Viscous heating triggers strain localization: Experimental evidence

Strain localization is a natural deformation process that has been variously attributed to brittle, chemical or geometrical precursors. Despite some theoretical consideration, experimental evidence for temperature softening was lacking. We report thermally-activated strain localization in prismatic samples of homogenous and isotropic glassy polymer. Uniaxial compression was performed at room temperature and at different but constant displacement rates while the temperature was captured with an infrared camera. Results show temperature increase due to viscous heating along planar zones before any rupture along these zones. We validated the experimental results with a thermo-mechanical numerical model. This experimental investigation extrapolated to geological conditions shows that viscous heating can induce strain localization in all levels of deforming lithosphere.