Contact with springs to stabilise the model
I am trying to model three boxes stacked on top of each other sitting on the floor using NL static, with contact between each box and the floor.
I successfully modeled one box on the floor using a contact between the floor and lower edge of the box. I constrained the top surface using a symmetric cross allowing the bottom edge to splay out naturally when contacting the floor. The contact is type>Slide with 0.2 mm clearance. The floor is rigid and has a single point SPD fully fixed. The load is off centre on the top edge of the box.
I connected the lower edge of the box with HMSPRING elements to the floor with a very low stiffness trying to avoid CNTSTB and help the model solve. This worked well and the springs did not effect the results.
When I apply the same approach to three boxes stacked with CONT>TYPE>SLIDE, it solves. The first box on the floor has the Sym SPC applied at the top and the 2nd and 3rd box is 0.2 mm above each other and connected with 1D HMsprings. The idea is that the spring aid with the initial gap closure then the contact takes over.
When I create a contact property and add friction = 0.3 I get a MUMPS -90 error and the model does not converge.
Is there a better way to model this type of problem?
