Dear all,
I have a very basic problem regarding how abaqus calculate reaction forces, nodal forces and contact forces at nodes with displacement boundary conditions. I am analysing a vertical anchor plate buried in sand. The anchor is given a 0.01 displacement. Reaction forces I get after geostatic step and load step are as below. But reaction forces of corner nodes are lower than middle nodes. I wonder why? Geostatic stresses in soil are correct. Also during the analysis the direction of RF1 in left edge which separate from soil contact change directions. I am expecting a triangular RF and contact force distribution as theory suggests. Which force is best for representing soil force exerted on anchor RF or CNF?
Can anyone help me. Thanks in advance
Dear Hansini Mallikarachchi, the possible reason of your result "reaction forces of corner nodes are lower than middle nodes" is a bending of anchor plate. The resistance to sand penetration is a great enough, thus the bending factor plays the sinificant role. You may try to mignify the bending stiffness of plate, for example, by means of multiple increasing of Young modulus of material, and compare results obtained. Good luck !
Triangular distribution should appear along the vertical line passing through the center of the plate. As you go away from the center toward the edges/corners you may observe deviations because the plane strain conditions at the centerline (vertical) would be no longer the case. Try much wider plate and observe variations along several vertical axis starting from centerline towards the edges. Stiffness of the plate may also play a major role.
Dear sir,
I increased the stiffness of anchor by 1000,but it did not make any difference. I can not increase much since it causes convergence problems. when I make the anchor rigid, I dont get RF1 individually at each node, but I can get total RF1 at the reference point.. I can try a larger plate, but I am not interested in stresses in anchor. I need only the total load on pipe exerted by soil. In that case isnt CNORF more appropriate?
Dear sir,
I increased the stiffness of anchor by 1000,but it did not make any difference. I can not increase much since it causes convergence problems. when I make the anchor rigid, I dont get RF1 individually at each node, but I can get total RF1 at the reference point.. I can try a larger plate, but I am not interested in stresses in anchor. I need only the total load on pipe exerted by soil. In that case isnt CNORF more appropriate?
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