CSIR-National Aerospace Laboratories, Bangalore, India
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Lecture on Integrity Assurance and Design of Pressure Vessels for Storing Hydrogen

Unified platform for Indian Structural Integrity

Prof. Ashok Saxena

Founding President and Fellow, InSIS

Date & Time : Monday 10th February 2020, 4:00pm

Venue : Lecture Theatre, Materials Engineering

Abstract of the Talk

Cost-effective, pressure vessels for use in ground storage of hydrogen in refueling stations require vessels that can safely store up to 750 liters of gaseous hydrogen at 1000 bars or 90 MPa. This research uses fracture mechanics analysis to assist in the design and structural integrity of a Type 2 pressure vessel to meet this need.

Metal cylinders have been used for storing hydrogen for several decades but are limited to pressures of 55 MPa due to hardenability of the material and the ability to reliably inspect for flaws.The designs must also meet safety requirements of standards such as the ASME PVP Section VIII – Division 3 odes. Using the time-tested, metal cylinders as liners and wrapping them with high strength steel wires that are 2 GPa or higher in strength is an effective approach for doubling the pressure capability of these metal composite cylinders. The wire-wrapped cylinders are further subjected to an autofrettage process in which they are subjected to pressures high enough to plastically deform the inner liner, but the wire jacket remains elastic. Upon release of the autofrettage pressure, the inner liner is left with high residual compressive hoop stresses. This process decreases the maximum tensile hoop stress in the liner under the operating pressure and can thus enhance the fatigue life of the vessel very significantly.

Bio-Sketch of Prof. Ashok Saxena

Dr. Saxena currently serves as a Distinguished Professor and Dean Emeritus in the Department of Mechanical Engineering at the University of Arkansas where in the past he served as the provost and vice-chancellor of academic a􀈞fairs, dean of engineering and the founding head of the Department of Biomedical Engineering. He also held the 21st Century Endowed Graduate Research Chair in Materials Science (2003-2007), Irma and Raymond Giffels’ Endowed Chair in Engineering (2007-2012), and the George and Boyce Billingsley Endowed Chair (2014-2015). Prior to University of Arkansas, he served as a Regents’ Professor and Chair of the School of Materials Science and Engineering at Georgia Institute of Technology in Atlanta.

Dr. Saxena has primarily worked in the multidisciplinary fields of linear and nonlinear fracture mechanics within the disciplines of mechanical engineering and materials science and engineering. His awards and recognitions include the George Irwin Medal (1992) from ASTM for his contributions to creep fracture mechanics, the ASTM Award of Merit and Fellow (1994), Fellow of ASM International (1996), Fellow of International Congress on Fracture (2009), Fellow of the Indian Structural Integrity Society (2018), and the Georgia Tech Outstanding Research Author (1993). He received the Wohler Fatigue Medal from the European Structural Integrity Society (ESIS) in 2010 and the Fracture Mechanics Medal from ASTM (2011), and the Paul C Paris Gold Medal from the International Congress on Fracture. He is the author, co-author or editor of ten books and over 250 research publications.

Dr. Saxena received his B.Tech. in mechanical engineering from the Indian Institute of Technology, Kanpur in 1970 and his master’s and doctoral degrees in materials science & metallurgical engineering from the University of Cincinnati in 1972 and 1974, respectively. His major industrial experience was at the Westinghouse Research and Development Center in Pittsburgh, where he served from 1976 to 1985 and rose to the rank of Fellow Scientist.