10. Testing of Composites

Composites are produced from two or more constituent materials with dissimilar chemical or physical properties that are emerged to create a material with properties unlike the individual elements. Of the various types of composites the most important category is the fiber composites, in which a matrix is reinforced with continuous fibers. Fiber composites are anisotropic materials that need special methods for the study of their mechanical behavior, much more complicated than those of isotropic materials. In this chapter we present test methods for the mechanical characterization of a unidirectional lamina of fiber reinforced composite materials under tension, compression and shear. We also present methods for the determination of the interlaminar fracture toughness of laminates under mode-I, II, III and mixed-mode loading. Finally, we introduce the sandwich materials, and study their failure mechanisms.