Fatigue of glass‐fiber‐reinforced polyester laminates

Abstract Materials used in making glass‐fiber‐reinforced plastic pressure vessels are tested in uniaxial tensile fatigue. Specimens of mat/woven roving/mat are tested with the warp direction parallel to the load axis and ±45 degrees to the load axis. Filament‐would specimens are tested at ±54.7 and ±35.3 degrees to the load. A stress ratio of R = 0.1 is used with load control. The residual properties of surviving specimens after 400,000 cycles indicate they have sustained no damage. The S′‐N curves show a strength loss of about 10 percent per decade of cycling. The failure mode of the filament‐would specimens is similar to that of angle‐ply laminates. Stress levels of one‐third the strength appear safe for the range of cycles investigated.