The state of a 2-D random resistor network, resulting from the simultaneous
evolutions of two competing biased percolations, is studied in a wide range of
bias values. Monte Carlo simulations show that when the external current I is
below the threshold value for electrical breakdown, the network reaches a
steady state with a nonlinear current-voltage characteristic. The properties of
this nonlinear regime are investigated as a function of different model
parameters. A scaling relation is found between /0​ and I/I0​, where
is the average resistance, 0​ the linear regime resistance and I0​
the threshold value for the onset of nonlinearity. The scaling exponent is
found to be independent of the model parameters. A similar scaling behavior is
also found for the relative variance of resistance fluctuations. These results
compare well with resistance measurements in composite materials performed in
the Joule regime up to breakdown.Comment: 9 pages, revtex, proceedings of the Merida Satellite Conference
STATPHYS2