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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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bar simulation

Posted 2012年10月9日 GMT-4 22:26 Version 4.3 2 Replies

Erdinc Yenigul
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i have a bar that is applied a force from both side. bar has a hole in the middle of of it and at a certain point bar is fillet to a smaller area. i draft the solid model with solid works and saved it as sldt file and import it to the comsol. but when i try to simulate for stress analysis for fillet and hole...
a. bar gets deformation in the direction of where there is no external forces
b. comsol simulation gives 20% error compare to hand calculation from hibbeler mechanic of materials.
any idea what i am doing wrong, or is there any similar simulation i can compare mine . thank you .

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2 Replies Last Post 2012年10月10日 GMT-4 13:10
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2012年10月10日 GMT-4 01:20
Hi

it could be the effect of nu the Poisson coefficient that links transverse to linear stress (it's a true phenomena, and often simplified/ignored in hand calculations).

Try setting nu = 0 and see. You ca observe it in flexure, of a regular bar, the stress changes along the top/bottom height region, as there is no more material that symmetries the transverse stress build-up

--
Good luck
Ivar
Hi it could be the effect of nu the Poisson coefficient that links transverse to linear stress (it's a true phenomena, and often simplified/ignored in hand calculations). Try setting nu = 0 and see. You ca observe it in flexure, of a regular bar, the stress changes along the top/bottom height region, as there is no more material that symmetries the transverse stress build-up -- Good luck Ivar
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago 2012年10月10日 GMT-4 13:10
There is deformation perpendicular to the force direction is most likely due to Poisson's effect as Ivar noted. Regarding the difference between simulation and hand calculations, I suggest two things: (i) double check that you are using the appropriate formulae, and (ii) refine the COMSOL mesh to see if the results change. Also the distance between the fillets and the hole may not be big enough to totally isolate the stress concentrations resulting from these two features.

Nagi Elabbasi
Veryst Engineering
There is deformation perpendicular to the force direction is most likely due to Poisson's effect as Ivar noted. Regarding the difference between simulation and hand calculations, I suggest two things: (i) double check that you are using the appropriate formulae, and (ii) refine the COMSOL mesh to see if the results change. Also the distance between the fillets and the hole may not be big enough to totally isolate the stress concentrations resulting from these two features. Nagi Elabbasi Veryst Engineering

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