Learning Forum

[VishalAstekar]

Can anyone tell what is the amount of deflection that should be considered as large, in order to decide whether the option of Large Deflection should be switched on?nThanks in advancen

[Erik Kostson]

So ideally we should always use large deflections - linear static (no large deflections) is in theory only valid for infinitesimal displacements, so always best to run it with large deflections.n(There are some rule of thumbs , say for a simple beam or plate bending - we can say that roughly if out of plane displacements are larger than about a quarter of the plate thickness then we can/are starting seeing nonlinear geometric effects - also if bodies have rigid body motion/rotation, then we need large deflections also, since otherwise we might see some stresses which should not be there during such a motion).Erik

[VishalAstekar]

Thanks for the reply.. But if we always keep the large deflection on, it usually increases the solver time.. n

[peteroznewman]

Yes, that's why you have the option to turn it off if it is unnecessary.n

[VishalAstekar]

Is there any standard or deciding factor which mentions what should be considered as large deflection? n

[peteroznewman]

nYes, said what that is in his reply, 1/4 of the plate thickness.n

[VishalAstekar]

but this you will know only after running the analysis? n

[peteroznewman]

Not unless you are applying a displacement load, or have a hand calculation for a force load to estimate the deformation.n

[VishalAstekar]

Thanks Thanksn