JPH0145014B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a data acquisition device for a material testing machine,
In particular, the present invention relates to a data acquisition device suitable for tests in which repeated loads are applied, such as fatigue tests.

(B) Prior art In general, fatigue phenomena in material fatigue tests can be understood by storing data from the start to the end of the test in a storage device, etc., and analyzing the data after the test is completed. However, the amount of data usually reaches a huge amount. In conventional tests of this kind, therefore, a large-capacity auxiliary storage device was required, and furthermore, it was necessary to process a large amount of data during data analysis. Here, even if data is appropriately thinned out to reduce the amount of data to be collected, there is a risk that serious errors may occur in the analysis results because the changes in the physical properties of the test object are unknown. The reality is that the timing cannot be determined.

(c) Purpose The present invention has been made to solve the above technical problems, and it makes it possible to reduce the number of data collections in the above-mentioned tests, and moreover, the timing of data collection is based on the physical characteristics of the test object. The purpose of the present invention is to provide a data collection device that automatically determines data based on changes in properties and does not affect analysis results in any way.

(d) Configuration The configuration of the present invention will be explained based on the functional block diagram shown in FIG.

The testing machine applies repeated loads to the test object, and the stress and strain that act on the test object due to the load,
Continuously measure other data required for analysis, such as the number of repetitions. The compliance calculation method is
Input the stress and strain data from the testing machine and sequentially calculate the compliance of the test object in the elastic strain range during repeated loading cycles.
The compliance change amount calculation means calculates the amount of change in compliance that is calculated one after another,
The amount of change determining means determines whether the amount of change has reached a predetermined set value. The data storage means is configured to collect and store data from the testing machine only when the amount of change reaches a set value based on a command from the amount of change determination means.

(e) Examples Examples of the present invention will be described below based on the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

Testing machine 1 applies repeated loads to the test object,
The resulting stress and strain on the test object, as well as data necessary for analysis of other fatigue phenomena, etc., are measured, and the data is supplied to the A-D converter 2.
-D converter 2 based on a control signal issued from CPU 4 via input/output interface 3,
Converts data into digital quantities, and the digitally converted data is sent via input/output interface 3.
It is configured to be supplied to the CPU 4. CPU
A memory 5 is further connected to the memory 5, and is configured such that only data at a necessary point in time among the data supplied every moment is stored in the memory 5 by an operation described later.

Next, the operation of the embodiment of the present invention will be described. FIG. 3 is a flowchart showing a data collection program according to an embodiment of the present invention. First, at the beginning of the test, the initial compliance λ of the test object is calculated from the stress σ and strain ε data among various data from the testing machine 1, and the value is stored as the reference compliance λ ₀ . From then on, the compliance λ of the test object is 1 of the repeated load.
Calculated every cycle. These compliances λ are determined by the unloading part in the repeated loading cycle, that is, the predetermined part of the elastic strain range εer in the hysteresis curve of the repeated stress/strain cycle of the test object shown in Fig. 4 (for example, the part 20% from the maximum strain). ) is calculated using the stress σ and strain ε data as λ=dε/dσ. Next, it is determined whether the ratio (λ/λ ₀ ) to the above-mentioned standard compliance λ ₀ has reached a preset predetermined value α, and only when it is determined that the ratio has reached a predetermined value α, A data group is stored in the memory 5. At the same time, the above-mentioned predetermined value α is updated according to a preset order, and the reference compliance λ ₀ is updated to the compliance λ at that time. in this way,
The compliance λ of the test object is measured moment by moment,
Only when the value shows a predetermined change with respect to the standard compliance λ ₀ , the data group required for the test is stored in the memory 5, and other data is not stored. In other words, the timing of collecting data required to analyze fatigue phenomena is
Changes in the compliance of the test object are defined as parameters, and only the desired data is automatically stored.

In addition, in the above-mentioned embodiment, an example was shown in which α is updated as appropriate, but it may be fixed as a predetermined constant value. In addition to understanding the amount of change in compliance based on the ratio to the standard compliance, it is also possible to understand the amount of change based on the difference. Furthermore, it goes without saying that instead of compliance, the reciprocal of stayness may be measured and the amount of change may be used as a parameter.

(f) Effects As explained above, according to the present invention, the degree of fatigue progression of the test object due to an increase in the number of load repetitions is grasped using the amount of change in compliance as a parameter, and the test data is calculated based on this. Since the data is selective, only the data required for analysis is stored reliably. As a result, the memory capacity for storing data can be reduced, improving memory usage efficiency and being economical.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the functional configuration of the present invention, Fig. 2 is a block diagram showing the structure of an embodiment of the present invention, Fig. 3 is a flowchart showing the data collection program, and Fig. 4 is a test object. This is an example of a stress/strain cycle curve that acts on the body. 1... Test machine, 2... A-D converter, 3... Input/output interface, 4... CPU, 5... Memory, εer... Elastic strain range of the test object.

Claims (1)

[Claims] 1. In a testing machine that has a means of repeatedly applying a load to a test piece and a means of measuring the stress and strain acting on the test piece due to the load, the above stress and strain measurement data are input moment by moment, and the repeated loading cycle is performed. means for sequentially calculating the compliance of the test piece in the elastic strain range for each elastic strain range; means for calculating the amount of change in the compliance; means for determining whether the amount of change has reached a predetermined set value; Data of a material testing machine characterized by being equipped with means for collecting and storing data necessary for the test, including at least the measurement data of the stress and strain, only when the amount reaches the set value. Collection device.