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Thread: A new free vehicle dynamics resource - Dan's Vehicle Dynamics Corner

  1. #51
    Hi Danny,

    first of al thanks for your posts and the material you publish.

    Would be nice to have something new more often, but i understand it's not good for your business to show your competitors what you do and how.

    I have a question about your article on hand calculations, in particular regarding the approach you propose to build a first aproximated tire model.

    After you have calculted vertical loads based on Downforce and Lateral Load Transfer, you increase that load by 20% to save for situation where you could potentially have more donwnforce. But the maximum load value is influencing also the shape of the parabola you build up based on ka and kb, right? So increasing it (or anyway changing the MAX LOAD value) lead to a different tire model...in particular to different intial Coefficient of Grip and load sensitivity.

    So this way of proceeding seems to me a bit arbitrary...or maybe i am loosing something?

    Thanks!

  2. #52
    Silente,

    Thank you for the compliment. It gives me a real thrill to see guys like you getting something out of this thread.

    My apologies for the delay in answering your questions. I've been flat out developing new features for ChassisSim.

    In terms of the extra 20% of the load that's there to cover you for bump load variation and as a safety margin. To put this in perspective look at a plot of tyre loads at a place like Sebring!

    However the whole point of this is to create something to get you started. It's also a great educational tool because it gets you prepared for the loads you can expect. Then you use data and ChassisSim's toolboxes to refine the results.

    I trust this makes things clear. If you have any more questions please don't hesitate in contacting me and sorry for the hold up.

    All the Best

    Danny Nowlan
    Director
    ChassisSim Technologies

  3. #53
    Hey Guys,

    I've just posted this video on how to make best use of the ChassisSim quick start features,

    http://www.chassissim.com/blog...o-modelling-features

    I've posted this because it puts into perspective how to use computational tools such as ChassisSim as calculators as opposed to blindly relying on the results.

    This is something all engineers need to keep in mind and I hope you get something out of it.

    All the Best

    Danny Nowlan
    Director
    ChassisSim Technologies

  4. #54
    Danny,

    thanks for your reply.

    i understand your point and this explanation was already pretty clear from your paper.

    Anyway, what i meant is that, if you change the max load value, the complete Lateral (Longitudinal) Force vs Vertical Load curve is changing, leading at the end to a completely different tyre model.

    So ok, we than take into account for bigger vertical loads, but which is then the "better" tire model to represents our tire?

    I would post a picture of the two different curves i get changing maximum load, but i am not able to in this forum...

  5. #55
    Silente,

    Again my friend the apologies for the delay.

    When starting a tyre model I always advocate a larger tyre load range. You lose sensitivity but it's the safer road to take. I've seen tyre loads from racecars in the order of 1000kgf! This is the key reason I put a safety factor on my tyre modelling.

    Just remember this hand calculation gets you going. The key thing is you start on the hand calculation then you use tools such as the ChassisSim tyre force modelling toolbox to finish the job.

    I hope this helps.

    All the Best

    Danny Nowlan
    Director
    ChassisSim Technologies

  6. #56
    Hey Guys,

    I've just put this post on my blog,

    http://www.chassissim.com/blog...d-to-do-to-get-going

    It's about how to get going when using simulation.

    What this does is it articulates the process you need to get going with simulation. If you want to get started with simulation this is a great start point.

    All the Best

    Danny Nowlan
    Director
    ChassisSim Technologies

  7. #57
    Hey Guys,

    I was going through some of my old Racecar Engineering articles and I found this,

    http://www.chassissim.com/blog.../the-damper-workbook

    It's the damper workbook which outlines the basic calculations you need to get on top of your dampers. The equations and approaches in this article have saved my neck at the race track more times than I can remember. You'll find it a very useful tool.

    Enjoy

    Danny Nowlan
    Director
    ChassisSim Technologies

  8. #58
    Hey Guys,

    I just posted this tutorial about the ChassisSim optimisation toolbox,

    http://www.chassissim.com/blog...optimisation-toolbox

    The reason I bring it up is I think it's a good lesson about how to use optimisation techniques. However I also mention when not to use it and that is something to keep in mind.

    Enjoy

    Danny Nowlan
    Director
    ChassisSim Technologies

  9. #59
    Hey Guys,

    I've just released ChassisSim v3.21. You can find out more details here,

    http://www.chassissim.com/blog...m-v3-21-new-features

    What is of particular interest to the FSAE community is the ability to run open loop simulation, being able to predict hot pressures from cold conditions and revised algorithms to deal with structural flexibility.

    Enjoy

    Danny Nowlan
    Director
    ChassisSim Technologies

  10. #60
    Hey Guys,

    I just posted this video on circuit modelling,

    http://www.chassissim.com/blog...ing-chassissim-v3-21

    It shows you how to create high fidelity circuit models that can really nail down bumps and other nuances of the circuit to really represent what is going on with the car.

    I think you'll get a lot out of it.

    Enjoy

    Danny Nowlan
    Director
    ChassisSim Technologies

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