Damage Tolerance of Layer-Wise Hybrid Laminates Consisting of Glass Reinforced Flexible and Rigid Epoxy Resins

Open Access
Author:
Bossenbroek, Kirsten
Graduate Program:
Engineering Mechanics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Charles E Bakis, Thesis Advisor
  • Clifford Jesse Lissenden Iii, Thesis Advisor
  • Edward C Smith, Thesis Advisor
Keywords:
  • layer-wise hybrid
  • damage resistance
  • damage tolerance
  • composite
Abstract:
The objective of this investigation is to develop and characterize co-curing rigid and flexible epoxies, develop and implement a fabrication process for filament winding layer-wise hybrid composite structures, and evaluate the effect of including a flexible matrix composite layer for increasing the damage tolerance of a composite structure. Rigid composites, which are often found in aerospace structures, tend to be very brittle and susceptible to damage caused by low velocity impact. This study aims to investigate the effectiveness of incorporating a flexible matrix composite layer in a traditional rigid matrix composite laminate. Layer-wise hybrid laminates were fabricated and quasi-statically indented to simulate low velocity impact. Damage resistance was evaluated by measuring the delaminated area and evaluating the extent of matrix cracking through the thickness of the wall. The residual stiffness and strength of the laminates were measured by testing unindented and indented laminates in axial compression. It was found that placing a flexible matrix composite, angle-ply layer at a key interface in the laminate resulted in the highest percent strength retention when compared to placing the flexible matrix layer at any other location in the laminate or compared to an all-rigid matrix laminate. The layer-wise hybrid laminate also had the least amount of intra-ply matrix cracking through the thickness, but did have a larger damaged area overall.