Characterization of Bistability Behavior in Unsymmetric CFRP Laminates

<p>Composite laminates of unsymmetric layup families often exhibit twin stable shapes at room temperature, a phenomenon known as bistability. Unsymmetric bistable composite laminates have often been suggested for applications in aerospace morphing structures, damping, and energy storage, because of their ability to easily change their shape while being homogenized with the rest of the composite structure.</p> <p>This study analyzes the mechanisms responsible for bistability in unsymmetrical [0/0/90/90] laminates through a combination of experiments and modeling. Several unsymmetrical laminates with different aspect ratios were fabricated using autoclave processing. Digital image correlation (DIC) is used to monitor laminate strains in situ during the processing of the composite and to correlate processing strains to the degree of bistable behavior in differently sized samples. Room-temperature curvatures were measured and compared with analytical and FEA models. Load responses to changes in the shape of the laminate were measured for each sample size to determine the effects of the size and aspect ratio for both as-fabricated and machined samples. It is shown that the “snap-through” load and curvatures of the laminates decrease as the length of one side of the sample decreases. It is also shown that the snap-through load of samples further machined with a water jet cutter post-cure decreased significantly, but possessed only slightly less curvature compared to identically sized samples that were not machined. The results show that there are significant limitations to the application of this type of laminate, but there is ample potential for property modification during processing, which can increase the size of the design space.</p>

Name thesis:degree_name

Master of Science in Aeronautical Engineering

Level thesis:degree_level

Thesis - Open Access

Discipline thesis:degree_discipline

Aerospace Engineering

Year

2023

Author dc:creator

• Medora, Evan

• CFRP Bistable Bistability Laminates
• Digital image correlation (DIC)
• composite laminates
• aerospace morphing structures
• Aerospace Engineering
• Structures and Materials

Repository record dc:identifier

https://commons.erau.edu/edt/748

OAI identifier oai:identifier

oai:commons.erau.edu:edt-1773