The bogie is a welded S355 steel plate structure, sized for a 64 t total vehicle mass, 23.3 t car body mass and 8.7 t bogie mass.
Before serial production could begin, the design had to be verified against EN 13749, the European standard for bogie structural requirements, for both static load-bearing capacity and weld-seam fatigue life.
With the GH250-2.1-M design frozen and serial production approaching, the EN 13749 verification had to be closed out before manufacturing tooling was committed — a late-stage structural failure would have meant a full redesign. Ganz engaged eCon Engineering Kft. to run the full verification virtually: static load-bearing capacity and weld-seam fatigue life across every load case defined by the standard.
Ganz's in-house simulation capacity is scaled to day-to-day design support — local mesh checks, isolated component analyses. A full-bogie finite element model combined with weld-seam-by-weld-seam fatigue-life estimation across an entire structure is a different workload: one that requires both specialist tooling and standard-compliant interpretation.
Ganz had already worked with eCon on an earlier powered-bogie programme, and engaged the same team again on that basis.
The average shell element size is 10 mm; at the weld seams the shell elements meet at a common edge, and the shells adjacent to that edge were treated as weld elements.
To transfer forces correctly, the wheelsets were modelled as mechanisms built from bar elements, and the stabilising sub-frame and the centre pivot with shell elements. The parts were connected to the structure in accordance with the physical connections — with hinges and with spring elements representing the steel and rubber springs. The bump-stop travel range was modelled with non-linear spring elements: negligible stiffness within the operating range (0.02 N/mm), stiffening abruptly on reaching the travel limit (10⁹ N/mm).
Following the guidance of EN 13749, the real service loads on the bogie were approximated by static loads modelling different operating states. The load cases fall into two groups: exceptional loads (extraordinary vertical, lateral, longitudinal and torsional loads) and normal service loads (vertical and lateral, longitudinal, longitudinal shear and torsional loads) — 24 identified load cases in total.
Static load-bearing capacity was evaluated as utilisation relative to the material yield stress. The weld-seam fatigue-life evaluation was carried out on the basis of Eurocode 3 (MSZ EN 1993-1-9:2005) fatigue theory: every weld seam was classified, and the governing stress amplitude was determined at every node. Utilisation was determined using the SN curves appropriate to the weld class and to the direction of the stress component, as the ratio of the calculated stress amplitude to the allowable amplitude at the required cycle count.
The full fatigue duty cycle was assembled on the basis of figures G.2 and G.3 of EN 13749 as a vertical-vibration-dominated load profile: 6×10⁶ cycles from the combined vertical and lateral loads, 6×10⁵ cycles for the service torsional loads, and 1×10⁶ cycles each for the service longitudinal loads associated with braking and acceleration.
The finite element calculation was performed with the OptiStruct 2017.0 solver, and the Eurocode 3 weld-seam evaluation with FemFat 5.3.1.
In the full fatigue duty cycle, maximum utilisation reached 1.17 at a single stress concentration formed by the intersection of two triangular elements — a geometry at which the evaluation method is known to overestimate. Three design iterations were required to bring every weld seam within the fatigue endurance envelope. The GH250-2.1-M passed EN 13749 verification for both static load-bearing capacity and the full virtual fatigue duty cycle.
eCon verified EN 13749 compliance quickly and professionally. The design recommendations built on the calculation results kept the development solution-focused throughout, and everything was in place on the deadline.
— Horváth András, Head of Engineering, Ganz Motor Kft.
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