On high-speed craft acceleration statistics

Razola, Mikael; Olausson, Katrin; Garme, Karl; Rosén, Anders

doi:10.1016/j.oceaneng.2016.01.004

Cited by 23 publications

(17 citation statements)

References 18 publications

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“…It is also noted that the horizontal threshold method commonly used to identify the acceleration peaks (see e.g. McCue (2012), Riley et al (2013) and Razola et al (2016)), which uses a constant sliding time window calculated from the wave encounter frequency to search for the peak, would identify false peaks in this case.…”

Section: Characteristic Resultsmentioning

confidence: 99%

“…To better capture the tail of the distribution a threshold value is introduced and the Weibull distribution is only fitted to the peak values above the threshold. The procedure for choosing the optimal threshold value and estimating the Weibull parameters is similar to that presented in Razola et al (2016) and is as follows,…”

Section: Weibull Parameters Estimation and Threshold Selectionmentioning

confidence: 99%

“…Wang & Moan (2004) and Wu & Moan (2006)), sloshing loads (e.g. Graczyk & Moan (2008)) and, more recently, high-speed craft accelerations Razola et al (2016). Razola et al (2016) studied in detail the statistical character of high-speed craft accelerations.…”

Section: Introductionmentioning

confidence: 99%

“…Graczyk & Moan (2008)) and, more recently, high-speed craft accelerations Razola et al (2016). Razola et al (2016) studied in detail the statistical character of high-speed craft accelerations. The Weibull and Generalized Pareto distributions are used to describe the acceleration peaks and estimate extreme values.…”

Section: Introductionmentioning

confidence: 99%

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Full-scale measurements of slamming loads and responses on high-speed planing craft in waves

Camilleri

Taunton

Temarel

2018

Journal of Fluids and Structures

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Full-scale trials on a high-speed planing craft in waves were conducted to investigate the characteristics of slamming impacts and related rigid body and structural response. Measurements of acceleration, pressure, strain and global hull deflection were made in different sea conditions and at different speeds and headings. Low pass filtering is used to remove unwanted noise from the acceleration signals and extract the rigid body response. Methods for removing trends from the strain signals and identifying the peaks in the pressure and strain signals are established. Characteristic results including time series, distributions of peak values, averages of the largest 1/3 rd and 1/10 th peak values and individual impact events, are presented and discussed. The Weibull and Generalized Pareto models are used to describe the pressure and strain peak values and for estimating extreme loads and responses. Automated algorithms for fitting the statistical models to the peak value distributions are developed and the goodness-of-fit of the models to the data is examined.

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Section: Characteristic Resultsmentioning

confidence: 99%

Section: Weibull Parameters Estimation and Threshold Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Full-scale measurements of slamming loads and responses on high-speed planing craft in waves

Camilleri

Taunton

Temarel

2018

Journal of Fluids and Structures

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“…The wave components have been uniformly distributed in the period domain, resulting in a wave sequence periodicity far longer than the 3-h simulation time, even for the limited number of wave components. 6…”

Section: Exposure Conditionsmentioning

confidence: 99%

Monitoring and characterization of vibration and shock conditions aboard high-performance marine craft

Alwis

Garme

2018

Proceedings of the IMechE

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The stochastic environmental conditions together with craft design and operational characteristics make it difficult to predict the vibration environments aboard high-performance marine craft, particularly the risk of impact acceleration events and the shock component of the exposure often being associated with structural failure and human injuries. The different timescales and the magnitudes involved complicate the real-time analysis of vibration and shock conditions aboard these craft. The article introduces a new measure, severity index, indicating the risk of severe impact acceleration, and proposes a method for real-time feedback on the severity of impact exposure together with accumulated vibration exposure. The method analyzes the immediate 60 s of vibration exposure history and computes the severity of impact exposure as for the present state based on severity index. The severity index probes the characteristic of the present acceleration stochastic process, that is, the risk of an upcoming heavy impact, and serves as an alert to the crew. The accumulated vibration exposure, important for mapping and logging the crew exposure, is determined by the ISO 2631:1997 vibration dose value. The severity due to the impact and accumulated vibration exposure is communicated to the crew every second as a color-coded indicator: green, yellow and red, representing low, medium and high, based on defined impact and dose limits. The severity index and feedback method are developed and validated by a data set of 27 three-hour simulations of a planning craft in irregular waves and verified for its feasibility in real-world applications by full-scale acceleration data recorded aboard high-speed planing craft in operation.

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