Inside Extreme Scale Tech|Sunday, December 28, 2014
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Simulations Sail into the Shipyard 

The automotive and aerospace industries jump quickly to mind when we think of digital manufacturing for transportation. There, digital manufacturing is an integral part of the entire product lifecycle. It helps designers create and preview an initial concept, and it helps engineers test the safety and performance of the designs without costly investments in crash test centers and wind tunnels.

But as far as modeling and simulation are concerned, nautical transportation isn’t one of the first things to come to mind. Still though, it presents a unique use case for computer-integrated manufacturing, as the focus of the modeling and simulation is on the construction process itself.

Hoping to demonstrate the advantages that digital manufacturing with a particular emphasis on CAD can offer the industry are Yasuhisa Okumoto from Kinki University and Kentaro Hiyoku of IHI Marine United, who have been studying digital manufacturing for shipbuilding and its implementation in IHI MU Kure shipyard in Japan.

According to Okumoto and Hiyoku, shipbuilding has traditionally been dominated by tacit knowledge in shipbuilding and manufacturing that is organized by humans alone. However, it is currently undergoing a transformation whereby worker knowledge is digitized and quantified to speed up production and aid in decision-making.

To be fair, modeling manufacturing itself is not exactly new. Tools already exist to test the efficacy of assembly lines to ensure that moving parts will never accidentally collide during the production process.

But this is manufacturing on a massive scale: coordinating cranes and transporting house-sized hull blocks around which workers scramble to connect the pieces to bring life to the larger vessel. Here, simulation isn’t just about designing a better ship and producing it faster: it helps to ensure the safety of all of the building dock’s workers.

Making this possible over the last decade are significant improvements in compute capacity and performance that have ushered in the transition from 2D to 3D modeling.  Aside from the obvious benefit of creating and utilizing more complex and accurate models, the advent of 3D modeling software has meant that key data can be viewed holistically and can be more easily distributed through various departments.

But perhaps even more important are the complex simulations that can only be run when models are accurately rendered in three dimensions, which is precisely the advantage that the researchers are seeing shipbuilders take advantage of.

Of course, to many industries, this is nothing new. The automotive and aerospace industries have already taken advantage of sophisticated modeling and simulation software to design and test the safety and aerodynamics of their products, but for shipbuilders, this is a different beast altogether.

When we think of simulation, we often picture computational fluid dynamics or multiphysics-enabled collision simulations. For shipbuilding, the picture changes a bit. High on the priority list there is the construction process itself, and determining the safest, most efficient construction procedure.

During the construction process, cranes are responsible for moving, turning and connecting each of the blocks comprising the ship’s eventual hull. Simulation helps to prevent interferences from coming up between each of these units, particularly in the engine room, where many workers are engaged and safety is a major concern.

Lowering entire hull blocks by crane may sound daunting, but that’s not the only tricky part of the process. Inserted blocks are also lowered into the body of the ship by crane, but in this case it has to fit perfectly between all of the adjacent structures and avoid any obstructions that could be in the crane’s path. Because so much work goes into assembling and loading equipment into these blocks on the ground, it’s essential that the insertion itself goes as smoothly as possible so that no backtracking for repairs is necessary. Because of its complexity, Okumoto and Hiyoku claim that CAD should be integral to this process.

Scaffolding is another construction element that simulations have helped to more effectively plan. While some shipyards have looked to aerial vehicles to help solve outer hull construction problems in high places, potential interference between the vehicle’s boom and the hull itself mean that scaffolding is the best option for getting a worker to the upper limit of the hull. Here, simulations mean that scaffolds are better organized and less likely to interfere with operations on the dock.

Lastly, the researchers looked at the most important component of shipbuilding: human workers. They explain that full automation is just not feasible, and human physiology must be taken into account when designing both permanent structures for accessibility as well as temporary construction-specific structures such as ladders. Here, simulations of human physiology have helped to minimize strain on the back and knees, as well as helping to improve safety by designing ladders where workers are less likely to slip and fall.

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