Fatigue behavior of FRP composites and CNT‐Embedded FRP composites: A review

Composite materials have emerged as an effective substitute for conventional materials in various fields of engineering and structural science. For replacement of regular metals, composites, especially fiber‐reinforced polymer composites, have proved to be a suitable alternative. One of the important tests that conventional and composite materials have to undergo is fatigue test. It refers to the testing of materials for their cyclic behavior. In fatigue testing, depending on the choice of the researchers, materials are loaded till reaching their failure or till reaching a fraction of the total stiffness loss. Composite materials are different from metals and they show a distinct behavior under fatigue loading. In metals, failure occurs from the commencement of a single crack and then its propagation. In composite materials, conversely, it is a complex process as these materials possess crack‐arresting properties. This review paper highlights various aspects of the cyclic or fatigue behavior in composite materials. Factors triggering such behavior in composite materials include reinforcing substance, matrix material, fiber orientation or stacking sequence, fiber content, testing environment and so on, together with the damage development process at the microscopic level. Loading condition parameters pertain to stress ratio, mean stress, loading condition, multiaxial stress, and testing frequency. This article also includes the effect of carbon nanotubes on the fatigue life of the polymer composites. POLYM. COMPOS., 39:1785–1808, 2018. © 2016 Society of Plastics Engineers