Jesus, what can’t you study in more detail in grad school?
Seriously, an undergrad in Mechanical Engineering (which I have) serves only to introduce you to the fundamentals; unless you’ve spent a considerable amount of time in extracurricular study, you barely know anything beyond basic engineering priciples. In particular, areas of advanced study include computational fluids dynamics, nonlinear and digital controls theory, materials fatigue theory, micro-electrical-mechanical systems (MEMS), aeroelasticity, systems design, adaptive systems, heuristic automation design (AI robotics, machine vision), adaptive tribology, nonlinear vibrations theory, biomechanical systems, and so forth.
Don’t get stuck on the idea of a “pure” ME degree; cross-training in another field (physics, computational science, chemistry, materials science, even biology) gives you a greater breadth of knowledge, allowing you to apply skills traditionally used in one field (say, controls theory) into a entirely seperate one (biomechanics).
Structural finite element analysis (FEA) has become rather old hat; there are plenty of very accessible commerical codes out there that permit even a moderately trained engineer to perform analysis. (Whether that makes them qualified to correctly interpret the results is another question, but I’ve found that a graduate degree is often no qualifer of that capability; such skill comes only with experience and test validation.) I wouldn’t select a graduate thesis on some aspect of FEA unless you’ve really got a novel idea.
OTOH, don’t expect any technical degree to make you wealthy, or even offer stable employment. If you want the six figure income, get yer MBA and go into management.
::sigh:: I hate giving that kind of advice.