Numerical and experimental determinations of contact heat transfer coefficients in nonisothermal glass molding

Heat transfer at the interfacial contact is a dominant factor in the thermal behavior of glass during nonisothermal glass molding process. Recent research is developing reliable numerical approaches to quantify contact heat transfer coefficients. In most previous studies, however, both theoretical and numerical models of thermal contact conductance in glass molding attempted to investigate this factor by either omitting surface topography or simplifying the nature of contact surfaces. In fact, the determination of the contact heat transfer coefficient demands a detailed characterization of the contact interface including the surface topography and the thermomechanical behavior of the contact pair. This paper introduces a numerical approach to quantify the contact heat transfer by means of a microscale simulation at the glass-mold interface. The simulation successfully incorporates modeling of the thermomechanical behaviors and the three-dimensional topographies from actual surface measurements of the contact pair. The presented numerical model enables the derivation of contact heat transfer coefficients from various contact pressures and surface finishes. Numerical predictions of these coefficients are validated by transient contact heat transfer experiments using infrared thermography to verify the model.