Demonstration of bond quality improvement for closed loop control of thermoplastic tape-laying

In thermoplastic tape-laying, the temperature at the interface between the top ply and substrate is critical to achieving interlaminar bonding. Based on a three lump process model, a Kalman filter and a state feedback control ler were built to successfully estimate and control the interlaminar bondin g temperature during the process. A practical advantage of this controller is that the only measurement required is the heater temperature. In this wo rk, two methods are used to examine the bond quality when applying this fee dback control method. One method is a microscopy study and the other is a l ap shear strength test. Specimens were manufactured using the developed con troller to regulate the bonding temperature. The microscopy pictures show t hat the interlaminar bond width is reduced as the bonding temperature is in creased. The lap shear strength tests show that the bond strength is signif icantly improved as the bonding temperature is raised. Both test results ha ve consistently demonstrated the causal relationship between interlaminar b onding temperature and bond quality. The control method produces high quali ty laminates by using temperature feedback from the heater to estimate the interlaminar bonding temperature.