PSI - Issue 28

Shayan Eslami et al. / Procedia Structural Integrity 28 (2020) 659–666 Shayan Eslami/ Structural Int grity Procedia 00 (2019) 000–000

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Figure 3- a) the new developed welding tool, combination of rotary and stationary shoulders, and b) the tested specimen using this tool.

This innovative tool showed a promising result and with further investigation and improvement, it has the capacity to produce sound welds with much higher tensile strength and better surface quality. The improvements that need to be considered are: maximum probe penetration to eliminate the root defect, ceramic coating of the stationary shoulder for better surface quality, heat isolation of the copper sleeve to localize the frictional heat, and increase the spindle capacity to generate more torque. 4. Conclusion The aim of this work is to propose a new technological solution of joining thermoplastic based composites. 30% short glass fiber PA6 was chosen as the base material in the butt-joint configuration. FSW method was selected as the based technology to analyze the possibility of welding polymer-based composites. As the tool design proved to have a significant effect in this process, the main focus of this research was regarding the tool design and process optimization. Three different tool designs were tested and welding temperature and active forces during welding were recorded during all the welding processes. Like the polymeric materials, it was concluded that to achieve sound welds, a stationary shoulder tool is necessary to avoid formation of flash defects. The PEEK stationary shoulder was able to obtain welds with maximum tensile strength of 43% compared to the base material. All the welding parameters had significant effect on the weld strength as following: rotational speed (57%), welding speed (12%) and axial force (7%). Even though the PEEK stationary shoulder produced welds with excellent surface quality, the produced welds were suffered from lack of frictional heat. In order to improve the weld quality, a new tool concept was designed and tested, which produced welds with 58.8% strength of the base materials. From the initial experimental tests, it was proved that FSW is a promising method for joining thermoplastic based composites, and with an appropriate tool design and compatible welding parameters it has the potential to produce sound welds with good quality surface. However, this area suffers from lack of investigations, and in order to be a reliable joining method, further study is required, especially regarding the tool design and process optimization.

5. References Biron, M. (2018). Thermoplastics and thermoplastic composites : William Andrew. Campbell, F. C. (2011). Joining: understanding the basics : ASM International. Eslami, S. (2019). Friction stir welding of polymers: an innovative technological approach.

Eslami, S., Francisco Miranda, J., Mourão, L., Tavares, P. J., & Moreira, P. M. G. P. (2018). Polyethylene friction stir welding parameter optimization and temperature characterization. The International Journal of Advanced Manufacturing Technology . Retrieved from https://doi.org/10.1007/s00170-018-2504-x doi:10.1007/s00170-018-2504-x