ABSTRACT
This chapter focuses on macromechanical behaviour that is the behavior when only averaged apparent mechanical properties. Knowledge of the mechanical behavior of a lamina is essential to the understanding of laminated fiber-reinforced structures. Engineering constants are generalized Young's moduli, Poisson's ratios, and shear moduli as well as some other behavioral constants. The shear strength in the principal material coordinates is seen to be independent of differences in tensile and compressive behavior, as it must be by definition of a pure shear stress. For negative shear stress, compressive stresses exist in the fiber direction and tensile stresses occur transverse to the fibers. The apparent shear strengths and shear stiffnesses are different for positive and negative shear stresses applied at 45° to the principal material coordinates. A unidirectionally reinforced lamina would need 'help' carrying in-plane stress perpendicular to its fibers, but that help can be provided by other layers that have their fibers in the direction of the stress.
