How do composite materials combine fibres and a matrix to improve strength?

In materials science, composite materials improve strength by combining fibres with a host matrix to create a substance with superior properties compared to its individual components.1

The matrix acts as an adhesive, binding the fibres together to provide solidity and structural integrity. This synergy functions through several key mechanisms:

• Load Distribution: The rigid fibres provide structural strength, while the matrix protects them from physical damage and environmental stress.1
• Crack Arrest: The combination prevents complete structural failure. If one fibre breaks, the matrix often prevents the crack from propagating to adjacent fibres, a common weakness in monolithic materials.12
• Elasticity and Toughness: By dispersing a rigid, brittle material within a matrix of different elasticity, the composite can approach the theoretical strength limits of its components while maintaining resistance to stress failure.2

While simple composites may only be strong in the direction of their fibres, engineers can create materials with strength in all directions by weaving fibres into three-dimensional structures.1