Optimization of Friction Stir Welding Parameters of PP/AA5052 Hybrid Structures

  • Yasser Jamal Eddin Aldaghestani

Student thesis: Master's Thesis

Abstract

Over the past decade, friction stir welding of dissimilar materials has attracted substantial attention since it can be used in various industrial applications such as shipbuilding, aerospace, automotive and robotics, and most of these applications require light weight, cost effective, clean, and relatively safe components. In this study the joining of metal to polymer in a hybrid joint using friction stir lap welding was investigated. An experimental setup was built in order to test the feasibility of welding AA5052 to polypropylene (PP) in a lap joint. To begin with, multiple screening experiments were conducted to identify the working envelope. After that a full factorial design with three levels of each process parameter was performed. Forces in three directions (axial, welding, and lateral), joint lap shear strength, and the temperatures at the advancing and retreating side were analyzed by varying rotational speed, traverse speed, and tilt angle. Sound hybrid joint was achieved, and it was found that increasing the rotational speed and tilt angle resulted in an increase of the joint strength, while increasing the traverse speed lead to a decrease in the joint strength. Moreover, microstructure analysis was done by using scanning electron microscope (SEM) and revealed that mechanical interlocking induced by the generation of metal hooks contributed to the strength and performance of the joint. Direct relationship was found between hook size on the advancing side and lap shear strength. Also, elemental mapping at Al-PP interface was done and discovered the existence of magnesium, aluminum, carbon, and oxygen.
Date of AwardJul 2022
Original languageAmerican English

Keywords

  • Friction stir lap welding
  • mechanical interlocking
  • AA5052
  • PP
  • tilt angle
  • plunge depth.

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