DE4412724A1 - Detecting cracks during dynamic material testing - Google Patents

Detecting cracks during dynamic material testing

Info

Publication number
DE4412724A1
DE4412724A1 DE19944412724 DE4412724A DE4412724A1 DE 4412724 A1 DE4412724 A1 DE 4412724A1 DE 19944412724 DE19944412724 DE 19944412724 DE 4412724 A DE4412724 A DE 4412724A DE 4412724 A1 DE4412724 A1 DE 4412724A1
Authority
DE
Germany
Prior art keywords
test
dynamic material
material testing
signal
during dynamic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
DE19944412724
Other languages
German (de)
Inventor
Erich Gerards
Harald Neumann
Robert Spahl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to DE19944412724 priority Critical patent/DE4412724A1/en
Publication of DE4412724A1 publication Critical patent/DE4412724A1/en
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/006—Crack, flaws, fracture or rupture
    • G01N2203/0062—Crack or flaws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0688—Time or frequency

Abstract

The method involves making use of the force magnification caused by the natural resonance of the system consisting of the test structure and test component and observing the natural frequency of this system to detect crack formation.A measurement transducer continuously passes the vibration signal to a monitoring unit, in which the amplitude (A), or a corresp. parameter, is determined and the deviation of this signal from the initial value used to derive the depth of the cracks in the material.

Description

Die Erfindung bezieht sich auf ein Verfahren zu Ermittlung von Anrissen an Meßproben (Proben oder Bauteilen) bei dynamischen Werkstoffprüfverfahren, die in der Nähe der Resonanz des Systems Schwingungserreger-Bauteil arbeiten.The invention relates to a method for determining cracks Measurement samples (samples or components) in dynamic material testing procedures, which in work close to the resonance of the vibration exciter component system.

Verfahren zur Anrißerkennung durch die Beobachtung der Resonanzfrequenz der zu prüfenden Meßprobe sind bekannt. Bei diesen Verfahren wird die Probe über Ultra­ schall oder über Hydraulik angeregt. Die Eigenfrequenz wird gemessen und als Maß für die Rißtiefe verwendet.Crack detection method by observing the resonance frequency of the test sample are known. In this procedure, the sample is over Ultra excited by sound or hydraulics. The natural frequency is measured and as a measure used for the crack depth.

Gemeinsam ist diesen Verfahren, daß das Bauteil entweder zusätzlich zur Prüffrequenz in seiner Resonanzfrequenz angeregt wird, oder daß die Prüffrequenz genau der Resonanzfrequenz entspricht. Ersteres Vorgehen erfordert zusätzliche Vorrichtungen sowie meist eine Unterbrechung des Testbetriebes. Das zweite Ver­ fahren eignet sich meist nur für dämpfungsarme bzw. hochfrequente Prüfungen.Common to these processes is that the component is either in addition to Test frequency is excited in its resonance frequency, or that the test frequency corresponds exactly to the resonance frequency. The former approach requires additional ones Devices and usually an interruption of the test operation. The second ver driving is usually only suitable for low-damping or high-frequency tests.

Aufgabe der vorliegenden Erfindung ist es, ein Verfahren zur Rißerkennung während einer dynamischen Werkstoffprüfung anzugeben, daß mit extrem niedrigem Aufwand eine genaue Rißüberwachung für verschiedenste Proben ermöglicht, ohne daß die Prüfung unterbrochen werden muß.The object of the present invention is to develop a method for crack detection a dynamic material test to indicate that with extremely low effort accurate crack monitoring for a wide variety of samples allows without the Examination must be interrupted.

Diese Aufgabe wird erfindungsgemäß gelöst, indem das Prüfsystem nahe an der Re­ sonanzfrequenz betrieben wird und dabei, bei konstanter Frequenz, das Verhältnis der Amplituden im augenblicklichen Zustand und zu Beginn der Prüfung als Maß für die Rißtiefe herangezogen wird.This object is achieved by the test system close to the Re is operated resonance frequency and, at constant frequency, the ratio the amplitudes in the current state and at the beginning of the test as a measure for the crack depth is used.

Fig. 1 zeigt einen möglichen Aufbau: Eine Probe 2 ist in einer Halterung 1 befestigt und wird von einem Schwingungserreger 3 in der Nähe ihrer Eigenfrequenz ange­ regt. Ein Meßwertgeber 4 mißt den Weg der Schwingung oder die aufgebrachten Kräfte und liefert dieses Schwingungssignal an eine Meßwertverarbeitung 5, in der aus der Schwingung die Amplitude, oder ein anderes die Amplitude der Schwingung charakterisierendes Maß (z. B. den Effektivwert), ermittelt wird. Dieses Signal wird mit einem Sollwert 6 verglichen und als Maß für die Rißtiefe dargestellt 7. Unter- oder überschreitet dieser Wert einen wählbaren Grenzwert, so wird die Prüfung ab­ gebrochen, da eine gewisse Rißgröße erreicht wird. Fig. 1 shows a possible structure: A sample 2 is fastened in a holder 1 and is excited by a vibration exciter 3 near its natural frequency. A transducer 4 measures the path of the vibration or the applied forces and delivers this vibration signal to a measured value processing unit 5 , in which the amplitude, or another measure characterizing the amplitude of the vibration (e.g. the effective value), is determined from the vibration. This signal is compared with a target value 6 and shown as a measure of the crack depth 7 . If this value falls below or exceeds a selectable limit value, the test is terminated because a certain crack size is reached.

Bei einem Anriß der Probe ändert sich deren Steifigkeit und damit auch die Reso­ nanzfrequenz des Systems Schwingungserreger-Bauteil. Je nachdem, ob die Prüfung bisher im unter- oder oberkritischem Bereich arbeitete erhöht oder erniedrigt sich aufgrund der geänderten Amplitudenüberhöhung die Amplitude der Schwingung um die Differenz DA.When the sample is torn, its stiffness changes and with it the reso Frequency of the vibration exciter component system. Depending on whether the Examination previously worked in the subcritical or supercritical area increased or decreased the amplitude of the oscillation changes due to the changed amplitude increase by the difference DA.

Fig. 2 und Fig. 3 zeigen die vier möglichen Fälle. Bei Fig. 2 wird von einer Steifig­ keitsverringerung beim Anriß ausgegangen, in Fig. 3 von einer Steifigkeitserhöhung. Jeweils sind die Fälle A, unterkritische Prüfung, und B, überkritische Prüfung, darge­ stellt. Fig. 2 and Fig. 3 show the four possible cases. In Fig. 2 it is assumed that the stiffness is reduced when cracked, in Fig. 3 an increase in stiffness. Cases A, subcritical testing, and B, supercritical testing, are shown.

Prüfkräfte und Prüffrequenzen können je nach Wunsch eingestellt werden, indem die Kenngrößen des Schwingungssystems (Massen und Federsteifigkeiten) angepaßt werden.Test forces and test frequencies can be set as desired by using the Characteristics of the vibration system (masses and spring stiffness) adjusted become.

Claims (1)

Verfahren zur Ermittlung von Anrissen an Meßproben bei dynamischen Werkstoffprüfungen, die die Kraftverstärkung durch die Eigenschwingfähigkeit des Systems Prüfaufbau-Bauteil ausnutzen und zur Anrißerkennung die Lage der Eigen­ frequenz des Systems beobachten, dadurch gekennzeichnet, daß ein Meßwertaufnehmer kontinuierlich das Schwingungssignal an eine Kontrolleinheit weiterleitet, in der die Amplitude, oder ein entsprechendes Maß, ermittelt wird und die Abweichung dieses Signals vom Anfangswert als Maß für die Tiefe von Rissen im Bauteil herangezogen wird.Process for the determination of cracks on test samples in dynamic material tests, which utilize the force amplification through the inherent vibration ability of the system test-component and observe the position of the natural frequency of the system for crack detection, characterized in that a transducer continuously forwards the vibration signal to a control unit, in which determines the amplitude, or a corresponding measure, and the deviation of this signal from the initial value is used as a measure of the depth of cracks in the component.
DE19944412724 1994-04-13 1994-04-13 Detecting cracks during dynamic material testing Ceased DE4412724A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19944412724 DE4412724A1 (en) 1994-04-13 1994-04-13 Detecting cracks during dynamic material testing

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19944412724 DE4412724A1 (en) 1994-04-13 1994-04-13 Detecting cracks during dynamic material testing

Publications (1)

Publication Number Publication Date
DE4412724A1 true DE4412724A1 (en) 1995-10-26

Family

ID=6515293

Family Applications (1)

Application Number Title Priority Date Filing Date
DE19944412724 Ceased DE4412724A1 (en) 1994-04-13 1994-04-13 Detecting cracks during dynamic material testing

Country Status (1)

Country Link
DE (1) DE4412724A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109813597A (en) * 2017-11-22 2019-05-28 株式会社岛津制作所 Material Testing Machine and curable grip detection method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
P 44 12 724.3-52 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109813597A (en) * 2017-11-22 2019-05-28 株式会社岛津制作所 Material Testing Machine and curable grip detection method
CN109813597B (en) * 2017-11-22 2021-08-17 株式会社岛津制作所 Material testing machine and holding force detection method

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OP8 Request for examination as to paragraph 44 patent law
8131 Rejection