mmccall Posted May 22, 2005 Share Posted May 22, 2005 (edited) Algor.. Surface Contact.. and Free Surface The 2 photos show an example of the difference between Surface and Free surface contact What we have is a simple assembly with a load on the end (from left to right: base plate, middle plate, upper and lower pins, and end plate) We are only concerned with the load carrying ability of the pins.. the shear across the pins.. so this is not a bolted joint and assuming no friction between the plates.. The constraints are applied so that only vertical movement is allowed in all the plates.. the base is fixed in all axis In the 8020 test 2 we took an easy setup and simply applied a surface to surface contact condition across all the components.. At first glace it would seem that this type of setup would be just fine for this case.. we dont want any of the components to pass through each other.. and we dont want any friction between the plates, so we force the pins to carry the load but notice that you have a high stress concentration at the corner of the middle plate and the top edge of the end plate this is where the 2 nodes try to slide past each other.. What Does Surface-to-Surface Contact Do? By default, in order for loads to be transferred between nodes, the nodes must be matched at the beginning of the analysis. For example, if two bodies begin an analysis separated, no interaction will occur during the analysis; the bodies will pass through each other. Surface-to-surface contact allows you to create pairs of surfaces that may come into contact with each other during the analysis. The processor will determine the distance between the nodes on these surface at each time step of the analysis. When the nodes are sufficiently close to each other, a stiffness will be applied to prevent penetration. Now lets look at the 8020 test case here we actually applied a free no-contact condition between the end plate and the middle plate, but left the surface contact condition between the pins and the end plate.. This condition still has no friction and with our boundary condition applied such that the plate can only move in the vertical direction, we see that we are now loading only the pins the max stresses have moved to a more logical location in the assembly Edited May 22, 2005 by mmccall Quote Link to comment Share on other sites More sharing options...
mmccall Posted May 22, 2005 Author Share Posted May 22, 2005 UUUhhh... cant seem to get the pics loaded.. Quote Link to comment Share on other sites More sharing options...
mmccall Posted May 22, 2005 Author Share Posted May 22, 2005 8020_test_2.zip Quote Link to comment Share on other sites More sharing options...
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