How to find a good topic for a PhD research proposal?
Jot down your interests.
Future goals (long term and short term). Doesn't have to be accurate but just to give you the "big picture".
Speak with your PhD advisor (if you already have one).
Align his/her interests with yours and see if you have common ground (you may need to lean towards his interests or find another advisor)
Once you have a list of topics that you could explore, do a literature review and figure out for what topics you'd have a taste.


Each person has his own formula on what to choose as their PhD proposal. This was the way I went about it.

PhD (Mechanical Engineering Expected Fall 2012)