How to write your research work in simple way
Use a hierarchical structure that is clearly shown to the reader.    https://www.amazon.com/Pyramid-Principle-Logic-Writing-Thinking/dp/0273710516  Make a bulleted outline of each section of work before writing.
Be honest and direct.  https://ocw.mit.edu/courses/media-arts-and-sciences/mas-111-introduction-to-doing-research-in-media-arts-and-sciences-spring-2011/readings/MITMAS_111S11_read_ses5.pdf
Look at the "directions to authors" for each journal you submit to and follow them rigorously, like a checklist.
Write frequently and get frequent feedback and incorporate it.  Look for those who are good writers to review your work.  


P.s.  I disagree with the advice to write in your native tongue and then have a translation made.  You will not learn well that way.  Stick to your flawed English but get better as you use it.  If anything being weaker in English will force you to a simpler sentence structure (fine).  Issues with clarity are very likely not the language problem but poor structure or poor logic.  "Clear writing is clear thinking."