Co-curing holds great promise to minimize assembly weight, time, and cost for stiffened aerospace structures, which are conventionally fabricated separately and then integrated either through mechanical fastening or adhesive bonding—also known as secondary bonding. This study presented a low-cost co-curing process using VARTM to fabricate stiffened shells, particularly composite box beams. The experimental investigation was performed and the co-curing process was improved by scrutinizing the critical process parameters, such as foam strength and coating, and curing cycle. This work was also intended to present the demonstration of the proposed co-curing method and its comparison with the conventional secondary bonding technique for three-cell carbon fiber-reinforced polymer (CFRP) composite box beams. Fiber volume fraction measurements were carried out to the specimens extracted from the various section of the co-cured part, namely top skin, web, and bottom skin and as a result, around 60% of fiber volume fraction was measured, which was in good agreement with the results obtained from optical microscopy-based image analysis. Structural-level four-point bending test results showed that the weight normalized maximum and the ultimate load of the part increased by 44% and 45% with the use of the co-curing process, respectively. The improved mechanical properties indicated that stronger structural integration can be achieved by integrally curing structures. SEM micrographs revealed a favorable fiber-matrix interface, bolstering the superior integration of the co-cured part. These findings suggest that the low-cost co-curing process can be a potential candidate for the fabrication of stiffened aerospace structures, such as composite box beams.

共固化有望最大程度地减少加固航空航天结构的组装重量、时间和成本，这些结构通常单独制造，然后通过机械紧固或粘合剂粘合（也称为二次粘合）进行集成。这项研究提出了一种使用 VARTM 制造加筋壳，特别是复合箱梁的低成本共固化工艺。进行了实验研究，并通过仔细检查关键工艺参数（如泡沫强度和涂层以及固化周期）来改进共固化工艺。这项工作还旨在展示所提出的共固化方法及其与用于三单元碳纤维增强聚合物 (CFRP) 复合材料箱梁的常规二次粘合技术的比较。即顶部皮肤、网和底部皮肤，因此，测量了大约 60% 的纤维体积分数，这与基于光学显微镜的图像分析获得的结果非常一致。结构级四点弯曲试验结果表明，采用共固化工艺后，零件的重量归一化最大值和极限载荷分别增加了44%和45%。改进的机械性能表明通过整体固化结构可以实现更强的结构整合。SEM 显微照片显示出良好的纤维-基质界面，支持共固化部件的卓越集成。这些发现表明，低成本的共固化工艺可以成为制造加强航空航天结构（如复合箱梁）的潜在候选者。