On the influence of process control on temperature uniformity and bondline characteristics in electrical resistance welding of carbonfiber-reinforced polyphenylene sulfide

Abstract

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 suita-bility and scalability for high-volume production. In this study, we investi-gate the application of electrical RW for CF/PPS using a CF-based weld con-ductor. We focus on the validation of temperature homogeneity during the heating phase and the characterization of the resulting welding properties us-ing non-destructive and destructive testing methods. Two methods of apply-ing power with constant voltage and pulsed voltage were investigated and compared with regard to the temperature homogeneity of the weld. Experi-ments were conducted to characterize the properties of the welds and vali-dated using a Design of Experiments (DoE) based screening test plan. The welds were validated for heating time, attenuation losses during water cou-pled ultrasonic testing (acc. to AITM 6- 4010) and single lap shear strength (acc. to ASTM D1002). Furthermore, the weld results were examined in de-tail 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.