TABLE OF CONTENTS The mechanical properties of simple unidirectional continuous fiber composites depend on the volume fraction and properties of the fibers (including flaw and strength distribution), the fiber/matrix bond strength, and the mechanical properties of the matrix. The alignment (waviness) of the fibers also has a significant effect on some properties notably, compression strength. Elevated temperature and moist environments also significantly affect properties dependent on matrix properties or interfacial strength.
Because of these and several other factors, the efficiency of translation of fiber properties into those of the composite is not always as high as may be expected. Stiffness can be predicted more reliably than strength, although static tensile strength is easier to predict than other strength properties. Chapter 2 provides some elementary equations for estimating the mechanical properties of unidirectional composites, which are reasonably accurate in estimating elastic properties, providing fiber alignment is good. The equations can also provide ball-park figures for the matrix-dominated shear and transverse elastic properties and the fiber-dominated tensile strength properties. However, estimation of matrix-dominated or fiber/matrix bond strength dominated strength properties, including shear and compression, is complex. Prediction problems also arise when the fibers are sensitive to compression loading, as is the case for aramid fibers, as discussed later.
Chapter 7 describes the experimental procedures for measuring the mechanical properties, including those for assessing tolerance to damage and fatigue. These tests are used to develop a database for design of aerospace components and as part of the information required for airworthiness certification, as described in Chapter...
