[Bloodworth et al., 2008] Bloodworth T., Cook G., Strauss A. “Properties and forces of

immersed friction stir welded AA6061-T6”. 8th International Conference of

Trends in Welding Technology. Pine Mountain, GA. (2008). 1-5.

Or you can read his thesis directly...

http://research.vuse.vanderbilt.edu/vuwal/IFSW.shtml

In fact, this topic is new and has not been discussed extensively, and following is some researches that have touched it:

https://www.sciencedirect.com/science/article/pii/S1003632609603095

https://www.ripublication.com/iraer-spl/iraerv4n2spl_12.pdf

http://journals.sagepub.com/doi/abs/10.1177/0954405414555560?journalCode=pibb

You can meet me i will give you some solution