Friction Spring, 1 Node

Introduction:
(If you want to skip this intro, click here) 

The Usfos 2 Node Non Linear Spring element is a beam element, which gets it's properties in the 6 degrees of freedom by the P_d curves referred to through the material reference MREF. All  6 degrees of freedom may have different properties, and refrerring to a P_D curve with ID=0, the actual degree of freedom gets no stiffenss. The properties defined for the non linear spring to ground are referred to the local beam coordinate system similar to what's the case for "ordinary" beams. 

The non linear spring has following properties, only one (bold) is  mandatroty, the rest are optional:

• Material (MREF, referring to P_D and M_theta curves)
• Local Coordinate System definition
• Eccentricities (offset)
• Dashpot Damping

Non linear Spring behaviour:

Properties of the spring are defined by discrete points as shown in the example below. (If pure linear behaviour is required, specify a straight P_d curve).

The curves are always defined from the very left side (3'rd qudrant) towards right (1'st quadrant) as indicated above. The curve may have any shape, and different behaviour in tension (1'st quadrant) and compression (3'rd quadrant) is possible. F ex: A simple contact spring is obtained by specifying ~Zero tension capacity and relatively high stiffenss in compression (too high stiffness might cause numerical problems!).  

Colum Supported on a Friction Spring to Ground

=> Usfos Control File
=> Structural File