Creep rupture of viscoelastic fiber bundles

We study the creep rupture of bundles of viscoelastic fibers occurring under uniaxial constant tensile loading. A fiber bundle model is introduced that combines the viscoelastic constitutive behavior and the strain controlled breaking of fibers. Analytical and numerical calculations showed that above a critical external load the deformation of the system monotonically increases in time resulting in global failure at a finite time $t_f,$ while below the critical load the deformation tends to a constant value giving rise to an infinite lifetime. Our studies revealed that the nature of the transition between the two regimes, i.e., the behavior of $t_f$ at the critical load ${\sigma }_c,$ strongly depends on the range of load sharing: for global load sharing $t_f$ has a power law divergence at ${\sigma }_c$ with a universal exponent of 0.5, however, for local load sharing the transition becomes abrupt: at the critical load $t_f$ jumps to a finite value, analogous to second- and first-order phase transitions, respectively. The acoustic response of the bundle during creep is also studied.