Structural Safety in Rail Systems: FEM-Based Strength, Vibration, and Compatibility Analyses

Structural Safety in Rail Systems: FEM-Based Strength, Vibration, and Compatibility Analyses


Rail systems form the backbone of critical transportation infrastructure such as metros, trams, commuter trains, and freight railways. In these systems, safety is not limited to structural strength alone; it also requires the integrated evaluation of ride comfort, vibration behavior, wheel–rail compatibility, dynamic clearance (gauge), crashworthiness, aerodynamic effects, HVAC performance, and weld durability.

To address these multidimensional engineering challenges, Finite Element Method (FEM), Multi-Body Dynamics (MBD), and advanced fatigue assessment techniques have become indispensable tools in modern rail vehicle design and validation.

Why Structural Safety Is Critical in Rail Systems

Rail vehicles and infrastructure components are continuously exposed to demanding operational conditions:

High static and dynamic loads

Continuous vibrations and shock effects

Acceleration, braking, and curving motions

Irregular forces caused by track roughness

Environmental effects (temperature variation, humidity, corrosion)

Fatigue due to millions of load cycles

Over time, these effects may lead to cracks, deformations, and performance degradation in car bodies, bogies, welded joints, and connection elements.
FEM-based engineering analyses make it possible to predict these risks digitally long before physical production begins.

Core FEM-Based Analysis Types

1. Static Strength Analyses

Used to verify the structural integrity of rail system components under maximum loading conditions.

Car body primary load-carrying members

Bogie frames

Couplers and connection elements

Suspension mounting points

Objective:
To ensure that stresses do not exceed material yield limits and that safety factors comply with design requirements.

2. Modal (Natural Frequency) Analyses

Performed to identify vibration modes and natural frequencies of structures.

Detection of resonance-prone frequency ranges

Optimization of suspension and bogie design

Reduction of noise- and vibration-related comfort issues

Objective:
To prevent operational frequencies from coinciding with the system’s natural frequencies.

3. Harmonic and Random Vibration Analyses

Used to simulate vibration loads under real operational conditions.

Track roughness effects

Wheel–rail interaction forces

Continuous speed variations

Objective:
To predict vibration-induced damage and long-term fatigue risks.

Advanced Rail-Specific Analyses

4. Ride Comfort Analyses

Passenger comfort is one of the most critical quality criteria in modern rail projects.

Body acceleration levels (m/s²)

Vertical and lateral vibration spectra

Compliance with ISO 2631 and similar standards

Optimization of suspension parameters

Objective:
To keep vibration and shock levels within acceptable passenger comfort limits.

5. Dynamic Clearance (Gauge) Analyses

Conducted to ensure that vehicles do not collide with surrounding structures during curving, suspension travel, and track irregularities.

Vehicle sway motions

Maximum lateral and vertical displacements

Tunnel, platform, and infrastructure clearances

Objective:
To verify safe vehicle–infrastructure distances and eliminate collision risks.

6. Wheel–Rail Compatibility Analyses

The contact behavior between wheel and rail profiles is vital for both safety and ride quality.

Contact stress distribution

Slip and friction behavior

Wear prediction

Stability and derailment risk assessment

Objective:
To extend wheel and rail life, reduce maintenance costs, and improve running stability.

7. Vehicle and Buffer Crash Analyses (EN 15227)

Crashworthiness is a critical regulatory requirement, especially for urban rail systems.

Collision scenarios in accordance with EN 15227

Low- and medium-speed impact simulations

Energy absorption mechanisms

Structural deformation zones

Passenger safety performance criteria

Objective:
To preserve structural integrity, control energy dissipation, and protect passenger survival spaces during collisions.

8. Bogie and Car Body Strength Analyses According to VDV 152, EN 12663, and EN 13749

Compliance with international standards is mandatory in rail projects.

VDV 152: Structural loading and strength requirements for bogies

EN 12663: Load cases and safety factors for rail vehicle bodies

EN 13749: Bogie frame design and structural validation criteria

Objective:
To validate regulatory compliance and accelerate certification processes.

9. Weld Strength Calculations According to DVS 1612 and EN 15227

Welded joints are among the most critical weak points in rail vehicles.

Modeling of weld seam geometry

Stress concentration analysis

Determination of fatigue class (FAT class)

Weld life estimation

Compliance with DVS 1612

Verification of weld integrity under crash loads (EN 15227)

Objective:
To prevent early crack initiation in weld zones and ensure long-term service life.

10. Vehicle Dynamics Analyses (EN 14363)

Dynamic performance analyses are carried out to ensure safe and stable vehicle operation.

Lateral and vertical acceleration measurements

Derailment risk assessments

Running stability and ride comfort criteria

Suspension behavior optimization

Objective:
To ensure that vehicles operate safely and stably in compliance with EN 14363.

11. Aerodynamic Analyses (EN 14067)

Aerodynamic effects become critical at higher speeds.

External airflow analysis around the vehicle (CFD)

Pressure fluctuations and tunnel effects

Crosswind stability

Aerodynamic drag forces

Noise and acoustic effects

Compliance with EN 14067

Objective:
To improve aerodynamic stability, reduce energy consumption, and validate vehicle safety under high-speed conditions.

12. HVAC (Heating and Cooling) Analyses and Performance Tests (EN 14750)

HVAC system performance for rail vehicles is validated according to standards.

Cooling and heating capacity tests

Cabin temperature distribution

Humidity and air quality measurements

Performance evaluation under different ambient conditions

Thermal comfort simulations (CFD)

Compliance with EN 14750

Objective:
To guarantee passenger comfort and verify HVAC system efficiency under all operating conditions.

FEM + MBD Integration for Realistic Simulation

FEM alone is often insufficient for capturing real operating behavior.
Therefore, rail projects increasingly rely on an integrated Multi-Body Dynamics (MBD) approach (e.g., RecurDyn):

Vehicle motions → calculated via MBD

Resulting loads → transferred into FEM models

Structural responses → solved under realistic boundary conditions

This workflow significantly improves correlation between simulation results, field data, and physical tests.

Digital Validation of Rail Projects with FETECH

At FETECH Advanced Engineering, we provide end-to-end engineering solutions tailored specifically for the rail industry.
Using advanced simulation platforms such as ANSYS, LS-DYNA, RecurDyn, CivilFEM, and Endurica, we deliver:

Static and dynamic strength analyses

Modal, vibration, and ride comfort analyses

Dynamic clearance and wheel–rail compatibility studies

Crash and impact simulations (EN 15227)

Bogie and car body analyses (VDV 152, EN 12663, EN 13749)

Weld strength and fatigue calculations (DVS 1612)

Vehicle dynamics analyses (EN 14363)

Aerodynamic analyses (EN 14067)

HVAC analyses and performance tests (EN 14750)

In addition to project-based engineering services, we also offer software sales, installation, training, and technical consultancy under one roof.

Digital Engineering for Safe, Comfortable, and Certifiable Rail Systems

Structural safety in rail systems can no longer rely solely on physical testing.
Modern rail projects must simultaneously address strength, vibration, comfort, clearance, crashworthiness, aerodynamic performance, HVAC efficiency, and weld durability.

With FEM-based digital engineering:

Safety risks are identified early

Designs become lighter and more optimized

Certification processes are accelerated

Maintenance costs are reduced

Time-to-market is shortened