Innovative Test Technology and Test Procedures for Components of Railway Chassis
Agenda (1) Introduction - Accidents, developments and current status (2) Testing and state-of-the-art test systems in 2019 (3) Perspective test systems (4) Test standards (5) Summary
Accidents, developments and current status
Accidents – Eschede 1998 Elastomer Spring Mounted Construction of Railway Wheels The cause of this failure is a combination of high operational loading to a worn out railway wheel and a very high number of endured load cycles. The wheel was additionally fatigued by the friction between the wheel and the mounted rubber elements (fatigue crack).
Accidents – Eschede 1998 Prior to the introduction of rubber mounted wheels in 1992 neither a numerical estimation of fatigue strength or an estimation of occurring loads was done even though this was possible at that time nor have sufficient driving tests been carried out. Suitable calculations would have shown risks of possible fracture initiation points enabling further fatigue tests and improvements for the construction. The significant differences between actual stresses on a standing and a rotating wheel have not been considered during the stress analysis on a standing wheel. The stress on a rotating wheel is significant higher. Consequence --> This construction was prohibited after the accident!
Accidents – Cologne 2008
S E T - U P O F W H E E L S E T A X L E wheel disks hollow bored shaft shaft journal shaft journal Fittings for transmission output
S T R E S S G R A D I E N T local tension σ < σ zul Changing of diameter from shaft journal to press fit nominal tension S < S zul Press fit Changing of diameter from press fit to axle local tension σ < σ zul Moment gradient incl. torque
C R I T I C A L A R E A O F W H E E L S E T A X L E Press fit Three-centre curve
Stress and Load Assumption Actual Strength (“Wöhler” curve) p F Stress Allowed p B Tension σ zul > Calculated Load Assumption σ Actual Stress (Collective) Statistic frequency / Load cycles
Historical Rotating Bending Test Machine from August Wöhler (1866)
G U I D A N C E O F W Ö H L E R 1. Dynamic loads stressing the component must be known. → Analysis of stress 2. Bearable stress level of used material must be known. → Strength 3. Material parameters for reliable stress calculations need to be known. (1819 – 1914) 4. Effect of anomalies inside the component must be known, e.g. cuts, sharp edges and damaged surfaces
S I T U A T I O N Railway chassis are mostly designed by calculations only according to technical guidelines (i.e. EN) These guidelines are based on decades of experience dating back to documents with more than 50 years of age Lack of transparency … Hence, inadequate adaptability to modern engineering requirements (other materials, different constructions, higher loads) Comparability with measurements, tests and general guidelines (FKM-guideline, Euro-Codes etc.) is hardly possible.
F U N D A M E N T A L S O F S T R E N G T H T E S T Nationale Regelwerke Der europäischen Bahnen Harmonisierung durch den Internationalen Eisenbahnverband (UIC) ORE Dokument B 136 DIN 5577 Lastfälle, Werkstoffe, Gestaltung und Berechnung von Laufradsätzen Gestaltung und Berechnung bis 1979 von Laufradsätzen 1990 UIC-Kodex 515 – 3 Lastfälle, Gestaltung, Werkstoffe und Berechnung vor allem Laufradsätze BN 421 022 1994 Lastfälle, Werkstoffe und Berechnung EN 13260 - Produktanforderungen von Treibradsätzen EN 13104 - Treibradsätze 1992 EN 13103 - Laufradsätze Lastfälle, Gestaltung, Werkstoffe und Berechnung 2000
Testing and state-of-the-art test systems in 2019
RESONANCE ROTATING BENDING Testing according to various standards Unbalanced Motor-Drive Four-point-measurement (Low deviation) High-precision crack detection by frequency drop Highly accurate control due to special control algorithms, < 0,3% inaccuracy Comfortable strain measurement and crack observation by direct accessibility and fixed shaft High test frequency 10 – 50 Hz High bending moment up to 350 kNm High level of safety for operating personnel Low testing costs due less energy consumption
B E N D I N G M O M E N T D I S T R I B U T I O N / G R A D I E N T s
F U N C T I O N A L P R I N C I P L E Component Dynamic Decoupling
C O N T R O L O F R E S O N A N C E T E S T R I G Ampl. Control Range Regelbereich Frequenz
Fatigue testing with RESONANCE ROTATING BENDING
EVALUATION AND RESULTS after rotating bending test Overview of component strength of wheelset axles, test data (average value), standardized verified and allowed tension
EVALUATION AND RESULTS after rotating bending test Example diagram* of test results shown in the „Wöhler“ curve (left) and as process sequence (right) of wheelset axles made of 34CrNiMo6 (rotating bending, shoulder Kt = 1,2, stem diameter 160 mm) *Source: DB Systemtechnik, Minden
Test System „EWALD“ GER: Fahrdynamischer E isenbahn w ellen Riß a usbreitungs- und L ebens d auer Prüfstand ENG: Driving-Dynamic Railway Shaft Crack Growth and Fatigue Life Time Test Machine
Description of EWALD EWALD was developed by SincoTec Group for fatigue testing of wheelset axles with realistic driving-dynamic environmental conditions in VHCF range. Possible tests are: • Fatigue Testing • Crack Propagation Tests • Crack Initiation Behaviour of press fit, transmission fit etc. The system is capable for applying symmetrical and asymmetrical loads of driving-dynamic conditions to every shaft type and size. Rotating bending of shaft with 2.500 rpm minimizes test duration (10 8 load cycles in only 28 days). Optionally bearing tests are possible.
Functional principle: Load F F Transmission Rotation Support Bearing Force Transmission
Adjustable for different axles, e.g.: InterCityExpress (ICE) Tram
Technical Data: l = 4.200 mm; w = 1.800 mm; h = 2.100 mm Size: 17 t Weight: 250 kW Input Power: 2 x 1.000 kN Test load: 200 kNm Reference Torque: 2.500 U/min (41 Hz) Nominal Speed: lubricated and cooled by external oil circulation Bearing: 13.000 h (2,496 x 10 9 load cycles) Lifetime of Bearing: 4 x force transducer, every 450kN Sensor System: (2 per force transmission) 2 x displacement transducer (1 per force transmission) 8 x temperature sensor 4 x tri-axial accelerometer 4 x volume flow sensor to control oil flow
BEARING TEST RIGS specified to „High Speeds“ and „High Loads“
Functional principle: Support Bearing Support Bearing Supportlager Supportlager Test Bearing Test Bearing Prüflager Prüflager ±Fa ±Fa ±Fr ±Fr
EN12082 - Test Rig Specification:
Test rig „Heavy Duty“ for fatigue testing of roller bearings used in railway rolling stock The dynamic railway bearing test system is a multi-axial rotating bending test system for applying of static and dynamic wheel loads and axial loads. Rotation speed is freely adjustable. l = 5.700 mm; w = 3.400 mm; h = 3.600 mm Size: 19,5 t Weight: 100 kW Input Power: 2 x 300 kN servo-electric Test load Fz: 2 x 150 kN servo-electric Test load Fy: 3.000 U/min (50 Hz) Nominal Speed: lubricated and cooled by external oil circulation Bearing: 4 x force transducer, 300 kN and 150kN Sensor System: 4 x displacement transducer 8 x temperature sensor 4 x tri-axial accelerometer 4 x volume flow sensor to control oil flow
Test rig „Heavy Duty“ for fatigue testing of roller bearings used in railway rolling stock
Test rig „High Speed“ for fatigue testing of roller bearings used in railway rolling stock The dynamic railway bearing test system is a multi-axial rotating bending test system for applying of static and dynamic wheel loads and axial loads. Rotation speed is freely adjustable. l = 5.500 mm; w = 2.800 mm; h = 3.000 mm Size: 14,5 t Weight: 100 kW Input Power: 2 x 150 kN servo-hydraulic Test load Fz: 2 x 30 kN servo-hydraulic Test load Fy: 4.000 U/min (66 Hz) Nominal Speed: lubricated and cooled by external oil circulation Bearing: 4 x force transducer, 150 kN and 50kN Sensor System: 4 x displacement transducer 8 x temperature sensor 4 x tri-axial accelerometer 4 x volume flow sensor to control oil flow
Test rig „High Speed“ for fatigue testing of roller bearings used in railway rolling stock
Crack growth analysis on wheelset axles, test-setup with resonance rotating bending Optical crack growth analysis Permanent recording of critical area Detection area h 48 mm User-defined optical barrier Resolution < 0,1 mm (37µm/px) Connected to control software “EMOTION”
3-axial test and measurement system for railway elastomer-wheels Rotation: 60 rpm (fulling elastomer) Radial load: 125 kN (alternating) Axial load: 125 kN (alternating) Torque: 40.000 Nm Controlling: TESTPILOT
Fatigue testing of wheel tires 3- or 4-point bending Very fast fatigue testing by high frequency pulsator up to 100 Hz Strain controlled using applied strain gauges on the wheel tire
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