The Behavior of Isotropic Pyrolytic Carbons under Cyclic Loading

Abstract

Measurements of the endurance limit of pure and siliconalloyed, isotropic, pyrolytic carbons and a glassy carbon show that, for all the materials, the endurance limit is equal to the single-cycle fracture stress. The endurance limit of a glassy carbon is 25 ksi. The endurance limit of the unalloyed pyrolytic carbons increases with density from about 38 ksi for p = 1.46 g/cm³ to about 50 ksi for p = 1.97 g/cm³. Silicon additions increase the endurance limit to about 80 ksi for 23 wt% silicon, the highest silicon concentration investigated.