ASTELAB Fatigue damage calculation to compare 1D with 3D vibration test loads

Transcription

1 ASTELAB 2016 Fatigue damage calculation to compare 1D with 3D vibration test loads Presented by Martin Engelke, IMV Europe Ltd. Contributors: Dr. Christian Dindorf, Robert Bosch GmbH Holger Boller, Vibration Research

2 Motivation Excitation in the real world is always 3D and often quite complicated! Up to now, no clear and/or standardized methodology available yet how to derive 3D profile (possibly accelerated) out of vehicle measurement data.

3 Motivation You won t eat....like this (Pictures by Ursus Wehrlit)

4 Test Sample Hot-film air mass sensor (HFM) for measuring the air intake to determine the required mixture of air and fuel for ideal combustion. Test sample chosen as it is a small and light component, as well as an (almost) ideal oscillator with a clearly defined resonance. Actual automotive component, not some hypothetical model test body.

5 Compare: Typical Test Profile 1D electrodynamic shaker test (sine sweep), e.g. 3 x 30 h Hz, 1 Oct/min, ISO , Test III Based on many vehicle measurements by the industry and Bosch

6 Compare: Measurements Actual real world measurements Measurement of excitation put into sensor on flange Also measurement of response on sensor tip Engine run-up with wide-open throttle and cold engine (usually worst condition for this component) Excitation Response

7 Compare: 3D Shaker Compare: 3D Shaker System in Munich

8 Compare: 3D Shaker

9 Results: Typical Test Profile 3x1D excitation: 8 g sinusoidal sweep at room temperature Sharp resonance in Z direction around 400 Hz Minor resonance in X close to 1000 Hz Flat response in Y

10 Results: Measurement Peak vs. engine rpm for all 3 directions. Excitation Response A=X B=Y C=Z Most pronounced resonance in Z/C direction. Y/B again flat.

11 Results: 3D Shaker 3 days of fundamental investigations by IMV and Bosch in November days of additional measurements in February 2016 by IMV, VR and Bosch.

12 Results: 3D Shaker Measurement Campaign: Characterization of bare table Sequential (3x1D) Simultaneous (1x3D) Sinusoidal test profile from ISO , Test III ( Hz, 50% max. a) Sequential (3x1D) Simultaneous (1x3D) No phase shift (X=0 ; Y=0 ; Z=0 ) With phase shift (X=0 ; Y=45 ; Z=90 )

13 Results: 3D Shaker Measurement Campaign: Random test profile created out of vehicle measurement signal Sequential (3x1D) Simultaneous (1x3D) Correlated Uncorrelated Time history playback out of vehicle measurement signal (2 different ones) Sequential (3x1D) Simultaneous (1x3D)

14 Acceleration (G peak) Acceleration (G peak) Acceleration (G peak) Results: 3D Shaker Uniaxial/sequential characterization with 1g sinusoidal sweep up to 1000 Hz. Two tri-axial sensors at corners used to record response of table. 4.0 Acceleration Profile - measurement X axis VP U LW X LW X Frequency (Hz) 4.0 Acceleration Profile - measurement Y axis VP U LW Y LW Y 4.0 Acceleration Profile - measurement Z axis VP U LW Z LW Z Frequency (Hz) Frequency (Hz)

15 Acceleration (G peak) Acceleration (G peak) Acceleration (G peak) Results: 3D Shaker Triaxial/simultaneous characterization with 1g Sine sweep up to 1000 Hz. Two tri-axial sensors at corners used to record response of table. 4.0 Acceleration Profile - X/Y/Z simultaneous - measurement X axis VP U LW X LW X Frequency 1450 Hz VP U LW X 1.62 LW X Frequency (Hz) 4.0 Acceleration Profile - X/Y/Z simultaneous - measurement Y axis 4.0 Acceleration Profile - X/Y/Z simultaneous - measurement Z axis VP U LW Y LW Y Frequency 120 Hz LW Z Frequency 115 Hz LW Z VP U LW Z LW Z Frequency 1380 Hz LW Z Frequency 1410 Hz LW Z Frequency 1440 Hz VP U LW Y LW Y Frequency (Hz) Frequency (Hz) Bearing Resonance/ Rotational Mode

16 Setup 3D control with one control sensor in each direction, as close to the set-up as possible. 2 additional triaxial accelerometers as a reference on top of the fixture, and as pick-up for the response of the HFM.

17 Results: 3D with Specimen Simultaneous (1x3D) and sequential (3x1D) response on sensor tip (MP2) Z with almost no difference, X with slight and Y with severe difference at resonance frequency of the sensor.

18 Fatigue Damage Spectrum Calculation Incorporates Henderson-Piersol method into random testing Gets real world data transferred into profiles for the shaker Provides a method vor accelerated testing FDS Comparison b t e e t e b t e t T T T T * oder

19 FDS Comparison The acceleration waveform is converted to a velocity waveform Velocity is desired because Henderson-Piersol equations utilize velocity - Velocity has a direct relationship to stress Stress waveform is narrow-band filtered and the Q value is used Cycle counting and damage calculation ensure in each frequency-bin to determine damage contributions over a spectrum of frequencies. Q value determines filter width Spectrum spacing determines number of points in spectrum (number of frequency bins)

20 FDS: Comparison Enveloping the FDS from the individual, sequential measurements leads to a very similar shape of the FDS for simultaneous excitation. The Z response is dominant. Some differences in certain frequency ranges. Let s take a closer look

21 FDS: Comparison Comparison of the Response PSD spectrum s between sequential and simultaneous excitation

22 FDS: Comparison FDS for Sine excitation in Y Distinct difference in response and fatigue damage in Y direction for simultaneous vs. sequential excitation. 3D Shaker Mode? Transducer? Non-linear mode shape?

23 FDS: Comparison FDS for Random excitation in Y Again clear difference in FDS around frequency of primary resonance in Z Indeed different mode shape?

24 Mode shapes from simulation First resonance in Z with very good fit to the uniaxial excitation. Higher harmonic of that resonance could explain discrepancy in Y for comparison of sequential and simultaneous excitation?! Possible cross-checks: response measurement by laser vibrometry or turning the set-up 90 to rule out any shaker effect. 1st resonance in 1D 1st resonance in 3D??

25 Comparing FD sums 1D vs. 3D Fatigue damage sums calculated from sensor response in Z. out of 3x1D vs. 1x3D, e.g. 3 x 10 min and 1 x 10 min, 1x3D set to 100% For random profile created out of vehicle measurement data approx. 2/3 test time reduction possible with 1x3D testing vs. 3x1D testing. With sinusoidal profile a bit more extreme reduction possible, for time history playback of vehicle measurement data currently totally implausible outcome.

26 Comparing FD sums 1D vs. 3D Fatigue damage sums calculated from sensor response in Z. out of 3x1D vs. 1x3D, e.g. 3 x 10 min and 1 x 10 min, 1x3D set to 100%

27 Open questions and Outlook Quantification of fatigue damage sums, comparing 1D vs. 3D excitation possible in general, however with some very basic assumptions (m, Q, single-mass oscillator ). Results promise to allow significant test time reduction by exciting 3D mode shapes that do not occur during 1D testing, while being closer to the reality 3D mode shape still has to be proven for this component by e.g. laser vibrometer. Relationship between 1D and 3D fatigue damage sums has to be proven for other, possibly bigger and more complex components. Fatigue damage sum of 2% when playing back 3x1D vehicle measurement data vs. 1x3D excitation still implausible, possibly some kind of artifact. Process and methodology how to create a 3D vibration profile out of a measurement still unclear, has to be further investigated and standardized.

28 Questions? Thank you! Dipl.-Ing. (FH) Martin Engelke