Year: 2013 Language: english Author: ARON JALKEVIK AND KARL TORESSON Format: PDF Quality: eBook Pages count: 82 Description: Master’s Thesis in the International Master’s Programme Naval Architecture and Ocean Engineering RoRo ships are an important ship type in transports at sea today. Reliable designs of their loading ramps are required to ensure the safe and efficient loading and unloading of cargo. Today, most ramps are designed against ultimate strength despite the fact that they are subjected to repeated loading from rolling cargo. The class rules, however, do not take fatigue damage into consideration. In this thesis, two RoRo ramps have been investigated from a fatigue point of view. An existing method for performing fatigue assessment and life estimations is to be modified to suit RoRo ramps in the future. The ramps investigated are a straight stern ramp and a quarter ramp. Two different methods have been used for investigating these ramps. On the straight stern ramp, fatigue damage has been found in the form of cracks in a specific area. Focus has therefore been on investigations of this area. First by stress analyses and subsequently by fatigue analyses based on these stresses. On the quarter ramp no such area is known and therefore a global stress analysis of the ramp has been performed to identify areas with stress concentrations and subsequently sub-models of these areas have been created to get more accurate stress levels in these areas. After the local stresses have been calculated, the stresses are used for estimating the fatigue life of the structure. For the fatigue assessment of the ramps, mainly the stress-based approach has been applied. The number of cycles to failure has been calculated and estimations of the load spectrum were made in order to give an approximation of the fatigue life.
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Fatigue assessment of stern ramps
Year: 2013
Language: english
Author: ARON JALKEVIK AND KARL TORESSON
Format: PDF
Quality: eBook
Pages count: 82
Description: Master’s Thesis in the International Master’s Programme Naval Architecture and
Ocean Engineering
RoRo ships are an important ship type in transports at sea today. Reliable designs of
their loading ramps are required to ensure the safe and efficient loading and unloading
of cargo. Today, most ramps are designed against ultimate strength despite the fact
that they are subjected to repeated loading from rolling cargo. The class rules,
however, do not take fatigue damage into consideration.
In this thesis, two RoRo ramps have been investigated from a fatigue point of view.
An existing method for performing fatigue assessment and life estimations is to be
modified to suit RoRo ramps in the future.
The ramps investigated are a straight stern ramp and a quarter ramp. Two different
methods have been used for investigating these ramps. On the straight stern ramp,
fatigue damage has been found in the form of cracks in a specific area. Focus has
therefore been on investigations of this area. First by stress analyses and subsequently
by fatigue analyses based on these stresses. On the quarter ramp no such area is
known and therefore a global stress analysis of the ramp has been performed to
identify areas with stress concentrations and subsequently sub-models of these areas
have been created to get more accurate stress levels in these areas. After the local
stresses have been calculated, the stresses are used for estimating the fatigue life of
the structure. For the fatigue assessment of the ramps, mainly the stress-based
approach has been applied. The number of cycles to failure has been calculated and
estimations of the load spectrum were made in order to give an approximation of the
fatigue life.
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