Strength

The mechanisms of fracture of a laminate are different under tension and compression. Surface layers can lose stability under compression.

Inner defects and edges are sources of fracture initiation. Transfibrous defects are the most dangerous. Delamination has no great effect on strength of the composite system.

Holes and cracks decrease the tensile strength of composites. Composite materials are less В«sensitiveВ» to small defects.

Cracks perpendicular to the applied load are more dangerous than a hole with the same maximum size.

Tensile strength reduces В«fasterВ» than shear strength in presence of voids and cracks in multi-layer composites.

Curved and inclined fibers decrease the compression strength of the composite. The first factor is more critical in reducing the strength.