Is "polish and coat with a hard brittle varnish" the answer to this question?
I've made a "square-cornered U" of RHS100x50by8thk (4"x2"by5/16"thk.).
45degree mitres full-pen'd for the two corners. About 150mm (6") between the parallel Rectangular Hollow Sections (RHS) heading towards the open end of the "U". Lying flat, presents the 100mm (4") faces of the RHS (obviously(?!)). It's about 490mm long (about 19") overall.This was for practicing various skills and getting used to the facilities & equipment - plus the following intention...
I'd like to put a hydraulic cylinder / hydraulic jack toward the open end of the parallel sections forming the "U", and see what happens when it's increasingly loaded.
Precautionary note - one assumes it would be a good idea to lash the hydraulic cylinder with rope to constrain it if it were elastically ejected from its original position...
If things go well and forces pass those necessary to cause yielding - how would one reveal where that plastic yielding is happening? I've heard of polish surfaces smooth and apply a hard brittle lacquer... If so, exactly what type? Economical preferred - this is very rough-and-ready and my own interest. Nail varnish sounds alright - but might not be the cheapest.
I've finite-element'ed the thing and get a prediction of about 8 tonnes force near the outer "open" end to reach general yielding. More accurately - at 250mm from the closed end, the thing should caliper as having grown by 3.9mm across the overall width at the moment at which it starts to yield.