A micromechanics model was proposed to analytically estimate composite stresses based on strain data of a unidirectional CFRP obtained from in a biaxial tensile proportional loading test. The validity of the model was investigated by comparing it with an elasto-plastic finite element analysis. The results demonstrated that the stress values under all loading conditions were in close agreement not only during elastic deformation of the matrix but also in the post-yield region. The yield curves of the composites were also predicted analytically and compared with the approximate curve of the composite fracture stresses. The transverse crack (TC) mode was found to occur either before or immediately after the matrix yield, whereas fiber breaks (FB) and combined TC&FB modes continued to sustain biaxial loading even after the matrix yields. A comparison between the stresses at composite fracture obtained from the proposed model and those from orthotropic anisotropic elastic analysis showed an approximate agreement under loading conditions associated with the FB mode. However, significant discrepancies in the 90° direction stress were observed in the TC-involved modes. Furthermore, the stress boundary separating the TC-involved and FB modes was analytically predicted based on the strain condition: ε₂＝0. The analysis indicated that the this boundary occurred approximately at σ₂＝30 MPa.

Traditional composite manufacturing methods for carbon fiber-reinforced plastics (CFRPs), such as autoclave molding, are costly and unsuitable for mass production. Electrodeposition resin molding (EDRM), a cost-effective alternative, is a novel resin-impregnation method in which the resin is electrochemically deposited around the fibers without external pressure. This study investigated the effect of terminating conditions of the EDRM process on the bending modulus and strength of the resulting CFRP using resistance as an indicator of resin impregnation. Four-point bending tests demonstrated that the bending modulus and strength increased with resistance for values below 13,000 Ω. Specifically, specimens prepared at 12,000 Ω showed approximately 33％ higher bending strength than those prepared at 5,000 Ω, which can be attributed to reduced void content and improved fiber-resin bonding. At values above 13,000 Ω, the bending modulus showed no correlation, and the bending strength exhibited a weak negative correlation with the resistance. This is likely due to excess resin deposition, which lowers the volume fraction of the fiber. Thus, an optimal resistance threshold of approximately 13,000 Ω is required for maximizing the mechanical performance of CFRPs produced by EDRM.

Resin infusion simulations based on Darcy’s law and the Kozeny-Carman equation are widely utilized to mitigate molding defects in liquid resin infusion methods such as vacuum-assisted resin transfer molding (VaRTM). The permeability of textile reinforcements varies significantly with weave structure, as differences in the void distribution between fiber bundles directly affect resin flow. This study quantified void distributions in two types of plain-woven glass cloths with distinct weave structures. Permeability, flow behavior, and flow direction were assessed through both resin infusion experiments and simulations based on the Kozeny-Carman equation. The findings demonstrated that variations in weave structures result in significant differences in void distribution, which in turn have a substantial impact on resin flow characteristics.