Abstract: Abstract:When the unit load is changing or the unit operates in peak shaving process, under the action of alternately changing load with nonzero average stress, the ratchetingcreep behaviour of the fastening bolts of the turbine cylinder may occur. Therefore, to research the damage development of the bolts during ratchetingcreep process is of important significance. The uniaxial ratchetingcreep rupture experiment was carried out for the nickel base alloy material Nimonic 80A at 550℃. The user selfdefined program, which is based on AbdelKarimOhno kinematic hardening criterion, was embedded into the finite element software Ansys, and the ratchetingcreep process of the bolt was simulated. The macroscopical deformation obtained by simulation was identical with experiment result. Under the ratchettingcreep interaction, the damage development speed of the screw rod of the bolt is greater than that of the thread of the bolt, which is the region of stress concentration, and the rupture may occur there.

Key words: Key words:viscoplasticity, fastening bolt, ratchettingcreep, Ansys, rupture