Hi there,
I am preparing myself for the oral exam and couldn’t find any answers for couple questions: 1). How the hull strength maintained at cargo doors?
2).How forecastle and end of the accommodation superstructure faired in to the main hull structure? I will appreciate any help. Thanks
Okay, here we go:
Hull strength at shell openings is maintained by compensating structure.
This involves a combination of increased thickness plating surrounding or at the corners of the opening(s), and internal structure such as headers, to carry the loads “around” the opening itself. Gussets and brackets may be used, or for very large openings such as those on a car or vehicle carrier, a purpose designed structure may be fitted around the door opening(s) to transmit the loads in the hull girder itself. The corners of openings, large or small, will likely be radiussed to avoid stress concentrations.
The hull structure in way of raised forecastles incorporates bulwark plating that smoothly transitions or is inclined from the forecastle deck level down to the deck below it. This may take the form of a large radiussed curve, or it may be a straight (inclined) line. This can be clearly seen on profile or side on photographs of such vessels. Again, the idea is to smoothly transmit the loads in the hull girder itself and avoid localized stress concentrations.
The transition in way of accommodations zones is similarly treated, however the accommodation many newer ships does not extend to the hull side and is not on a raised section of deck ,but rather is on the main deck, several meters inboard of the hull side. In such cases, no transtion is needed.
If I was handier with posting photos, I could show examples of all the above, but alas, I am old and computer posting feeble.
====================
A finite element analysis model will be often be prepared and the loads imposed various parts of shipboard structure will be evaluated to confirm the engineering assumptions are correct for the resutlting structure and the hull girder itself. You might learn more about that on the web sites of the various classification societies and see an example for a simple mechainical part at the following link:
http://www.jjgeng.com/html/results.html
I have seen this type of van mises diagram or FEA done often for (a) ships and ship parts - including shell side openings and cargo hatches - at the design stage, (b) to facilitate movements of large objects like deck or platform modules and (3) when ships or structures are damaged and it is important to see where the strength remains (or not) and where highest stresses will be found. All fun stuff, because you can relate the drawings and FEA to the actual ship very easily when you see both !
Good luck
[QUOTE=+A465B;80300]Okay, here we go:
Hull strength at shell openings is maintained by compensating structure.
This involves a combination of increased thickness plating surrounding or at the corners of the opening(s), and internal structure such as headers, to carry the loads “around” the opening itself. Gussets and brackets may be used, or for very large openings such as those on a car or vehicle carrier, a purpose designed structure may be fitted around the door opening(s) to transmit the loads in the hull girder itself. The corners of openings, large or small, will likely be radiussed to avoid stress concentrations.
The hull structure in way of raised forecastles incorporates bulwark plating that smoothly transitions or is inclined from the forecastle deck level down to the deck below it. This may take the form of a large radiussed curve, or it may be a straight (inclined) line. This can be clearly seen on profile or side on photographs of such vessels. Again, the idea is to smoothly transmit the loads in the hull girder itself and avoid localized stress concentrations.
The transition in way of accommodations zones is similarly treated, however the accommodation many newer ships does not extend to the hull side and is not on a raised section of deck ,but rather is on the main deck, several meters inboard of the hull side. In such cases, no transtion is needed.
If I was handier with posting photos, I could show examples of all the above, but alas, I am old and computer posting feeble.
====================
A finite element analysis model will be often be prepared and the loads imposed various parts of shipboard structure will be evaluated to confirm the engineering assumptions are correct for the resutlting structure and the hull girder itself. You might learn more about that on the web sites of the various classification societies and see an example for a simple mechainical part at the following link:
http://www.jjgeng.com/html/results.html
I have seen this type of van mises diagram or FEA done often for (a) ships and ship parts - including shell side openings and cargo hatches - at the design stage, (b) to facilitate movements of large objects like deck or platform modules and (3) when ships or structures are damaged and it is important to see where the strength remains (or not) and where highest stresses will be found. All fun stuff, because you can relate the drawings and FEA to the actual ship very easily when you see both !
Good luck[/QUOTE]
So greatly explained, thanks a lot!!!