Tatmyshevskiy K.V.  

Solution of the problem of impact elastoplastic deformation of a thin layer of mechanoluminophor using the methods of the dislocation microdynamic theory of plasticity

In the present work, the results of numerical modeling of output optical signals of mechanoluminescent sensors of impact influences are presented. Such sensors are based on the principle of direct transformation of mechanical energy of impact to optical radiation energy. The sensitive element of such sensor consists of a phosphor layer concluded between two transparent flexible polymeric films. The most commonly used working substance in the sensitive element is fine crystals of zinc sulfide, alloyed by the activator (manganese or rare-earth metals). Under the influence of an impact, optical signal is generated in the layer of a phosphor. This signal is transmitted to the photoreceiving device by fiber-optic cable, and further to the recorder. The mathematical model of the sensor is based on the process of exaltation of the centers of luminescence (activator atoms) in the stronger electric field of a moving dislocation. The equation of the centers of luminescence excitement rate and the equation of kinetics of an intra-center mechanoluminescence are formulated. The intense strained state of the film sensitive element under a quasistatic monoaxial load under the influence of a single impulse of pressure is examined. The defining formulas of elasto-plastic deformation and the formulas of the dislocation theory are analyzed. The formula defining plastic deformation is given based dislocational understandings. For the calculation of deformation of the sensitive element, microscopic model of isotropic elasto-plastic continuum with hardening is used. Corresponding to this model, the plastic deformation is viewed as a result of movement and manifolding of dislocations, and hardening – as result of their partial locking because of increased density. Using such model is convenient because the mechanoluminescence kinetics equation is based on a direct determination of two components: average density of the mobile dislocations and average velocity of the dislocations, averaged over the whole volume of crystal. Density of the mobile dislocations was defined as a fraction of the general density of dislocations with their manifolding and locking. The received results of numerical calculations correspond well with the experimental results.

To reports list