MACROMECHANICAL BEHAVIOR OF A LAMINA

The macromechanical behavior of a lamina was quantitatively described in Chapter 2. The basic three-dimensional stress-strain relations for elastic anisotropic and orthotropic materials were examined. Subsequently, those relations were specialized for the plane-stress state normally found in a lamina. The plane-stress relations were then transformed in the plane of the lamina to enable treatment of composite laminates with different laminae at various angles. The various fundamental strengths of a lamina were identified, discussed, and subsequently used in biaxial strength criteria to predict the off-axis strength of a lamina. 

Hence, the four measured engineering constants E, E, Glt, and Plt are sufficient to describe the linear elastic macromechanical behavior of a thin orthotropic composite lamina subjected to plane stress. 

---