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چکیده
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One of the main challenges in recent friction stir welding (FSW) investigations is the welding of pipelines. Limited numbers of researches have been investigated on FSW of metallic pipes while the FSW of polymeric pipes still remains challenging. In the present study, the FSW process of high-density polyethylene (HDPE) pipes is developed which is to the best of our knowledge for the first time to be reported. A stepwise fixture design is performed in order to achieve complete and high-quality welds. It was concluded that using a holder with an inner expandable support helps to enhance the welding condition of pipes. The yield strength of friction stir welded pipes as one of the mechanical properties is investigated using Taguchi approach. Rotational speed, transverse speed, and tool offset are selected as input parameters. Results of analysis of variance (ANOVA) indicated that rotational speed is the most effective parameter on yield strength followed by tool offset and transverse speed. Based on the results of the signal to noise ratio (S/N) analysis, the optimum levels of input variables that give the maximum yield strength were 2500 rpm of rotational speed, 110 mm/min of transverse speed, and 3.5 mm of tool offset.
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