Stress-Life Fatigue Testing Basics

ADMET CEO and Chief Engineer Richard Gedney's article on fatigue testing applications was published on the Quality Magazine August 2017 issue. 

The article starts with brief descriptions of the four stages of metal fatigue:

Stage 1: Crack Initiation

Stage 2: : Slip Band or Stage 1 Crack Growth

Stage 3: Stage II Crack Growth

Stage 4: Ductile Failure 

Cycle testing carried out under stress based constant amplitude loading is then discussed. Readers are then introduced to waveform properties, stress-life testing, and Wohler's laws based on the findings of August Wohler, a German railway engineer who was the first to run systematic fatigue tests between 1852 and 1870,. 

To read further about Wohler's laws, the S-N or the Wohler diagram, and fatigue testing applications, click here.

Fatigue tests described in the article can be perfomed using the following equipment: https://www.admet.com/products/fatigue-testing-machines/