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Understanding how kurtosis is transferred from input acceleration to stress response and it's influence on fatigue life

Understanding how kurtosis is transferred from input acceleration to stress response and it's influence on fatigue life
Understanding how kurtosis is transferred from input acceleration to stress response and it's influence on fatigue life
High cycle fatigue of metals typically occurs through long term exposure to time varying loads which, although modest in amplitude, give rise to microscopic cracks that can ultimately propagate to failure. The fatigue life of a component is primarily dependent on the stress amplitude response at critical failure locations. For most vibration tests, it is common to assume a Gaussian distribution of both the input acceleration and stress response. In real life, however, it is common to experience non-Gaussian acceleration input, and this can cause the response to be non-Gaussian. Examples of non-Gaussian loads include road irregularities such as potholes in the automotive world or turbulent boundary layer pressure fluctuations for the aerospace sector or more generally wind, wave or high amplitude acoustic loads. The paper first reviews some of the methods used to generate non-Gaussian excitation signals with a given power spectral density and kurtosis. The kurtosis of the response is examined once the signal is passed through a linear time invariant system. Finally an algorithm is presented that determines the output kurtosis based upon the input kurtosis, the input power spectral density and the frequency response function of the system. The algorithm is validated using numerical simulations. Direct applications of these results include improved fatigue life estimations and a method to accelerate shaker tests by generating high kurtosis, non-Gaussian drive signals.
kurtosis, non-Gaussian, fatigue, vibration, linear filter
Kihm, Fred
0ad1771d-47bc-46c8-a2b7-abf69fbe2601
Rizzi, Stephen
167aec5c-66fc-410a-9b66-cb4af6922e29
Ferguson, Neil
8cb67e30-48e2-491c-9390-d444fa786ac8
Halfpenny, Andrew
51f64624-298c-4c69-9dd2-4c21bd0511f5
Kihm, Fred
0ad1771d-47bc-46c8-a2b7-abf69fbe2601
Rizzi, Stephen
167aec5c-66fc-410a-9b66-cb4af6922e29
Ferguson, Neil
8cb67e30-48e2-491c-9390-d444fa786ac8
Halfpenny, Andrew
51f64624-298c-4c69-9dd2-4c21bd0511f5

Kihm, Fred, Rizzi, Stephen, Ferguson, Neil and Halfpenny, Andrew (2013) Understanding how kurtosis is transferred from input acceleration to stress response and it's influence on fatigue life. RASD 2013, Pisa, Italy. 01 - 03 Jul 2013. 16 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

High cycle fatigue of metals typically occurs through long term exposure to time varying loads which, although modest in amplitude, give rise to microscopic cracks that can ultimately propagate to failure. The fatigue life of a component is primarily dependent on the stress amplitude response at critical failure locations. For most vibration tests, it is common to assume a Gaussian distribution of both the input acceleration and stress response. In real life, however, it is common to experience non-Gaussian acceleration input, and this can cause the response to be non-Gaussian. Examples of non-Gaussian loads include road irregularities such as potholes in the automotive world or turbulent boundary layer pressure fluctuations for the aerospace sector or more generally wind, wave or high amplitude acoustic loads. The paper first reviews some of the methods used to generate non-Gaussian excitation signals with a given power spectral density and kurtosis. The kurtosis of the response is examined once the signal is passed through a linear time invariant system. Finally an algorithm is presented that determines the output kurtosis based upon the input kurtosis, the input power spectral density and the frequency response function of the system. The algorithm is validated using numerical simulations. Direct applications of these results include improved fatigue life estimations and a method to accelerate shaker tests by generating high kurtosis, non-Gaussian drive signals.

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More information

Published date: 1 July 2013
Venue - Dates: RASD 2013, Pisa, Italy, 2013-07-01 - 2013-07-03
Keywords: kurtosis, non-Gaussian, fatigue, vibration, linear filter
Organisations: Dynamics Group

Identifiers

Local EPrints ID: 355355
URI: http://eprints.soton.ac.uk/id/eprint/355355
PURE UUID: ccbea78f-b274-490e-8035-fc8129353d02
ORCID for Neil Ferguson: ORCID iD orcid.org/0000-0001-5955-7477

Catalogue record

Date deposited: 28 Aug 2013 12:22
Last modified: 15 Mar 2024 02:34

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Contributors

Author: Fred Kihm
Author: Stephen Rizzi
Author: Neil Ferguson ORCID iD
Author: Andrew Halfpenny

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