how to calculate the loads on an A-Arm

[Julien Sirois]

Hi all,

I'm currently designing the new suspension for next year's car and I'm having trouble to figure out how to calculate the loads and forces on the A-Arms. I've read Racecar Vehicle Dynamics, To Win series, and I know how the suspension works, I can calculate the wheel loads etc, but I haven't read anything about how to properly calculate the loads on the lower and upper wishbone. Does anyone have a good book or a software that could help?

Thanks

Julien Sirois
FSAECVM

[Julien Sirois]

Hi all,

I'm currently designing the new suspension for next year's car and I'm having trouble to figure out how to calculate the loads and forces on the A-Arms. I've read Racecar Vehicle Dynamics, To Win series, and I know how the suspension works, I can calculate the wheel loads etc, but I haven't read anything about how to properly calculate the loads on the lower and upper wishbone. Does anyone have a good book or a software that could help?

Thanks

Julien Sirois
FSAECVM

[Rotary Sprocket]

All you need is your statics book. Since you know the wheels loads you can calculate the forces in the individual links. This can get pretty time consuming so once you get the equations down I would recommend creating a matlab code or excel spreadsheet so you can perform iterations without having to number crunch everytime.

[StevenWebb]

you have an upright with 4 forces,tyre, lower balljoint, upper balljoint and tie rod

the tyre can apply a force in all directions

the lower balljoint (or upper if pullrod) can apply a force in all directions

the upper wishbone (lower if pullrod) can only apply a force along the plane defined by the 3 upper wishbone points

the tie rod can only apply a force in the direction of the line defined by the 2 tie rod points.

then press ctrl+shift+apple+function+% and your computer should do the rest

[MegaDeath]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rotary Sprocket:
All you need is your statics book. Since you know the wheels loads you can calculate the forces in the individual links. This can get pretty time consuming so once you get the equations down I would recommend creating a matlab code or excel spreadsheet so you can perform iterations without having to number crunch everytime. </div></BLOCKQUOTE>

Or, just give it to the only honors student on your team and let her do it....Right??

[Ben K]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MegaDeath:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rotary Sprocket:
All you need is your statics book. Since you know the wheels loads you can calculate the forces in the individual links. This can get pretty time consuming so once you get the equations down I would recommend creating a matlab code or excel spreadsheet so you can perform iterations without having to number crunch everytime. </div></BLOCKQUOTE>

Or, just give it to the only honors student on your team and let her do it....Right?? </div></BLOCKQUOTE>

Kind of a good call.

Ben

[The AFX Master]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MegaDeath:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rotary Sprocket:
All you need is your statics book. Since you know the wheels loads you can calculate the forces in the individual links. This can get pretty time consuming so once you get the equations down I would recommend creating a matlab code or excel spreadsheet so you can perform iterations without having to number crunch everytime. </div></BLOCKQUOTE>

Or, just give it to the only honors student on your team and let her do it....Right?? </div></BLOCKQUOTE>

If for "honors" you mean the great ones, i should say:

Not so.. sometimes the "bees knees" students are plain dumb for practical stuff. Or have no time to do/practice them, because they´re so busy studying for finals due in five months. Or because they are toooo goood to perform pleb jobs.

Go ahead and read, if you don´t solve that free body diagram, then go for an arts major http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Julien Sirois]

Thanks guys, the solution was too obvious, I was expecting something a lot more complex than a free body diagram...


Julien
FSAECVM

[RollingCamel]

Check "Automotive Chassis Engineering Principles". A great resource and a must have.