Mechanical behavior of nylon 66 fibers under monotonic and cyclic loading

The deformation and fracture behavior of partially oriented nylon 66 fibers with a diameter approximately 33 μm exposed to uniaxial monotonic and cyclic loading was studied using a unique test technique. Prior cyclic deformation resulted in a ratchet strain as well as a decrease in residual strength and ductility of the fibers. A description of the fracture process is hypothesized and supported by critical flaw size and energy calculations. The critical flaw size at fracture did not depend on the prior cyclic loading history.