Study of a contact in the gearing of a tooth with its wheel by optical shadow method

The gearing between a tooth of a synchronous belt and its wheel is experimentally simulated. The areas and the levels of great stresses are visualised the optical shadow method. This study permitted us to show that the order of loading tangential (the applied torque) followed by the normal load (static or gearing load) is more dangerous for the integrity of the belt's tooth than the reciprocal one (normal followed by tangential load). We found the analogy with the stress state at the beginning of a crack Beaded in mixed mode by the two above-mentioned loads.