Abstract A sandwich structure comprises layered composite materials formed by bonding two or more thin facings or face sheets to a relatively thick core material. Topics discussed in this article include: sandwich panel failure modes, nomenclatures and definitions, strength checks, stiffness and internal loads, flat panels under pressure loading, curved sandwich panels, local strength analysis methods, and flat panel stability.
Abstract Hygrothermal behavior of cured composite materials relates to the combined and commonly synergistic effects of moisture absorption and temperature on various physical, chemical, and mechanical properties. This article concentrates on polymer-matrix composites and is limited to the effects of moisture absorption after an established cure of the material has been completed. It presents general considerations in assessing hygrothermal behavior. The article focuses on hygrothermal testing and conditioning, discussing the physical and chemical effects on the composite. It also presents the variation of mechanical properties in composites.
Abstract Vacuum bag autoclave molding for producing composite parts is the oldest and most mature composite manufacturing process. This process can be used for various resin systems, monolithic and sandwich constructions, and geometries. For these reasons, the bag autoclave molding process is still a widespread and reliable process. The process has several steps, each of which is discussed in this article, including debulking, bagging, the curing procedure with autoclave operations, and debagging. Considerations for optimizing cost and quality are also discussed.
Abstract Lightweight structural cores were first used in aircraft in the 1940s to reduce weight and increase payload and flight distance. This article focuses on the three primary types of lightweight structural cores: honeycomb, balsa, and foam. In many applications, lightweight structural cores are used in sandwich panels. The article also presents an overview of various techniques available for modeling sandwich structures, providing the basic concept of a sandwich panel, where the facings carry the bending loads, and the honeycomb core carries the shear loads.
Abstract Recycling of synthetic fiber composites—primarily fiberglass and carbon-fiber systems—is a growing priority as end-of-life materials accumulate across aerospace, automotive, and wind energy industries. This article surveys the three principal recycling approaches—mechanical, thermal, and chemical—with emphasis on carbon-fiber-reinforced thermoplastic and thermoset composites, and reviews end-use applications for recycled materials including permeable pavement, porous asphalt, and commodity plastic reinforcement. Life-cycle analysis findings confirm that all recycling strategies offer environmental advantages over landfilling, with mechanical recycling remaining the most commercially viable option.
