Features of behavior of low-modulus viscoelastic polymer composites under changing strain amplitude of low-frequency component of biharmonic load

Uniaxial monoharmonic (one-frequency) tests under different values of pre-static strain, strain amplitude and uniaxial biharmonic (two-frequency) tests under different values of strain amplitudes of first (low-frequency) and second (high-frequency) harmonics were conducted on samples of low- modulus viscoelastic polymer composite. Complex operators method was used to describe behavior of a viscoelastic material under harmonic loads. Dynamic deformation properties of the composite material (loss angle, dynamic modulus under monoharmonic tests; loss angle, dynamic modulus first and second harmonics under biharmonic tests) were determined using special methods. Dependencies of dynamic modulus on pre-static strain under different values of strain amplitude of monoharmonic load were con- structed. And also dependencies of dynamic modules and loss angles low- and high-frequency compo- nents (harmonics) of biharmonic load on strain amplitude low-frequency harmonic under different values of strain amplitude high-frequency harmonic were constructed. It was shown that pre-static strain under monoharmonic tests corresponds to low-frequency harmonic under biharmonic tests (dependence of dynamic modulus on pre-static strain under one-frequency tests similar to dependence of dynamic modulus of second harmonic on strain amplitude of first harmonic under two-frequency tests). Compari- son of dynamic modules and loss angles of tested material under two-frequency (biharmonic) and re- lated one-frequency (monoharmonic) loads was conducted. We determined strain amplitude ratio of low- and high-frequency components in which the value of dynamic modulus of low-frequency compo- nent of biharmonic load does not differ from the value of dynamic modulus under monoharmonic load.