PSI - Issue 77

João Nuno Silva et al. / Procedia Structural Integrity 77 (2026) 657–664 Joa˜o Nuno Silva et al. / Structural Integrity Procedia 00 (2026) 000–000

658

2

(Hu et al. (2021)). In passenger vehicles, weight reduction and corrosion resistance are often prioritised, leading to the use of aluminium alloys (Zhu et al. (2019)), supported by guidelines such as DVS 1608 (2011), as well as stainless steels, particularly austenitic grades (Jaxa-Rozen (2014)). Freight wagons usually adopt welded constructions in structural steel grades (Milovanovic´ et al. (2013)). Across all these material classes, however, a common challenge persists: the susceptibility to fatigue damage under service life. Fatigue in metallic materials refers to the progressive and irreversible degradation of resistance to cyclic loading. Micro-cracks generally nucleate at stress concentration points, such as weld toes, inclusions, or surface defects, and subsequently grow under service-type amplitude spectra (Schijve (2009)). This process leads to macroscopic fracture and structural failure unless controlled through suitable design, inspection, or maintenance strategies. In this context, multiple reference documents coexist for fatigue design of railway steel components. These frame works include ERRI B 12 / RP60 (2001) technical code, EN 12663-2 (2010) standard, DVS 1612 (2017) technical code, EN 1993-1-9 (2025) standard, the IIW Recommendations (2024), and the more recent EN 17149-3 (2025) standard. These standards and guidelines adopt di ff ering load models, stress definitions, survival probabilities, and verification philosophies. Motivated by this lack of harmonisation, the present research provides a structured compar ative analysis of these documents and applies them to four representative welded details from a railway freight wagon, using a Finite Element Method (FEM) stress history. The resulting benchmarks the impact of verification approaches and position EN 17149-3 and DVS 1612 codes as primary railway baselines in current practice.

2. Methodology

2.1. ERRI B 12 / RP60

ERRI B12 / RP60 is a technical code for the fatigue assessment of railway vehicle structures, o ff ering two alterna tive design approaches: a fatigue damage accumulation method, and an infinite-life approach founded on the Good man / Haigh mean-stress interaction diagram. For the latter, fatigue resistance is defined according to notch classifi cations (Notch case A: parent metal; B: butt weld; C: butt weld with thickness change; D: fillet weld; E: projection weld). The code accepts stresses derived either from experimental measurements or finite element simulations. Fa tigue cycles are obtained through a critical plane method: the direction associated with the highest principal stress is taken as the candidate critical plane; the stress tensor from all relevant load cases is then projected onto this plane to obtain the envelope of normal stress; the higher and lower projected values define σ max and σ min , from which the mean stress ( σ m ) and stress range ( ∆ σ ) are obtained through the Equations 1 and 2.

1 2 ( σ max + σ min )

(1)

σ m =

(2)

∆ σ = σ max − σ min

Allowable stress limits are tabulated as functions of ultimate tensile strength ( R m ) equal to 370, 420, or 520 MPa, notch case, and the dynamic stressing coe ffi cient ( K ). These limits are further constrained by the Haigh diagram, which accounts for both mean stress and stress range. Verification under the infinite-life route is performed using the usage factor ( U f ), expressed in Equation 3, within a survival probability of 99.7%.

∆ σ cycle ∆ σ adm ≤

(3)

1

U f =

2.2. EN 12663

The EN 12663 standard is divided into two complementary parts and is built on the ERRI B12 / RP series. Part 1 specifies structural requirements for Locomotives and passenger rolling stock and includes an alternative method for