Базові моделі кінетики деформування-руйнування деревних композиційних матеріалів

Abstract

Existing models of kinetics of deformation and destruction are related mainly to the description of the transition from the undamaged state of the material destroyed into one stage. This applies both to classical theories of strength, including the kinetic theory of strength, and to the theory and models of damage accumulation (Continuum Damage Mechanics (CDM)). The purpose of this study was to create the basic models of kinetics of deformation-destruction, which describe this process in the form of several successive transitions of separate structural elements (SE), in a material that deforms from one rheological state to another in time. To describe this process is involved a formal kinetics apparatus, which allows, knowing the speed of the transition of the SE from one rheological state to another, predicting the time to reach the critical concentration of destroyed SE. It is established that the process of deformation-destruction can be considered as a process of gradual transition of the SE first of an elastic state, into viscoelastic and then destroyed. Moreover, this transition can occur both sequentially and in parallel. Thus, in the process of destruction, the number, and hence the concentration of SE, which are in different rheological states, is constantly changing. The change in the concentration of one or another SE can be determined experimentally by measuring the quantities that correlate with the parameters of deformation-destruction of one or another type of deformation of the body. In this case, the total number of elements of the structure, which are in different states, according to the law of conservation of masses at each time of deformation-destruction must remain constant. For the first time, a two-stage nonlinear kinetic model of resource loss with creep of composite materials based on wood is proposed. The application of formal kinetics methods in the simulation of physical-chemical processes that occur during deformation-destruction allows us to build multi-stage kinetic models. The application of the method of basic deformation diagrams in conjunction with the two-stage description of the process of accumulation of damage can increase the accuracy of the prediction of allowable time for different load patterns during creep.