CBUSH spring benchmark

Dear all,

before inserting the CBUSH spring into my model I decided to do a simple benchmark which in the end turned out unlogical (for me).

My benchmark model consists of CBUSH element - one end is fixed (1-6 DOF) while the other is loaded with a force of magnitude = 1 (axially in tension), 1D. I am using a PBUSH property with stiffness K = 1 (for axial direction, other K's are defined as RIGID).

The results yield a displacement of 10E-4 and not 1, as I expected. I am assuming Force = Stiffness x Displacement.

What did I miss here?

Thank you all for your time and help!