Some macroscopic observations of reverse torsional fatigue

Abstract

This article reports the study of torsional fatigue reverse, R =- 1, and the failure modes and crack
propagation for Steel SAE 1020 hot-drawn, Aluminum and Cast Iron Gray6063, in the literature is that the
patterns of failure always are combinations of modes I, Mode II and Mode III. In this document is given the
curve of fatigue specimens in the shape of an hourglass. It also investigates the patterns of failure from the
beginning of macroscopic crack untilthe final rupture of the specimen. Noting that in most cases the crack starts
in Mode II, with further branch to the Mode I to failure at high cycles, and branch to the Mode III for medium
and low cycle.