Modeling heat generation in polymer–polymer interfaces under ultrasonic vibration: a coupled friction and viscoelastic approach

To quantify the interfacial friction and volumetric viscous heating contribution of polymers during ultrasonic plasticization is of great significance for optimizing plasticization process parameters. This paper presents a coupled numerical analysis model considering multiple heat sources in a simplified ultrasonic plasticizing system. The contribution of contact position angles and ultrasonic process parameters to interfacial friction and volumetric viscous heating of polymers was considered, and the accuracy of the model was verified by infrared experiment and simulation. The following conclusions were summarized: the interface temperature increases first and then decreases during the experiment, and the heat generation mainly occurs in the first second of plasticization. The effects of process parameters on polymer heating, dynamic parameters, and energy were studied by simulation. It was found that the contact position angle and ultrasonic process parameters controlled the heat generation process by influencing the friction force and slip velocity between pellets. Under standard processing conditions, when the contact position angle ranges from 0°to 90°, both the heat production rate and total heat initially increase before subsequently decreasing, reaching a maximum at approximately 40°. At this optimal angle, the friction force is around 27.5 N, the slip rate is about 2250 mm s⁻¹, and the heat production rate measures 11 K ms⁻¹. The results indicate that when the amplitude is set at 40 μm, the frequency at 30 kHz, and the contact angle at 40°, the ultrasonic plasticizing effect is optimized. This configuration ensures a higher rate of heat generation while minimizing material degradation. The interfacial friction heat is significantly higher than the volumetric viscous heat under each condition. The interfacial friction heat is usually 3–5 times higher than the volumetric viscous heat. This study provides a basis for the high-quality molding of polymer ultrasonic plasticization.