I'd like to use GAP with preload for pretension analysis on the spring area. 1D bar or beam would not be appropriate for this analysis, because interested area is near spring in the suspension. It seems that PRETENS, PTFORCE keywords are not working with GAP preload. Could you please let me know how to use GAP preload? If tutorial is available, it would be very helpful to understand how to use GAP preload. I'm trying to run FRF with preload, which is working in the suspension spring of the automotive.