Ratneshwar (Ratan) Jha, ASME Fellow, AIAA Associate Fellow
Department Head & Professor of Mechanical Engineering
Rowan University, Glassboro, NJ, USA
Will present a talk titled:
Structural Health Monitoring Based on
Modified Time Reversal of Lamb Waves
Abstract: Structural Health Monitoring (SHM) aims at early detection of structural damages and cost-efficient condition-based maintenance. Among various SHM methods, the ultrasonic Lamb wave based techniques have shown a lot of promise due to their long-range, through-thickness damage detection capabilities. In most of the Lamb wave based SHM methods, the wave propagation response in pristine structures (baseline data) is required for the comparison with current wave motion obtained from a possibly damaged structure. However, Lamb wave propagation is affected by loading and environmental conditions and recording baseline data for each possible condition is impractical. Baseline-free SHM methods are therefore highly desirable. This presentation will focus on SHM using Modified Time Reversal (MTR) of Lamb waves, which was proposed by Watkins & Jha (Mechanical Systems and Signal Processing 31:345-354, 2012) at Clarkson University. Building up on the earlier work, the MTR method using Laser Doppler Vibrometer (LDV) based non-contact sensing will be introduced (Jayakody, 2019; https://scholarsjunction.msstate.edu/td/850). The validation of the current technique through experimental results and finite element simulations will be presented. The complexities arising from multiple wave modes and structural boundaries will be addressed. A novel technique developed in the frequency-time domain to detect damages will be discussed. The developed technique is highly suitable for the detection of damages in large structures, even when the damage is superficial and the severity is relatively low.
Date: Friday, September 10, 2021
Time: 11:00 am
Location: Science Center 160
Bio: Dr. Ratneshwar (Ratan) Jha (jhar@rowan.edu) is Department Head & Professor of Mechanical Engineering at Rowan University, Glassboro, New Jersey (Carnegie-classified R2 Doctoral institution ranked #95 in Top Public University). Dr. Jha has held leadership/managerial positions for over 10 years as department head, research center director, and industry manager. He is an ASME Fellow, AIAA Associate Fellow, and ABET Program Evaluator. He is an Academic Editor for the International Journal of Aerospace Engineering. Prior to Rowan, Dr. Jha served as Director of Raspet Flight Research Lab & Advanced Composites Institute and Professor of Aerospace Engineering at Mississippi State University (2012-2018). During 1999-2012, Dr. Jha served as Assistant/Associate Professor of Mechanical and Aeronautical Engineering at Clarkson University. Over the course of his career, Dr. Jha has supervised 30+ MS/PhD students, published 140 papers, and received over $16 million in research grants and contracts. Dr. Jha earned his Ph.D. in mechanical engineering from Arizona State University, and holds an MS in aerospace engineering from Georgia Tech. He received his BS in aeronautical engineering from the Indian Institute of Technology. Between his MS and PhD, Dr. Jha worked at Hindustan Aeronautics Limited (Bangalore, India) for 12 years leading a team of engineers to design Tejas combat aircraft under production at HAL.