| Polymeric composites, a combination of reinforcing fibers and polymer resin matrices, offer many advantages over traditional materials, and have been widely applied in the aerospace, automobile, and sporting goods industries. Especially in the field of advanced aircraft applications, the high modulus and strength-to-weight ratio of composites are very important to reduce gross weight and allow a resulting increase in aircraft payloads. On the other hand, the cost of acquisition and maintenance of aircraft parts has become a main concern in the airline industry. Therefore, the materials to build aircraft parts must demonstrate acceptable costs as well as sufficient performance improvements in durability over long-term usage in environmental use to justify the production application. From this perspective, a feasibility study was performed to develop composite Unit Load Devices (ULDs). To perform this, a new way to design ULDs was considered to maximize aircraft payloads by reducing the weight of ULDs using composite materials. On the technical side, work has been performed to evaluate phenolic resins as they use as fiber reinforced composites considering the economics of applying composites. Hygrothermal cycling effects on the long-term property changes of phenolic composites have been investigated through thermal, mechanical, and morphological tests. In addition, the concept of equivalent cycle time (ECT) was developed and applied to comprehend the long-term properties of composites to understand the effect of thermal cycling. Collectively, this work provides an understanding of how the economical aspects are considered and how the long-term properties are affected under the controlled environmental conditions by their inherent characteristics of anisotropy, heterogeneity, and viscoelasticity. |
