KINZOKU SANGYO SHIMBUNSHA (Japanese newspaper) reports that a designer named Kazutomi Oka from Kanagawa Prefecture of Japan developed the patent-pending "Slip Type Anti-loosening Bolt/Nut/Washer" utilizing spherical seating surface to prevent loosening. This design has completed testing this July. The designer is seeking licensee makers and die makers for collaboration.
The repeating vibration perpendicular to the thread axis causes the nut to rotate and leads to loosening. "Slip Type Anti-loosening Bolt/Nut/Washer" can prevent loosening by "bearing" and "releasing" forces. Its design utilizes Coulomb's law of friction and comes with a spherical seating surface. When vibration occurs that may lead to loosening, the spherical seating surface will slip before the threads do in order to release the force of vibration.
(Picture courtesy of KINZOKU SANGYO SHIMBUNSHA)