Professor Ramesh K. Agarwal is the William Palm Professor of Engineering in the department of Mechanical Engineering and Materials Science at Washington University in St. Louis. From 1994 to 2001, he was the Sam Bloomfield Distinguished Professor and Executive Director of the National Institute for Aviation Research at Wichita State University in Kansas. From 1978 to 1994, he was the Program Director and McDonnell Douglas Fellow at McDonnell Douglas Research Laboratories in St. Louis. Dr. Agarwal received Ph.D in Aeronautical Sciences from Stanford University in 1975, M.S. in Aeronautical Engineering from the University of Minnesota in 1969 and B.S. in Mechanical Engineering from Indian Institute of Technology, Kharagpur, India in 1968. Over a period of forty years, Professor Agarwal has worked in various areas of Computational Science and Engineering - Computational Fluid Dynamics (CFD), Computational Materials Science and Manufacturing, Computational Electromagnetics (CEM), Neuro-Computing, Control Theory and Systems, and Multidisciplinary Design and Optimization. He is the author and coauthor of over 500 journal and refereed conference publications. He has given many plenary, keynote and invited lectures at various national and international conferences worldwide in over fifty countries. Professor Agarwal continues to serve on many academic, government, and industrial advisory committees. Dr. Agarwal is a Fellow eighteen societies including the Institute of Electrical and Electronics Engineers (IEEE), American Association for Advancement of Science (AAAS), American Institute of Aeronautics and Astronautics (AIAA), American Physical Society (APS), American Society of Mechanical Engineers (ASME), Royal Aeronautical Society, Chinese Society of Aeronautics and Astronautics (CSAA), Society of Manufacturing Engineers (SME) and American Society for Engineering Education (ASEE). He has received many prestigious honors and national/international awards from various professional societies and organizations for his research contributions.
Abstract: In recent years, there has been emphasis on ‘Green Aviation’ with the dual aims of reducing the energy consumption as well as emissions. Several new concepts for the aircraft have been proposed to reduce drag, improve engine efficiency, and reduce mass. Majority of the wing-tube transport aircraft in service today are very efficient high speed air vehicles equipped with high bypass jet engines. Since early 1960s most improvements in aircraft efficiency have come from advanced turbofan propulsion technology (by 40%) and improved aerodynamics to increase the Lift/Drag (by 15%); however, the structural efficiency of the aluminum aircraft did not change much because of limited emphasis on considerations of novel materials, structures, and manufacturing processes. In recent years, reduction of aircraft mass has become one of the major drivers in developing new aircraft design concepts, novel materials and manufacturing processes without affecting the intrinsic qualities, namely the safety, reliability, durability and comfort. As a result, the metal composites based on textile-reinforced polymers that are locally blended with metal elements are being investigated for aircraft structures. Additionally, in the near future a tremendous leap in material morphologies is expected from intermediate components such as solid plates and slender beams that are assembled and joined mechanically to flexible bundles of fibers, which are then transformed into integral three-dimensional structures via both the traditional textile manufacturing and modern fiber placement machinery. These textile structures are impregnated (‘pre’, ‘in situ’ or ‘post’- before, during or after molding) and finally solidified into ultra-modern integral multipart and multifunctional solid lightweight composite structures. This keynote paper will describe these developments that will transform the ‘state of the art’ aircraft concepts into more efficient (more pay-load per unit weight and per dollar) transport, both by increasing the structural simplicity and efficiency and by use of modern materials and processes.
In addition, to address many challenges of ‘Green Aviation,’ nearly a decade ago NASA launched an initiative called the ‘Environmentally Responsible Aviation (ERA).’ In this initiative, Blended-Wing-Body (BWB) aircraft and other X-planes are being considered for a long-haul transport aircraft. BWB provides many aerodynamic advantages; however it presents structural challenges due to the noncircular cross section of the center part of its fuselage. Although significantly lighter than the conventional aluminum structures, even the most efficient composite primary structures used in today’s state-of-the-art aircraft are not adequate to overcome the weight and cost penalties introduced by the highly contoured airframe of the BWB. To address these issues, scientists at NASA and the Boeing Company are working together to develop a new structural concept called the pultruded rod stitched efficient unitized structure (PRSEUS). This concept is being analytically and experimentally evaluated using a building block approach that assesses the fundamental structural responses in representative loading environments of BWB. This presentation will also review the current status of PRSEUS.
Furthermore, 3-D printing and additive manufacturing are emerging as very promising techniques for fabrication of composite parts. This review will also address the state of the art of these technologies as they relate to the fabrication of some complex aircraft parts.