The 2006 ultrasonic benchmark problem involves pulse-echo angle beam scanning of a notch located on an inclined planar back surface. The response from a side-drilled hole is to be used as a reference. The models are to simulate (a) the peak-to-peak B-scan P- and SV- responses of the slots normalized by the appropriate SDH response and (b) the maximum peak-to-peak corner response of the slots (either mode-converted or not). At CNDE, several simulation tools are being developed to assess/predict UT response for various geometries. The Finite-Difference-Time-Difference (FDTD) scheme is one such simulation tool that has been under development in 1D, 2D and 3D. The FDTD is an explicit time domain tool that can simulate pulse propagation characteristics in acoustic/elastic media. The computational domain is limited by implementing Perfectly Matched Layers (PMLs) at the domain boundaries. We present the results of calculations based on 2D FDTD to determine the response of rectangular shaped surface-breaking defects located on an inclined planar back surface. Comparisons will be made between predictions and measurements made available for the pulse-echo response. © 2007 American Institute of Physics.

Krishnan Balasubramaniam

Department of Mechanical Engineering

C V Krishnamurthy

Department Of Physics

C. Sridharan

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

The 2006 Ultrasonic Benchmark Problem — FDTD Simulations in 2D

AIP Conference Proceedings

The present article addresses the development at Centre for Non-destructive Evaluation, Indian Institute of Technology Madras, of three different numerical methods, namely finite element, ray tracing and finite-difference time-domain methods for investigating the propagation of ultrasonic waves through polycrystalline media. These methods are believed to aid in better understanding of ultrasonic wave interaction in materials exhibiting both simple and complex grain morphologies. The understanding is expected to provide an improved non-destructive assessment of material and defect characterisation. © 2019, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Numerical Modelling Methods for Ultrasonic Wave Propagation Through Polycrystalline Materials

A simulation program SIMULTSONIC is under development at CNDE to help determine and/or help optimize ultrasonic probe locations for inspection of complex components. SIMULTSONIC provides a ray-trace based assessment initially followed by a displacement or pressure field-based assessment for user-specified probe positions and user-selected component. Immersion and contact modes of inspection are available in SIMULTSONIC. The code written in Visual C++ operating in Microsoft Windows environment provides an interactive user interface. In this paper, the application of SIMULTSONIC to the inspection of very thin-walled pipes (with 450 um wall thickness) is described. Ray trace based assessment was done using SIMULTSONIC to determine the standoff distance and the angle of oblique incidence for an immersion mode focused transducer. A 3-cycle Hanning window pulse was chosen for simulations. Experiments were carried out to validate the simulations. The A-scans and the associated B-Scan images obtained through simulations show good correlation with experimental results, both with the arrival time of the signal as well as with the signal amplitudes. The scope of SIMULTSONIC to deal with parametrically represented surfaces will also be discussed. © 2006 American Institute of Physics.

Fulltext

Simultsonic: A simulation tool for ultrasonic inspection

The 2004 ultrasonic benchmark problem requires models to predict, given a reference pulse waveform, the pulse echo response of cylindrical voids of various radii located in an elastic solid for various incidence angles of a transducer immersed in water. We present the results of calculations based on the patch element model, recently developed at CNDE, to determine the response of an SDH in aluminum for specific oblique incidence angles. Patch element model calculations for a scan across the SDH, involving a range of oblique incidence angles, are also presented. Measured pulse-echo scans involving the SDH response under oblique incidence conditions are reported. In addition, through transmission measurements involving a pinducer as a receiver and an immersion planar probe as a transmitter under oblique incidence conditions are also reported in a defect-free Aluminum block. These pinducer-based measurements on a defect-free block are utilised to characterize the fields at the chosen depth. Comparisons are made between predictions and measurements for the pulse-echo response of a SDH. © 2006 American Institute of Physics.

The 2004 ultrasonic benchmark problem - SDH response under oblique incidence: Measurements and patch element model calculations

The ultrasonic benchmark problem requires models to predict, given a reference pulse waveform, the pulse echo response of cylindrical voids of various radii located in an elastic solid for various incidence angles of a transducer immersed in water. We present a conceptually simple yet reliable numerical technique to determine these internal fields in any region of interest within the elastic solid for the specified angles made by the transducer in water. The technique, equivalent to evaluating the Rayleigh-Sommerfeld integral but through a computationally less demanding procedure, regards the transducer as made of elemental rectangular/square patches and uses the well-known expression for the radiation pattern of an elemental patch to obtain the total transducer radiation field. A ray-based method is adopted to propagate the elementary radiation field across a fluid-solid interface. The FBH is treated in terms of explicit patch element reflectors, its response is evaluated and validated with measurements. The P-wave scattering charactieristics of spherical voids are evaluated using the exact separation of variables method and the patch model for the transducer is used to determine their response. The advantages of the patch model for the transducer in the context of the benchmark problems in particular and non-destructive evaluation in general are indicated. © 2005 American Institute of Physics.

Patch element model for the evaluation of displacement fields within an elastic solid from a non-contact immersion transducer: Application to the 2004 ultrasonic benchmark problem

Journal	AIP Conference Proceedings
ISSN	0094243X
Open Access	No