Evolution of dynamic shear strength of frictional interfaces during rapid normal stress variations

Pressure shear plate impact tests have revealed that when normal stress changes rapidly enough, the frictional resistance is no longer proportional to but rather evolves with slip gradually. Motivated by these findings, we focus on characterizing dynamic strength of interfaces subject rapid variations in stress. To study this problem, use laboratory experiments featuring cracks interacting a free surface and resulting pronounced variations. As tend propagate close wave speeds material, capturing their behavior poses metrological challenge resolving displacements order microns over timescales microseconds. Here present our novel approach quantify full-field ruptures evolution friction during sudden stress, based ultrahighspeed photography (at 1-2 million frames/sec) combined digital image correlation. Our measurements allow us capture short transients enable decode nature friction.