Software for suspension analysis

Automotive Engineering general discussion Automotive Suspension
#1

by @GregLocock

Useful suspension analysis can be done from a bottom up approach, in which individual parts of the suspension mechanism are defined, and then loads are applied, or top down, in which the suspension is abstracted out to an overall axle performance for a given load and slip ratio, or anywhere in between these two extremes. Note that some of these packages are available with different add-ins which will have a significant impact on their cost.

I have used few of these programs in anger, but had a play with many of them. If you find any errors please let me know.

I have not included add-ins to solid modelling programs, as I have no experience with them. There are many other mechanism modelling packages out there, which could be used to develop the geometry and perhaps kinematics of the suspension. A good shareware example is:

http://www.3d-designer.com/index.html

Terminology notes:

A template is a predefined mechanism, in which you can modify the coordinates of the hardpoints and things like the spring rates, but generally you cannot change the way that the mechanism itself works. Some programs allow you to write your own templates, others don’t have any at all, so you have to write each suspension from scratch. So, I’ve called those that use T emplates [ T ] and there are those where you can F reely define any mechanism you like, which is good, but can be confusing. Basically, if you want to run double wishbones then any of these programs will do it.

There is a big difference between those packages that model compliance C at each hardpoint and those that don’t NC . The latter are fine for racing suspensions, but could (should) lock up when modelling modern passenger car suspensions.

Programs are generally either 2D or 3D . 3D is way more complicated to think about, but has obvious advantages. 2.5D programs work in 3D but are really based on a side view and a front view.

I’ve also identified whether programs are good for A xle, or V ehicle level simulation.

Some programs are K inematic only, others have full D ynamic modelling. Some programs are G eometric only, ie they do not consider forces.

I’ll present them in rough order of cost, freebies first. Costs are very approximate

  1. COSINE.BAS aka WISHBONE.BAS 2.5D NC A G T
  • an ancient and rather ugly text based suspension analysis package for QBASIC. It is designed for SLAs, or double wishbones. Works well. It does not generate curves, it just moves your hardpoints and tells you what the new toe, camber, jounce etc is. With care and dedication this is capable of excellent results.
    New version with diagram
    http://www.locostusa.com/yahoo/Wishbone_setup.exe
    Old version with source code, needs qbasic or quickbasic
    http://www.mgbv8.co.uk/frontsus.htm
  1. FreeCAD 3D C A/V D F
  1. SLARCK 2D NC A G T
  • a free Excel based tool developed by myself to examine the roll kinematics of SLAs, in front view only. Not a general purpose package, it is really all about roll centre height. It’s sole virtue is that if you want to search for a specific camber curve then it can use Excel’s solver to identify the required hardpoint locations.
    http://www.geocities.com/greglocock/downloadpage.h…
  1. SusProg3D 3D NC A K T
  • has a free limited demo that is very educational, and very good help files. Only analyses predefined suspension types, but many different templates are included. Full version costs about US$200.
    http://www.bevenyoung.com.au/suswin.htm

4.5 Suspension Analyzer by Performance Trends 3D NC A/V K T

  • The demo version of this is also great, I think it even allows full saves for a couple of months. Download it, try it. It’s a bit more expensive than Susprog3d, which also has a great demo, so try both and tell us what you think. Bear in mind that if your suspension type (template) is not included than you have to ask the developers to make it happen. One end $300, full vehicle $400
    http://www.performancetrends.com/download.htm
  1. Racing By The Numbers 3D NC A/V K/D? T
  1. Working Model 2D 2D C A/V D F
  • Quite handy for roughing mechanisms out. There used to be a no-save demo around that limited you to 5 ‘bodies’, but that was possibly enough to build a full vehicle model, with care. Good fun. There is a downloadable demo available $3000
    http://www.design-simulation.com/WM2D/Index.php as of 2013
  1. Working Model 3D 3D C A/V D F
  • I’ve only seen an old version of this, it is a general purpose mechanisms and non linear simulation package. You can build up just a corner, and then exercise it, or build a whole vehicle and manouevre it. The interface in the version I saw was nothing like as slick as WM2D, but it is a true 3d non-linear simulator. You could even model active suspension in it. No longer sold I think, replaced by visualNastran4D.
  1. visualNastran 4D 3D C A/V D F
  1. CarSim 3D NC A/V D T
  • used to be a free, good, fast 5 body model of a full vehicle. You may be able to find their old free version. It has a simple 5 link suspension model, so I’ve given it an A, but that is probably an overestimate of the usefulness of that part of the package. The manual is very good. This is what I use at home. carsimed v4.5.1 is the latest free version. Bizarrely you can hook this into Simulink and run any further complexity you like, if you can figure the command syntax out ( I haven’t, yet) Now they’ve gone commercial. $8500
    http://www.carsim.com/index.html
  1. Lotus SHARK 3D C A K F
  • This is a very slick package with a nice interface. It is a K&C simulator more than a whole vehicle package. Therefore the outputs are curves of camber vs jounce travel, toe vs jounce travel, and camber in roll, and roll centre locations, and so on. Bushes can only be represented as linear rates, not splines. The advantage of it is that by concentrating on one subset of the suspension design task it is simple and fast. The disadvantage is that /you/ need to know what the curves you get will mean on the track. I’m not convinced that this package is a big step forward from Susprog3D, and the help system is certainly far less interesting. You can write your own templates, it doesn’t look too difficult.
    Costs around $14000 US, can be rented by the month or longer
    http://www.lesoft.co.uk
  1. VeDyna 3D V D F
  • http://www.tesis.de/en/index.php?page=544 Easy to use, fast, rather like CarSim. Commonly used for HiL simulations, as it is very easy to patch external hardware into the program, and it runs in real time.
  1. LMS DADS 3D C A/V D F
  1. ADAMS 3D C A/V D F
  • comes in various flavours. At its heart it is a non linear mechanisms analysis package working in the time domain. ADAMS/Chassis and ADAMS/Car are front ends for this solver. They come with predefined templates, you just have to enter hardpoints and component values, and the thing runs itself! Well, not really. You can also write new templates yourself. Price: if you need to ask… (seriously, about 30k, I think)
    http://www.mscsoftware.com/products/products_detai…