Composite Design Principles

The key to composites is combining materials with complementary weaknesses. Carbon fibers are incredibly strong in tension but brittle. Epoxy resin is weak but flexible. Together they make a material that is both strong and resilient.

Fiber orientation sets a composite's directional strength. Laying all fibers one way gives maximum strength along that axis but leaves it weak across the grain. Cross-ply layups alternate the fiber directions to spread strength evenly.

Nature got there first. Bone is hard mineral plus flexible collagen. Wood is cellulose fibers in a lignin matrix — composite design that predates humans by billions of years.