Composite Materials

· For angle ply laminates with the fibers symmetrically placed with respect to the tensile axis of the composite, the graph shows the effect of the fiber angle on the lamina stresses.

· The stresses in the laminae are normalized by the applied stress on the composite, σ_a1 , and both have V_f = 0.5 to give a balanced composite.
· Lamina fracture will occur if these stresses cause fiber fracture (σ^*₁), transverse tensile cracking (σ^*₂), or shear fracture parallel to the fibers (τ^*₁).

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