A B S T R A C TThe effect of nut geometry, curved spring washer and a sealing material (Teflon tape) on the fatigue life of M12 and M16 ISO bolts was investigated. This was accompanied by the study of the axial and bending stress distribution in threads by numerical simulation of bolt and nut connections using the finite-element method. The experimental results showed that the highest fatigue life is achieved for a slotted tapered nut. The presence of a spring washer also increases the fatigue life, providing that the correct tightening torque is applied to produce a pretension in the bolt. The use of Teflon tape as a filling material between engaging threads of the bolt and nut is shown to significantly increase the fatigue life. On the whole, the highest fatigue life is obtained for a slotted tapered nut using washer. Four fracture mechanisms were observed for bolt-nut connections during the fatigue tests.Keywords curved spring washer; fatigue; finite-element analysis; fracture mechanism; ISO bolts; nut type; Teflon tape.
N O M E N C L A T U R EA root = root (core) area of bolt D = outside (nominal) diameter of bolt d p = pitch diameter d = root (core) diameter of bolt E = Young's modulus k t = stress concentration factor P = axial load on thread per unit length of contact p = thread pitch t, t * = actual and effective radial depth of thread w = total load on thread per unit load length of contact w m = average of w = Pp/π d p L x = normalized position along thread (the distance from the free face of the nut divided by the nut length β = half angle of thread δ = angle between the total bending load and bolt axis = β − φ φ = friction angle = a tan µ ν = Poisson's ratio µ = friction coefficient between bolt and nut σ e = endurance limit of bolt material σ t = combined stress due to bending and axial loads σ ult = ultimate tensile stress of bolt material
From the layout of a metallic structure`s beam-column connection w, while the seismic design is inside the dissipative method, precise contributors and zones ought to admit the growth of plastic deformation, and many metallic second resisting frames fail on the beam-column joints. This examines designed a unique structural machine with diverse slit dampers to triumph over this challenge, which can be easier to deliver overall seismic performance in the structural device that has been proposed. Plastic deformation is confined to the slit dampers at the end flange, which is the machine's key characteristic. The recommended connection's seismic overall performance changed into confirmed the use of the Abaqus software program utility to software systems with diverse slit damper forms. The proposed hyperlink exhibited first-rate hysteretic conduct in accordance to check results. Furthermore, on this machine, strength dissipation and plastic deformation focus on the diverse shapes of slit dampers, while the inelastic behaviour of the beams and columns is prevented via a suitable ability layout. The conduct of triangular and cubical shapes of slit dampers withinside the connection among a metallic beam and a container column is defined in this paper.
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