Table of Contents

Materials and Structure




Fatigue Behavior of Composites

The S-N curve shows the performance of some uniaxial fiber-reinforced composite materials and compares them to a 2024-T3 aluminum alloy. All samples were tested in cyclic tension-tension with (smax - smin) = 0.1 and with the maximum stress indicated on the graph for each life to failure. Compression testing shows a stress level decrease of about a factor of two for the same fatigue life.

These tests suggest that composites of various types can have tensile fatigue properties superior to the metal light alloy. Kevlar-epoxy, Graphite-epoxy, and S-glass epoxy, all perform better than the 2024-T3 aluminum alloy and are interesting bicycle materials. E-glass fiber-epoxy matrix composites are of lower cost but have a poorer performance compared to either the metal or the other composites.

From: Smith: "Principles of Materials Science & Engineering," McGraw Hill (1986)