NUMERICAL MODELING OF THERMOMECHANICAL STRESSES GENERATED IN A THIN TRIBOLUMINESCENT FILMS UNDER LASER-PULSE ACTION
Triboluminescent films attract the attention of scientists and engineers as perspective materials not only for development of ophysical quantities sensors for robotic technical complexes, but also for creation of a new generation nondestructive testing systems. Triboluminescence is a visible or infrared light generated under the action of mechanical forces. Those mechanical forces may occur because of static, dynamic, or pulsing fields of pressure or deformation. For example, in the formation of surface cracks, the region of greatest stress are located in the vertices as they are stress concentrators, which contribute to further development of the crack. The values of the mechanical stresses in these stress concentrators may greatly exceed the stresses values, which affect the design as a whole. Mathematical models that associate the triboluminescent emitting flow with the mechanical forces, which produce that flow in materials, are widely used in triboluminescence studies. During the experimental studies of triboluminescence, the mechanical forces in triboluminescent materials are usually generated by short laser-pulse action. Therefore, it is necessary to set a correspondence between the value of mechanical forces in triboluminescent material and parameters of laser-pulse. In most cases, it is difficult to set this correspondence by experiment. In this paper proposed is the mathematical model that allows calculating the thermomechanical stresses generated in a thin triboluminescent film under laser-pulse action, estimating the duration transients, and determining the profile and parameters of laser beam. This model could be used for calculating the values necessary for obtaining requirement to mechanical forces and temperatures in triboluminescent films. The model consists of heat and nonstationary thermoelasticity equations, which are numerically solved by finite difference method.