New approaches for evaluating rheological models in composites A N Bobryshev, A V Lakhno, P V Voronov et al. Abstract. Whole body vibrations have become a very popular method in recent years, both in physical therapy and in sports. This popularity is due to the fact that, as a result of analyzing the groups of subjects, the effects of small amplitude vibration and low frequency vibration, it was found an increase in the force developed by the feet, a hardening of bone strength or an increase in bone density. In this paper we propose to give a possible explanation of the stress relieving in muscle and/or bone after whole body vibration treatment. To do this we consider some rheological models which after whole body vibrations and after the analysis of their response lead to various experiments.
IntroductionThe results of the research on the influence of vibrations on the stress relaxation are controversial because there are no conclusive measurement methods whose effects can be demonstrated. Applying high frequency harmonic strain has been shown to stimulate bone resistance in different animals. However, the effects of whole body vibration on the human skeleton have rarely been studied. The effect of vibration on the whole body is difficult to quantify because the mechanical modelling of vibration behaviour of the whole body is not unitary but also offers many possibilities [1].In another paper [2], it was hypothesized that through a non-contact vibration device, qualitative changes could be detected in a periodontal ligament and alveolar bone, identifying the mechanical parameters of the system: tooth, periodontal ligament and alveolar bone. In this case, the mechanical modeling of the analyzed system was the starting point of the study.Whole-body vibration is a neuromuscular training method that recently has been developed and which increase strength compared with resistance training [3].As a biological material, muscle tissue and bone tissue exhibit a complex microstructure and micro components, which result in complicated mechanical properties. Because of the viscoelastic nature of collagen fibers in the bone matrix, bone itself has remarkable viscoelasticity [4][5][6].The vast majority of research has an experimental character and has not led to a clear view of the possibility of using vibrations to stress relaxation. The possibilities of reducing this stress are described in the paper [7] from the stress and deformation dependence, a characteristic of the material. Stress relaxation is based on the reinforcement of the material, meaning that by the influence of vibrations, the flow limit can be exceeded.In this paper we propose a rheological model describing the elasto-plastic behavior with linear reinforcement. By generalization some elasto-plastic models of solid bodies will be analyzed, which show rigidity characteristics, following the effect of stress relief under the influence of vibrations.
