JPH0387631A - Material testing machine - Google Patents

Abstract

PURPOSE:To exactly measure the mean value of the load - displacement characteristic of a test piece in the same production unit by deriving a loading value corresponding to a prescribed displacement value with an interpolating operation, based on the displacement and load data stored successively. CONSTITUTION:When it is started to apply a load to a test piece, its load is detected by a load cell 11, and also, the displacement of the test piece caused by the load is detected by an extensiometer 12. Signals of the detected load and displacement are A/D converted 13, 14, and thereafter, sampled in a prescribed time interval by a CPU 15, and stores in a memory 16 in the order of sampling. Subsequently, for instance, when the displacement sampled at a prescribed time interval exceeds a value determined in advance, the displacement sampled at the subsequent sampling time and load data are stored. In such a manner, based on the displacement and the load data stored successively, a load value corresponding to a prescribed displacement value is derived by an interpolating operation. Accordingly, the mean value of a load - displacement characteristic at every lot can be exactly measured.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a material testing machine that can accurately determine the load-displacement characteristics of a specimen per same production unit (lot).

B. Conventional Technology Conventionally, for example, as shown in Fig. 5, a pair of screw rods 2 are set up on a table 1, a crosshead 3 is placed horizontally thereon, and the screw rods 2 are rotated by a motor 4 to open the crosshead. A material testing machine is known that loads a specimen TP by raising and lowering the material. While the specimen TP is being subjected to compression or tensile loading, the displacement of the specimen relative to the applied load is sampled at predetermined time intervals using the load cell 5 and extensometer 6 (or pulse encoder 7), and the displacement is calculated based on the sampled applied load and displacement data. Measure the load-displacement characteristics of the specimen.

C1 Problem to be Solved by the Invention However, in the conventional material testing machine described above, when calculating the average value of the load-displacement characteristics of multiple specimens in the same production unit, the same sampling order number is used as a common standard. The average value of the load-displacement characteristics of the specimen in the same production unit is determined by averaging the displacement and load data. Therefore, if there are variations in the rate of increase in displacement even in the same production unit, the displacement values for the same sampling order number will vary, making it impossible to accurately measure the average value of the load for displacement in the same production unit. There was a point. Also, the load for each specimen -
If you average the load for any displacement from the displacement curve, it will no longer match the data obtained by the above method.

A technical problem of the present invention is to accurately measure the average value of the load-displacement characteristics of specimens in the same production unit.

D. Means for Solving HM The present invention provides a loading mechanism for loading a specimen, a load detection means for detecting the applied load acting on the specimen, and a displacement detection means for detecting the displacement of the specimen under load. , and means for measuring a load-displacement curve based on detection data of both detection means sampled at predetermined time intervals. The above-mentioned technical issues are a determination means for determining whether detected data of load or displacement exceeds a predetermined value, and a sampling time after it is determined that the detected data exceeds a predetermined value. The problem is solved by providing a storage means for storing detection data sampled in the storage means, and an interpolation calculation means for interpolating the predetermined one detection data and the other detection data using the sequential detection data stored in the storage means. be done.

E1 action For example, when the displacement sampled at a predetermined time interval exceeds a predetermined displacement value, the displacement and load data sampled at the subsequent sampling time are stored. Based on the displacement and load data sequentially stored in this manner, a load value corresponding to a predetermined displacement value is determined by interpolation calculation. Therefore, the average value of the load-displacement characteristics for each lot can be accurately measured.

F. Embodiment FIG. 1 is a block diagram showing an embodiment of a data processing section of a material testing machine to which the present invention is applied. Basically, the load cell 11° is used to measure the load acting on the specimen, and the extensometer 12 is used to measure the strain on the specimen. AD converters 13 and 14. Central processing unit (CPU) 15° memory 16. It consists of a CRT display device W17 and an e-printer 18. Further, a pulse encoder 19 detects the stroke of the crosshead, and a stroke counter 20 inputs the stroke value of the crosshead to the central processing unit 15 by counting the output pulses of the pulse encoder 19.
is provided.

First, the normal measurement operation of the load-displacement characteristics of a specimen will be explained.

When a load starts to be applied to specimen #- (not shown), the applied load is detected by the load cell 1, and the displacement (elongation) of the specimen due to the load is detected by the extensometer 12. Since the detected load and displacement signals are analog signals.

Each is converted into a digital value by AD converters 13 and 14. The digital value of load and displacement is calculated by the central processing unit 1.
5 at predetermined time intervals and stored in the memory 16 in the order of sampling. The load and displacement data stored in the memory 16 are read out when the test is completed, and the load and displacement data are displayed on the CRT display device F.
It is displayed as a graph as a displacement characteristic, and is printed out by the printer 18 if necessary.

Next, the operation of measuring the average value of the load-displacement characteristics of specimens in the same production unit will be explained.

In this case, the central processing unit 15 performs the sampling operation as shown in the flowchart of FIG. 2 and the data processing as shown in the flowchart of FIG. At a predetermined time interval t as shown in a).

Load and displacement data are sampled at tie ta.... Then, as shown in the flowchart of Fig. 2, it is determined in step P1 whether or not the starting load has exceeded the starting load, which is set so as not to introduce unnecessary components such as noise in the initial state, and if it is negative, step PL is executed. This is repeatedly executed, and when it is affirmed, the load R0 and displacement data SI (see FIG. 4) at the sampling time that appears immediately after that are stored in the memory 16 (step 111iP2). After that, in step P3, it is determined whether the displacement interval X specified from the outside has been exceeded, and if the displacement has exceeded 'S z = 86 + The data is stored in the memory 16 (procedure P4). Thereafter, "52=S6 + 2
XJ, '5x=Sa+3X'l++'
The load and displacement data at the sampling time that appears immediately after the detection of the displacement represented by "S n = S, +nx" are stored in the memory 16. That is, the central processing unit 15 does not store the applied load and displacement data at each sampling time in the memory 16 each time, but rather stores the applied load and displacement data sampled immediately after externally specified displacement is detected. memory 1 by selectively collecting
6. For example, in the time chart of FIG. 4, the sampling time toy tzt tap...
Load and displacement data of txt tott tze of tn is selected and stored in the memory 16.

Once the data of the designated displacement interval for each of the plurality of specimens in a certain production unit is stored in the memory 16 in this way, the central processing unit 15 stores the load of each specimen in the memory 16.
Regarding the displacement characteristics, as shown in the flowchart of FIG.
The load data of lo... is subjected to linear approximation or quadratic curve approximation to perform interpolation calculations. As a result, the specified displacement S~Sn
Find the true load value for each specimen. That is,
Each specified displacement S1. S2. Calculate the true load value R1゜R,, R, at S□ (procedure PIO), then calculate the average value of the applied load at each specified displacement for each specimen (step 11 [PLl), The average curve of the load-displacement characteristics of the specimens of the same production unit is displayed on the CRT display device 17 (step P12).

Therefore, by the above procedure, the load-displacement characteristic + i of each specimen in a certain lot is determined from multiple sets of load data corresponding to approximately equal displacements, so the average value of the load-displacement characteristic within that loft is Accurate measurement without error is possible without being affected by strain rate, etc. Furthermore, since the displacement interval at which the load is taken in can be appropriately selected, measurement can be performed with any measurement resolution. This means that the resolution of the memory 16 can be selected according to its capacity.

In the configuration of the above embodiment, the material testing machine main body serves as the loading mechanism, the load cell 11 serves as the load detection means, the extensometer 12 serves as the displacement detection means, and the central processing unit 15 serves as the load-displacement curve measurement means and determination means. , and interpolation calculation means, and the memory 16 constitutes storage means.

Note that the interpolation calculation in the flowchart in Figure 3 may be performed in real time while the load-displacement characteristics of each specimen are being measured, or it may be performed in real time while the load-displacement characteristics of all specimens have been measured. It may also be carried out at a later stage.
We have explained the method of storing the sampling data immediately after the detection of a predetermined displacement value in real time, but all the data is read and stored in advance at a predetermined sampling interval, and after the test is over, the immediately subsequent sampling data is stored every time the predetermined displacement value is exceeded. A method may also be used in which the average value of load-displacement is calculated by storing the following. Further, although the displacement and load data sampled at the sampling time immediately after the displacement exceeds the predetermined value are stored, it is not necessary to store the data immediately after as long as there is no error. Furthermore, although 5. the case where a predetermined displacement is designated and the corresponding load is determined, the reverse case may also be used. Furthermore, in the above, a method was shown in which a predetermined displacement value is set for each predetermined displacement amount X from the reference start displacement S0. You may also import data.

G0 Effects of the Invention Since the present invention is constructed as described above, even if there are variations in the displacement or load increase rate of the specimen in the same production unit, it is possible to calculate the applied load or displacement value at the same displacement or load. It is possible to collect and calculate the average value. Therefore, an accurate average value of the load-displacement characteristics can be determined.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a flowchart showing the sampling operation of the load-displacement characteristic, Fig. 3 is a flowchart of the operation of calculating the average value of the load-displacement characteristic, and Fig. 4 5 is a time chart for explaining the calculation operation of the average value of the load-displacement characteristic, and FIG. 5 is a front view for explaining the loading mechanism of the material testing machine according to the present invention. 11: Load cell 12; Extensometer 13.14: A
D converter 15: Central processing unit 16: Memory 1
7: CRT display device 18; printer

Claims (1)

[Claims] A loading mechanism that loads the specimen, a load detection means that detects the applied load acting on the specimen, a displacement detection means that detects the displacement of the specimen during loading, and both detection means that sample at predetermined time intervals. A material testing machine that includes a means for measuring a load-displacement curve based on detected data, and a determining means for determining whether the detected data of load or displacement exceeds a predetermined value; a storage means for storing detection data sampled at a sampling time after it is determined that the detected data exceeds a predetermined value; 1. A material testing machine comprising: interpolation calculation means for performing interpolation calculations based on data.