Roll Cage Design (CAD)

  • Steps to go on with, for designing your Roll Cage –

Design CAD

  • CAD stands for computer-aided design. You require CAD to design your roll cage and other subcomponents of your Automobile depending on the rule book.
  1. Take the dimension of track width and wheelbase
  2. Decide on the suspension geometry and powertrain combination you want to have.
  3. Calculate the length of Suspension Arms, Tyre width and Hub, Upright fitting space
  4. Decide where the suspension mounting should be on roll cage
  5. Start designing from front and proceed for the rear.
  6. Calculate the height of your seat mounting and other variables like the proper space you would require for your steering to fit
  7. Mark the coordinates in X, Y, Z and design a dummy Rollcage
  8. Proceed with the designing.

Selecting Roll cage material for BAJA

SOLIDWORKS TUTORIALS

  • Download and install the software. Follow the steps below –

https://www.solidworks.com/sw/purchase/solidworks-trial.htm?gclid=Cj0KEQjw4827BRDJvpbVuKvx-rIBEiQA2_CzsPYL1hoaEv2sxyqw2oZZtYCgJn9Xwdy9s-XkTSnL99AaAppB8P8HAQ&mktid=7627

Designing a Roll Cage for BAJA

Roll Cage Overview

FRAME
Elements of the Roll Cage
  • The roll cage must be a space frame of tubular steel. The required members of the roll cage are:Primary members :
  • Rear Roll Hoop (RRH)
  • Roll Hoop Overhead Members (RHO)
  • Front Bracing Members (FBM)
  • Lateral Cross Member (LC)
  • Front Lateral Cross Member (FLC)Secondary members :
  • Lateral Diagonal Bracing (LBD)
  • Lower Frame Side (LFS)
  • Side Impact Member (SIM)
  • Fore/Aft Bracing (FAB)
  • Under Seat Member (USM)
  • All Other Required Cross Members
  • Any tube that is used to mount the safety belts
  • When minimal dimensions are given that is to the centerline of the members, and when a clearance for the driver is given, it is defined by the outside edges of the roll cage members less the padding installed
  • Required dimensions between roll cage members are defined by measurements between member centerlines, except where noted.

To start with the designing of a roll cage, the first thing that has to be done is to create a new SLDLFP part for the weldments purpose of the roll cage. It has its own specified dimensions stated down by BAJA, therefore we have to design it ourself. There are two types of parts which you have to design, first for the primary tubes and second for the secondary tubes. If you have any confusion as to how to design an SLDLFP part, then check this article (Error: Library feature is empty! [SOLVED]) which will surely help you out with this. So let’s begin!

1.DESIGNING THE FIRST TUBE(PRIMARY TUBE):

Draw two concentric circles: Having outside diameter of the tube as 25mm(1 inch) and the thickness of the tube as 3mm(0.12 inch). Then save that file as SLDLFP part to C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\lang\english\weldment profiles\iso\TSI( This is the default path. TSI is a self-made folder by me, you can make a folder with a different name as well).

2.DESIGNING THE SECOND TUBE(SECONDARY TUBE):

Draw two concentric circles: Having a minimum outside diameter of the tube as 25mm(1 inch) and the minimum thickness of the tube as 0.89mm(0.035 inch). Then save that file as SLDLFP part to C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\lang\english\weldment profiles\iso\TSI. Screenshot (83).png The files will be saved as shown.

3. Then starts the sketching of the roll cage:

Open SolidWorks and in a new sketch click on 3-D SKETCH. Screenshot (84).png You will have a screen like this. Start sketching the roll cage abiding by all the rules of BAJA SAE India For the rules refer to the rule book by BAJA SAE.

After sketching, the figure looks somewhat like this:

Screenshot (89)

The Side View of the sketch.

Screenshot (90)

The Front View of the sketch.

Screenshot (91)

The Top View of the sketch.

Now comes the last part;  Weldments :

Exit the 3-D sketch.

  1. Click on Weldments option in the command bar.
  2. Click on Structural Memberoption. Under the Standard Option, select iso.
  3. Under type, select the name of the folder you created. (in my case its TSI)
  4. Click on size and click on either Primary or Secondary according to your choice and the part you are welding. But REMEMBER, it should not be violating any rule.
  5. Click on New Group.
  6. Click on the sketch where you want the weldments to be added.
  7. Continue the above process until the entire roll cage is welded.Screenshot (93)

After that, the figure would look like this:

Screenshot (85)
The Side View of the Roll Cage.
Screenshot (86)
The Front View of the Roll Cage.
Screenshot (87)
The Top View of the Roll Cage.

Watch the tutorials below –

Further Reading – https://forums.bajasae.net/forum/solidworks-sae-baja-tutorials_topic466.html 

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