Use of advanced fiber reinforced composites (FRC) has continuously increased in structural designs for aerospace, automotive and wind energy applications. With advancing manufacturing and characterization techniques and software specialized on composites, potential of the composites calls engineers and scientists to push the boundaries of broad composites research for making them even more competitive. That is, it drives us to “think outside the box” for composites design practices as opposed to traditional lay-ups, materials and production techniques. This talk will exemplify such efforts at Advanced Composites and Polymer Processing Laboratory (AC2PL) of Sabancı University.
First, the concept of nano-composite interlayers integrated into the traditional composite laminates for improved mechanical behavior will be introduced. Specifically, the epoxy cross-linking P(St-co-GMA) and P(St-co-GMA)/MWCNT electrospun nano-fibers are applied on conventional carbon/epoxy prepreg plies prior to curing under vacuum. Strain energy release rate under shear loading (End-notched flexure-ENF tests) is enhanced. Transversal impact tests also provided evidence for toughness increase (about %20) by the nano-fibrous/epoxy interlayers. Overall the experimental results suggest there is a significant potential by the nanofibrous interlayers that are chemically tailored for the matrix to increase the microcracking and delamination resistance of the laminated composites with no weight penalty.
The second part introduces thin-ply bi-angle non-crimp fiber (NCF) composites and addresses associated benefits and opportunities in the structural design process. A state of the art tow-spreading technique enables ply thickness to be as low as half of the typical commercial high quality prepreg ply thickness. Adding the ability of an off-axis ply, thin-ply NCF offers two different fiber orientations within the traditional one-axis ply thickness. On our quest for simultaneous weight and cost reduction at maximum performance and reliability, the thin ply bi-angle NCF building block reunite us with the anisotropy and homogenized laminate designs as opposed to more traditional composite designs typically imitating metals or isotropy.
Melih Papila received the B.S. and M.S. degrees in aeronautical engineering from the Middle East Technical University, Ankara, Turkey, in 1990 and 1995, respectively. He worked at Roketsan as a research engineer between 1993 and 1997. He received the Ph.D. degree in aerospace engineering from the University of Florida, Gainesville, in 2001, as a member of Multidisciplinary and Structural Optimization group.
Dr. Papila is currently faculty member in the Materials Science and Engineering Program at the Sabancı University (SU), Istanbul, Turkey. Prior to joining SU in 2004, he was a Postdoctoral Associate jointly in Interdisciplinary Microsystems and Multidisciplinary and Structural Optimization Groups at the Department of Aerospace and Mechanical Engineering of University of Florida, from 2002 to 2004. His current research focuses on the polymer and ceramic fibers by electrospinning and their polymer matrix composites for electroactive response, design and optimization of smart/composite materials and structures.