## 3 The Designing of the FLAT RACK Removable Module  
The efficiency of transportation can be enhanced by putting into operation the open-type FLAT RACK removable module. Structurally, such a removable module consists of main longitudinal beams 1, side longitudinal beams 2, end crossbeams 3, intermediate crossbeams 4, and corner fittings 5 (Figure 1). The basic dimensions of the removable module are taken as follows: width--2438 mm and length--6058 mm. Thus, these dimensions are identical to the ISO standards established for removable vehicles for international traffic. The choice of the optimal profiles in terms of the minimal material capacity for the removable module was made by means of the strength calculation with the finite element method in Lira [17,18]. The removable module was studied as a frame system on the hinged fixed supports in the corners. Two diagrams of loading on the module were studied. Figure 1: FLAT RACK removable module: (**a**) Structural elements of the removable module; (**b**) removable module on a flat wagon. The maximum value of the bending moment was recorded on the main longitudinal beams, and it was amounted to 53.9 kN\(\cdot\)m. The maximum torque moment also emerged in the main longitudinal beams on the area between the fittings and the first crossbeam from the end cross beam; it amounted to 3.08 kN\(\cdot\)m.  
The maximum value of the bending moment was recorded on the main longitudinal beams, and it was amounted to 53.9 kN\(\cdot\)m. The maximum torque moment also emerged in the main longitudinal beams on the area between the fittings and the first crossbeam from the end crossbeam; it amounted to 3.08 kN\(\cdot\)m.  
Under the longitudinal loading on the module, it underwent compression deformation because it was fastened in the corners. In this case, the maximum value of the longitudinal force emerged in the main longitudinal beams on the area between the fittings and the first crossbeam from the end cross beam, and it amounted to 231 kN (Figure 6). The maximum bending moment on the removable module emerged in the intermediate crossbeams, and it amounted to 309 kN\(\cdot\)m (Figure 3). In the end crossbeams, it amounted to 309 kN\(\cdot\)m. The value of the bending moment in the longitudinal beams was 283 kN\(\cdot\)m.  
The value of the optimal profile in terms of the minimal material capacity for the removable module was determined according to the values of moment and longitudinal force. When the bending moment affected the removable module, the resistance moment of the module components could be determined by formula [19]:  
\[W=\frac{M}{[\sigma]}, \tag{1}\]  
where \(M\)--the bending moment; \([\sigma]\)--the allowable stresses. With the longitudinal force on the module, the cross-section of the profile was determined as follows:  
\[A=\frac{F}{[\sigma]}, \tag{2}\]  
where \(F\)--the longitudinal force on the module; \([\sigma]\)--the allowable stresses. As far as the values of bending moments emerging in the module structure at Diagram I were insignificant, they were neglected for the determination of the profile components. Taking into account the calculation, the value of the resistance moment for the module components was \(W\) = 173.6 cm\({}^{3}\). Additionally, the allowable stresses were taken as 0.9\(\sigma_{\mathrm{S}}\), where \(\sigma_{\mathrm{S}}\) was the yield strength of the material. Steel 09C2 Cu, widely used for the production of rail vehicles, was used as such a material with a fluidity level of 345 MPa. In the calculation, the optimal cross-section of the module profile was 7.4 cm\({}^{2}\) according to Formula (2). According to the value of the resistance moment, the profile for the module components was chosen. It was a rectangular tube with a height of 180 mm and a wall thickness  
Figure 6: Diagram of the longitudinal forces (kN). of 4.5 mm at a resistance moment of 175.7 cm\({}^{3}\) (Figure 7[20; 21]). One meter of the pipe weighted 24.39 kg. Taking into account the profile parameters, the cross section was 32.4 cm\({}^{2}\).