Sunday, 30 March 2014

Risk - Based Ship Design: (Part Two)

As a continuation to the first part of this series (click on the picture below for link), the second article of the series is focused on presenting the framework of risk based design process by taking an example of the safety framework of an ocean going ship. Also get to know, how the design decision making is limited to the initial concept design stage and the economic advantages to making most of the decision changes at the initial concept design stages. 

This article has also been presented through a prezi below. Please view in fullscreen for better view. Wait for the prezi to load before you can view it. You can either advance the slides manually or set it to automatic slideshow for ease. 


Article By: Soumya Chakraborty

Author's Note: This article is different from the first one, as in it gives you and insight as to how the risk scenarios are actually framed in the design process and analyzed accordingly. Thank You for reading. In case of any doubts or queries please comment. You may also write to

Thursday, 27 March 2014

Print Me A Ship


3D printing is a technology which makes it possible to build real objects from virtual 3D objects. This is done by “cutting” the virtual object in 2D slices and printing the real object slice by slice. Slices are printed on top of each other and since each slice has a given thickness, (e.g. 0.5mm), the real object gains some volume every time a slice is added.

The technique builds a solid object from a series of layers - each one printed directly on top of the previous one. The machines’ operating software cuts the CAD model of the work piece into slices, whose thickness depends on the type of material used
Objects that are manufactured this way can be used anytime throughout the product life phase, from industry scale production in addition to applications and customization.

The term Additive manufacturing is also used to refer to methods that create or manufacture objects through progressive or uniform layering. [1]
Subtractive Manufacturing refers to the existing industrial techniques which rely on processes involving removal of unwanted material by milling, grinding, drilling, filing etc.
Our paper calls for its mainstream application in the Maritime Industry with a scaled up perspective.
We shall discuss the industrial manufacturing techniques to create functional and durable ships with reductions in costs and limitations of machining parts. Together with such high degrees of freedom in design and rapid progress in material sciences, a day is not far when we shall see such novel technologies become a reality.


Several different 3D printing processes have been invented since the late 1970s. The printers were originally large, expensive, and highly limited in what they could produce. It was not until the early 2010s that the printers became widely available commercially. The first working 3D printer was created in 1984 by Chuck Hull of 3D Systems Corp. [1]

First technology according to Mr Hull is Stereolithography Since the start of the 21st century there has been a large growth in the sales of these machines, and their price has dropped substantially. [2]

Fused deposition modelling (FDM) was developed by S. Scott Crump in the late 1980s and was commercialized in 1990 by Stratasys.
Also Selective Laser Sintering (SLS) was developed and patented by Dr Carl Deckard and Dr Joseph Beaman at the University of Texas at Austin in the mid-1980s, under sponsorship of DARPA.


Thermoplastics (e.g. PLA, ABS), HDPE, eutectic metals, edible materials, Rubber (Sugru), Modelling clay, Plasticine, RTV silicone, Porcelain, Metal clay (including Precious Metal Clay)
Almost any metal alloy
Almost any metal alloy
Thermoplastic powder
Plaster-based 3D printing (PP)
Light polymerised

As potential future techniques,only some of the following sound promising to us they are:



In this form of modelling the object is produced by casting out small globules of material which harden immediately to form layers. A metal wire that is wound on a coil is uncoiled to supply material to an extrusion nozzle head. The nozzle head heats the material and turns the flow on and off. Typically stepper motors or servo motors are employed to move the extrusion head and adjust the flow and the head can be moved in both horizontal and vertical directions. Control of this mechanism is typically done by a computer-aided manufacturing (CAM) software package running on a microcontroller.
FDM has some restrictions on the shapes that may be made-up. For example, FDM usually cannot produce stalactite-like structures, since they would be unsupported during the build. These have to be avoided or a thin support may be designed into the structure which can be broken away during finishing.

An example of a FDM manufactured part
using complex geometry

·         High Strength.
·         Cost Effective.
·         Water Proof.


Another 3D printing approach is the selective fusing of materials in a granular bed. The technique fuses parts of the layer, and then moves the working area downwards, adding another layer of granules and repeating the process until the piece has built up. This process uses the unfused media to support overhangs and thin walls in the part being produced, which reduces the need for temporary auxiliary supports for the piece. A laser is typically used to sinter the media into solid.


It is a process that sinters (diffuses atoms at temperatures below melting point) layers of powdered metal in a chamber of inert gas. When a layer is finished, the powder bed moves down, and an automated roller adds a new layer of material which is sintered to form the next section of the model. Repeating this process builds up the object one layer at a time. DMLS is a metal additive manufacturing technique the, DMLS refers specifically to metal sintering and is not used for plastics. The physical process is different from Selective Laser Melting (SLM) in that it only sinters the powder as opposed to achieving a full melt.


·         Excellent levels of purity and homogeneity in base material.
·         High strength materials can be fabricated.

A part of a fuel injector made using DMLS Technique, these are at par with their conventional counterparts


As the name implies, EBM uses an electron beam to melt a titanium powder. The additive fabrication processes builds parts on a layer-by-layer basis. After melting and solidifying one layer of titanium powder, the process is repeated for subsequent layers.
Within the electron beam gun, a tungsten filament incandesces and "boils off" a cloud of electrons 

When the high-speed electrons strike the metal powder, the kinetic energy is instantly converted into thermal energy. Raising the temperature above the melting point, the electron beam rapidly liquefies the titanium powder.

A simple trial for effective strength of components made
 from EBM Methods for dissimilar metals

  • Cycle time reductions of up to 40%.

  • Vacuum melt quality can yield high strength  properties of the material.
  • Combinations of dissimilar metals.[5]


The process starts by slicing the 3D CAD file data into layers, usually from 20 to 100 micrometres thick, creating a 2D image of each layer; this file format is the industry standard .stl file used on most layer-based 3D printing or stereolithography technologies. This file is then loaded into a file preparation software package that assigns parameters, values and physical supports that allow the file to be interpreted and built by different types of additive manufacturing machines.
With SLM thin layers of atomized fine metal powder are evenly spread using a coating mechanism onto a substrate plate, usually metal, that is fastened to an indexing table that moves in the vertical axis. 


·         The complete freedom in defining the geometry of the part.
·         The reduction of the production cycle.

SLM Techniques combine CAD and high end prototyping
to give complete freedom to the designer


Stereolithography was patented in 1986 by Chuck Hull.

Stereolithography is an additive manufacturing process which employs a cask of liquid ultraviolet curable photopolymer "resin" and an ultraviolet laser to build parts' layers one at a time. For each layer, the laser beam traces a cross-section of the part pattern on the surface of the liquid resin. Exposure to the ultraviolet laser light cures and solidifies the pattern traced on the resin and joins it to the layer below.

After the pattern has been traced, the SLA's elevator platform descends by a distance equal to the thickness of a single layer, typically 0.05 mm to 0.15 mm. Then, a resin filled blade sweeps across the cross section of the part, re-coating it with fresh material.

Stereo lithographic modelling of a car wheel rim


According to Mr Hull, the 3D Printing Market as a whole will be worth around 4.5 Billion US Dollars by 2018. [2]
Because of the promising possibilities it is assumed that Rapid Prototyping is going to spread out during the next years as it was the case with the introduction of CAD years ago. Besides others like speed and cost arguments we can see especially 2 reasons why naval architects should think about extending their toolbox by 3-D printing techniques. Below the table gives us an idea of costs


Ship Type
Average Light Ship
Cost [$US/1000 Ton]
Conventional Submarine
103 to 347
Nuclear Submarine
185 to 250
122 to 168
Frigate or Corvette
70.8 to 217
Aircraft carrier
69.8 to 67.0
Cruise ship
US built crude oil tanker

Chemical product tanker


Container ship

Crude oil tanker (medium)

Oil product tanker

Bulk carrier  (small/medium)

Source: John Birkler, ET. al., “Differences between Military and Commercial                    Shipbuilding: Implications for the United Kingdom’s Ministry of Defence, RAND Report          MG-236 (Santa Monica: RAND Corporation, 2005), statistics taken from Table 3-1, available at   pubs/monographs/2005/RAND_MG236.pdf.

The initial cost savings of 3D printing come from the designs allowed by the layer-by-layer process.Experts predict 3D printing has the potential to completely revolutionize the manufacturing sector this year.
3D printing is on its way to becoming the next trillion dollar industry. It's all in the numbers...Manufacturing currently accounts for 17%, or $10.2 trillion of the $60 trillion global economy. That being said, if 3D printing is able to “capture” at least 10% of the manufacturing sector we'd easily have ourselves a $1 trillion (+) industry!

Metal Injection Moulding market has grown from $ 382 million USD in 2004 to $985 million USD in 2009. Further the market is estimated to be about $1.5 billion USD in 2012. [BBC Research]


Additive manufacturing's earliest applications have been on the tool room end of the manufacturing spectrum. For example, rapid prototyping was one of the earliest additive variants, and its mission was to reduce the lead time and cost of developing prototypes of new parts and devices, which was earlier only done with subtractive tool room methods.
 With technological advances in additive manufacturing, however, and the dissemination of those advances into the business world, additive methods are moving ever further into the production end of manufacturing in creative and sometimes unexpected ways. Parts that were formerly the sole province of subtractive methods can now in some cases be made more profitably via additive ones.

Example of a jet propeller made using Stereo lithographic techniques at 3D Systems, something that may be extended to propellers in ships


One of the most immediate ways 3D printing will impact the shipping industry is through the design and construction of ships, submarines, aircraft, and everything carried on board. This is due largely to the economic benefits derived from the technology.
If the “build volume” is large enough, a manufacturer can print a component as a whole, forgoing the need for further assembly. This means it can go without the brackets, flanges, and surfaces required for handling, bolting, or welding pieces of the component together—thereby saving material and weight. It also means internal systems such as ducting and piping can be designed to maximize fluid-flow efficiency from more rounded shapes, simultaneously eliminating unnecessary system volume and making it lighter still.
Additive manufacturing’s second cost savings come from the materials used in the process. The traditional production technique, subtractive manufacturing, starts with a “billet” of fill and whittles it down to the desired product, wasting up to 90 percent of the material. When working with the rare and expensive top-grade materials that the military demands in high-performance aircraft and precision weapons, the waste is all the dearer.[5]

Researchers at EADS, a major European aerospace company, found that a type of 3D printing using titanium powder could create parts just as strong as traditionally produced items using only 10 percent of the titanium. The production lines and shipyards of the future could be, in effect, enormous 3D printers that would maximize the economies derived from the additive manufacturing process. Augmenting shipboard supply departments with 3D printers can alleviate the need to carry large stocks of pre-manufactured stores. Instead of spending weeks trying to track down a repair part or seldom-used consumable, a repair-parts petty officer could scan the discarded part labelled with a barcode quick response (QR) code, or some other embedded identifier that, once scanned, sends the item’s schematics to queue at the nearest printer.
Some ship parts like the bulbous bow (see our article on bulbs)
may be easier to manufacture using these techniques
This simple scenario illustrates many potential benefits. 
The most obvious is the speed with which a ship could secure a replacement part. This is especially true of rare components or those   with low-failure rates not typically carried on board vessels or not in large numbers. “An individual ship has hundreds of thousands of parts,” “supply can’t stock all of them.
Advances in printing and robotics indicate how shipboard additive manufacturing may be useful beyond simple repair parts. Already researchers at the University of Southampton have successfully printed an entire working unmanned aerial vehicle, except for the engine.
Meanwhile, this year scientists at the Naval Research Laboratory will start testing on the ex-USS Shadwell of the Autonomous Shipboard Humanoid (ASH) fire fighting robot, meant to be able to “walk in any direction, keep its balance at sea, and go through narrow passageways and up ladders”. The Navy has also funded a similar project at the Georgia Institute of Technology for a “MacGyver Bot” that can solve complex problems and assist in dangerous situations by using whatever it finds nearby. If these trends are a clue, the future could hold the ability to print complete replacements of the robotic crew members, weapon systems, and remotely piloted or autonomous vehicles that fight the ship and project power.
3D printing can enable the creation of complex geometries which are very difficult, expensive, or impossible to be manufactured using conventional production methods. It will provide a boost to the art industry.It would also be possible to build individual intricate artistic designs never before possible while giving the architects freedom of design without sacrificing structural rigidity or safety of workers. This technology can also help engineers to rebuild and restore old heritage designs quickly yet accurately. Instrument makers are using 3D printed parts when crafting instruments.


The research comes to the conclusion that there is not one single system best suitable for all existing tasks in naval architecture. Each of the systems has some advantages but also drawbacks.
 As creating moulds is possible in very less time often in a few hours, we can take complete advantage in designing ships keeping this in mind. The profile of the ships now shouldn’t matter as it used to be because of bending limitations in steel. Naval Architects can now concentrate on hydrodynamics and aesthetics during the design stage making it more efficient and green.

By building durable concept models, prototypes, tooling and low-volume end-use parts in-house, engineers and designers can work more iteratively, test more thoroughly and move confidently into production.”-Stratasys

The Economist claims this to be the "Third Industrial Revoultion".

“As manufacturing goes digital, a third great change is now gathering pace.It will allow 
things to be made economically inmuch smaller numbers, more flexibly and with a
 much lower input of labour, thanks to new materials, completely new processes such as 3D printing, easy-to-use robots and new collaborative manufacturing services available online. The wheel is almost coming full circle, turning away from mass manufacturing and towards much more individualised production.”-The Economist

Three-dimensional printing makes it as cheap to create single items as it is to produce thousands and thus undermines economies of scale. It may have as profound an impact on the world as the coming of the factory did... Just as nobody could have predicted the impact of the steam engine in 1750 — or the printing press in 1450, or the transistor in 1950 — it is impossible to foresee the long-term impact of 3D printing. But the technology is coming, and it is likely to disrupt every field it touches. - The Economist 

Some food for thought, if you think 3D Printing is the new frontier think again and see this video.


The most capable machines, such as those that can print titanium alloy objects, are quite expensive and quite large and increasing the speed of printers is “daunting.” However, the competitive effects should drive down both costs and printing time. Printers will continue to get faster and faster,” moving ever-closer to providing true “object on-demand” capabilities. The costs of fill materials can be similarly prohibitive. This has been due in large part to the proprietary nature of the fill materials and requirements for interfaces with the machines. Printers can’t yet build with every material. A list of to be accomplished are: “Flexible plastics, polymers, rubbers, wax, translucent materials, and different types of metals.

Objects created layer by layer rather than through a traditional casting or moulding process are different at the molecular level. This allows designers to develop intricate internal structures that yield stronger-than-normal materials and equipment. But it also leaves some of the cheaper products, like those made with plastics, weaker, because they were not created as individual pieces. This need not remain the case, but it is so now.

It introduces new security challenges in efforts to prevent proliferation. In late June 2012, a Wisconsin engineer made headlines when he used a 3D printer to fashion a working receiver assembly for a firearm modelled on the AR-15. Although it was only a portion of the weapon, the project to create a complete gun continues with new supporters. It is not difficult to imagine the attraction of such a capability for some not-so-nice state and non-state actors. As the Navy introduces 3D printers into the fleet, it will need to secure them against cyber threats as it does other information systems.

 Unique vulnerabilities exist from the same 3D printers that are opportunities for our own cyber efforts. For example, a printer could be hijacked to create a self-destructing weapon or an infiltrating robot. Exploitable, unnoticeable design flaws could be introduced, or a crucial supply capability could simply be shut down.

It will take years, likely decades, to overcome all these challenges. But they will not stop the development and evolving opportunities afforded by 3D printers. One of the biggest tasks will be to evaluate each new breakthrough’s impact on the shifting economic calculus of consigning any one of the thousands of shipboard parts to print-on-demand status. Better understanding of the link between printer developments and new capabilities will allow to focus research the resources to achieve them. The potential cost and capability benefits are enormous. Let the great experiment begin.LSD


[2] CNN interviews Chuck Hull: 'The night I invented 3D printing'
[3] Rapid Manufacturing with Electron Beam    Melting(EBM) – A manufacturing revolution?-
· Ulf Lindhe, M.Sc., Manager of Marketing, Sales and Service, Arcam AB
· Morgan Larsson, Technical Manager, Arcam AB
· Ola Harrysson, Ph.D., Assistant Professor, Industrial Engineering Department, North Carolina State University

[4] Aerospace Case Studies

[5] Print Me A Cruiser

Article By: Sudripto Khasnabis
                 Vishal Kumar Jha
                 Sake Avi Kunal

Author's Note: This article is adapted from a paper titled "PRINTING SHIPS: A REALITY" presented by the authors at the "Samudra Manthan",the Annual Technical Meet of IIT Kharagpur's OENA Department.The paper discussed the potential of 3D Printing as a future manufacturing technique.Views expressed here are purely that are held by the authors themselves.The pictures do not belong to LSD, and full credit for the same goes to their respective owners. If you have any queries or doubts,do not forget to write to us at