Learning Forum

[fiatlux]

Hello I have to use non-linear spring elements in a linear guide system instead of rollers in Ansys-static structural, but for this I have to use joint bushing with a tabular-data, so that I can enter the values for the displacements-forces for stiffness. The problem is, I couldn't find it or apply it, so I dont know, how to do that, can anyone help?

[peteroznewman]

The manufacturer of the linear slide provides the 2 translational and 3 rotational stiffness values for the carriage on the rail.
You can replace the entire carriage with one node and the rail with another coincident node and put a COMBI250 element between them. Then put the 5 values of stiffness into the Real Constants for this elements. Use a value of 0 for the translational stiffness along the rail.
Under ANSYS Help, go to the Mechanical APDL section and then to the Element Reference to find more information.
The above describes a linear model of the carriage that is very useful for system models where the carriage is a small component of a large system and the important features are the freedom to slide along the rail and stiffness values in the other five DOF.
You said you have to use a nonlinear spring. Why is that? Where did this nonlinear data come from? What does it look like? Since you said you have force-displacement data, then you would use a COMBIN39 element and load the force-displacement data into that element. However, that only provides 1 DOF so you will have to use several of those springs to provide the 5 DOF to support the carriage on the rail. Do you have rotational force-angle data?

[fiatlux]

Thank you to answer my question I have from zero, a total of 10 positive and 10 negative forces and corresponding displacements. These values are experimental. For example: 50000 N Load corresponds to -3.e-004 displacement.
Yes, I have to use non-linear spring elements for each COMBINE 39 roller. I will compare the strain values of spring elements with rollers. Also, yes, I will use a spring for each roller and apply tensile / compressive forces, side load on the carriage and also three moments on it.
What I know is to use for this Joint Bushing but i dont know how. What I will is to enter the values of Displacements/Loads on Tabular. Do you have any idea or i have to calculate the stiffness for each spring?