The fretting fatigue analysis between strands of ACSR
In this paper, self-made fretting fatigue wear test bed was used to investigate fretting fatigue and wear properties of overhead transmission line between the strands, and then the fretting fatigue fracture life and the fracture surface microscopic morphology of ACSR in different testing conditions was analysed. The results show that under larger included angle, larger ACSR tensile force and larger fretting amplitude, the fretting fatigue life of the wire was reduced. The crack initiation and propagation occurs in the contact edge, and the angle is 45° between fracture surface and the wire axis. Fretting fatigue fracture can be divided into three areas: micro-crack nucleation area, fatigue crack propagation area, crack area, and the three regions have different fatigue properties.
Dynamic wear evolution and crack propagation behaviors of steel wires during fretting-fatigue
Abstract Dynamic wear evolution and crack propagation behaviors of steel wires during fretting-fatigue were investigated in this study. Wear scar and wear depth profiles of steel wires were quantitatively analyzed employing a three-dimensional white light interferometer. Theoretical models of maximum wear depth and wear coefficient of parabolic wear scars were established. Three-dimensional crack propagation characteristics of steel wires were presented using X-ray computed tomography. The results show that larger fatigue cycles induce decreased increase rates of elliptical wear scar area and parabolic wear depth of steel wires. An increase of relative displacement induces reduced damage and thereby better anti-wear properties of wires. The central zone of wear scar exhibits larger crack depth and faster crack propagation as compared to edge zones.
Inhibition of Mild Steel Corrosion Using L-tryptophan and Synergistic Surfactant Additives
The corrosion inhibition characteristics of nitrogen containing amino acid L-tryptophan on mild steel in 0.1 M HCl solution, in the temperature range of 30-50 o C, was studied by weight loss and potentiodynamic polarization measurements. L-tryptophan significantly reduces the corrosion rates of mild steel; the maximum inhibition efficiency being 83% at 50 o C in presence of inhibitor concentration of 500 ppm. The effect of the addition of very small concentrations of anionic surfactant, sodium dodecyl sulfate (SDS), and of cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), on the corrosion inhibition behavior of L-tryptophan was also studied. The inhibition efficiency (IE) of L-tryptophan significantly improved in presence of both surfactants. The effect of SDS and CTAB on the corrosion inhibition behavior of L-tryptophan appears to be synergistic in nature, the values of synergism parameter being greater than unity. The adsorption of inhibitors on mild steel surface obeyed Langmuir’s adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitors and the mild steel surface. The results obtained by electrochemical studies are consistent with the results of the weight loss measurements. L-tryptophan acts more anodic than cathodic inhibitor.