Modeling thermal processes using the equivalent point method

Evaluation of thermal processes requires accurate treatment of the time-temperature history of exposure. For the Equivalent Point Method (EPM) of thermal evaluation, the effectiveness of five different numerical methods has been assessed for estimation of both the equivalent time and the equivalent temperature. The performance of each method was tested with three simulated data sets. The traditional method of Line Intersections resulted in significant error. Both Least Squares Linear Regression and Least Absolute Value Linear Regression yielded only a slight improvement. By contrast, Nonlinear Least Squares Regression and Weighted Least Squares Regression (WLSR) resulted in excellent estimations with WLSR being easier to use. Error analysis demonstrated accurate predictions of concentration changes for constituents over a wide range of activation energies.