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What are we looking at and why did we do this?
First things first, what we are looking at are graphical representations of the stress the clutch fork sees in a highly loaded pressure plate situation. What is of most importance to us, is viewing the areas near, at, and above yield strength. Typical analysis set the legend from minimum to maximum stress the unit sees, but this doesn’t give an easy to read indication of problematic areas. Simple solution- change the legend so that the max legend value is yield strength and we can quickly and easily view what is happening.
Velox did this initial analysis to visualize trouble areas and give a starting point to compare the upgraded design to. Without this visualized data, it would be a guess where and how to make the design stronger. Ultimately, this quantifiably improves the design faster as well as design a better product at the end of the day.
Time to fix this issue!
Using the information gathered from the OEM FEA analysis, Velox was able to methodically improve the design. First, the part was machined from a stronger material than stamped sheet steel, so 4140 Chromoly steel was chosen. In the annealed state, 4140 is 12% stronger in yield strength than typical sheet steels. We then increased the wall thickness by 25% minimum throughout. Finally, we removed the major stress rising locations found in the initial analysis.
Results from Improvements
The Velox part effectively reduced maximum stress by 53% on the FRS/BRZ/GT86 fork and 53% on the WRX unit. Looking at the deformation (amount of deflection), it was reduced by 65% on the FRS/BRZ/GT86 fork and 71% on the WRX unit.
The Velox redesigned clutch fork no longer exhibits areas of high stress over the material’s yield strength. This is great news! The clutch fork should withstand even the strongest clutches on the market and last significantly longer than the OEM unit. The reduced clutch fork flex translates to a more consistent clutch pedal feel as well, which is great as driver feedback is improved.
Time to up-shift into prototypes:
Knowing what is expected from a machined part using CAE, a rapid prototype was built from plastic for test fitment knowing full well the improved design will withstand the loads. Rapid prototypes save time, reduce costs, and improve part fitment before ever cutting into a piece of metal. This technology is absolutely game changing for manufacturing!
