Texas Parasol Plans...

Cla

Bearing properties are used when designing mechanically fastened joints.
The purpose of a bearing test is to determine the the deformation of a
hole as a function of the applied bearing stress. The test specimen is
basically a piece of sheet or plate with a carefully prepared hole some
standard distance from the edge. Edge-to-hole diameter ratios of 1.5 and
2.0 are common. A hardened pin is inserted through the hole and an AXIAL
load applied to the specimen and the pin. The bearing stress is computed
by dividing the load applied to the pin, which bears against the edge of
the hole, by the bearing area (the product of the pin diameter and the
sheet or plate thickness).

Different axis and on edge rather than in tension or compression. The
flat surface described by the hole in the part as it passes through the
thickness of the tube or plate of the hole. The stress is spread through
the material differently.

Curtis S.

And I am not an engineer either, I make rocket motors, and need this
information constantly.



clare at snyder.on.ca wrote:
On Mon, 27 Feb 2006 15:14:24 -0500, Curtis Scholl
wrote:


Cla

Looking at the calculations for the spar, spar.pdf I do not see your
interpretation. The 67000 psi value is Bearing Ultimate, not tensile.

A MATWEB lookup is in order:

6061-T6

Tensile ultimate: 45000
Tensile yield : 39000

Bearing ultimate: 88000
Bearing Yield : 56000

The values presented in the spar calculation are correct, and the
bearing ultimate of 67000 is below spec.



Thjat may well be true, but is "bearing strength" the proper
charachteristic of the material to be used in this calculation?

As I said - not an engineer - just asking.
Please explain for the rest of us how the bearing ultimate and / or
yeild values impact the calculation, vs tensile.
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