Identification of glass pad lubricant viscosity using a trapping thermomechanical test

Glass lubricants are often used for many hot forming processes to minimize friction and to protect tools from premature thermal fatigue. In this paper, an identification procedure is presented to identify the viscosity of a glass lubricant. The identification of the viscosity of the glass lubricant is performed using an upsetting thermomechanical test. The test is designed to trap the lubricant between two workpieces made with the same super alloy as the one used for the industrial process. The measurement of the trapped lubricant thickness for different temperatures and strain rates conditions enables the identification of the lubricant's viscosity. Numerical simulations are performed using the identified viscosity to validate the methodology. Two different numerical approaches are compared. A classical updated Lagrangian approach and a monolithic Eulerian approach. (C) 2012 Elsevier B.V. All rights reserved.