, and a waveform generation means for generating a test waveform based on time series data output from the random wave generation means. (2) A storage means for storing the power spectrum obtained by actually measuring the waveform to be generated in advance and analyzing the obtained data, and developing the power spectrum stored in the storage means into a Fourier spectrum and performing inverse Fourier transform. random wave generating means for generating a random wave based on the time series data outputted from the random wave generating means; a data collecting means for collecting the response data obtained by the data collecting means; a calculating means for Fourier-transforming the data collected by the data collecting means to obtain a Fourier spectrum and further calculating a power spectrum; Comparison and determination means for comparing the power spectrum stored in the means and determining whether or not the power spectrum is within a preset tolerance range; A test waveform generator comprising: a correction calculation means for determining a transfer function of a load system from the Fourier spectra of a waveform to be loaded and a response waveform, respectively, and correcting a Fourier spectrum of a waveform to be generated using the transfer function.