The determination of corrosion pits tension distribution of torsion exposed pins

Key Words : Corrosion pit, Torsion, Tension agglomeration factor, PinCorrosion pit is observed particularly at steel, high strength aluminum alloys and metals under the influence of corrosive medium and is defined as the beginning of potential crack formation. Safe and secure usage of materials are limited in many industry branches. The structural elements that carry loads and transmit motion become unable to match the task because of corrosion pits that form on the environment they work. The circular cross section that serves as structural element under the force of certain torque force and may be exposed to this situation. In this study the behaviours under torsinoal stress where corrosion pits formed in pins are examined and stress analysis are made with finite element method. For corrosion pits spherical pit, elliptical pit, and secondary pit geometries have been modelized in Ansys package program. Spherical pit models are changed from shallow pit model to deep pit model in different depths, elliptical pit models in different depths are changed from shallow pit model to deep pit model, also a change in shaft angle to the axis of the elliptical pits are positioned systematically. At the same time, a secondary spherical pit presence is thought at the base of semi-spherical pit, this secondary spherical pit geometry is modelized by magnifying in different diameters and depths. After these modelizing under torsional stres effect where there is no corrosion pit on the surface, a torque force is determined on the outer surface of the pins that may cause 1 MPa shear stress. The same torque of the above-mentioned hollow shafts of corrosion in different sizes and geometries using finite element method was applied using the program package Ansys. And much higher shear stresses emerged. This situation can be explained by the effect of stress concentration. The obtained results are measured as dimensionless by dividing them to ? ort one by one, so the stress concentration factor Kt is obtained directly.