The effect of multi-axial loading on single Kevlar® KM2 fibers is explored with an emphasis on correlating the results to fiber/yarn transverse impact. A 0.30 caliber fragment simulation projectile (FSP) is slightly modified to act as a transverse loading indenter. Fiber failure angles are forced between ∼0° and 50° in efforts to deduce the deleterious effect caused by such angles. Said angles are also enforced in order to create the geometry that would be produced at an impact velocity causing immediate fiber/yarn rupture in transverse impact experiments. The effect of fiber angle around the FSP indenter is experimentally studied along with an analysis of the specific angle causing immediate fiber failure. It is shown that there exists a demonstrative reduction in fiber longitudinal failure strain of KM2 filaments due to this multi-axial stress state, thereby questioning the recurrent assumption that fiber performance within a body armor system is dominated by failure in pure tension.
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