IHB Ship Design в числа – 15 години опит, 80 инженери, 400+ завършени проекта
Case Study – Heavy Cargo carrier Conversion to Container carrier update
1. Main outline of the project
The project consists of three major steps:
2. Container plan and design loads
Based on the requirements of the client firstly we determine the available container positions. In general, there are two options when deciding this:
After performing strengths calculations in this particular case the containers are positioned in the Cargo holds. Below is the General Arrangement showing the positions of the containers that will be placed on deck.
3.Container Socket Installation
Reinforcements are installed into deck structure, in places where container sockets are installed, and in places where deck lashing points are arranged. There are two types of locking sockets:
4.Loads on container fittings and external lashing
The purpose of this step is to determine racking, compressive, and lifting loads of containers. Loads from external lashing on deck are determinate as well. All forces are applied at container COG.
Calculations were performed in ANSYS – Workbench 19.0*
The calculations are being performed on:
4.1. Central stacks
There are three types of loads acting on the central stacks:
Central stacks weight Central stacks wind load
Central stacks motion
4.2. Side stacks
There are three types of loads acting on the side stacks:
Side stacks weight Side stacks wind load
Side stacks motion
5. Deck stiffening strength check-up
One of the most integral parts of the ship is its bottom structure. It is designed not only to give the hull the required strength to withstand the weight of the cargo but also to withstand the external hydrostatic loads that act on the bottom of the hull.
A calculation model is created based on the vessel‘s structural drawings. Aft part of cargo deck is used, as in this area deck plate thickness and under deck structure thicknesses are smallest. Calculations were performed in ANSYS – Workbench 19.0.
Deck structure Additional Deck reinforcement
5.2. Loads on deck
Calculation model – Container weights Calculation model – Wind forces
Calculation model – External lashing forces Calculation model – Motion forces
Calculation model – Deformations under deck detail
Calculation model – Shear stress
The main purpose of the stress calculations is to prove the sufficiency of the designed structure according to RMRS rules. Some peak extreme values are concentrated in very small areas on the surface of the elements or in areas with big swaps in the geometry parameters and are judged to be non-physical, but rather a result of numerical approximations. Therefore, such values are ignored and actual values are considered to be around the average values of the stresses outside the peak extreme values areas.