Experimental Study of Dynamic Frictional Sliding Modes along Incoherent Interfaces

bimaterial structure;crack-like rupture;Dynamic frictional sliding;homogeneous system;incoherent interface;photoelasticity;pulse-like rupture;subshear wrinkle-like pulse;supershear rupture;velocimetry

Lykotrafitis, Georgios C. ; Rosakis, Ares J.

University:California Institute of Technology

Department:Engineering and Applied Science

关键词: bimaterial structure;    crack-like rupture;    Dynamic frictional sliding;    homogeneous system;    incoherent interface;    photoelasticity;    pulse-like rupture;    subshear wrinkle-like pulse;    supershear rupture;    velocimetry;   

Others  :  https://thesis.library.caltech.edu/196/1/GLYKO_Thesis.pdf

美国|英语

来源: Caltech THESIS

【 摘 要 】

Dynamic sliding along incoherent (frictional) interfaces is investigated experimentally in a microsecond time scale. A bimaterial system comprised of Homalite and steel plates and a homogeneous system consisting of two Homalite plates are considered. The plates are held together by a uniform compressive stress while dynamic sliding is initiated by an impact-induced shear loading. The evolution of maximum shear stress contours is recorded by high-speed photography in conjunction with dynamic photoelasticity. Simultaneously with photoelasticity, a newly-developed technique based on laser interferometry is employed to locally measure the sliding speed at the interface.

The response of the Homalite-steel bimaterial system differs according to whether the impact loading is applied to the Homalite plate or to the steel plate. In the first case, a disturbance traveling along the interface at a constant speed close to the Rayleigh wave speed of steel generates a shear Mach line crossing the P-wave front. Sliding initiates behind the P-wave front in the Homalite plate and it propagates at a supershear speed with respect to the shear wave speed of Homalite. A disturbance, traveling at constant speeds between the shear wave speed and the longitudinal wave speed of Homalite, appears behind the sliding tip. Wrinkle-like opening pulses, propagating along the bimaterial interface at a constant speed between the Rayleigh wave and the shear wave speed of Homalite, are also observed. When the impact loading is applied to the steel plate, sliding at a given point initiates with the arrival of the P-wave front there, so that the rupture is sonic with respect to steel and supersonic with respect to Homalite.

In all the experiments performed on the bimaterial structure (Homalite-steel), sliding always occurred in a crack-like mode. In the case of a homogeneous system of Homalite plates however, direct physical evidence of different modes of sliding is recorded. Crack-like sliding, pulse-like sliding and mixed mode sliding in the form of pulses followed by a crack are discovered. Supersonic trailing pulses are also recorded. Behind the sliding tip, wrinkle-like opening pulses are developed for a wide range of impact speeds and confining stresses.