I am having trouble applying pressure as a function of displacement and direction. I have a piston that moves down with variable pressure curve (pressure vs. piston displacement) and when the piston moves up it has a different pressure curve. Can LS-DYNA only apply load as a function of time?
I have explored *DEFINE_CURVE_FUNCTION and have had some minimal success with the IF function, but it still only evaluates the curves pointed at in the IF function as a function of time.
I have also explored *LOAD_SEGMENT_SET_ANGLE but I don't have a crankshaft that rotates with this piston and I don't want to attach joints to the piston and cause an overconstrained solution.
I have also explored *LOAD_MOTION_NODE but I am reluctant to convert pressure loads to nodal concentrated forces.
Thanks for any assistance.
S