ELASTIC AND STRENGTH PARAMETERS DETERMINATION OF POLYMER COMPOSITE MATERIALS AND CYLINDRICAL SHELLS

Abstract

The article presents a method for layout optimization in polymer composite materials that allows to assess their strength. In order to assess the stress-strain state of each layer, an orthotropic elasticity model is used assuming that the fibers in the material are parallel. The behavior model of polymer composite materials is based on the Hashin criterion, which makes it possible to separate the destruction mechanisms of matrix and fiber. The strength assessment was carried out in accordance with the structural approach involving studying the strength of each layer separately. The parameters of the deformation model and the Hashin strength criterion were determined based on the results of testing. Tests were carried out on unidirectional polymer composite materials samples cut at angles of 0, 90 and 45° to the direction of reinforcement. The verification was based on the results of bending tests of polymer composite materials samples. Verification showed high proximity between the calculation results and the experimental data. A method for selecting the layout angles of each layer of polymer composite materials has been developed making it possible to calculate the greatest strength of the cylindrical shell under various external loads. The method involves determining the stresses in each of the polymer composite materials layers, as well as Hashin indicators corresponding to the destruction of the fiber or matrix under tension or compression. Based on the indicator values, the optimal angle and layout pattern can be selected, providing the greatest margin of safety for the shell. This method allows for a preliminary assessment of the safety factor of cylindrical shells made of polymer composite materials based on the experimentally determined elastic parameters of the material and the parameters of the Hashin strength criterion. The method takes into account the angle and layout of the prepreg under the influence of internal pressure, axial compressive force and torque.