The quantitative assessment of both, the length and width, of a delamination in quasi-isotropic composite laminates, using experimentally generated B- and D-scan imaging techniques employing ultrasonic Lamb waves was presented. Distinct zones were identified in B- and D-scans and the sizes of zones were expressed in terms of the width and length of delamination, the probe separation distance, and the probe diameter. B-scans generated through numerical simulations gave an insight and significance of each zone. B- and D-scans were used to estimate the width and length of delaminations, respectively. The estimated width and length of delaminations were found to be in concurrence with the actual values. © 2011 Elsevier Ltd.

Krishnan Balasubramaniam

Department of Mechanical Engineering

C V Krishnamurthy

Department Of Physics

B-SCAN

Characterisation

composite laminate

D-SCAN

ISOTROPIC COMPOSITES

Lamb wave

Lamb waves

numerical simulation

Quantitative assessments

SCAN IMAGES

Separation distances

ULTRASONIC LAMB WAVES

Elastic waves

Imaging techniques

Laminated composites

Laminating

Probes

Steel sheet

Ultrasonic testing

Ultrasonic waves

Delamination

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

NDT and E International

This paper demonstrates an approach for rapid non-contact air-coupled ultrasonic inspection of composite ailerons with complex cross-sectional profile including thickness changes, curvature and the presence of a number of stiffeners. Low-frequency plate guided ultrasonic modes are used in B-scan mode for the measurements in pitch-catch mode. Appropriate probe holder angles suitable for generating and receiving lower order guided wave modes are discussed. Different embodiments of the pitch-catch tandem positions along and across stiffener and curved regions of the test sample enable a rapid test campaign capturing the feature-rich sample profile. Techniques to distinguish special features in the stiffener are presented. © 2016 AIP Publishing LLC.

AIP Conference Proceedings

Rapid non-contact inspection of composite ailerons using air-coupled ultrasound

An experimental method to visualize the propagation of ultrasonic Lamb waves in composite plates with delaminations, using air coupled ultrasonic transducers, is described here. Using this method experiments are done, on glass fiber reinforced plastic(GFRP) laminates, to study the Lamb wave interactions with delamination type defects. The S0 and A0 modes are chosen for experiments at an excitation frequency of 200 kHz. Defect dimensions are calculated from the visualization images and compared with actual values. A method for detecting depth of defects using deviation of wave-fronts, at the defect contours, is presented. © 2014 AIP Publishing LLC.

Visualization studies of Lamb wave propagation and interactions with anomalies in composite laminates using air-coupled ultrasonics

With increasing demand for solar energy, the need for reliable inspection systems has increased tremendously. In this paper, a combination of air coupled ultrasonics and Lamb waves have been utilized to frame a crack detection system. Monocrystalline and polycrystalline silicon wafers of 200 μm thickness were used for experimentation and theoretical Lamb mode dispersion curves were plotted for Lamb wave generation in these wafers. A set of defect-free and cracked samples were scanned and the results are presented in this paper. A complete laboratory based cracked detection system was developed and the demonstrated to detect cracks in silicon wafers. © Springer Science+Business Media, LLC 2011.

Journal of Nondestructive Evaluation

Crack detection in full size Cz-silicon wafers using lamb wave air coupled ultrasonic testing (LAC-UT)

Composites Science and Technology

Health monitoring of aerospace composite structures – Active and passive approach

Smart Materials and Structures

A Lamb-wave-based technique for damage detection in composite laminates

Composite Structures

Interaction of Lamb waves on bonded composite plates with defects

Ultrasonics

Air-coupled ultrasonic investigation of multi-layered composite materials

Lamb wave-based quantitative identification of delamination in CF/EP composite structures using artificial neural algorithm

Characterisation of rectangular type delaminations in composite laminates through B- and D-scan images generated using Lamb waves

Journal	NDT and E International
ISSN	09638695
Open Access	No