A COMPUTATIONAL ANALYSIS OF THE HEATING OF GLASS MAT THERMOPLASTIC (GMT) SHEETS BY DUAL-BEAM MICROWAVE SOURCES

The use of dual beam microwaves to heat glass mat thermoplastic has be en investigated numerically using a finite difference technique, known as the alternating difference implicit (ADI) method. The variation in thermophysical properties throughout the GMT has been accounted for u sing a table look-up procedure, which provides the appropriate thermop hysical properties for the thermal conditions at each mesh point. The use of dual beam microwaves has been shown to significantly reduce the heating times under all geometric conditions, material variations, an d glass loadings. Sheet thicknesses were varied from 1 to 12 mm, glass loadings from zero to 40 wt% polypropylene, polycarbonate and nylon w ere all simulated. The computations indicate a clear advantage in heat ing times when dual beam microwave heating sources are employed.