Threaded joints can be used to join different polymers or polymers to metals at high loads. Design with self-threading screws or threaded inserts requires dynamic mechanical properties. Results are presented on threaded joints of glass fiber reinforced polyamide 6 under static and dynamic loads. Dynamic load limits are determined by using the hysteresis measurement method with stepwise load increment experiments and single load level experiments. The failure and fatigue behavior of threaded joints is characterized by several parameters calculated from the hysteresis loop. These parameters change in a characteristic manner as a function of load and time. Significant changes exhibited by the damping and stiffness curves in stepwise load increase experiments can be used to determine the loss of preload on the screw and the beginning of screw pull out. Specially designed self threading screws for threaded joints capable of bearing high dynamic loads are discussed. These joints can attain a life in the endurance range (10(6) cycles) without loss of preload. In comparison with S-N curves, the dynamic load limits for threaded joints can be determined more quickly by the hysteresis measurement method.