Plane stress or plane strain for Railway Ballast system ?
I am working on a wooden rail sleeper analysis.
Using the Druker Prager model for Ballast and soils, Initially, I assumed the 2D Behavior of RailSleeper and Rails was Plane Stress and for Ballast and soil were Plane stress but I received Huge deflections in the model as you can see in figure 1.
Later I assumed everything in Plane stress and received very small deflection as you can see n figure 2.
Which one is suitable plane stress for the entire model or plain strain for soils and ballast and plane stress for a sleeper?
Kindly give suggestions, thank you.