Title: Flexural Response and Failure Mechanisms of Digitally Manufactured Truss Core Sandwich Panels

Authors: Sumaiya S. Tanu, Clement Brousse, Donald W. Radford

DOI: 10.33599/nasampe/c.24.0345

Abstract: "Composite sandwich panels are critical structural components in aerospace, wind energy, and automotive industries due to their lightweight and high flexural stiffness. Sandwich panels are comprised of high-performance fiber reinforced facesheets and low-density cores, providing high strength and stiffness per weight. While closed-cell foam or honeycomb structures are conventionally used for the cores, recent research has replaced these traditional core materials using fiber-reinforced truss core constructions as they promise comparable strength and stiffness levels while further reducing the weight of the structural panel. An inherent part of this progress is the need to understand the mechanical behavior of these novel structures. Previous studies have shown that in conventional sandwich structures, the core fails due to shear stress during flexural loading. However, there is a lack of research on the flexural behavior of continuous fiber-reinforced thermoplastic matrix truss core structural panels. This work utilizes a customized 3-axis gantry-based fiber deposition system to create continuous fiber-reinforced Navtruss core sandwich panels without the need for the extensive tooling that has limited the application of truss core panel to-date. The study includes an experimental investigation to analyze the bending response and failure mechanism of the Navtruss core sandwich panels made from continuous fiber reinforcement thermoplastic (CFRTP) commingled material, by performing three-point bending. Three sets of specimens are manufactured to study the three failure modes: core buckling or crushing, facesheet wrinkling, and facesheet crushing. The response of these digitally manufactured sandwich panels under flexural testing is measured until failure. The results are compared more traditional sandwich panels with (a) Fused Deposition Modeling (FDM) printed truss core, (b) FDM printed honeycomb core, both with the same relative density and (c) a baseline commercial PET closed-cell foam with continuous E-glass fiber (EG) reinforced thermoplastic facesheets bonded to the core using hand layup and vacuum bagging method. The results show that while yielding promising flexural response results, the continuous fiber truss core panels are limited by the quality of the composite placed out-of-plane, without rigid tooling. Future research will focus on processing adjustments to improve the consolidation and uniformity of the internal truss core segments printed with radically reduced tooling."

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Conference: CAMX 2024 | San Diego CA

Publication Date: 2024/9/9

SKU: TP24-0000000345

Pages: 14

Price: $28.00