Virtual Testing and Its Role in Certifying Composite Aerospace Structures
Anthony Waas, Felix Pawlowski Collegiate Professor of Aerospace Engineering
University of Michigan
The design of lightweight composite structures, for example airframe structures, relies on extensive testing, coupled to a bottom-up, pyramidal building block approach, to ensure structural integrity and damage tolerance. Reducing the number of tests can lead to a substantial decrease in the total design cost of many vehicles. Cost reduction is enabled by developing high fidelity computational models which can provide valuable information regarding the performance of a structure up to and including failure, provided the modeling is based on material parameters that can be measured, and is validated using laboratory tests that are designed to be discriminatory. This activity, which is now a major area of research falls under the broad umbrella of “virtual” testing, and also includes parallel activities such as ICME (integrated computational materials science and engineering), and “digital twin” (the process of creating a high fidelity computational model of individual aircraft, to integrate computation of structural deflections and temperatures in response to flight conditions, with a depository of local damage evolution so that the “state” of the vehicle is updated and current at any given time). In this talk, the state of the art in virtual testing and the future challenges and opportunities in this area will be highlighted. Finite element models developed for laminated composites that can be used in ICME and “digital twin” activities of aero-composite structures will be presented and the material parameters that are needed to execute the model and how these can be measured using coupon level samples will be discussed. Validation of the models through notched tension and open hole compression tests of composite structural panels will be presented. Finally, the many opportunities available to extend modeling using multi-scaling strategies will be discussed and the challenges that one encounters will also be presented.
Anthony M. Waas is the Felix Pawlowski Collegiate Professor of Aerospace Engineering and professor of mechanical engineering, and director, Composite Structures Laboratory at the University of Michigan. He received his B.Sc. (first class honors) from Imperial College, University of London, U.K., in 1982, the M.S. in 1983 and Ph.D in 1988 with a minor in applied mathematics from the California Institute of Technology, all in aeronautics. He joined the faculty of the Department of Aerospace Engineering at the University of Michigan in 1988, where he has risen through the ranks, associate professor in 1994, professor in 2000, and Felix Pawlowski Collegiate Professor, 2009. His current research interests are related to lightweight aerostructures, with a focus on automated manufacturability, structural integrity and damage tolerance. He is also researching ceramic matrix “hot” structures, nano-composites, and multi-material structures. Several of his projects have been funded by numerous US government agencies and industry. In addition, he has been a consultant to several industries in various
capacities, most recently with the Boeing Company in connection with the 787 Dreamliner airplane. Waas has served and chaired several AIAA and ASME committees. He is a recipient of
several best paper awards, the American Academy of Mechanics Junior Research Award (1997), The UM College of Engineering David Liddle Award for Research Excellence (2006), an AIAA
Sustained Service Award (2006), and most recently, the American Society of Composites Outstanding Researcher Award (2013). He is a Fellow of AIAA, ASME, and the AAM, and a member of the American Society of Composites and the American Association for the Advancement of Science. He has served on the editorial boards of several journals, notably, as an associate editor of the AIAA Journal (1995-02), the Editorial Advisory Board of the AIAA Journal of Aircraft (1995-00), The ASME Journal of Applied Mechanics (2007-2013), and the International Journal of Engineering Science. He is author or co-author of more than 200 refereed journal papers, and numerous conference papers and presentations.