A study on construction of evaluation method for defect sizing utilizing numerical simulation

Takao Yoshikawa, Masahiro Maeda, Hideyuki Hirasawa

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

To prevent the brittle fracture of the extremely thick plate which is used in the deck plate and the hatch side coaming of the large container ships, it is important to detect surely and repair the inner defects, which are possible to lead the brittle fracture at an early stage. Now Ultrasonic Testing is used in order to inspect the inner defect in a thick plate, and it is necessary to select adequately the probe size and oscillating frequency to evaluate the defect size accurately. The estimation of the defect size in vertical direction to plate surface is important from the viewpoint of fatigue strength. But the vertical flaw length and also the inclined flaw length are hardly to be estimated accurately. In this study, to clarify the characteristics of reflected ultrasonic wave from the defect, the wave propagation behavior is simulated with the numerical simulation program by FEM which is developed by the authors. In this program, the governing equation of elastic wave propagation is calculated in time domain with explicit method utilizing the central-difference scheme. First, the effect of the probe size and oscillating frequency on the accuracy of defect sizing are investigated utilizing the developed program. The numerical simulation is performed for imaging to examine the length of flaw which is parallel to plate surface by normal beam technique. And, the applicability of 6dB method, which is one of the methods for estimating flaw length, is examined. Moreover, a new method for estimating flaw length which cannot be estimated by 6dB method is proposed. Secondly, in order to examine the inclined flaw length, the angel beam test is performed. The accuracy of numerical simulation for angle beam technique is confirmed by comparing experimental result. And, it is examined how the inclined angle of flaw affects the echo height, and it is shown that 6dB method and L level method are useful for the defect which is perpendicular to wave beam and the tip echo method is useful for the defect which is inclined to wave beam. The actual structure usually has a paint film. Therefore, the echo height level will be affected by paint thickness, and the paint film effects on the accuracy of defect sizing. Thirdly, the effects on echo height by film thickness are clarified by experiments and numerical simulations.

Original languageEnglish
Title of host publicationASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011
Pages247-256
Number of pages10
Volume2
DOIs
Publication statusPublished - Dec 1 2011
EventASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011 - Rotterdam, Netherlands
Duration: Jun 19 2011Jun 24 2011

Other

OtherASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011
CountryNetherlands
CityRotterdam
Period6/19/116/24/11

Fingerprint

Defects
Computer simulation
Paint
Brittle fracture
Wave propagation
Hatches
Ultrasonic testing
Ultrasonic waves
Elastic waves
Containers
Film thickness
Ships
Repair
Imaging techniques
Finite element method

All Science Journal Classification (ASJC) codes

  • Ocean Engineering
  • Energy Engineering and Power Technology
  • Mechanical Engineering

Cite this

Yoshikawa, T., Maeda, M., & Hirasawa, H. (2011). A study on construction of evaluation method for defect sizing utilizing numerical simulation. In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011 (Vol. 2, pp. 247-256) https://doi.org/10.1115/OMAE2011-49349

A study on construction of evaluation method for defect sizing utilizing numerical simulation. / Yoshikawa, Takao; Maeda, Masahiro; Hirasawa, Hideyuki.

ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011. Vol. 2 2011. p. 247-256.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Yoshikawa, T, Maeda, M & Hirasawa, H 2011, A study on construction of evaluation method for defect sizing utilizing numerical simulation. in ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011. vol. 2, pp. 247-256, ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011, Rotterdam, Netherlands, 6/19/11. https://doi.org/10.1115/OMAE2011-49349
Yoshikawa T, Maeda M, Hirasawa H. A study on construction of evaluation method for defect sizing utilizing numerical simulation. In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011. Vol. 2. 2011. p. 247-256 https://doi.org/10.1115/OMAE2011-49349
Yoshikawa, Takao ; Maeda, Masahiro ; Hirasawa, Hideyuki. / A study on construction of evaluation method for defect sizing utilizing numerical simulation. ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2011. Vol. 2 2011. pp. 247-256
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