Heel and tow effect reversed
Heel and tow effect reversed
(OP)
Hi,
Head scratching question here.
If you bolt two plates, one over the other, with two rows of fasteners like this : (note that the two plus sign over one another means the lengths of the bolt linking one plate over the other...hope it's clear)
+++++++++++++++++
+ +
+ + v (1)
++++++++++++++++++++++++
^ (2)
If you try to peel off the plate (1), you will have a heel and toe effect, meaning that it's possible that the right fastener would be in tehnsion and the left fastener would be "in compression" meaning the bolt won't see any loads.
Here's my question. If we inverse the load (2)is it possible to have another king of heel and tow effect meaning that the right fastener would be "in compression" meaning it wont see any loads and the left fasteners would see tension. Is it something possible or the two fasteners will always be in tension?
Head scratching question here.
If you bolt two plates, one over the other, with two rows of fasteners like this : (note that the two plus sign over one another means the lengths of the bolt linking one plate over the other...hope it's clear)
+++++++++++++++++
+ +
+ + v (1)
++++++++++++++++++++++++
^ (2)
If you try to peel off the plate (1), you will have a heel and toe effect, meaning that it's possible that the right fastener would be in tehnsion and the left fastener would be "in compression" meaning the bolt won't see any loads.
Here's my question. If we inverse the load (2)is it possible to have another king of heel and tow effect meaning that the right fastener would be "in compression" meaning it wont see any loads and the left fasteners would see tension. Is it something possible or the two fasteners will always be in tension?





RE: Heel and tow effect reversed
now imagine you're loading the lower plate by piulling down; the left edge of the lower plate digs into the upper plate, and separates on the right side ... the opposite loads as above.
RE: Heel and tow effect reversed
RE: Heel and tow effect reversed
assume both plates are similar thickness. then, consider applying a load up on the left side of the upper plate, and the reaction is on the right side of the lower plate. then there is a plane of symmetry (between the bolts) so this is going to act like a fully fixed reaction. thus i think you'll have tension in left bolt, and no contact at the edge of the lower plate.
heel and toe ideally sets up when you have an angle fixed to a more substantial substrate with a single line of fasteners and a tension load, and is just a simple static solution to the situation where the load is offset from the reaction; the "toe" reaction provided moment equilibrium.
this example (with two bolts, presumably preloaded) is a more complex real world example. a lot of the external energy is taken up in splitting the clamped faces; again a simlification is to assume a gapped joint.
but returning to your question, if you apply a "compression" (down) load and lets assume a simple reaction (ie not think about the clamping forces) I'd say that the bolt reactions could be simply the opposite of the tension case ... the two bolts react the directly applied force (presumably equally) and they react the external moment as a couple. in this case you don't need a "toe" reaction for equilibrium; one could possibly develop depending on the stiffness of the plates and the plasticity of the plates.
any clearer ??
RE: Heel and tow effect reversed
corus
RE: Heel and tow effect reversed
But typically, if both plates are of reasonable stiffness, the right-hand bolt will be subjected to a small or negligible amount of applied tension, because the pivot will typically occur anywhere from, say, the right-hand bolt to near the right-hand edge of the upper plate. (In rigid-body mechanics, the pivot occurs at the right-hand edge of the upper plate).
RE: Heel and tow effect reversed
However, it is stiffness dependent, being affected by the plate edge overhangs, the plate bending stiffness, the fastener stiffness and the amount of preload, etc. You could easily design a system which had both bolts in tension (thick, stiff plates with a big overhang) or just one in tension.
NB: if the bolts are preloaded, then the problem is non-linear even with no yielding.