Abstract: In the composite pre-tightened tooth connections, the pre-tightening force determines the ultimate bearing capacity of the joint. When the pre-tightening force is applied by external extrusion, the size of external extrusion determines the pre-tightening force applied to the joint. In this paper, the relationship between external extrusion and pre-tightening force is studied by theory, finite element and experiment. Firstly, steel and aluminum alloy are simplified as ideal elastoplastic materials, and pultrusion composites are simplified as transversely isotropic materials. Then, through the thick wall cylinder theory, the theoretical formula for calculating the radial compressive stress of the interface under different extrusion variable is obtained, which is verified by finite element method and experiment. Finally, the parameters are studied on this basis. The results show that: (1) The theoretical solution is in good agreement with the finite element solution and the experimental value, which proves the correctness of the theoretical formula. (2) When only the wall thickness is changed, the radial compressive stress of the interface increases linearly with the increase of the wall thickness of aluminum alloy inner casing, while the external steel casing wall thickness has little influence on it. (3) When the material of inner sleeve is changed from aluminum alloy to steel and other conditions remain unchanged, the radial compressive stress of the interface will be significantly increased.

Key words: extrusion variable, pre-tightening force, composite material, finite element