Hello, For my rear suspension, I have a pure trailing arm setup. I used the semi-trailing arm template and modified it by deleting the toe link and making the trailing bushings parallel to each other, according to the geometry, the roll center height should be zero should lie on the ground plane but according to the simulation during roll analysis, the roll center height is going up to -45 mm and the lateral displacement is to -12500mm. Best, Premkumar
Hi @premkumar_07,
It looks like you are plotting the results with respect to multiple KnC events. If you enable only the Ride Analysis, do you still see considerable vertical movement of your roll center?
Are you creating these plots manually or are you extracting them from a Standard Report?
Do you have any compliance in your model, such as bushings?
Are you able to attach your model?
It should also be mentioned that the Roll Center is calculated by the following definition:
"The suspension roll center is found by intersecting the line connecting the left tire patch and the left tire patch front view instant center with the line connecting the right tire patch and the right tire patch front view instant center. The roll center height is defined as the difference between the roll center z coordinate and the average tire patch z coordinate."
https://help.altair.com/hwdesktop/hwx/topics/motionview/sdf_roll_rate_tramp_rate_and_roll_center_location_r.htm?zoom_highlight=roll+center
Hope this helps!
Adam Reid
Hello @GTT Adam I tried with only the roll analysis in the simulation modes; however, the results remain the same. But for the ride analysis, the results are as expected. I have attached the plots for both. All my joints are compliant, and I am extracting the plots from the standard report. And is there any way the results can be populated after every iteration? Now I have to reload them every time to get the results. I have attached the model file with the name 'Rear_V10'.
Roll Analysis-
Ride Analysis-
In any HyperMesh Desktop application, you can save the current session as a Flexible Report using File » Session » Save As » Report Template.
Using this report, you can then reuse any plots/animations and specify different files as an input:
Regarding your model, I see that if compliance is removed from the suspension does some strange things. I think it is due to the inclination laterally in the struts:
Are they meant to be purely vertical?
Hello @GTT Adam, Thanks for the prompt reply. I will look at the flex report. Regarding the model, if I make the strut purely vertical, will that solve my issue?
Hello, I simulated without compliance and moved the strut upper joint inwards to make it vertical, and in the second iteration, kept it in its original position. As a result, the roll center height migration has been resolved, but the lateral displacement remains unchanged in both cases.
There should be lateral displacement of the roll center shown based on how the roll center is calculated and how your rear suspension is parallel to the ground.
The instantaneous roll center (IRC) is calculated based on the location of the contact patch as it moves through the roll event. If you trace the location of nodes on the bottom of the tire, you can determine that the lateral location of those nodes do fluctuate (ever so slightly) during the simulation:
The actual travel is very small, which means the radius of that arc will be quite large.
