Learn / Contact Mechanics
Contact Mechanics
Contact, friction, wear,
and the numbers we
pull from them.
How surfaces touch, how they slide and wear, and what an indent or a scratch really measures.
Start here
New to Contact? Read these first.
StoryThe Mountain Range You Cannot See
A scrolling illustrated story about tribology: zoom into a contact until the real touching area appears, follow one…
GuideAsperities & the Real Area of ContactInteractive contact mechanics: single-asperity Hertz geometries, elastic to fully plastic transition,…
GuideHow a Hardness Number Gets MadeWhere hardness and modulus actually come from: fit the unloading curve yourself, watch S, hc and the contact area move,…
All topics
Surfaces & contact1 page
Wear2 pages
GuideHow to Measure WearWhat wear rate, specific wear rate and the wear coefficient K each mean, how Archard's equation links them,…Foundation · 10 minToolWear Rate CalculatorTurn what you measured into every wear rate at once: a profile area, a mass loss, a ball scar diameter or a…Foundation · 7 min
Indentation5 pages
GuideHow a Hardness Number Gets MadeWhere hardness and modulus actually come from: fit the unloading curve yourself, watch S, hc and the contact…Foundation · 12 minGuideWhen Your Hardness Number LiesIndentation size effect or a blunt tip? Pile-up wrecking the contact area? Substrate showing through a thin…Advanced · 12 minGuideWhat Indentation Tells You Beyond HardnessSpherical indentation stress–strain curves and the effective zero point, pop-in statistics against the…Advanced · 12 minGuideHow to Decide a Loading ModeEight indentation loading schedules side by side: what each one looks like in load–time, what curve it gives…Advanced · 10 minGuideWhen Does Oliver-Pharr Fail?Ten ways an Oliver-Pharr hardness goes wrong, run on one synthetic indent where the true answer is known: the…Advanced · 12 min
Scratch & adhesion2 pages
GuideWhat a Scratch Test's Critical Loads MeanLc1, Lc2 and Lc3 from a progressive-load scratch test, built from the contact mechanics up: Hertzian and…Foundation · 10 minGuideScratch vs. Indentation HardnessScratch hardness from the groove width, why four defensible width conventions give four different answers,…Advanced · 10 min
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Other chapters: TEM · EBSD · APT · Structure & Transformations · In-situ Testing.