BBM Crankshaft Modeling
Drag racing provides myriad opportunities to evaluate designs and use virtual methods to predict failures. Crankshafts are one area that is of particular interest as you can't really see inside it and magnafluxing or dye penetrants are dependent on the skill of the technician to execute and interpret properly. This example is more of a post mortem inspection, geometry creation and modal analysis using different boundary conditions to help understand what RPM to stay away from to help the crankshaft live longer.
A little history on this crankshaft is in order to help understand what may have contributed to its failure.
1. First potential contributor may have been when the ring and pinion failed early in a run and allowed the engine to zing unloaded.
2. Second, at 900 feet, a rocker arm broke and oil pressure went to zero. This "blackened" the crank and was polished to restore the bearing surfaces.
3. The NOS hit was increased from 100HP to 300HP. NOS is typically used on this car as a last resort
and is only for durations of less than 2 seconds.
4. The crank broke in a big money race immediately after the "button" was hit. The race was won but the damage caused the driver to DNS the next round.
5. Prior to the crank breaking, the #4 main bearing was replaced every 75-125 laps due to the bearing face being overstressed.
The over-stressed face of the King main bearing proved to be an unrecognized symptom of the propagating crack in the main bearing fillet.
With this information, the Callies XL Magnum crankshaft was modeled in Solidworks and then analyzed using SIMSOLID and Altair Inspire 2019.3. The modal frequencies were compared to see the agreement between the two solvers as SIMSOLID is a new generation meshless analysis tool.
