This master’s thesis deals with the design and calculation of a torsion bar as an element of a tracked vehicle suspension. The development of suspension systems is described throughout the history and different types of suspension systems are listed with the description of principle of operation for each one of them. Also, mathematical models for describing the movement of a tracked vehicle on rough terrain are presented and explained, which actually show the importance of the suspension systems and the specifics related to its selection and design. The paper presents an ISO standard related to vibration frequency ranges and describes their impact on the passengers in the vehicle, which is actually the beginning of the design calculation of the suspension system after selecting the initial mathematical model. The paper also lists the materials that have been used throughout history in design and production of torsion bars and how their mechanical properties changed over time due to requirements given by client with an emphasis on greater mobility and more comfortable ride. Also, there are listed some of the manufacturing processes by which the mechanical properties of the material are improved, one of which is described in detail with the help of the theory of material hardening. The design calculation of the rod was carried out with regard to the geometry of a vehicle body, which is determined by the tool mounted on the vehicle and the analysis of individual parameters of vehicle mobility for which calculation is not shown in the paper. Numerical analysis was performed in Abaqus for the phenomenon of material hardening during the production process which changes the state of the material from elastic to elastic-plastic. A three-dimensional torsion bar model was designed in Catia, while other software, such as AutoCAD, Excel and Mathcad, were used to define material model, which would be used in the analysis, and the loads to be compared with the numerical analysis results. Since mechanical engineering students do not encounter elastic-plastic analysis during their education, this paper required the expansion of knowledge in the field of material strength and development of smaller and simplified models by which the analysis setting were determined during a time-consuming iteration process. During the analysis, the density of finite element mesh was increased in order to monitor the convergence of the solution, and finally, to be able to present and interpret the obtained results. The paper ends with a conclusion that gives an overview on the analysis process, and at the end the obtained solutions and their meaning are commented.