Roll Cage tube material and specification
The CAMS/FIA regulations stipulate exactly what material specifications are required to be used in the construction of a Roll Cage for motorsport use. There are two main options available, and largely depend on your budget and individual needs.
Cold Drawn Seamless (CDS) high tensile steel tube (350MPa): The most commonly used material for Roll Cage use, offering a great affordable ROPS solution. The design of a ROPS with this material only needs to comply with the standard design principles as published in the CAMS regulations (Schedule J), to be eligible for registration needed for Australian competition use.
Cromoly (650MPa): The more exotic of materials, with a great benefit in the weight department, being significantly lighter than other materials due to higher yield strengths allowing the use of thinner wall thickness. However, this material is harder to work with and requires more time in the fabrication process. It is also the more expensive option for a ROPS, with a higher material cost, requiring a lot more intricate design to satisfy CAMS/FIA regulations. Cromoly also requires a designated and independent ROPS specialist engineer to assess and sign off the design before CAMS registration can be given. This additional engineering consultation is not cheap and adds to the overall cost of installation.
3D Cad Design
The use of 3D CAD modelling software has become increasingly beneficial to research and development work in almost all technical manufacturing industries. Brown Davis has taken full advantage of these new computer techniques, to design and model components for certain components. From the footplates, to the rollbar joiners, each component is drafted into a workable 3D model. This in turn gives much greater scope for development and testing any new concepts and ideas.
Roll Cage design and Finite Element Analysis (FEA)
Finite Element Analysis (FEA) offers a detailed visualisation of where ROPS structures bend or twist, indicating the distribution of stress. This allows designs to be created, optimised and finalised in 3D before the design is manufactured. FEA in ROPS creation has become a very useful tool, with its ability to allow insight into real world outcomes prior to destructive testing of actual prototypes. The resulting stress and deformation can be measured for simulated rollover loads from nearly any axis, and therefore each component of the structure can be re-designed or modified accordingly, until an effective computer model meets the load levels Brown Davis Automotive or CAMS deem acceptable.
Brown Davis incorporates both physical (destructive testing), as well as computer based analysis. Physical testing is carried out to confirm FEA results and substantiate the computer model. Complex motorsport ROPS produced by Brown Davis Automotive have been compared against FEA models and revealed a result within 5% (FIA approval cannot be issued without such FEA proof for ROPS in motorsport).
It is this combination of critical data that enables very efficient progress of each design, and ultimately produces a superior product, providing the maximum roll over protection achievable. Furthermore, for Brown Davis to be able to obtain the necessary documentation and engineering checks required to comply with CAMS/FIA specification, such FEA models are required for approval.