The fracture of SVM aramide fibers upon a high-velocity transverse impact

Behavior of SVM aramide fibers tested by high-velocity transverse impact wi th a heavy metal ball incident at a velocity of 670 m/s was experimentally studied using yam with a linear density of 58 tex composed of 300 elementar y fibers. The impact interaction was monitored by high-speed photography. T he impact leads to fracture of the SVM fibers. According to calculations pe rformed within the framework of a classical theory, no fracture of the fibe rs should take place. It is suggested that the discrepancy is related to tw o nonlinear effects. The first is a nonlinear character of the stress-strai n relationship at a high level of material deformation, which gives rise to additional tensile strain waves in the fiber with an amplitude different f rom that predicted by a theory based on linear behavior. The second effect is related to a more complex character of interaction between fiber and bal l in the course of impact, whereby the fiber loading is at a least a two-st age rather than a single-stage process. This leads to additional overloadin g of the fiber, with the resulting stresses exceeding the ultimate tensile strength of the material.