Samsonov A., Dreiden G., Semenova I.

Propagation of bulk solitary density waves in lengthy elastic wave guides, having strong dissipation is studied. Isotropic polymers are among best materials for shock and vibration damping. PMMA was named as the material with the highest loss modulus and high damping capacity value. Even for isotropic solids the theoretical decay rates of density waves are often far from being confirmed by experiments, and shock dissipation in polymers was shown to be strong at very short distances. The dissipation decrements are 0.17 1/cm for PS and 0.25 1/cm for PMMA. Non-linear elasticity of materials results in generation of strain solitons even under short-run and reversible (elastic) loading. We dealt the lengthy bars (1x1x60 cm) made of polymers with remarkable linear dissipation, that leads to decay of both linear and shock waves at short distances. We study generation and propagation of bulk strain solitons produced by a laser-induced impact in nonlinearly elastic isotropic PS and PMMA bars. Firstly we certified the observed wave as a genuine bulk solitary wave. New experiments in lengthy bars confirm that the dissipation decrements for bulk solitons are 0.005 1/cm for PS and 0.009 1/cm for PMMA and therefore, we proved first that while moving along a thin bar over half a meter the bulk solitons do not reveal any considerable amplitude decay and shape transformation, while linear or shock waves disappear completely at much shorter distance. It is in excellent agreement with the general theory of solitons, and confirms that an elastic energy may propagate with bulk solitons along solids without considerable losses.