Because practicality. Strain generally occurs across mm scales at most for most traditional tensile tests and relevant materials. Normally it’s actually much less than mm. Occasionally you see micrometers/micrometers.
Comment on Stress
azi@mander.xyz 8 months agomm/mm?? why not call it m/m?
Umbrias@beehaw.org 8 months ago
azi@mander.xyz 8 months ago
How is it more practical when 1 m/m = 1 mm/mm = 1 μm/μm?
Umbrias@beehaw.org 8 months ago
Because excel doesn’t have built in unit handling so when you enter in readings from the strain gauge you’ll probably enter them in what’s being reported.
You can write the units of strain however you like, I often say ul for unitless.
nooneescapesthelaw@mander.xyz 8 months ago
The original specimens and data are usually in mm, not meters so mm/mm makes more sense than m/m, although you do have a point
bleistift2@feddit.de 8 months ago
Why km/h (or mph) and not ft/year? Because the numbers have a nicer magnitude then.
nooneescapesthelaw@mander.xyz 8 months ago
Doesn’t apply here, say for example i have a piece of steel with length 100mm and it stretches 10mm, is mm/mm the strain would be 0.1 mm/mm, in meters it would be 0.1m/m
Really strain is dimensionless but occasionally people add units
bleistift2@feddit.de 8 months ago
I feel like I should’ve spotted that… they’re the same units. 🤦
captainlezbian@lemmy.world 8 months ago
Because we’re precise!