Browsing by Author "Engelbrecht, MC"

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    Human responses to wave-induced motion, slamming and whipping.
    (Stellenbosch : Stellenbosch University, 2023-11) Engelbrecht, MC; Bekker, A; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: Ship motion is known to a ect comfort, rest and productivity. On ships, these factors could in uence fatigue-related accidents. Discomfort on cruise ships could adversely a ect customer satisfaction. The crew and passengers of vessels, live and work in this dynamic environment, often for months on end. Research regarding human comfort, as a result of impulsive wave slamming is specifically limited. Wave slamming is the random impact of waves against the ship hull leading to the phenomenon called whipping which causes vibration to propagate through the ship structure. This study investigated the effects of impulsive vibration on activity disturbance in the operational context of a slamming-prone vessel. Metrics from whole-body vibration standards were investigated as a possible means to quantify comfort. A possible threshold of the onset of discomfort was determined and compared to likely responses to whole-body vibration as documented in whole-body vibration standards, maritime standards and ship classification society documents. Subjective data was obtained from daily diary surveys conducted willingly by people on board. Additional human responses were reaped from instantaneous slam observations which were conducted from the Bridge during designated ship manoeuvres. Full-scale vibration measurements were recorded at several locations across the ship for the entire duration of the voyage and expressed in terms of metrics as provided in standards. Subjective and objective data were correlated. Subjective results show that slamming was prevalent on most days during investigated voyages. Sleeping was observed to be the activity most disturbed. Metrics such as vibration dose value and root-mean-square value had displayed positive strong correlations with the human response data. An hourly vibration dose value threshold of approximately 0.43 m/s1:75 and 0.47 m/s1:75 resulted from both the surveys and instantaneous slam ratings. This corresponds to the threshold where 50% of the sample population felt discomfort. The determined threshold for root-mean-square value of 0.03 m/s2 is much lower than guideline values provided in ISO 2631-1 for discomfort in public transport applications.