Deformation Model of [±45]S Cross-Ply Fiber Reinforced Plastics Under Tension

A series of experiments on tensile testing of specimens from cross-ply reinforced plastics made from unidirectional tape ELUR-P and cold-curing binder XT-118 and stacking sequence [±45°] were carried out. Tests were carried out on different specimens at three maximum stress values. It was established that the total axial strain can be represented as a sum of four components, including: reversible strain, residual (irreversible) strain, irreversible creep deformation and reversible creep strain due to the viscoelastic properties of the epoxy. The questions of the choice of relations for the description of the components of the strains and the identification of their mechanical characteristics are considered. The conclusion is formulated that for a hereditarily elastic model, one can use the Abel creep kernel and determine its parameters from an experiment for long holding times. To determine the parameters included in the irreversible creep relations, we use the results obtained immediately after the start of exposure at maximum stresses, and a method for their determination is proposed. After this is the initial modulus of elasticity. At the last stage, after determining the rheological characteristics and the initial modulus of elasticity, the nonlinear elastic reversible part of the strain can be singled out.