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Shear out in acrylic

Shear out in acrylic

Shear out in acrylic

(OP)
Hi all,
I am designing a small experiment where I have a pinned joint near the edge of a sheet of PMMA.

I considered the formula e=F/(2*S*t), where e is the minimum distance from the centre of the hole to the edge of the plate, F the applied load, S the shear strength, and t the thickness of the sheet.

I am concerned that this analysis may not be sufficient to prevent shear-out during the loading. Does anyone have experience with this type of loading in soft materials?

Kind regards,
Melle

RE: Shear out in acrylic

Plastics are terrible in that type of loading and will either creep or stress-crack if the load is continuous.

RE: Shear out in acrylic

(OP)
I like the idea of the bushing, am I correct in thinking that the compression of both sides of the bushing help distribute the load, and thus reduce the local shearing stress on the plastic?

RE: Shear out in acrylic

These are actually adhesive mount. The system uses an acrylic adhesive and the red rubber plug thing squeezes the bushing together while the adhesive cures. It is discarded later.

RE: Shear out in acrylic

The bushing will alleviate the point contact at the bottom of the hole. That's limit creep a little, but it'll still happen to some degree if the loads are high. The bushing will also distribute the same load over a larger area which again will help. But don't expect miracles.

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