CompositeStructureDiagram

Composite structures are assemblies that combine two or more materials to achieve properties greater than those of the constituents alone. A typical composite consists of a reinforcing phase (fibers, particles, or foam) and a matrix phase (polymer, metal, or ceramic). The load transfer between components and the quality of the interface give composites their characteristic strength, stiffness, and damage tolerance, while enabling tailored behavior through orientation and architecture.

Common forms include laminated fiber-reinforced composites, where multiple plies are oriented to meet design loads; sandwich structures with a lightweight core bonded between strong face sheets; and particulate- or whisker-reinforced matrices. Fiber-metal laminates combine metal layers with composite plies to improve impact resistance and damage tolerance. The choice of constituents and geometry governs properties such as stiffness, strength, density, and thermal expansion.

Manufacturing methods range from manual layup and filament winding to automated processes such as resin transfer molding and prepreg curing, often in an autoclave. Process parameters, cure cycles, and tooling quality influence porosity, fiber alignment, and interfacial bonding, which in turn affect performance and durability.

Design and analysis of composite structures use anisotropic material models and lamination theory to predict stiffness and strength. Common failure criteria include Tsai-Hill, Tsai-Wu, and Hashin rules. Damage mechanisms include matrix cracking, fiber breakage, and delamination, which can be detected by nondestructive evaluation techniques such as ultrasonic C-scan or X-ray imaging.

Applications span aerospace, automotive, wind turbines, sports equipment, and marine structures. Environmental sensitivity (moisture, temperature) and aging can influence long-term behavior. Sustainability challenges include limited recyclability of thermosets, though thermoplastic matrices and emerging recycling methods are expanding options. Standards such as ASTM D3171 for fiber content and ASTM D3039 for tensile properties guide testing.