Structural Engineering & Statics
where the load goes
Generator

The stress-strain generator

Rendered here at the parameters it defaults to, with every essay that calls it — which is the same list as the blast radius of changing it.
Three materials pulled until they stopThree stress-strain curves — mild steel, high-strength steel, aluminium alloy — plotted to a strain of 2.0%. One of them has a plateau, so the stress at which yielding starts is something the specimen does rather than something anyone chooses. The 0.2% offset construction is drawn on the high-strength steel: a line of slope E from a strain of 0.002, cutting the curve at 460 N/mm².00.5%1%2%2%0100200300400500600strainstress, N/mm²the 0.2% proof stress: 460 N/mm²mild steelhigh-strength steelaluminium

3 essays call stress-strain. The drawing above is what it returns with no arguments at all; every call below passes it something, because a placement that passes nothing draws whichever member of the family the generator happens to default to rather than the one its essay argues about.

Where it is called

Changing this generator changes every one of these figures.

00.5%1%2%2%0100200300400500600strainstress, N/mm²the 0.2% proof stress: 460 N/mm²mild steelhigh-strength steelaluminium Materials

The stress at which nothing in particular happens

One material in six has a yield point that a specimen actually does something at. For all the others the yield stress is a construction — a line drawn at an arbitrary offset — and every calculation on this site depends on it.

 00.1%0.2%0.3%0.4%0.5%0.6%050100150200250300350strainstress, N/mm²mild steelaluminiumconcretetimber Materials

The one number a stronger steel does not change

Geometry beats material almost everywhere on this site. Stiffness is the exception in the other direction — it cannot be bought at all, because every steel ever made has the same elastic modulus.

 00.5%1%2%2%050100150200250300350strainstress, N/mm²mild steelcast iron Materials

The property that appears in none of the equations

Ductility is in no design formula on this site. Every method on this site depends on it — and a brittle structure does not merely fail early, it makes the analysis wrong.

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