Four poster Test Rig

KATARI LOKESH

Hello Experts,
I have a doubt regarding N-Post analysis.
what are the requirements to apply the actuation at Spindle and Wheels? and how do when to use each thing?

 

Thanks

Chris Coker_21312

Hi-

Your question is pretty broad, so I will make an attempt to answer it.

 

This analysis is meant to replicate a physical test.  The inputs, where tire or spindle coupled, typically come from test data.  So, if you have measured data from a tire coupled test, you should use a Tire coupled simulation, and apply the displacements to the actuators.  If you have data collected at the spindle, then that data would be used with a spindle coupled analysis.

Some general tips:

1.  If you are using a tire coupled analysis, you will almost always be using displacement data to drive the actuators.  As a result, you will not have any issues with drift in the data, and therefore you should not use any body constraints.

2. If you are using a spindle coupled analysis, and you have acceleration (or force) data that you want to use as inputs, I can guarantee you will almost always have some sort of drift, and you will need to utilize a body constraint.  If the physical test has the vehicle locked to ground, then you can use the joint option to fix the body.  If the vehicle body is free during the physical test (for example, you have wheel force transducer data that you want to use as inputs), then you will have to chose a bushing based constraint.  The number of DOF to constrain with a bushing, and the stiffness value to use is problem and data specific, so there is a bit of trial and error involved to initially set up the model.  The general idea, however, is to use the softest bushing possible, so you have minimal influence on the results.  The bushing constraints typically have little influence when the inputs are high frequency/low amplitude, but have a higher influence when the inputs are low frequency high amplitude.

 

Hope this helps.