Session: 12-15-01: Dynamic Failure of Materials & Structures

Paper Number: 100182

100182 - Directionally Controlled Impact-Debris Propagation of Origami-Inspired Composite Panels 

Conventional composite structures used in aerospace and military applications are often made with a sandwich core of honeycomb or synthetic polymer foam. Due to their closed-cells and sealing structures, honeycomb and foam core materials have limited geometric customization and are susceptible to water/moisture contamination. An alternative to legacy core materials is the foldcore. A folded sandwich core (foldcore) is based on an origami fold pattern such as the “Miura” fold. Foldcore geometry can conform to complex shapes and the design has open channels that allow moisture elimination and heat transfer. Orientation of these unidirectional channels can facilitate directional control of debris in a hypervelocity impact (HVI, 2~8 km/sec) event. Directional control of debris can be used to protect selected regions of substrate from damage. An improved foldcore design has application as a light-weight defensive armor and structural element.

 

This work will present HVI response of carbon fiber reinforced polymer (CFRP) foldcore sandwich composites (FSCs) to understand the effectiveness of foldcore design parameters on HVI energy absorption. The foldcore (14 x 14 x 1.8 cm³) and facesheet (14 x 14 x 0.15 cm³) are each fabricated by curing eight plies of AS4/3501 woven fabric prepregs. Foldcores are fabricated in Miura folding pattern. Cured facesheets are bonded to the foldcore to construct the FSC using a two-part epoxy adhesive with hydraulic press. An FEA model was used to optimize the foldcore unit cell geometry simulate failure modes.

A series of normal (0°) and oblique (45°) HVI experiments were performed on FSC targets impacted with 4 mm diameter aluminum 2017 spherical projectiles using a two-stage light-gas gun. High-speed camera footage captured images of the debris cloud for characterization and comparison against legacy core structures. Foldcore geometry and orientation were found to affect impact energy absorption and debris redirection. The FSC successfully redirected HVI projectiles and manipulated debris cloud formation/expansion. The debris cloud propagated through the foldcore open channels in a directional orthogonal to the projectile path. The back-face debris clouds fanned out in foldcore channel direction. The HVI response of FSC targets strongly depends on the impact location and angle of incoming projectile. This suggests that FSCs prepared with optimal core architecture and materials may perform better than conventional sandwich panels during an HVI event. The unidirectional foldcore channels successfully controlled the direction of debris cloud propagation, demonstrating tunable impact performance. Impact performance can be further improved by changing geometry, material, and stacking of FSCs.

Presenting Author: Chase Mortensen Utah State University

Presenting Author Biography: Undergraduate Senior in Mechanical Engineering

Authors:

Nathan Hoch Utah State University
Chase Mortensen Utah State University
Juhyeong Lee Utah State University