Rolling Contact Fatigue: Roller Bearing Spalling

This simulator models a cylindrical roller bearing under radial load and tracks one fixed point on the inner-race raceway as rollers pass over it thousands of times. Each pass is a real Hertzian line-contact event: the sim computes the contact half-width, peak pressure, and the subsurface orthogonal shear stress that Lundberg–Palmgren theory identifies as the true driver of rolling-contact fatigue — a stress component that reverses sign under the surface every time a roller rolls by, rather than at the surface itself. Damage accumulates cycle by cycle until a fatigue crack breaks through and a spall pit forms, exactly the failure mode inspectors look for when they pull a worn bearing and see a flaked, pitted raceway.