Poisson's Ratio as a Function of Time in Composite Material of Viscoelastic Behavior by Depending on Creep Test


In viscoelastic behavior of composite material, such as those made of thermo-setpolyester and one layer random fiber glass, the Poisson’s ratio is described in newfunction of time and stress. The relaxation stress is obtained experimentally to describethe non-linear viscoelastic behavior in composite material. The results show that,Poisson’s ratio increases with an approximate rate of 16% as a result of the increasingstress from 6.877 MPa to 8.239 MPa and decreases with increasing the time at constanttemperature 30 Co.The investigation demonstrated that such time dependence is not a necessaryconsequence of the theory of viscoelasticity to describe viscoelasticity behavior.