Effect of weaving patterns on the wettability and mechanical properties of 3D woven I-beam composites

Abstract

The thesis explores the production of I-beam preforms using the 3D weaving method for load-bearing applications in the aerospace and automotive industries, with a particular focus on how weaving pattern variations affect the mechanical properties and wettability of the resulting composite structures. The research specifically employs 600 TEX E-glass fibers for their ease of weaving, paired with room-temperature curing thermoset resins to ensure effective fabric consolidation. Using an automatic weaving machine equipped for 3D weaving, I-shaped preforms were produced with two distinct designs: LB-X, which features an X connection point in the web region, and LB-I, which lacks this connection. These preforms were then transformed into composite structures using vacuum-assisted resin infusion, a process designed to ensure minimal void formation and enhance resin wettability. The mechanical performance of these I-beam composites was evaluated through both 3-point bending and compression tests. The results indicated that the LB-I design exhibited superior mechanical properties, with a maximum bending force of 3725 N and a compression force of 28.7 kN, outperforming the LB-X design. Additionally, the resin permeability and wettability of these structures were thoroughly investigated during composite production, with microscopic analysis used to assess the quality and consistency of the composites. This detailed examination allowed for a better understanding of how the different weaving patterns influenced resin distribution and mechanical behavior. In conclusion, the study demonstrates that altering the weaving patterns, particularly by optimizing those that could potentially lead to mechanical issues, results in significant improvements in the bending and compressive strengths of the I-beam composites. The research highlights the advantages of the 3D weaving method, which not only enhances delamination resistance and out-of-plane strength but also maintains the lightweight characteristics essential for aerospace and automotive applications. This approach presents a viable solution for producing high-performance composite structures with improved mechanical properties and durability.