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Advanced Vibration Testing: Proposal for Evaluating Vibration Profiles for Different Load Quantifications

This proposal suggests test profiles to quantify the load of various vibration types on test specimens. It includes detailed procedures for 8g-sweep and 2g-sweep tests, specifying frequency ranges, accelerations, and sweep patterns. The proposal outlines testing methodologies for measuring strain, fatigue damage, and power spectral density, with examples of vertical vibrations on car bodies. Results from vibrationsignal data on proving grounds and random vibrations are analyzed to assess potential damages on test specimens. Additionally, it discusses the possibility of customized test profiles based on manufacturer requirements and vehicle applications.

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Advanced Vibration Testing: Proposal for Evaluating Vibration Profiles for Different Load Quantifications

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  1. RESS-4-19 vibration-test for RESS1. quantification the load of different vibration profiles with a test specimen 2. proposal for a test-profil

  2. evaluated profils for vibration test • vibration signal of a car on proving ground (example) • random vibrationISO12405 vertical • 8g-Sweep UN38.3 • 2g-Sweep proposal approx. 75 Hz approx. 30 Hz approx. 15 Hz strain gage load direction test specimen

  3. sweep-signal • The vibration shall be a sinusoidal waveform with a logarithmic sweep between 7 Hz and 200 Hz and back to 7 Hz traversed in 15 minutes. This cycle shall be repeated 12 times for a total of 3 hours for each of three mutually perpendicular mounting positions of the RESS. • UN38.3 8g-sweep • from 7 Hz to a peak acceleration of 1 gn is maintained until 18 Hz is reached. The amplitude is then maintained at 0.8 mm (1.6 mm total excursion) and the frequency increased until a peak acceleration of 8 gn occurs (approximately 50 Hz). A peak acceleration of 8 gn is then maintained until the frequency is increased to 200 Hz. • Proposal 2g-sweep • from 7 Hz to a peak acceleration of 1 gn is maintained until 18 Hz is reached. The amplitude is then maintained at 0.8 mm (1.6 mm total excursion) and the frequency increased until a peak acceleration of 2 gn occurs (approximately 25 Hz). A peak acceleration of 2 gn is then maintained until the frequency is increased to 200 Hz.

  4. vibrationsignal from proving-ground (example) random vibration ISO12405 vertical 8g-sweep UN38.3 2g-sweep proposal power spectral density (PSD)of test-profils

  5. vibrationsignal from proving-ground (example) random vibration ISO12405 vertical 8g-sweep UN38.3 2g-sweep proposal load of test speciment • max. strain on test specimen max. strain [mV/V] measuring point 15Hz measuring point 30Hz measuring point 75Hz

  6. vibrationsignal from proving-ground (example) random vibration ISO12405 vertical 8g-sweep UN38.3 2g-sweep proposal load of test speciment • fatigue damage on test specimen, relative to vibrationsignal from proving-ground extrapolated to target relative fatigue damage measuring point 15Hz measuring point 30Hz measuring point 75Hz

  7. measured accelerations,power spectral density • range of measured accelerations (vertical) on car body, approx. 50 different cars • micro compact car • luxury sedan • roadster • SUV • … PSD [g²/Hz]

  8. car body - frequency spectrum car body - frequency spectrum micro compact car accelerationy [g] accelerationy [g] frequency [Hz] frequency [Hz] measured accelerationsfrequency spectrum FFT micro compact car • no significant response upwards 50 Hz • highest peaks for micro compact car

  9. RESS vibration test proposal acceleration – frequency curve • maximum acceleration 10m/s^2 (1g), maximum frequency 50 Hz • sinusoidal waveform with a logarithmic sweep

  10. RESS vibration test proposal At the request of the manufacturer, a higher acceleration level as well as a higher maximum frequency can be conducted. In the case of a higher maximum frequency, the lowest frequency can be greater than 5 Hz, but shall not exceed 10% of the highest frequency. At the request of the manufacturer a test profile determined by the vehicle-manufacturer, verified to the vehicle application and agreed by the Technical Service can be used as a substitute of the frequency – acceleration correlation of the proposal.

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