sher locking

[saranam]

hai all
what is meant by shear locking and memberane locking ? how can we know this is happening in our problam..

 

[zuardy]

there are some discussions about this phenomenon in some threads directed by our expert : bradh.
One can formulate as following : Shear locking, or parasitic shear, is caused by an inaccuracy in the displacement field of a linear quadrilateral or hexahedral element (Elements without mid-side nodes). This linear element is unable to accurately model the displacements caused by curvature. A shear stress, which does not occur in the infinitesimal particle, is introduced into the element by this deformation state.
This extraneous shear “absorbs” strain energy and the element reaches equilibrium with smaller nodal
displacements. Consequently, the element does not predict the bending displacements accurately and will
have overly stiff behavior.
So, if you have modeled your structure with linear elements and find that the nodal displacements are smaller then they should be, e.g. from analytical solution (hand calculation) then your model may underlay that phenomenon : Shear locking!

regards