This paper focuses on computational simulations of selected mechanical tests of polymer composites, such as cyclic loading tests even at selected ambient temperatures. The ANSYS FEM software product is used with the addition of support programs for determining the input material parameters. Strain-stress analyzes will be performed. The results will be verified with experimental data, such as low uniaxial cyclic tensile load for temperatures of 20 °C and 120 °C. The computational results can be used in conditions where the polymer composites mentioned are exposed to cyclic loading at unsteady temperatures, such as conveyor belts, and can also be used for computational modeling of the composites, such as tire casings for automobiles. Acknowledgments: This research work has been supported by the Cultural and Educational Grant Agency of the Slovak Republic (KEGA), project No. 003TnUAD-4/2022 "Simulations of basic and specific experiments of polymers and composites based on experimentaldata in order to create a virtual computational-experimental laboratory for mechanical testing".