PSI - Issue 20

V.S. Kossov et al. / Procedia Structural Integrity 20 (2019) 212–217 V.S. Kossov et al. / Structural Integrity Procedia 00 (2019) 000–000

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3

nature of the propagation of strains and the dependence of the yield strength of steel materials on the strain rate were taken into account. The shock resistance of a locomotive driver’s cab (head car) was evaluated against the following conditions: • The supporting frame of the cab must stand, without the integrity damage of its structural elements (strains are allowed), the impact of a longitudinal load, uniformly distributed over the under-window part of the cab, of at least 290 kN, i.e. the frame must be robust enough • The maximum longitudinal movement of the under-window moulding inside the cab at the specified load should not exceed 200 mm, i.e. the frame must be rigid enough. Conditions of strength and rigidity of the frame are necessary to ensure the locomotive driver survival space (not less than 0.75 m in depth of the cab) during an emergency collision and to allow easy cab escape after a collision • Due to plastic strains of the supporting frame and impact protection units the absorption of the mechanical impact energy of at least 35 kJ should be ensured 3. Method of the calculation In accordance with the specified conditions, the general problem of the stress-strain state calculation of the cab is divided into the following sub-problems: • The stress-strain state calculation as a result of the load action on the outer front part of the cab frame in order to determine the absorbed energy due to its crash • The stress-strain state calculation as a result of the load action on the impact protection wall of the cab in order to estimate its longitudinal movement • The impact protection unit calculation in order to select its optimal form, ensuring maximum energy absorption • All calculations are performed in the elastic-plastic set up. Beyond the yield strength, the material is considered ideally plastic (preliminary calculations) and hardenable (final calculations). Such calculations are a complex physically and geometrically nonlinear dynamic problem In view of the foregoing, the following three versions of the driver’s cab design are considered: 1) a frame without an impact protection unit; 2) a frame with a single-layer impact protection unit and 3) a frame with a double layer impact protection unit (fig. 1). Table 1 shows the comparative measures of the structural protection effectiveness of the 2 ЭС 6 К electric locomotive cab under the accepted conditions for the three design versions.

Table 1. The comparative measures of the cab structural protection effectiveness. Measure (estimation criteria) Frame without an impact protection unit

Frame with a single-layer impact protection unit

Frame with a double-layer impact protection unit

W , kJ ([ W ] ≥ 35)

40

33,7 290

42

F max , kN ([ F max ] ≤ 290) X max , mm ([ X max ] ≤ 200)

185 232

290

11

11

The method of performing calculation studies of the stress-strain state of structural elements of the driver’s cab frame under static and dynamic (impact) loads on the front part of the locomotive includes: • Building a three-dimensional geometric model with the required level of structure details with the use of an application software package • Importing a geometric model into the application software package to solve nonlinear problems of deformable solid mechanics using the finite element method • Building a finite element model with specifying the boundary and initial loading conditions • Solving the dynamic problem of an elastic-plastic contact interaction of the body with an obstacle • Comparative analysis of the obtained results and evaluation of the impact resistance of the structure under the conditions of passive safety by Krasyukov (2019)