The basic aim of this current research is to reliably detect and size defects in complex geometry welds using the well-known ultrasonic time of flight diffraction (TOFD) technique. A complex geometry weld specimen with various artificial defects was designed and fabricated. Different combinations of probe angles and probe center spacings were used in experiments for determining the optimum one. TOFD models were also developed for sizing the defects and experimentally verified. Copyright © 2009 by ASME.

Krishnan Balasubramaniam

Department of Mechanical Engineering

C V Krishnamurthy

Department Of Physics

ARTIFICIAL DEFECTS

Complex geometries

TIME OF FLIGHT DIFFRACTION

ULTRASONIC TIME-OF-FLIGHT DIFFRACTION

WELD INSPECTION

Computational geometry

Defects

Inspection

Position control

Probes

ULTRASONIC DIFFRACTION

Ultrasonics

Welding

Welds

Ultrasonic testing

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IIT Madras

Detection and Sizing of Defects in Complex Geometry Weld by Manual Ultrasonic Time of Flight Diffraction Inspection

Journal of Pressure Vessel Technology, Transactions of the ASME

Sizing a surface-breaking crack in a complex geometry component, for example a steam turbine's solid rotor shaft, is a challenging inspection task. This paper deals with experimental work for the evaluation of the Time-of-Flight Difftaction (TOFD) technique for sizing of surface-breaking cracks in such a complex geometry component. The experimental results show that with the help of the mathematical model explained here, TOFD can size such cracks with reasonable accuracy.

Insight: Non-Destructive Testing and Condition Monitoring

Sizing of surface-breaking cracks in complex geometry components by ultrasonic Time-of-Flight Diffraction (TOFD) technique

It is necessary to size the cracklike defects accurately in order to extend the life of thin-walled (< 10 mm) components (such as pressure vessels) particularly for aerospace applications. This paper discusses the successful application of ray techniques to simulate the ultrasonic time-of-flight diffraction experiments for platelike structures. For the simulation, the diffraction coefficients are computed using the geometric diffraction theory. The A and B scans are simulated in near real time and the different experimental parameters can be interactively controlled due to the computational efficiency of the ray technique. The simulated results are applied to (1) defect signal identification for vertical defects, (2) inspection of inclined defects, and (3) study the effect of pulse width or probe frequency on experimental results. The simulated results are compared with laboratory scale experimental results. Copyright © 2005 by ASME.

Ray based model for the ultrasonic time-of-flight diffraction simulation of thin walled structure inspection

The ultrasonic Time-of-Flight Diffraction (TOFD) technique is a well developed technique for sizing defects in thick sections (thickness >10 mm). Attempt has been made here to extend this technique for thin sections (6-10 mm). An automated defect sizing algorithm using the Embedded Signal Identification Technique (ESIT) was developed for separating partially superimposed signals often encountered in thin sections and the results were compared with the manual sizing method. Both EDM notches and more realistic fatigue cracks in thin section were used to evaluate the proposed technique.

Ultrasonic TOFD flaw sizing and imaging in thin plates using embedded signal identification technique (ESIT)

Insight - Non-Destructive Testing and Condition Monitoring

Practical limitations of TOFD on power station main steam pipework

An approach to power station boiler and turbine life management

Detection and sizing of defects in complex geometry weld by manual ultrasonic time of flight diffraction inspection

Journal	Journal of Pressure Vessel Technology, Transactions of the ASME
ISSN	00949930
Open Access	No