Hello All,

I am trying to simulate an impact problem (Simply supported steel beam impacted by a steel ball) using conventional shell element, in Abaqus explicit (Pic-4). Defined general contact with pressure - overclosure as “Hard” and “default” constraint enforcement method. The contact force (CFT3) obtained at the ball surface, is much more higher than the actual value (Which is also solved by FEM). Dimension of the beam is 16 cm x 1cm x1 cm, and ball diameter is 2 cm. I have tried to define the ball in different way, like discrete rigid, solid etc. However, contact force almost 7 times ,35 N (Pic-1) higher than the expected value, i.e. 5 N (Pic-2), In my case i am getting multiple impact as against the single impact in (pic-2). 

There is one warning mesg-

“In step 1, some contact thicknesses used in general contact were reduced from the parent element or specified values due to a large thickness compared to element dimensions. The most significant thickness scaling factor was 0.13345 for an element attached to node 15 of instance BEAM-1. An element set named "WarnElemGContThickReduce" has been created to locate the regions of reduced thickness. To avoid this thickness reduction, exclude self-contact for these regions.”

If I exclude the surface pair (beam lower surface with ball), this warning message disappear, however, I get a more wired result (Pic-3).

I would be highly grateful, if anyone can provide any help.

Thanks

KB