Photoviscoelastic Stress and Strain Analysis around a Surface Groove under Rolling Contact Load

The authors discuss the first step in the approach to the fundamental mechanism of small-scale local fracture near the contact surface between a rigid traveling roller and a viscoelastic plate which has a deep groove on the upper edge of the plate, which simulates pitting or surface cracking around the contact surface. The photoviscoelastic method is applied to investigate the time-dependent stress and strain state under the condition of nonproportional loading, taking a typical case of the interaction of stress fields due to a traveling contact load and a surface groove into account. Complicated variations of the time-dependent photoviscoelastic fringe pattern are observed near the tip of the surface groove. The time variations of not only the principal stress difference and principal strain difference, but also principal directions of stress, strain and birefringence are evaluated using a convenient computer-aided photoviscoelastic technique under the temperature at which the material shows marked viscoelastic behavior. Time variations of stress intensity factors, K I and K II , are also evaluated using the least-squares method following the technique proposed by Sanford and Dally.