The relation between the tightening torque and preload of the fastener used in a certain aviation application was analyzed. Taking MJ8 multiplied by 1 size titanium fastener as the research object

this article focused on the influence and corresponding change law of different head-type fastener and tightening times when the titanium alloy fastener is under actual installation environment of aviation and aerospace model. The following results are acquired: The preload of the bolt reached 5%–35%Fmax (Fmax means the required minimum tension load of the bolt)

with all other elements

such as thread accuracy level and the property level

etc

stayed the same except the head-type

for the headtype fastener with larger loading area on the bolt head

the generated end face friction torque is larger

and the required tightening torque is also larger to reach the same preload. The needed install moment and torsion modulus are all increased in the same bolt stress level with the addition of the install times.