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I am currently working with ADAMS on our suspension geometry kinematics and am having some problems with my static roll center numbers corelating with my numbers from Mitchell and a SolidWorks program we created. I've looked through tons of threads at www.adams.com (http://www.adams.com) and haven't found much to help me. If you have experience with ADAMS and with the FSAE Tutorials, i'd greatly appreciate any help you could provide. Thanks in advance. jmandre@clemson.edu
I am currently working with ADAMS on our suspension geometry kinematics and am having some problems with my static roll center numbers corelating with my numbers from Mitchell and a SolidWorks program we created. I've looked through tons of threads at www.adams.com (http://www.adams.com) and haven't found much to help me. If you have experience with ADAMS and with the FSAE Tutorials, i'd greatly appreciate any help you could provide. Thanks in advance. jmandre@clemson.edu
Those "FSAE Tutorials" were meant to be the FSAE templates.
Mi_Ko
11-22-2003, 03:28 PM
Where have you found FSAE Templates??? I'm trying to build my own, but it's a lot to work, so I would be glad to have a template.
2002/03 University of MARIBOR - Team Member
Mi_Ko
11-22-2003, 03:35 PM
O.k. I found them
For everyone else:
ADAMS FSAE TEMPLATES (http://university.adams.com/student_competitions/templates/templates_main.htm)
Could be usefull!!! Thanks http://fsae.com/groupee_common/emoticons/icon_smile.gif
2002/03 University of MARIBOR - Team Member
dancin stu
11-23-2003, 11:31 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Andy:
I am currently working with ADAMS on our suspension geometry kinematics and am having some problems with my static roll center numbers corelating with my numbers from Mitchell and a SolidWorks program we created. I've looked through tons of threads at http://www.adams.com and haven't found much to help me. If you have experience with ADAMS and with the FSAE Tutorials, i'd greatly appreciate any help you could provide. Thanks in advance. jmandre@clemson.edu)<HR></BLOCKQUOTE>
know what you mean, its a very steep learning curve! one were currently at the bottom of.
the conclusions we have come to is that beacause of the sheer number of variables, tyre stiffness, cg location, brake force, drive force etc, that ADAMS uses to determine points of the geometry, if you havnt got all of them the results will be different.
also, the mitchell software doesnt roll the car around the roll center, instead it rolls it round the ground,and it might not take into account tire stifnesses etc, ahve you included these in your solid works model??
i would however stick with it, it is very powerful, but our problem is that there are only two of us using it, and the uni's only real experience with it is with road car modelling.
the main problem i see with it is that it doesnt have parametric input, and as such if you draw out your desired geometry in CAD or paper, assuming principles, it very rarley correlates because of the sheer number of assumptions that paper drawings take, anti dive being our main bugbear at the minute.
RichE
11-24-2003, 12:38 AM
I have been using ADAMS for some time. I would make sure that when you run a supension analysis that you have input the correct tyres on your testrig, you will need rolling radius and tyre stiffnes. The next thing is to make sure that you do not have any bump/roll steer as this can completely change your results for the roll centre location when using ADAMS.
Rich
Cardiff Uni
FS Team Manager
RichE,
Just out of curiousity, do your RC heights come out as negative numbers when you plot RC vs Wheel Travel? With our geometry there is no way they could be below ground and I was wondering if ADAMS might use a negative sign convention for RC about ground. Thanks in advance!
RichE
11-25-2003, 02:28 AM
No above ground is posative as you would expect, make sure that you have the correct tyre sizes and not too much tyre deformation as this can completely mess up the results.
Rich
Cardiff Uni
FS Team Manager
Schumi_Jr
11-25-2003, 07:12 PM
If you search the ADAMS/Car documentation for "roll center" there is a section that explains how it's location is calculated (uses force vector intersections instead of the instant center method). I've spoken with some people at MSC Software and ADAMS users at my work, and apparently the method ADAMS uses has been proven to correlate better. Of course, as with any computer analysis: garbage in, garbage out...
Make sure to select ISO (tilting tables) coordinate system when looking at your roll center movement in roll.
Aaron Johnston
University of Waterloo FSAE
www.eng.uwaterloo.ca/~fsae (http://www.eng.uwaterloo.ca/~fsae)
Schumi_Jr
11-25-2003, 07:15 PM
One more, thing... go to ask.adams.com webboard for ADAMS questions. You can get help from MSC employees as well as people in industry
Aaron Johnston
University of Waterloo FSAE
www.eng.uwaterloo.ca/~fsae (http://www.eng.uwaterloo.ca/~fsae)
RichE,
Do you know if the ADAMS templates work fine with a pull-rod suspension? I've tried about everything I can think of to get my RCs right and they're still not there. I saw on the ADAMS sight that it said the templates contained a pushrod template, so I didn't know if something needed to be changed when modeling around a pullrod system. I figure it was fine for both pullrod and pushrod, but I figured i'd ask just in case it's what is causing my troubles. Thanks in advance. jmandre@clemson.edu
The templates have switch parts that connect the p_rod to both the top and bottom wishbones. You can toggle it to be push or pullrod.
The best way to understand the model is using graphical topology in the database navigator.
Ben
University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)
Ben,
How do you toggle between the pullrod and pushrods? I simply just changed my hardpoints according to the ones in my model. Shouldn't this work?
Also, when I was looking at the topology of the model in ADAMS, it has lots of connections to the ground? Such as lca to ground via lca inner- Revolute and tierod inner to ground via swl_fixed 3- Fixed joint. There are several different ones and I was wondering if these should be there? One last question, several of the joint types in the model topology say field. I did not find anything about this field reference in the guides and was wondering if you knew what this refered to. Thank you very much for all of your help.
Admittedly I did have some problems with the switch parts, I couldn't get them to consistantly work. I believe you have to do it before creating the sub assembly, i.e. in template mode. In the end I modified the template to firmly fix the position and deleted the switch part.
In terms of ground. The hardpoints are located on the ground then they are attached to the test rig or chassis depending on the setup of the communicators.
What sort of tech support do you guys have? The forums are good, we also have full access to MSC UK tech support via an exclusive sponsorship deal. The forums usually suffice though.
Ben
University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)
Ben,
Thanks again for the advice and help. Unfortunately we do not have a lot of tech support. I have spent many hours on the forums and have some helpful information, but nothing to get my RC numbers to where they should be. Also, no one at the University knows how to use the program very well, so that doesn't make it any easier. If I had someone that knew how to use it very well sit down with me I have a feeling it could all be worked out quickly, but unfortunately I don't have that kind of resource at the moment. I'll look into MSC Tech support and see what I can get out of that. Thanks again!
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