Materials and Structure

Crack propagation in a glass fiber-polyester resin composite is shown.

The crack initiates in a high stress region of the matrix, which debonds from the fiber. Crack propagation passes through similar high-stress regions in the composite, the open crack having a stress concentration at its sharp termination.

When the crack tip reaches a matrix zone relatively free of fibers, crack blunting and resin flow occurs.

From: Hull, "Introduction to Composite Materials," Cambridge (1992)