Experimental evaluation of joint strength in polypropylene-glass fiber reinforced composites under tensile load

Thermoplastic composites are widely used in various industries due to its inherent properties. One of the most important parameters in the composite industry is the junction of composite components. In this research, the strength of joints of thermoplastic composites has been investigated empirically. Composite specimens are made of Commingled fibers which consist of glass/polypropylene, using a pultrusion process and as rectangular cross section profiles. For junction of the samples three methods are used including, bolted joint, ultrasonic weld and hot press. Based on the experimental results, the mechanical performance and failure of the ultrasonic weld and hot press methods were compared with the mechanical couplers. The results show that the ultrasonic bonded samples are better than the hot press method. In ultrasonic welding, the best strength is obtained for highest welding time of 1.8s, and for hot pressing the best result related to the maximum temperature of 200 ° C and the maximum pressure of 1.5 bar. The maximum force for bolted joint belongs to the specimens with a diameter to width ratio of 0.2 and a hole to width ratio of 1.25. Also, the results of the tensile test show that the junction strength for ultrasonic and hot pressing methods compared to the bolted joint increased by approximately 4 and 1.5 times, respectively.