NUMERICAL STUDY ON THE FORCEMATE BUSHING COLD EXPANSION OF COMPOSITE HOLES USING A NOVEL ASSISTING SLEEVE

Cold expansion technology has been one of the most common anti-fatigue strengthening technologies for fastening holes. In this paper, a newly developed assisting sleeve is employed to install the ForceMate bushing, and the resulting deformation, rebound, drawing force, contact pressure, residual stress and damage are compared to those resulting from traditional ForceMate bushing process. The 3D Hashin failure criterion was implemented into finite element simulation via a specially written user subroutine to simulate the deformation and failure of cold expanded composite holes. The results show that a more uniform distribution of residual contact pressure and residual circumferential stress is achieved by introducing the assisting sleeve, and less damage around the composite hole is induced under the same interference level. In comparison with the traditional ForceMate bushing process, a better anti-fatigue performance of cold expanded composite holes can be expected by using the assisting sleeve.