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УДК 539.376

 

Pavluk Ya., Ragulina V., Fernati P.

Institute of Mechanics, National Academy of Sciences of Ukraine, Kyiv, Ukraine

 

FORWARD AND THE RETURN CREEP NONLINEAR- VISCOELASTIC-PLASTIC MATERIALS AT MONOAXIAL LOADING

 

The problem of the calculation of deformations of forward and the return creep nonlinear- viscoelastic plastic materials at monoaxial loading is considered. For the description of process of deformation the nonlinear model of creep with nonlinearity independent of time like Yu. N. Rabotnov's model is used. Nonlinearity of model is set by the tensile stress-strain diagram which is set by a smoothing cubic spline. The exponential-fractional function as kernel of heredity is used. The loading behaviours are given by the Hevyside’s function. The constructed equations allow to consider irreversible in time viscoplastic deformation. Parameters of the equations are defined from the basic experiments including the tensile stress-strain diagram and some curves of creep at a constant tension. The area of viscoelastic and viscoelastic-plastic deformation is determined by the tensile stress strain diagram. Experimental approbation of the results of calculation on problems of forward and the return creep of fibreglass of contact modeling and nylon fibers FM 10001 is executed. 

Keywords: nonlinear model of creep, return creep, exponential-fractional function, heredity kernel, experimental approbation, viscoplasticity.


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