Hello, researchers. I have difficulty in understanding the physical meaning of Green-Lagrangian strain (E) and Eulerian-Almansi strain (A) measures. Mathematically speaking, I can derive the equations of these strains in different ways. But physically speaking, it's a bit harder to understand how these strains (E and A) can be pictured and how to give a proper physical definition for them. In a simple case, considering a uni-axial bar (Please refer the attached file), Engineering strain can be understood easily, but in E and A equations, from where do the squares of the lengths originate? and how does it came into the picture?. or Is E and A are the true strain measures and engineering strain is the linearization of E and A?. How to understand this? I referred several books and online sources, but I failed to understand the clear interpretation of these strain measures (E and A). Would be much appreciated if someone explains me this or give me the useful references to read. Thanks in advance.