Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping

Interpretation of field data from shock tests and subsequent assessment of product safety margins via laboratory testing are based on the shock response spectra (SRS). The SRS capture how a single degree of freedom (SDOF) structure responds to the shock at differing frequencies and, therefore, no lo...

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Main Author: Arup Maji
Format: Article
Language:English
Published: Wiley 2020-01-01
Series:Shock and Vibration
Online Access:http://dx.doi.org/10.1155/2020/8832815
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author Arup Maji
author_facet Arup Maji
author_sort Arup Maji
collection DOAJ
description Interpretation of field data from shock tests and subsequent assessment of product safety margins via laboratory testing are based on the shock response spectra (SRS). The SRS capture how a single degree of freedom (SDOF) structure responds to the shock at differing frequencies and, therefore, no longer contain the duration or other temporal parameters pertaining to the shock. A single duration can often be included in the technical specification or in the recreation of acceleration vs. time history from the specified SRS; however, there is little basis for that beyond technical judgment. The loss of such temporal information can result in the recreated SRS being the same while its effect on a system or component can be different. This paper attempts to quantify this deficiency as well as propose a simple method of capturing damping from shock waves that can allow the original waveform to be more accurately reconstructed from the SRS. In this study the decay rate associated with various frequencies that comprise the overall shock was varied. This variation in the decay rate leads to a variation in the acceleration vs. time history, which can be correlated to a “Damage Index” that captures the fatigue damage imparted to the object under shock. Several waveforms that have the same SRS but varying rates of decay for either high- or low-frequency components of the shock were investigated. The resulting variation in stress cycles and Damage Index is discussed in the context of the lognormal distribution of fatigue failure data. It is proposed that, along with the SRS, the decay rate is also captured to minimize the discrepancy between field data and representative laboratory tests.
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spelling doaj-art-3294ee1c0c864639a5569883b32665bf2025-02-03T01:00:12ZengWileyShock and Vibration1070-96221875-92032020-01-01202010.1155/2020/88328158832815Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in DampingArup Maji0Org 1557, Sandia National Laboratories, Albuquerque, NM, USAInterpretation of field data from shock tests and subsequent assessment of product safety margins via laboratory testing are based on the shock response spectra (SRS). The SRS capture how a single degree of freedom (SDOF) structure responds to the shock at differing frequencies and, therefore, no longer contain the duration or other temporal parameters pertaining to the shock. A single duration can often be included in the technical specification or in the recreation of acceleration vs. time history from the specified SRS; however, there is little basis for that beyond technical judgment. The loss of such temporal information can result in the recreated SRS being the same while its effect on a system or component can be different. This paper attempts to quantify this deficiency as well as propose a simple method of capturing damping from shock waves that can allow the original waveform to be more accurately reconstructed from the SRS. In this study the decay rate associated with various frequencies that comprise the overall shock was varied. This variation in the decay rate leads to a variation in the acceleration vs. time history, which can be correlated to a “Damage Index” that captures the fatigue damage imparted to the object under shock. Several waveforms that have the same SRS but varying rates of decay for either high- or low-frequency components of the shock were investigated. The resulting variation in stress cycles and Damage Index is discussed in the context of the lognormal distribution of fatigue failure data. It is proposed that, along with the SRS, the decay rate is also captured to minimize the discrepancy between field data and representative laboratory tests.http://dx.doi.org/10.1155/2020/8832815
spellingShingle Arup Maji
Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping
Shock and Vibration
title Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping
title_full Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping
title_fullStr Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping
title_full_unstemmed Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping
title_short Probabilistic Assessment of Damage from Same Shock Response Spectra due to Variations in Damping
title_sort probabilistic assessment of damage from same shock response spectra due to variations in damping
url http://dx.doi.org/10.1155/2020/8832815
work_keys_str_mv AT arupmaji probabilisticassessmentofdamagefromsameshockresponsespectraduetovariationsindamping