Computer Aided Engineering at ARRC

Fitting custom cages to ARRC's standards means that the tubes should be as tight a fit as possible to the car's body. We use Bend Tech software to design the required bends. The program allows for different materials, different tube sizes, different wall thickness and the inevitable "spring back" which occurs after bending.

Our standard full 3D CAD package is Ironcad, Andy and Luke Robinson are both fully trained users. Click to visit their site.

We use Ironcad to design parts for outside manufacture. This example was developed by Andy and Luke to provide inboard disc brakes for an independent rear end. An outside contractor then used CNC machines to make these brackets from the ARRC developed model.

Click 3D to view this model with full rotation and zooming using Adobe Acrobat ... the model does take a little while to load. You can download the latest free version of Acrobat reader here. Other pdf readers may not work.

This shows the original bearing carrier housing in silver with the new design in black which includes caliper mounts.

And the complete assembly with discs mounted to the drive shaft inners.

Ironcad allows us to reverse engineer existing products. We used it to create a model of a damaged chassis brought in for replacement so we could check out the finished chassis for dimensions.

Click 3D to view this model with full rotation and zooming using Adobe Acrobat ... the model does take a little while to load. You can download the latest free version of Acrobat reader here. Other pdf readers may not work.

 

The use of Ironcad also enables ARRC to accept customer CAD models as input to the fabrication process.  Typical file formats used for this are IGES or Autocad dwg.

When the FIA introduced new standards for roll cages in Appendix K historic racing cars we were able to use Ironcad to design a cage and then an FEA consultancy to check its' characteristics. The specification demanded that the cage moved less than a maximum amount when a point load was applied to a specific part of the cage. We evolved the design through several iterations checking at each stage to see if it met the standard. The illustration shows a visualisation of the stresses in the cage at maximum load.

The geometry of the cage as defined by Ironcad and the characteristics of the materials were input to a Finite Element Analysis program which was then able to calculate loads and movement as a result of an applied force. We submitted the results to the FIA and gained their approval to our design, the first such approval for the E-type Jaguar.

The calculations involved in setting up the typical 4 link suspension can be done by hand but the use of this program speeds up the process enormously. This in turn allows for a number of alternatives to tried quickly in order to find the optimum. This is a classic example of computer garbage in - garbage out because any error in measurement for input to the program can easily multiply the error in results.

Independent suspension geometry is even more complex and we use this suspension analyser to search for the optimum dimensions. Most often this will be for circuit cars or road cars; our extensive experience with drag racing chassis means that appropriate geometry will be built in and this program used as a check and balance rather than creating from scratch.

Date

03-Nov-2012

Pictures by

Webmaster

CAD by

Andy & Luke