Primary creep transients due to non-uniform obstacle sizes

The effect of a heterogeneous population of site strengths on creep is considered. It is argued that all of the common creep transients (fast plastic, logarithmic and power-law or Andrade creep) can be explained by a single simple model that is based on a large number of interacting sites. The model naturally develops exhaustion of flow on weaker sites by shedding stress to stronger sites, which themselves are able to flow. Systematic changes in the creep behavior with temperature from the model are similar to those observed experimentally.