There are many concepts in Research Methodology such as Research Paradigm, research approach, rationale of research, hypothesis and its testing, etc.But I haven't seen any of these in research papers of mechanical engineering. Why is that so ?
Assuming you are talking about the methodology for empirical research as it has established itself for investigations on the living, from agriculture via medicine to psychology (this range and the order neither complete nor historically correct, but reflects my personal knowledge about it), it was motivated by the stunning sampling variation that adds to the measurement variation known from physics, and is conceptually different from any replication variability in manufacturing processes of technical products. Without an appropriate methodology that addresses the sampling variation of biological individuals, progress in the pertinent sciences and associated technologies (e.g. pharmaceuticals) would have been hindered by schools of thought, schools of application, and mainly beliefs by trend-setting peers - notwithstanding that intuition still is and will always remain an important factor in practising of medicine.