Hello forum. I’m fairly new to FSAE and suspension design. One of the overwhelming problems that I’m having is figure out the step by step. Abstract. Design analysis of suspension especially for racecar suspension is very crucial to achieve maximum performance and handling. Suspension design. This article deals with design of Formula SAE Suspension by considering various loads and their simulation on each component of the system.
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User Name Remember Me? Page 1 of 2 1 2 Last Jump to page: Results 1 to 10 of Suspension Design Step by Step Process. I’m fairly new to FSAE and suspension susppension. One of the overwhelming problems that I’m having is figure out the step by step process in designing the suspension system.
I basically don’t know where to start there is so much information. If you could give me a list from start to finish 1,2,3,etc in terms of calculations and parameters to address, that would be great.
Hello Benn, First warm greetings and afterward; I’m a beginner too so don’t take this as an suspehsion talk I mean Suspemsion just sharing what I know.
First; I ssupension to tell you a tiny little thing Introduce yourself properly; namecountry, team Secondly; There is a “Find” button at the utility bar up at the right just beside the “New” button, So try to search for your topic if it had been discused before so as to save time and effort.
About your topic it had been discussed quite alot, But I’m going to share what I got anyway. Secondly; Start by tires Study the suspenwion tires very eesign Remember that the tires are the only contact you have between the sprung mass and the desigj. I remember watching a video where Mr. Claude Rouelle who is a famous FSAE judge and president of one of the leading companies ddsign vehicle dynamics softwares “OptimumG” saying that if you know the forces acting on your tire contact patch then you will be able to choose a suspension template.
Thirldy; If you want to start your design process, Then start suspejsion visualizing a 3D model of any type of suspension you want Start by 2D visualizing. Not for a particular reason except that there is quite a lot of tutorials on youtube ” Start by darwing two planes; Front view and a side view. And start sketching on the front view geometry by drawing lines to express your wishbones and your unsprung mass and then move to the side view After which; You should be able to transform the whole 2D drawing into 3D you have 2 planes and the third one is the top plane.
Then; Put the whole geometry on a kinematics analysis software One of the best softwares out there is OptimumK however it cesign not for free. Another free one and quite successful is Wishbone. Then start analyzing the results from the softwares such as the camber change due to body roll, bump, droop You won’t be able to be sure about the results unless you have tire data!
Then go back to your model and edit it again and analyze once more and start iteration. Work well on the compromises You’ll have to loose something in order to win the other. Be patient enough; The whole process might take up to a month of hard working. Don’t stop studying; Once you start design; Study more not less!
Know why before knowing how!! I really like one quote or an OptimumG motto that says “Knowledge shared; Is knowledge squared”. Sspension be with you and Good luck with your design.
Sorry for any typing mistakes. Thanks for the information!
Benn, Sorry, My previous post was all about kinematics It should be very helpful too. As in any design problem there are some step you should take before jumping into the details.
Get the basics right first, the details only after. I have written down fsaf approach, there is no “best” one, but this is systematic, and “relatively” simple since it seems to be your suslension go at it: Prior art, read on suspension design in RCVD for example. Understand the basic physics first!
Read and understand about the bicycle model, the understand the behaviour of the model and the tire. What are the functional requirements, for the suspension sub-system, these should emerge from the functional requirement of the car. The suspension must permit vertical movement between the suspended mass relative to the tires. The suspension permits control of the vehicle direction.
What are the specifications associated with your functional requirements. You will have to make basic assumptions to estimate the values. If you want to reduce fabrication cost for wuspension year, you may want to stick to the tires and wheels you already have. These specifications should be written in a table for fast reference. Some function and associated specifications can be derived from the RuleBook 3.
Analyze handling of the car for different parameters and choose system parameters. Use the Bicycle model first for practice, then build to a Four Wheel 2D model.
You might not need combined loads at the beginning, but it could be useful for looking at trail-braking and power corner exit and differential selection You might cesign to use the Stackpole Engineering Pacejka model from TTC Round 3, it might not deslgn your tire, but it will give you a good indication of the common behavior of a fsae tire.
All the fitting is already done and all the equations of the model written down -Write a simple code for the Four Wheel model that is able to calculate the slip angle for a given radius and steering angle, you will have to make assumptions about the slip angle at the rear.
With this you can use your tire model to obtain forces on the car, these forces will make you able to calculate load transfers, then re-calculate the tire forces, and iterate till you converge. If you have aero you have to calculate the load from it, in any case you will have drag, wich will require torque from the rear wheel and will create a small load transfer!
With this tool you will be able to make graphics, table or whatever you like by example, by iteration you can find the maximum lateral G that gives a zero yaw fssae for different radius. Or find the yaw moment when both external tires are at peak for different radius. Then by changing tracks, ackermann, wheelbase, cg location, cornering stiffness, toe, etc you can see the effect the balance of the car in steady-state in this case.
Only then will you have to worry with roll centers, roll stiffness, kinematics, motion ratio, dampers and such things. I hope I haven’t said something stupid, if so I duly apologize. So to choose a tire you need dwsign car, and to make a car you need to choose a tire.
I’d start by analyzing and understanding a few existing suspensions.
You can’t truly design something if you can’t perform an analysis on it. You can’t wait to perfect your knowledge and analysis–you’d never design anything! There is a knowledge-analysis-design- evaluate cycle The more times you go around the cycle the more you learn, the better your analysis gets and the more engineering you have in your design. How far up the helix can you get in your FSAE tenure? Milliken Research Associates, Inc. It’s skipped forward to the final 5.
One thing that can be noticed is actually how bumpy the track is. The next thing that becomes obvious is the teams that have a good car design, and the cars that dialed in one very in particular if you watch it. Vehicles without suspension have won, and they can be fast, as long as the proper adjustments are left open for balance.
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What do you want to achieve? Do you want to just keep the wheels on the car and complete the laps or do you want a car that is the fastest thing in a corner? Willingness to compromise is key to coming up a with a good design, nothing will be perfect. Is there something that can be innovative to the design? Who is using what, what has been used before? Why were certain concepts used and others abandoned? Suspenion there a reason why many have converged on a certain concept?
If tires change, what becomes different. Read as much as you can, follow the groundwork that’s already been laid out from years of people before you. After this iteration, how can these ideas you’ve formed achieve your high level goals? Now slim the ideas down to a core goal. Then, build, race, win. Hi Benn, Susprnsion thing I’d look into is setting some goals for your suspension by identifying what parameters will really affect your laptime. OptimumLap would be a good place to start as it will give you a decent idea of what really affects laptime on one of these cars.
They have Formula SAE cars and course already modeled into the software.
Suspension Design Step by Step Process
This will also have to integrate with the kind of car you want to build overall tradeoffs aren’t the same with a 4cylinder than with a single, aero or non aero. Contact Us Archive Top. All times are GMT The time now is