Composites unite many of the best qualities that traditional materials have to offer. The two components of a composite include a reinforcement (often a high-performance fiber such as carbon or glass) and a matrix (such as epoxy polymer). The matrix binds the reinforcement together to merge the benefits of both original components.

Composites are improving the design process and end products across industries, from aerospace to renewable energy. Each year, composites continue to replace traditional materials like steel and aluminum. As composite costs come down and design flexibility improves, fiber-reinforced composites like carbon fiber and fiberglass open up new design opportunities for engineers.

Carbon fiber composite sports car
Carbon fiber’s high strength and low weight improves speed and engine efficiency in auto design.

1. Composites have a high strength-to-weight ratio.

Perhaps the biggest advantage of composites is their high strength-to-weight ratio. Carbon fiber weighs about 25% as much as steel and 70% as much as aluminum, and is much stronger and stiffer than both materials per weight. High-end auto engineers use composites to decrease vehicle weight by as much as 60% while improving crash safety; multilayer composite laminates absorb more energy than traditional single-layer steel. Harnessing the power of composites benefits manufacturers and consumers alike.

Fiberglass composite wind turbines in a field
Fiberglass wind turbine blades are some of the largest man-made composite structures.

2. Composites are durable.

Composites never rust, regardless of their environment (though they are prone to corrosion when bonded to metal parts). Composites have less fracture toughness than metals but more than most polymers. Their high dimensional stability allows them to maintain their shape, whether hot or cold, wet or dry. This makes them a popular material for outdoor structures like wind turbine blades. Engineers choose composites over traditional materials to reduce maintenance costs and ensure long-term stability, major benefits for structures that are designed to last decades.

3. Composites open up new design options.

Composites offer design options that would be hard to achieve with traditional materials. Composites allow for part consolidation; a single composite part can replace a full assembly of metal parts. The surface texture can be altered to mimic any finish, from smooth to textured. Over 90% of recreational boat hulls are constructed from composites, in part because fiberglass can be molded into a wide range of boat shapes. These benefits save production time and reduce maintenance costs in the long run.

4. Composites are now easier to produce.

In the past, engineers had to use a complex lay-up process to fabricate composites, which was time-consuming and restricted the design geometry. Digital Composite Manufacturing (DCM) has changed this. DCM is a patented manufacturing process that fabricates composite parts without manual labor. With DCM, composites can be tailored in three dimensions locally or globally, creating just the right strength, density, and flexibility for the project. DCM is enabling engineers to design for the flexibility of 3D printing, combined with the high performance of composites.

Fiberglass composite boats near a dock in Boston
Most recreational boat hulls are made of composite materials such as fiberglass and carbon fiber.