Innovative Test Technology and Test Procedures for Components of - - PowerPoint PPT Presentation

Innovative Test Technology and Test Procedures for Components

• f 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

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

• r 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 – Eschede 1998

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 Fittings for transmission output shaft journal shaft journal

S T R E S S G R A D I E N T

Changing of diameter from press fit to axle Changing of diameter from shaft journal to press fit Press fit Moment gradient incl. torque

 local tension σ < σzul  local tension σ < σzul  nominal tension S < Szul

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

Actual Strength (“Wöhler” curve)

Statistic frequency / Load cycles

Actual Stress (Collective) Calculated Load Assumption σ Allowed Tension σzul

>

pF

Stress and Load Assumption

pB

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. 4. Effect of anomalies inside the component must be known, e.g. cuts, sharp edges and damaged surfaces

(1819 – 1914)

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

EN 13260 - Produktanforderungen ORE Dokument B 136 Lastfälle, Werkstoffe, Gestaltung und Berechnung von Laufradsätzen bis 1979 DIN 5577 Gestaltung und Berechnung von Laufradsätzen 1990 Harmonisierung durch den Internationalen Eisenbahnverband (UIC) BN 421 022 Lastfälle, Werkstoffe und Berechnung von Treibradsätzen 1992 EN 13104 - Treibradsätze EN 13103 - Laufradsätze Lastfälle, Gestaltung, Werkstoffe und Berechnung 2000 UIC-Kodex 515 – 3 Lastfälle, Gestaltung, Werkstoffe und Berechnung vor allem Laufradsätze 1994

Nationale Regelwerke Der europäischen Bahnen

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
• bservation 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

Dynamic Decoupling Component

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

Regelbereich Frequenz Ampl.

Control Range

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

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

EVALUATION AND RESULTS after rotating bending test

Test System „EWALD“

GER: Fahrdynamischer Eisenbahnwellen Rißausbreitungs- und Lebensdauer Prüfstand ENG: Driving-Dynamic Railway Shaft Crack Growth and Fatigue Life Time Test Machine

• 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 (108 load cycles in only 28 days).
• Optionally bearing tests are possible.

Description of EWALD

Functional principle:

Load Transmission F F Support Bearing Force Transmission

Rotation

Adjustable for different axles, e.g.:

Tram InterCityExpress (ICE)

Technical Data:

Size:

l = 4.200 mm; w = 1.800 mm; h = 2.100 mm

Weight:

17 t

Input Power:

250 kW

Test load:

2 x 1.000 kN

Reference Torque:

200 kNm

Nominal Speed:

2.500 U/min (41 Hz)

Bearing:

lubricated and cooled by external oil circulation

Lifetime of Bearing:

13.000 h (2,496 x 109 load cycles)

Sensor System:

4 x force transducer, every 450kN

(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“

±Fa ±Fa ±Fr ±Fr Prüflager Prüflager Supportlager Supportlager

Test Bearing Test Bearing Support Bearing Support Bearing

Functional principle:

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. Size: l = 5.700 mm; w = 3.400 mm; h = 3.600 mm Weight: 19,5 t Input Power: 100 kW Test load Fz: 2 x 300 kN servo-electric Test load Fy: 2 x 150 kN servo-electric Nominal Speed: 3.000 U/min (50 Hz) Bearing: lubricated and cooled by external oil circulation Sensor System: 4 x force transducer, 300 kN and 150kN 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.

Size: l = 5.500 mm; w = 2.800 mm; h = 3.000 mm Weight: 14,5 t Input Power: 100 kW Test load Fz: 2 x 150 kN servo-hydraulic Test load Fy: 2 x 30 kN servo-hydraulic Nominal Speed: 4.000 U/min (66 Hz) Bearing: lubricated and cooled by external oil circulation Sensor System: 4 x force transducer, 150 kN and 50kN 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”

• Rotation:

60 rpm (fulling elastomer)

• Radial load:

125 kN (alternating)

• Axial load:

125 kN (alternating)

• Torque:

40.000 Nm

• Controlling:

TESTPILOT

3-axial test and measurement system for railway elastomer-wheels

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

Perspective test system

• Servo-hydraulic resonance test rig
• Fast fatigue testing of railway chassis

components with:

• Large strokes up to 50 mm
• High forces up to 600 kN
• Test frequencies up to 70 Hz

• First successful trials of running a test rig

with large strokes and high forces

• Fatigue testing of bogie with

resonance drive

Perspective test system

SincoTec

Introduction of testing according to standards DIN EN 13260 (Press Fit Fatigue Test) DIN EN 13261 (Shaft Fatigue Test) DIN EN 13262 (Wheel Fatigue Test)

Test system according to standards RESONANCE ROTATING BENDING

Integrated calibration device for carrying out calibration works according to standards:

• DIN EN 13260 (Press Fit Fatigue Test)
• DIN EN 13261(Shaft Fatigue Test)
• DIN EN 13262 (Wheel FatigueTest)

Control of bending moment

• The axle is instrumented with four half bridges aligned 45° to each other
• 300 mm above the bending moment reference position
• The control software EMOTION is reading the output voltage of the half

bridges continuously and runs the system near its natural (resonance) frequency.

• A change of the stiffness of the samples due to cracks is affecting the

resonance frequency

• The test system stops the test when a pre-set frequency drop is achieved.

The tests are performed in a frequency range between 12 Hz and 28 Hz.

Characterization of „Interference Fit“ Test DIN EN 13260

• “F3 test” (of the wheel press fit, solid axle)
• “F4 test” (of the wheel press fit, hollow axle)
• Scope of the test is the interference fit of wheel and axle.
• The bending moments applied related to the calculated nominal stresses at

the edge of the interference fit, which are calculated from Force*Lever arm and the axle’s diameter in the interference fit.

• Prior to test to the test the deviation of static and dynamic loading is to be

determined using a wheelset instrumented with a strain gauge

• The material A4 has to endure a maximum nominal stress of 145 MPa over

10.000.000 load cycles without any cracks or fractures.

Characterization of „Free Surface“ Test DIN EN 13261:

• F1 test (on the axle body)
• The tests are to be carried out at a load corresponding to σnominal = ± 200 MPa nominal

stress relating to the edge of the press fit. The diameter of the shaft shall be used for calculating the section modulus respectively σnominal

• Instrumentation of the axle with a strain gauge array (10 grids) in the area of

maximum local stresses in the radius near the press fit (identify maximum local stress)

• For this purpose the sample is instrumented in the three center curve with a strain

gage chain, comprising 10 measuring grids (4/120LY11). By a static calibration the location of maximum local stresses is determined and thus the reference gauge is determined.

• Prior to test to the test the deviation of static and dynamic loading is to be determined

using the reference gauge.

• The material A1 has to endure a maximum nominal stress at the loaction of maximum

local stresses of 200 Mpa over 10.000.000 load cycles without any cracks or fractures.

Characterization of „Wheel FatigueTest DIN EN 13262” :

• Scope of the test is the high stressed area of the wheel
• The bending moments applied related to the maximum radial

stresses measured in the critical area of the wheel.

• Wheel web critical position identification: Uniaxial strain gauge

array will be glued critical position

• Max. radial stress determination: A 3D rosette strain gauge will

be glued in a critical position

• The material ER8 has to endure a maximum radial stress at 240

Mpa over 10.000.000 load cycles without any cracks or fractures.

Critical Radial Position

Characterization of „Wheel FatigueTest DIN EN 13262”

• Application of strain gauges
• Instrumentation acc. to FEM Data

Identification of Critical Radial Position Rosette in Critical Radial Position

Identification of bending moment to adjust 240 MPa radial Stress

Characterization of „Wheel FatigueTest DIN EN 13262” stress measured by rosette-application

Static calibration

Dynamic calibration

Evaluation of static and dynamic calibration

For example:

• 1. Max. stress was measured at strain gauge 5 (r = 255 mm)
• 2. Data from calibration diagrams for strain gauge 5:

Static calibration diagram: 240 MPa = 155.127 Nm (100%) Dynamic calibration diagram at 16 Hz: 240 MPa = 160.852 Nm

• 3. Dynamic deviation:
• 3,56%
• 4. Dynamic factor:

1,037 Test parameter in software: 240 MPa = Static bending moment x Dynamic factor

Fatigue limits of reduced test pieces according to prEN 13261:2018

• Determining fatigue limits of reduced test pieces of the axles
• Rotating bending up to 107 load cycles
• Test results to verify effect of notches for the used material,

comparison if value is in accordance with the EN13261 standard: RfL = Fatigue limit of unnotched surface RfE = Fatigue limit of notched surface

• Accidents due to breakdown of railway chassis can be avoided by

extensive component testing.

• Most fatigue tests are done with energy efficient Resonance Rotating

Bending Test Systems (e.g. tests according to standards DIN EN 13260, 13261, 13262)

• Operating load test simulation and crack propagation tests are important for

additional safety. “EWALD” test system was developed by SincoTec to perform the tests.

• Modern Bearing Test Systems “High Speed” - and “High Load” are used for

fatigue testing of railway bearings besides the standard tests of axles.

Summary