Study on Viscoelastic Propertiesof Cord–Rubber CompositeSubjected to Biaxial Loading

Abstract

Creep and stress relaxation behaviors of unidirectional nylon6–rubber composite under biaxial tensile loading are studied in this paper.Experiments of creep and stress relaxation are performed at room temperatureat different stress levels and different strain levels on both longitudinal andtransverse directions respectively. The influence of different stress levels oncreep strain and the interaction between longitudinal and transverse stressesare studied. Similar analyses are conducted to assess stress relaxation whenspecimens are subjected to biaxial tensile loading. These analyses provide solidexperimental foundation for understanding nylon6–rubber compositeproperties. A new relaxation-type constitutive model is presented for predicting stressrelaxation behaviors under biaxial tensile condition. In this model, octahedralshear strain is introduced as a variable parameter, which is related tolongitudinal strain and transverse strain respectively. Schapery unidirectionalintegral model and the least square method are applied to determine parametersin the constitutive model. Comparisons of experimental data with theoreticalcurves are made and good agreements are obtained for rubber compositesubjected to biaxial tensile loads.