Which is the best Book for Mechanical Engineer of SOM(I.e Strength of Material)?
Here are some of the books you can prefer which is good to understand the basic concept & overall.
Elements of Strength of Materials 5 Edition by D. H. Young, S. P. Timoshenko
Advanced Mechanics of Solids 3 Edition by LS Srinath
A Textbook of Strength of Materials : Mechanics of Solids (S.I. Units) 5 Edition by R.K Bansal
Strength of Material by R.K Rajput
Good Luck!