Design Report Questions (Please Reply)

[Sprocketeers2010]

Hello everyone,

As stated in our very first post, we are new to these forums and to the competitions themselves. We have been filling out the Design Report (excel document) due May 1st and have found a couple of things that we are not clear on. We have several book references, but have not found a clear explanation for them. We have looked through the forums and were unable to find answers. Please provide us with descriptions, formulas and/or ways of physically measuring any of them. Programs to acquire the values for these terms are great, but it will require us to learn how to use it in the little amount of time we have left. Seeing as there are very few days remaining to submit this report, we will greatly appreciate it if anyone is willing to help us out. Here are the terms:

Within the Suspension Parameters
*Wheel Rate
*Sprung Mass Natural Frequency
*Jounce Damping
*Rebound Damping
*Camber Coefficient in bump (deg/m)
*Camber Coefficient in roll (deg/deg)
*Roll Center Position Static
*Roll Center Position at 1g lateral acc

We hope that this also helps clear any doubts that other teams might have. Thank you very much in advance.

-The Sprocketeers-

[Sprocketeers2010]

Hello everyone,

As stated in our very first post, we are new to these forums and to the competitions themselves. We have been filling out the Design Report (excel document) due May 1st and have found a couple of things that we are not clear on. We have several book references, but have not found a clear explanation for them. We have looked through the forums and were unable to find answers. Please provide us with descriptions, formulas and/or ways of physically measuring any of them. Programs to acquire the values for these terms are great, but it will require us to learn how to use it in the little amount of time we have left. Seeing as there are very few days remaining to submit this report, we will greatly appreciate it if anyone is willing to help us out. Here are the terms:

Within the Suspension Parameters
*Wheel Rate
*Sprung Mass Natural Frequency
*Jounce Damping
*Rebound Damping
*Camber Coefficient in bump (deg/m)
*Camber Coefficient in roll (deg/deg)
*Roll Center Position Static
*Roll Center Position at 1g lateral acc

We hope that this also helps clear any doubts that other teams might have. Thank you very much in advance.

-The Sprocketeers-

[ed_pratt]

Sprocketeers

This is quite a difficult question to answer because if you have a design for a suspension, you should have answers for all of these things.

The template which you fill out has example answers for each thing in it already.

http://www.formulastudent.com/...heetClass1.sflb.ashx (http://www.formulastudent.com/Libraries/Documents/DesignSpecSheetClass1.sflb.ashx)


If it is a case of English not being your first language, then I hope the following can help.

Wheel Rate:
This is the effective (measured) spring rate at the wheel. This will very likely be different to your actual spring rate, depending on how you mount your dampers.

Sprung Mass Natural Frequency:
this is tricky to explain, but basically it is a means of describing how stiffly sprung your car is. Most FSAE cars operate in the range of 1-5Hz

Jounce damping:
this is a description of how much damping your have when the wheel is in jounce(bump)

Rebound damping:
As above, but for rebound

Camber Coefficient in bump:
this is the amount of camber the wheel has for each cm of bump. eg. 1 degree per cm (1deg/cm)

Camber Coefficient in roll:
the amount of camber the wheel has for each degree of roll eg. 1 degree per degree (1deg/deg)

Roll Centre Position Static:
The position of your roll centre when the car is stationary. eg. 30mm above ground, on the centreline of the car.

Roll Centre Position at 1g lat acc:
where the roll centre has moved to when the car is experiencing 1g of lateral acceleration.


Ed

[ed_pratt]

post awaiting approval

[Adambomb]

One other thing, the excel sheet is just the spec sheet, you get another 4 pages of text plus a couple more for drawings.

But the rules discuss this in detail...