JPS5724804A - Detector for crack depth - Google Patents

Detector for crack depth

Info

Publication number
JPS5724804A
JPS5724804A JP9990180A JP9990180A JPS5724804A JP S5724804 A JPS5724804 A JP S5724804A JP 9990180 A JP9990180 A JP 9990180A JP 9990180 A JP9990180 A JP 9990180A JP S5724804 A JPS5724804 A JP S5724804A
Authority
JP
Japan
Prior art keywords
crack
frequency
potential difference
amplifier
frequency current
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.)
Pending
Application number
JP9990180A
Other languages
Japanese (ja)
Inventor
Makoto Hayashi
Sadao Nemoto
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.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP9990180A priority Critical patent/JPS5724804A/en
Publication of JPS5724804A publication Critical patent/JPS5724804A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/26—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring depth

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

PURPOSE:To enable a reliable measurement of a depth of a crack produced in the proximity of a surface, by a method wherein a lock-in amplifier is connected to a middle position between an input terminal of a high-frequency current and a crack, and detects a difference potential of a signal whose frequency is equal to that of the high-frequency current. CONSTITUTION:A high-frequency current from a signal generator 1 amplified by means of means of an alternating current constant current device 2 is energized to an input terminal 5 for a crack 7 in an object 4 to be measured, and a high-frequency runs to the surface of the object 4 to be measured. A lock-in amplifier 8 is coupled to output terminals 6, and is adjusted so as to detect only an output signal whose frequency is equal to that of the high-frequency current. Thus, a potential difference E between the output terminals 6 is detected by the amplifier 8 to be indicated in a microcomputer 9. As a crack depth increases, the potential difference E increases, and thereby this constitution permits the measurement of the crack depth by means of the potential difference E. This permits the precise measurement of the crack in the proximity of a surface by means of a wide change in the potential difference.
JP9990180A 1980-07-23 1980-07-23 Detector for crack depth Pending JPS5724804A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP9990180A JPS5724804A (en) 1980-07-23 1980-07-23 Detector for crack depth

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP9990180A JPS5724804A (en) 1980-07-23 1980-07-23 Detector for crack depth

Publications (1)

Publication Number Publication Date
JPS5724804A true JPS5724804A (en) 1982-02-09

Family

ID=14259671

Family Applications (1)

Application Number Title Priority Date Filing Date
JP9990180A Pending JPS5724804A (en) 1980-07-23 1980-07-23 Detector for crack depth

Country Status (1)

Country Link
JP (1) JPS5724804A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4914378A (en) * 1986-10-20 1990-04-03 Hitachi, Ltd. Method and apparatus for inspecting surface defects
CN109765271A (en) * 2018-12-30 2019-05-17 河海大学 Judge the devices and methods therefor of metal fatigue crackle hammering closure

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4914378A (en) * 1986-10-20 1990-04-03 Hitachi, Ltd. Method and apparatus for inspecting surface defects
CN109765271A (en) * 2018-12-30 2019-05-17 河海大学 Judge the devices and methods therefor of metal fatigue crackle hammering closure
CN109765271B (en) * 2018-12-30 2021-09-07 河海大学 Device and method for judging hammering closing of metal fatigue crack

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