JPH0648233B2

JPH0648233B2 - Yield elongation detector

Info

Publication number: JPH0648233B2
Application number: JP59205865A
Authority: JP
Inventors: 英雄増瀬
Original assignee: Shimadzu Corp
Current assignee: Shimadzu Corp
Priority date: 1984-10-01
Filing date: 1984-10-01
Publication date: 1994-06-22
Anticipated expiration: 2009-06-22
Also published as: JPS6183936A

Description

【発明の詳細な説明】（イ）産業上の利用分野本発明は引張試験において得られる応力−ひずみ曲線の
降伏伸び値を自動的に検出する降伏伸び検出装置に関す
る。The present invention relates to a yield elongation detecting device for automatically detecting a yield elongation value of a stress-strain curve obtained in a tensile test.

（ロ）従来技術降伏伸び値を検出する場合、始点の検出は従来から比較
的簡単に検出できるが、終点の検出は材料により種々の
カーブになりパターン認識が難しく、このため従来降伏
伸び値を自動的に検出する有効な方法はなく、誤差も大
きかった。このため応力−ひずみ曲線より人間がチャー
トより読み取っていた。(B) Conventional technology When detecting the yield elongation value, it is relatively easy to detect the starting point from the conventional method, but the end point is detected in various curves depending on the material and pattern recognition is difficult. There was no effective method to detect automatically, and the error was large. For this reason, the human being read the chart from the stress-strain curve.

（ハ）目的本発明は上記従来技術の欠点を解消し、降伏伸び値を自
動的に検出できる降伏伸び検出装置の提供を目的とす
る。(C) Purpose The present invention solves the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a yield elongation detection device capable of automatically detecting a yield elongation value.

（ニ）構成本発明は、試片に加わる荷重を検出する荷重検出器と、
試片に生じる伸びを検出する伸び検出器と、これらの検
出器からの荷重信号と伸びに対応する時間信号とを一対
にして引張試験の開始から同期して順次格納してゆくバ
ッファ装置と、前記格納された荷重値を微分する微分装
置と、荷重の微分値と時間とから降伏伸びの終点を演算
する演算装置とを有し、該演算装置は荷重の一次微分値
−時間曲線を逆にさかのぼる方向に微分値の変化を演算
し、微分値に一定以上の落差を生じる変曲点があるとき
はそのときの時間に対応する伸びを、また微分値に一定
以上の落差を生じないときは微分値が初めて負になると
きの時間に対応する伸びを降伏伸びの終点として算出す
ることを特徴とする降伏伸び検出装置である。(D) Configuration The present invention includes a load detector that detects a load applied to a test piece,
An elongation detector that detects elongation occurring in the test piece, a buffer device that sequentially stores the load signal from these detectors and a time signal corresponding to the elongation in pairs in synchronization with each other from the start of the tensile test, It has a differentiating device for differentiating the stored load value and a computing device for computing the end point of the yield elongation from the differential value of the load and time, and the computing device reverses the primary differential value of the load-time curve. Calculate the change of the differential value in the backward direction, and if there is an inflection point that causes the differential value to drop more than a certain amount, increase the time corresponding to that time, and if the differential value does not drop more than a certain amount, The yield elongation detecting device is characterized in that the elongation corresponding to the time when the differential value becomes negative for the first time is calculated as the end point of the yield elongation.

（ホ）実施例第１図は降伏点Ａの見られる材料の荷重−伸び曲線図
で、第２図は第１図の荷重−伸び曲線の微分図である。
第３図は実施装置の構成図、第４図は実施装置による操
作のフローチャートである。(E) Example FIG. 1 is a load-elongation curve diagram of a material having a yield point A, and FIG. 2 is a differential diagram of the load-elongation curve of FIG.
FIG. 3 is a block diagram of the embodying apparatus, and FIG. 4 is a flowchart of the operation by the embodying apparatus.

第１図において降伏伸びはＡ点からＢ点までの伸びであ
る。In FIG. 1, the yield elongation is the elongation from point A to point B.

この場合、Ａ点は明瞭であるので、問題は降伏伸びの終
点であるＢ点の検出である。本装置においては、第３図
に示すように試片に加わる荷重を検出する荷重検出器
１，試片に生じる伸びを検出する伸び検出器２，例えば
５０msec毎のクロック発生装置３，このクロック発生装
置３により得られた荷重信号と伸びに対応する時間信号
とをペアで同期して順次格納してゆくバッファ装置４，
格納した荷重値を微分してその値をメモリする微分装置
５，得られた荷重の微分値と時間とから降伏伸びの終点
を演算する演算装置６，及びプリンタ７を少なくとも有
している。前記演算装置６は荷重の一次微分値と時間の
ペアを時間的に逆にさかのぼる方向にサーチするように
構成されている。前記バッファ装置４と微分装置５によ
るデータの取得は引張試験開始により発生するスタート
指令から降伏現象終了後に生じる硬化領域に十分入った
点Ｅを検出して発せられるストップ指令があるまで行わ
れる。前記点Ｅは予め定めておく。In this case, since point A is clear, the problem is detection of point B, which is the end point of yield elongation. In this device, as shown in FIG. 3, a load detector for detecting the load applied to the sample 1, an elongation detector for detecting the elongation occurring in the sample 2, for example, a clock generator for every 50 msec 3, this clock generator A buffer device 4, which sequentially stores the load signal obtained by the device 3 and the time signal corresponding to the elongation in synchronization in pairs.
It has at least a differentiating device for differentiating the stored load value, a memory for storing the value, a computing device 6 for computing the end point of yield elongation from the obtained differential value of the load and time, and a printer 7. The arithmetic unit 6 is configured to search for a pair of the primary differential value of the load and time in a backward direction going backward. The data acquisition by the buffer device 4 and the differentiator 5 is performed until a stop command is issued from a start command generated by the start of the tensile test to a point E sufficiently detected at a point E in the hardening region generated after the end of the yield phenomenon. The point E is set in advance.

演算装置６による演算は第４図に示すフローチャートに
したがって行われる。まずＥ点付近の平均の荷重の微分
値を求め、これをａ_１とする（第２図参照）。次にＥ点
からＡ点の方に向かって逆に微分値をサーチして微分値
が初めてマイナスになる点Ｃを求める。次にＥ点からＣ
点方向に微分値の変化ａ_１−ｂ_ｉをサーチする。そして
ａ_１−ｂ_ｉ＞ｘであるとき、その時間ｉに対応する伸び
を降伏伸びの終点とする。ここで、ａ_１：Ｅ点付近での平均微分値ｂ_ｉ：ある時間ｉにおける微分値ｘ：降伏伸びの終点で予想される微分値の落差Ｆに対してＦ
より大きな値から予め定められた最低落下Ｈまで順次小
さく設定されてゆく変数である。The calculation by the calculation device 6 is performed according to the flowchart shown in FIG. First, the differential value of the average load in the vicinity of point E is obtained, and this is designated as a ₁ (see FIG. 2). Next, the differential value is searched backward from point E toward point A to find point C where the differential value becomes negative for the first time. Then from point E to C
The change a ₁ -b _i of the differential value is searched for in the point direction. Then, when a ₁ -b _i > x, the elongation corresponding to the time i is set as the end point of the yield elongation. Here, a ₁ : average differential value near the point E b _i : differential value at a certain time i x: F with respect to the differential value difference F expected at the end point of yield elongation
It is a variable that is gradually set from a larger value to a predetermined minimum drop H.

一方、Ｅ点からＣ点に至るまでにａ_１−ｂ_ｉの値がＨ以
上にならない場合にはＣ点に相当する伸びを降伏伸びの
終点とする。On the other hand, if the value of a ₁ -b _i does not exceed H from the point E to the point C, the elongation corresponding to the point C is set as the end point of the yield elongation.

このように演算によって得られる降伏伸びの終点（第１
図Ｂ点）の伸びから降伏点（第１図Ａ点）の伸びを引算
することにより自動的に降伏伸びを検出することができ
る。In this way, the yield elongation end point (first
The yield elongation can be automatically detected by subtracting the elongation at the yield point (point A in FIG. 1) from the elongation at the point B in the figure.

（ヘ）効果本発明は以上の構成よりなり、従来人間が判断していた
降伏伸び値を自動的に検出することが可能となり、人為
的誤差ないし個人差による誤差がなくなり、正確を期す
ることができる。また検出の能率もアップする。(F) Effect The present invention is configured as described above, and it is possible to automatically detect the yield elongation value that has been conventionally determined by humans, and eliminate errors due to human error or individual differences, and to ensure accuracy. You can Also, the detection efficiency is improved.

[Brief description of drawings]

第１図は降伏点の見られる材料の荷重−伸び曲線図で、
第２図は第１図の荷重−伸び曲線の微分図である。第３
図は本発明の実施装置の構成図、第４図は実施装置によ
る操作のフローチャートである。１……荷重検出器、２……伸び検出器３……クロック発生装置、４……バッファ装置５……微分装置、６……演算装置７……プリンタFigure 1 is a load-elongation curve diagram for materials with a yield point.
FIG. 2 is a differential diagram of the load-elongation curve of FIG. Third
FIG. 4 is a block diagram of an embodying apparatus of the present invention, and FIG. 4 is a flowchart of an operation by the embodying apparatus. 1 ... Load detector 2 ... Elongation detector 3 ... Clock generator 4 ... Buffer device 5 ... Differentiator, 6 ... Arithmetic device 7 ... Printer

Claims

[Claims]

1. A load detector for detecting a load applied to a test piece, an elongation detector for detecting elongation occurring in the test piece, a load signal from these detectors and a time signal corresponding to the elongation are paired. A buffer device for sequentially storing the tensile test in synchronism with the start of the tensile test, a differentiating device for differentiating the stored load value, and a computing device for computing the end point of the yield elongation from the differential value of the load and the time. The calculation device calculates the change of the differential value in the direction going back to the first derivative value-time curve of the load, and when there is an inflection point that causes a drop of a certain value or more at the time at that time. A yield elongation detecting device, wherein the corresponding elongation, or the elongation corresponding to the time when the differential value becomes negative for the first time, is calculated as the end point of the yield elongation when the differential value does not cause a drop of a certain amount or more.