Investigation of mechanical behaviour of high-strength swage lockbolts subjected to combined tension and shear
To investigate the mechanical behaviour of Grade 8.8 and 10.9 high-strength swage lockbolts subjected to combined tension and shear,the mechanical behaviour of swage lockbolts under combined tension and shear was conducted.The mechanical properties of swage lockbolts,including failure modes and load-displacement relationships under various combined tension and shear were obtained experimentally.The underlying failure mechanisms of lockbolts were analyzed based on fractography using scanning electron microscope.The research findings revealed that the swage lockbolt specimens failed at collar pull-out or rivet fracture,exhibiting ductile characteristics.Through the characterizations of the microstructure for the fracture surfaces,it was demonstrated that the swage lockbolts exhibited quasi-cleavage fracture under the combined tension and shear loads,indicating limited ductility.Based on the experimental results and theoretical analysis,the mechanical models of swage lockbolts for these two limit states were proposed,and the design method of swage lockbolts subjected to combined tension and shear was established.The results demonstrate that the proposed design method could offer predictions with satisfactory accuracy,with the strength ratios of calculation value to test value for the Grade 8.8 and 10.9 swage lockbolt being 0.92 and 0.97,respectively.
swage lockboltcombined tension and shearcollar failurerivet fractureultimate strengthdesign method
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