Synthetical fatigue testing system and method for extensional vibration and torsion of composite insulator

The invention relates to a synthetical fatigue testing system and a synthetical fatigue testing method for extensional vibration and torsion of a composite insulator. The system comprises a linkage mechanism, a tension sensor, a static and dynamic load linkage loading mechanism, a cooling system and a torsion loading mechanism which are connected end to end, wherein the tension sensor, the static and dynamic load linkage loading mechanism, the cooling system and the torsion loading mechanism are respectively connected with a measurement control system; the static and dynamic load linkage loading mechanism and the torsion loading mechanism are respectively connected with a base. According to the system, one end of the composite insulator is applied with static tension along the axial direction and the dynamic tension with adjustable frequency, and the other end of the composite insulator is applied with the torsion tension with adjustable frequency by the measurement control system; a testing condition is provided for the fatigue property research of the composite insulation under the comprehensive effects of static load, dynamic extensional vibration load and the torsion load.