A Methodology to Determine Tooling Interface Temperature and Traction Conditions from Measured Force and Torque in Materials Processing Simulations Based on Multimesh Error Estimation

摘要

A methodology is presented for estimating average values for the temperatureand the frictional traction over a tool-workpiece interface using measuredvalues of force and torque applied to the tool. The approach was developedspecifically for friction stir welding and friction stir processingapplications, but is sufficiently general to be of use in a variety of otherprocesses that involve sliding contact and heating at a tool-workpieceinterface. The methodology works with a finite element framework that isintended to predict the evolution of the microstructural state of the workpiecematerial as it undergoes a complex thermomechanical history imposed by theprocess tooling. We employ a three-dimensional, Eulerian, finite elementformulation; it includes coupling among the solutions for velocity, temperatureand material state evolution. A critical element of the methodology is aprocedure to estimate the tool interface traction and temperature from typical,measured values of force and torque. The procedure leads naturally to anintuitive basis for estimating error that is used in conjunction with multiplemeshes to assure convergence. The methodology is demonstrate for a suite ofthree experiments that had been previously published as part of a study on theeffect of weld speed on friction stir welding. The probe interface temperaturesand torques are estimated for all three weld speeds and the multi-mesh errorestimation methodology is employed to quantify the rate of convergence.Finally, comparison of computed and measured power usage is used as a furthervalidation. Using the converged results, trends in the material flow,temperature, stress, deformation rate and material state with changing weldconditions are examined.