In modern times, the aspiration to make products and designs more efficiently with the utmost utilization of materials is one of the basic requirements in production. The development of numerical algorithms and tools as well as increasingly powerful computers, allow engineers to very accurately predict the physical behavior of the material, ie the product during the exploitation, without the use of highly expensive experimental analysis. In the field of mechanics of deformable bodies, the Finite Element Method (FEM) is the most significant numerical method, whose roots date back to the 1950s. During this time, engineers have developed a number of algorithms to solve a broad spectrum of problems, from very simple ones to very complex ones. During most of its history, FEM acted exclusively on a macroscopic level, ie the micro and nano level on which each material rests was not part of the calculation model. For a good description of the physical behavior of any material, it is necessary to know and describe its micro, ie nano structure. The very idea of an analysis of the influence of microstructure on the mechanical behavior of materials dates back to the 19th century, and in the past twenty years, primarily with the development and growth of computer resources, there is an intense development of numerical methods for modeling the mechanical behavior of materials at the micro level. At nano, but also at the micro level, no material is homogeneous, instead, it represents a heterogeneous structure of several constituents of different mechanical properties. Steel, for example, is on a micro level a heterogeneous structure which consists of three constituents: perlite (which contributes to strength and hardness), ferrit (which contributes to ductility and toughness), and graphite nodules, while modeling on the macro level as homogenous and isotropic material. This assumption of homogeneousness and isotropism for static loads (steel constructions), where stresses and strains are in linear – elastic area will not lead to significant error. But for structures that are exposed to dynamic loads, where there is a great risk of crack formation and crack propagation, the heterogeneity of the material will have a major impact on the behavior of the structure. This paper will include a micromechanical modeling of uniaxial tensile test of nodular cast iron – a design material which in these days if frequently used on constructions which are exposed to dynamic loads due to its high ductility and fatigue strength. The analysis will be performed on nodular cast obtained by two different production processes: Tundish and Inmodul. Based on the result of metallographic analysis, obtained by experimental studies conducted at the Office of technical mechanics of the Faculty of mechanical engineering and naval architecture University of Zagreb, three Representative Volumetric Elements (RVE) will be created on which the numerical analysis will be performed. It will be shown how the size of the RVE affects the final result, and how well the numerical analysis and experiment itself coincide. The analysis will include the linear – elastic areoa of the nodular cast iron, and the calculation itself will be carried out with the Abaqus program package.