Fracture of drawn tungsten wires

Conditions that govern the process of fracture in fibrous material were examined with fine, heavily deformed tungsten wires. In particular, the nature of interaction between fiber rupture and delamination in the fracture process was determined by deforming wires under different loading conditions. This was accomplished by testing fine wires under simple uniaxial and bend-and-stretch loading conditions so that the effective stress state could be altered in the deforming fibers. Results of mechanical testing and scanning electron microscopy examination indicated that the process of fracture was controlled by fiber rupture but only to the extent that it could be accommodated by the delamination of fiber interface. The degree of the delamination process in turn was dependent on the magnitude of the radial stress in outer fibers. This view point was supported by an experiment with wires that contained surface flaws