Session: 01-04-01: Advances in Aerospace Structures

Paper Number: 138371

138371 - Designing Effective Modulus of 3d-Printable Curvilinear Fiber-Reinforced Composites 

Curvilinear fiber reinforced composites constitute a special class of composites and have attracted wide attention in defense, aerospace, and energy applications. With the remarkable progress in additive manufacturing, composites can now be created in complex architectures to achieve a desired set of properties. One key challenge is however to determine what architecture to 3D-print. While single material structures are susceptible to failure from printing defects, composite structures have a myriad of sources of stress-concentrations and discontinuities to trigger a failure event. It is therefore critical to develop a predictive guidance on modulus-architecture correlations and determine how material distribution affects effective properties at critical locations. For two-phase fiber-based composites, effective properties can be strongly anisotropic depending on the distribution and orientation of the fibers. They can be tailored substantially to design a wide variety of composite properties and functions. For instance, unidirectional fibers exhibit fiber properties for loading along the fiber direction and matrix properties for loading along the lateral direction. Nonetheless, methodologies for determining modulus of aperiodic composites with arbitrary orientations remain less developed. As a result, there is a lack in understanding and tools to determine effective modulus of architected advanced composites. This presentation will demonstrate a methodology to address this deficiency. We used a combination of theoretical analysis, FE simulations, and experimental tests to determine the interconnection between curvilinearity and effective modulus for a specific set of high-symmetry architectures (such as unidirectional fibers) and low-symmetry architectures (such as sinusoidal and hyperbolic fibers). The modulus of unidirectional fibers shows a non-monotonic trend with respect to increasing the orientation angle, with the minimum appearing at around 60 degrees. Below 60 degrees, the fibers are the majority stress carrier and the modulus changes exponentially with the fiber-orientation and, above 60 degrees, the matrix is the majority stress carrier and the modulus is relatively insensitive to the fiber orientation. This change in fiber vs. matrix dominance forms the mechanistic basis of local modulus change in the low-symmetry composites. For the low-symmetry curvilinear structures, the effective behavior is well-predicted by an `effective theory' that decomposes the fibers' contours into a sum over high-symmetry zones and short fibers. Both the orientation of the midline and amplitude of the fibers for such composites strongly influence their effective behavior. We will also show the applicability of 3D printing to create analogous composite structures. The findings and procedures are applicable to arbitrary fiber architectures and expected to advance the design of advanced composites for applications in aerospace structures. 

Presenting Author: Zubaer Hossain Texas A&M University

Presenting Author Biography: Dr. Hossain received his PhD degree in Mechanical Engineering from the University of Illinois at Urbana-Champaign (UIUC). Prior to joining Texas A&M as an associate professor of instruction, he was a faculty member at UD and served as a postdoctoral scholar at California Institute of Technology. He also worked as a visiting scientist at Lawrence Livermore National Laboratory and as a visiting scholar at Johns Hopkins University. He completed his BS and MS degrees from Bangladesh University of Engineering and Technology and served as a faculty member in its mechanical engineering department before pursuing doctoral studies at UIUC. His research and teaching interests include mechanics and physics of deformation and fracture in semiconductors, heterogeneous materials, and composites. He explores the role of material and structural anisotropy and asymmetry in controlling effective properties at multiple scales. Improving domestic students' success and participation in higher education and research drives his teaching and mentoring ambitions.