The Mechanical Property Of Polymer With Vice In Hydraulic Engerineer

Because of special mechanical properties, the using of polymer material in hydraulic engineering has attracted great attention in recent years. By means of theoretical methods, the microvoid growth, the macroscopic constitutive relations and Poisson's ratio of the microcellular foams are studied; and the viscosity dissipation and damage dissipation, as well as their effects on the macroscopic properties of particulate-reinforced polymer materials are analyzed. At last, the constitutive relations of particulate-reinforced polymer materials under the condition of low stress triaxiality are also studied.The microvoid growth in viscoelastic materials is one of the key problems in the study of the failure mechanisms. Firstly, a single microvoid growth with pressure in the infinite matrix is studied, and the expression of strain is derived. In the expression, we can know that the strain of microvoid with pressure depends not only on the remote strain history, but also on the pressure of microvoid. Basing on it, the macroscopic constitutive relations and the Poisson's ratio of microcellular foams with pressure are derived. In this expression, the pressure affects the strain of microvoid, macroscopic constitutive relations and Poisson's ratio of material. Then, theoretical analysis and numerical results show that the influences of pressure to the constitutive relations and the Poisson's ratio of the material can be not neglected when the loading ratio or loading time are small. And the Poisson's ratio depends not only on the pressure of microvoid, but also on the loading condition. In this work, the Poisson's ratio is discussed when it is non-negative, oddity and const.Secondly, based on the microvoid growth, the energy dissipation in the rigid particulate-reinforced polymer material is studied. According to the dissipation mechanisms, the material energy dissipation is divided into damage dissipation and viscosity dissipation. Under the condition of high stress triaxiality, the expression of damage dissipation and viscosity dissipation are derived. Moreover, porosity and viscosity strain of material can reflect the energy dissipation. Then the relation between porosity and viscosity strain, and the relation between damage dissipation and viscosity dissipation are found. As a result, damage dissipation and viscosity dissipation of material are coupling.Under the condition of low stress triaxiality, the evolution of microviods is partial debonding. Hence, based on the study of the microvoids nucleation and growth, by using micromechanical method, the constitutive relations material with microdamage evolution are derived. The effects of loading rate, particle volume fraction, the dispersion degree of particle size and the matrix relaxation time on the constitutive relations under uniaxial tension are also discussed.This work may be used to supply guidelines for the design of polymer composites used in hydraulic engineering.