This happens to be one of the best websites for mechanical engineering concepts. There is but no alternative to MIT OCW (OpenCourseWare). It’s a good source of information for not only mechanical engineers but for many other streams. Every content taught at MIT is also available online through MIT OpenCourseWare. It could be audio/video lectures, text content, e-books or latest inventions and patents, MIT OCW has it all for a student to expand his/her knowledge.
NPTEL by MHRD is one of the finest sources of information for Mechanical Engineers. Some of the well-renowned courses are Thermodynamics by Prof. S.K. Som and Fluid Mechanics by Prof. S.K. Som.
Began in March 2014, ME Mechanical has published many articles on various topics in engineering like automotive, machine design, manufacturing, hydraulic machines, thermodynamics, power plant engineering, heat transfer and fluid mechanics.