A First Course in the Finite Element Method
This book provides plenty of examples and easy to follow algorithms to help visualise and understand the theory of what Finite Element Analysis (FEA) is about. Creating models in CAD software and then simulating stresses/ strains can be made more accurate simply by understanding the constraints and the problem itself.
Schaums Outline of Finite Element Analysis
This book is much more mathematical then the First Course book (discussed above) but does cover a broader range of problems. For the price, another useful reference to have and there will no doubt be a similar problem and solution that you can adapt and modify for your own work.
Roarks Formulas for Stress & Strain
This book outlines the equations and diagrams of just about every possible situation for stresses and strains. Examples are written clearly and in depth, whilst towards the back are pages of tables with a diagram showing a particular situation, and the equation required to solve it. Very comprehensive and worth having as a structural engineer and the principles are the same if you are designing a spacecraft or anything else structurally relevant.