JAD was first implemented by IBM in the late 1970's to involve the end user in the design of applications. This was to make the final developed system more user focused than machine/hardware focused. It really never had a separate life cycle but was part of the overall development life cycle used on the project. Whether waterfall, evolutionary, prototyping or some form of Agile, JAD fits in as a set of user focused methods in every phase of the cycle.

SDLC is not a methodology.  Waterfall, Agile and so on are methodologies. JAD is more of an approach and is a term not used so much these days. Have a look at Agile.