Close linear contact using KEYOPT

Initial adjustment (close or open) for linear contacts. Sometimes there may be a need to close a linear contact that has initial gap (or open one that has initial penetration). This could be used to generate prestress with bolts in a situation where using bolt pretension is not possible or some similar preload case. Key to this is setting KEYOPT(9)=2 for the bonded (or no separation) contacts that have gap or penetration initially. With KEYOPT(9)=2 initial penetration or gap is closed or pulled open instead of the default option that ignores initial penetration or gap. Simply set contact behavior->asymmetric, add a commands object under the contact that needs to close and add a command:

KEYOPT,cid,9,2

KEYOPT command sets keyoptions for element type, cid points to element type number of current contact element. 9 selects which keyoption we are setting and 2 is the value we want for this application. Check the KEYOPT command help and element type documentation for details on keyoptions.