, Volume 49, Issue 12, pp 2979–2990 | Cite as

Thermomechanical coupling effect of graphite electrodes upon the electric arc furnace dynamics

  • Eugenio Brusa


Prediction of the dynamic behavior of electrodes of the electric arc furnace (EAF) fed by AC current is rather difficult because of several phenomena superposed, particularly during the first step of the melting process, i.e. the so-called perforation, and in case of the melting of scrap. Unexpected ruptures of electrodes are often observed as a consequence of vibration. Dynamic excitation is applied by the vertical position control of the mast supporting the electrodes and by the Lorentz’s forces generated by the magnetic flux provided by each electric phase. Moreover, the irregular distribution of stiffness along the electrode, being due to the sensitivity of the material properties upon temperature, affects quite a lot the dynamic response of this structure. To identify the origin of the observed ruptures and to suitably predict the dynamic behavior of the whole system a modeling activity was performed. A numerical model of the EAF structures was built, by resorting to an integrated approach based on the finite element method and on the multi body dynamics, then it was preliminarily validated on an existing plant. It was demonstrated that stiffening effect upon the graphite electrode induced by the temperature distribution makes dangerous the action of the vertical position control, when it is applied too fast and excites the flexural modes of the electrode. Numerical model allowed refining the design of the electrode and improving the safety factor as well as finding some design requirement to suitably limit the operation of the position control system.


Multi-body dynamics Finite element method Steelmaking equipment Mechanical design Graphite material 

List of symbols


Alternate current


Thermal expansion coefficient at 100 °C


Thermal expansion coefficient at current temperature


Diameter of the electrode


Elastic coefficient, Young’s modulus


Electric Arc Furnace


Electro-Motive Force


Reference Young’s modulus (computation of the distribution along the electrode)


Finite Element Method


Tangential elastic modulus


Transversal inertia of the electrode cross section


Polar inertia of the electrode cross section


Elastic constant


Torque applied to the electrode


Multi Body Dynamics



T21 °C

Temperature at 21 °C


Reference temperature for the computation of the distribution along the electrode


Distance between the cross section and the gripper along the electrode length


Coordinates of the global reference of the EAF system


Increment of thermal expansion coefficient


Increment of temperature along the axial direction of the electrode


Increment of temperature along the circumferential direction of the electrode


Increment of temperature along the radial direction of the electrode


Axial strain inside the electrode material


Circumferential strain inside the electrode material


Radial strain inside the electrode material


Axial strain inside the electrode material


Circumferential strain inside the electrode material


Radial strain inside the electrode material


Cross section rotation in torsion


Poisson’s coefficient


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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Department of Mechanical and Aerospace EngineeringPolitecnico Di TorinoTurinItaly

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