On the Influence of Process Control on Temperature Uniformity and Bondline Characteristics in Electrical Resistance Welding of Carbonfiber-Reinforced Polyphenylene Sulfide

Resistance welding (RW) of high-performance carbonfiber-reinforced (CF) thermoplastics such as polyphenylene sulfide (PPS) have high potential for the use in aircraft primary and secondary structure assembly due to its suitability and scalability for high-volume production. In this study, we investigate the application of electrical RW for CF/PPS using a CF-based weld conductor. We focus on the validation of temperature homogeneity during the heating phase and the characterization of the resulting welding properties using non-destructive and destructive testing methods. Two methods of applying power with constant voltage and pulsed voltage were investigated and compared with regard to the temperature homogeneity of the weld. Experiments were conducted to characterize the properties of the welds and validated using a Design of Experiments (DoE) based screening test plan. The welds were validated for heating time, attenuation losses during water coupled ultrasonic testing (acc. to AITM 6- 4010) and single lap shear strength (acc. to ASTM D1002). Furthermore, the weld results were examined in detail by means of reflected-light and scanning electron microscopy for a clear interpretation of the DoE results. Thus, the present investigations served to further understand important process variables in relation to RW, paving the way for the detailed design of a robust process cycle.