What is the Goodman relation in materials science?

The Goodman relation is an equation used in material failure theory to quantify how mean and alternating stresses interact to affect a material's fatigue life. It is typically represented as a linear curve plotting mean stress against alternating stress to determine maximum safe cycles before failure. This linear approach provides a conservative estimate compared to parabolic alternatives like the Gerber line, while cyclic loading itself initiates cracks as detailed in broader material fatigue studies.

What we know

• The Goodman relation is an equation used to quantify the interaction of mean and alternating stresses on the fatigue life of a material within material failure theory. [2]
• Fatigue involves the initiation and propagation of cracks in a material due to cyclic loading, which can eventually lead to complete fracture once a critical size is reached. [3]
• A scatterplot of experimental data can be approximated by a parabola known as the Gerber line, which can in turn be conservatively approximated by the Goodman line. [2]

Where to go next

• the bigger pictureWhat is material fatigue?
• compared withHow does the Gerber line compare to the Goodman line?
• a case in pointHow do polymer materials experience fracture and fatigue?
• how it workedWhat causes microscopic cracks to form under cyclic loading?
• the bigger pictureWhat is material failure theory?
• an unexpected connectionWhat links material fatigue to medical chronic fatigue syndrome?Although they study entirely different domains of stress and breakdown, both fields share the terminology of fatigue to describe system degradation over time.

Sources

• [1]Goodman relation (Wikidata Q17018341) · CC0 1.0
• [2]Goodman relation · CC BY-SA 4.0
• [3]Fatigue (material) · CC BY-SA 4.0
• [4]Fracture in polymers · CC BY-SA 4.0
• [5]Management of ME/CFS · CC BY-SA 4.0