Reply To: Connecting beam elements to solid elements

[king79]

HI,

I have tried using *Constrained_Interpolation to model the connection of the beam element to the solid element but did not obtain realist results. Perhaps if I describe my FEM model, you may be able to assist me. I am evaluating the soil-structural interaction between an embeded concrete pile and the surrounding the soil medium. The concrete pile and surrounding soil medium have been modeled using soild elements. Both parts have been meshed such that thier nodes at the contact interface are merged. The top of the pile is flused with the top of the surround soil per the figure below. A beam element representing a cantilever superstructure is connected to the top of  concrete pile using *Constrained_Nodal_Rigid_Body. A lumped mass is attached to the cantilever end of the beam and a time varying force is also appiled at the cantilever end. The issue that I am attempting to resolve is that Ls Dyna seems to capture the relative lateral displacemen of  the cantilever end of the beam element but significantly underestimates the displacement of the pile head. I think this is a modeling issue because Ls Dyna does an excellent job estimating the displacment of the pile head when the load is directly placed on the pile head. However, in this case, a resultant force from the beam element is being transfered to the top of the pile. I have double checked the units, boundary conditions as well as material properties, but all to no avail. Is there a better way to model the connection of a beam element to solid element in Ls Dyna that ensures that the resultant force is transfered accurately? I appreciate any suggestions that you may offer. Thank you