S2020 Dynamics Assembly Overhaul
- Leif Blake (Deactivated)
Analytics
Motivation
The current Dynamics Assembly (July 2020) is a mess. Some of the sub-assemblies are well constructed, but others (see suspension) are not. Broken mates, missing files, hardware inserted at the wrong level, hardware that’s no longer in use, hardware that’s missing altogether, you get the idea. Working with this assembly is a hindrance to component designers, and will make working out assembly even harder.
The assembly used to be good, and was initially constructed with sound philosophy, but was not well kept as it grew and changed. At this point, it’s best to start over.
How we’re gonna build it and why
The new assembly will be broken down into several subassemblies. This is already done to varying degrees but needs an overhaul. Subassemblies allow for components to change while only affecting relevant components, and allow for people to work within smaller assemblies most of the time.
Within the Dynamics assembly, each subassembly should be located relative to the global coordinates of the car, not by mating surfaces/features. This makes the assembly less prone to over-constraining, less likely to break as sub-assemblies are modified, and reveals mating problems between sub-assemblies.
To elaborate on this latter point, remember that the suspension geometry was calculated using a lot of math, and is represented by a series of virtual nodes connected in a 3D sketch. This geometry drives our suspension design. Now consider two mating components in the suspension. If they are mated by their faces and someone shifts the face of one component, the assembly will still look correct, but the virtual node will have shifted away from the desired geometry. If the two components are fixed to the global coordinate system, a gap will appear between the components, which can be immediately recognized as a problem.
IMPORTANT: Ideally, every component, even within the subassemblies, would be referenced to the global coordinate system. However, we are choosing not to do this for 3 reasons:
Not every component has been designed to be referenced to the global coordinate system, so we would have to make component-level changes
Following from 1), we want to finish this by EOT
All our component design is done, so we’re less concerned with changes
So, in short, within each subassembly, one component must be fixed to the global coordinate system, and the rest can be mated using regular mates. Each subassembly must be integrated into the Dynamics assembly using global coordinates.
As for OTS parts (bolts, nuts, bushings, bearings, etc.), they should be integrated into the lowest-level assembly possible.
The structure
The following structure will be used in both CAD and the file system (GrabCAD):
