Study of the laminas’ stress-strain state for cross-ply composites with the [± 45°]_2s lay-up: tensile tests

¹ Kazan National Research Technical University named after A. N. Tupolev – KAI, 10, K.Marx St., 420111 Kazan, Russia
² Kazan Federal University, 18, st. Kremlyevskaya, 420008 Kazan, Russia

^* Corresponding author: vpajmushin@mail.ru

Abstract

In this paper we have analysed the relations that allows one to determine the components of strains and stresses in the orthotropic axes of layered fiber reinforced composite materials in tensile and compression experiments for test specimens with the [±45^°]_2s lay-up. In particular, such relations were compiled on the assumption that in a cross-ply fiber composite two adjacent layers with the [±φ] lay-ups can be considered as one symmetrically reinforced layer with orthotropic properties. To establish the degree of accuracy of these relationships and assumptions, numerical experiments were carried out to determine the parameters of the stress-strain state of specimens consisting of two and four monolayers of a unidirectional fibrous composite material with the [±45^°]_2s lay-up. The analysis has been performed in the ANSYS finite element analysis program system in a linear formulation of two- and three-dimensional problems. It is shown that in the central zone of the specimen, the theoretical-experimental methodology based on the above mentioned relations has a sufficient degree of accuracy. Based on the analysis of results of three-dimensional problems, the formation of a linear torque in the specimen, which causes the twisting of some zones of the specimen along its length, has been revealed.