Modeling the Flow and Distribution of Nanoparticles in Friction Stir Processed Polymeric Composite Materials

Friction stir processing is an advanced manufacturing process in which a specially designed rotating pin is first inserted into the adjoining edges of the materials to be processed with a proper tool tilt angle and then move all along the adjoining edges. The pin produces frictional and plastic deformation heating in the processing zone. As the tool pin moves, materials are forced to flow around the pin. Material flows to the back of the pin, where it is extruded and forged behind the tool, consolidated and cooled under hydrostatic pressure conditions. The primary research about friction stir processing has been focused on aluminum alloys. In recent years many researchers have been trying to apply this technology for processing other alloys and materials including stainless steels, magnesium, titanium, and copper. In addition, this technology has been used to modify the microstructure of reinforced metal matrix composite materials. However, friction stir processing polymeric based materials are much less studied. Friction stir processing has the advantage of reducing distortion and defects in materials. It has potential to be used in manufacturing nanoparticle-reinforced polymeric composite materials. In this work, modeling the flow pattern and the distribution of nanoparticles in friction stir processed polymeric composite materials was performed. The internal pressure in friction stir processed composite materials was also derived, which may be used to predict the residual stress state in the nanocomposite material joint. It is found that the pressure in the joint is a function of radial position from the tool pin. The magnitude of the pressure is related to the tool geometry and the welding conditions such as tool rotating speed etc.