Ultrasonic measurement of the crack depth and the crack opening stress intensity factor under a no load condition

Masumi Saka, M. A Salam Akanda

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

This paper describes a new methodology for evaluating the crack depth and the crack opening stress intensity factor of small closed cracks using an ultrasonic technique. Surface connected back-wall cracks of depth ranging from 0.4 to 4.0 mm in steel specimens are considered. The crack corner echo amplitude of an ultrasonic shear wave, SW, beam of 50° incidence in material is used. First, the ultrasonic echo response of an open crack is determined as a function of crack depth. Next, based on changing the crack closure stress, an empirical relation between the crack closure stress and the crack-echo response is formulated. The crack depth and the crack closure stress of an unknown closed crack based on these relations are determined by inverse analysis of the ultrasonic response of the crack. From the evaluated crack depth and crack closure stress, the crack opening stress intensity factor is determined. The accuracy and reliability of this new nondestructive evaluation (NDE) method is verified by comparing the evaluated crack depth with the actual one. The latter is measured on the fractured surface obtained after carrying out ultrasonic testing. The ultrasonic method developed is proved to be a powerful tool for quantitative and nondestructive evaluation of the crack depth as well as the crack closure stress.

Original languageEnglish
Pages (from-to)49-63
Number of pages15
JournalJournal of Nondestructive Evaluation
Volume23
Issue number1
Publication statusPublished - 2004 Mar 1

Keywords

  • Crack closing stress
  • Inverse analysis
  • Small closed crack
  • Stress intensity factors
  • Ultrasonic nondestructive evaluation

ASJC Scopus subject areas

  • Materials Science (miscellaneous)

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