The Impact of High-Frequency Vibration on the Performance of Railway Fastening Systems

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1 The Impact of High-Frequency Vibration on the Performance of Railway Fastening Systems Departement of Civil, Geo and Environmental Engineering Chair of Road, Railway and Airfield Construction Maximilian V. Steger, M.Sc. June 14th 2016 short-pitch corrugation (Source: Correa, 2011) 1

2 Outline I: The Impact of High-Frequency Vibration on Fastening Systems Dynamic behavior of fastening clamps (eigenmodes) Compare eigenfrequencies with excitation frequencies II: Countermeasures to Avoid Deterioration of Clamps Dynamic absorbers Modifications to the geometry of clamps Modifications to the angle guiding plate 2

3 Dynamic Behavior of Skl 15 Lab Testing Laboratory Tests to Determine the Eigenmodes To determine the eigenfrequencies and the corresponding deformation Specimen: Single support point System 300 mounted Test equipment: Laser Doppler Vibrometer Excitation via impact hammer 3

Dynamic Behavior of Skl 15 Lab Testing Laboratory Tests - Results 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.

4 Dynamic Behavior of Skl 15 Lab Testing Laboratory Tests - Results Frequency Response Function Frequency [Hz] Actual deformation (lab testing) Eigenmode at 570 Hz consists of a combination of a sliding movement and a tilting movement 4

5 Dynamic Behavior of Skl 15 - FEA Finite Element Analysis Model setup Actual deformation (lab testing) Idealization 700 a b c d k k k k Eigenfrequency [Hz] Sliding k 0 k Spring stiffness k [N/mm] Tilting 5

6 Dynamic Behavior of Skl 15 - FEA Calibrated FEA model - First Eigenmode (570 Hz) 6

Excitation Frequencies due to Rail Defects v [km/h] long-pitch corrugation short-pitch corrugation 300 250 200 150 100 Excitation frequency: Imperfections L [mm] sleeper spacing

7 Excitation Frequencies due to Rail Defects v [km/h] long-pitch corrugation short-pitch corrugation Excitation frequency: Imperfections L [mm] sleeper spacing 600 long-pitch corrugation short-pitch corrugation ,0 0,5 Frequency response function of Skl 15 Spacing L f err [Hz] 7

8 Dynamic Behavior of Skl 15 Summary: Fastening clamps of the type Skl 15 have a first eigenfrequency at 570 Hz At the first eigenfrequency the arms of the clamps show a sliding and tiltingmotion This eigenmode leads to additional stresses at the bending of the arms of the clamps Short-pitch corrugation leads to vibrations in the railway superstructure, which can match the eigenfrequencies of the railway fastening clamps To avoid deterioration of clamps, the project proposes different measures that influence the dynamic behavior of the railway fastening clamps 8

Model Lab testing Dynamic Absorber Modified Geometry

9 Possible Countermeasures to avoid Deterioration Design of countermeasures based on the calibrated FEA model: FEA Model Lab testing Dynamic Absorber Modified Geometry Modified Angle guiding plate MATLAB-tool: Optimized geometries 9

10 Dynamic Absorber - Theory m 2 Amplitude Without Absorber k 2 m 1 With Absorber k 1 Dynamic Absorber eigenfrequency f [Hz] 10

08 Frequency Response Functions Skl 15 (VFS) (without absorber) First prototypes during laboratory tests

11 Dynamic Absorbers Neutralize Vibrations FEA Design of vibration absorbers resulted in first prototypes Experimental testing in the laboratory reveals a good efficacy of the absorber elements: Frequency Response Functions Skl 15 (VFS) (without absorber) First prototypes during laboratory tests Amplitude Skl 15 WITH absorber (colored lines) Frequenz [Hz] 11

Modifications to the Geometry of Clamps A

eigenfrequency by decreasing the mass moment of

12 Modifications to the Geometry of Clamps A MATLAB-tool allows us to make rapid modifications to the geometry of the clamp to optimize the dynamic behavior (increasing the first eigenfrequency by decreasing the mass moment of inertia) curvature rotation diameter extending length of arm height of arm broadening 12

13 Modified Geometries Increase the Eigenfrequencies of Clamps Skl 15 Skl 15 Variation I Skl 15 Variation II [mm] [mm] [mm] The project proposes modified geometries of fastening clamps. The new geometries lead to higher eigenfrequencies, while the spring characteristics of the clamps are maintained. 13

14 Design of a Modified Angle Guiding Plate Increasing the bearing surface raises the eigenfrequencies 700,00 680,00 First Eigenfrequency [Hz] 660,00 640,00 620,00 600,00 580,00 560,00 540,00 520,00 500, Bearing Surface [mm²] 14

Prototype of a Modified Angle Guiding Plate Frequency response function 0.1 0.09 0.08 0.

15 Prototype of a Modified Angle Guiding Plate Frequency response function Skl 15 (570 Hz) Frequency [Hz] 15

16 Summary Results: Original frequency response function of a clamp Skl 15 Frequency response function Frequency [Hz] Skl 15 (570 Hz) 16

17 Summary Results: To avoid deterioration caused by resonance effects, different measures were proposed. All measures influence the dynamic behavior of the clamps and showed a good efficacy in lab testing and simulation. Frequency response function Skl 15 (570 Hz) Skl 15 with dyn absorber Frequency [Hz] 16

18 Summary Results: To avoid deterioration caused by resonance effects, different measures were proposed. All measures influence the dynamic behavior of the clamps and showed a good efficacy in lab testing and simulation. Frequency response function Skl 15 with dyn absorber Frequency [Hz] Skl 15 (570 Hz) Modified geometries (>700Hz, best solution 760Hz) 16

19 Summary Results: To avoid deterioration caused by resonance effects, different measures were proposed. All measures influence the dynamic behavior of the clamps and showed a good efficacy in lab testing and simulation. Frequency response function Skl 15 with dyn absorber Frequency [Hz] Skl 15 (570 Hz) Modified AGP Modified geometries (>570Hz, best solution 760Hz) 16

20 Acknowledgment Funding for this research has been provided by the Karl-Vossloh-Stiftung, Essen, Germany. Questions? contact:

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