February 16, 2021

Composites Essential for TKMS & SAAB Subs

Composites are essential for submarines due to their non-magnetic nature, light weight, ease of shaping and many other benefits (below). Lightweight makes for a lower displacement, not top heavy with less contervailing need for ballast. Composites are easier than steel to shape. 

So a submarine making company skilled in composites has economic-sales advantages over  one that has a greater percentage of steel in its sub.

Following this composites article Anonymous's February 8, 2021 comments led to the following:

1.  TKMS uses SIEMENS composite materials technology:

Composite materials are seaworthy and offer many benefits. First, they stand up well to the harsh and salty marine environment, resisting any corrosion while possessing much better aging capabilities than metals. Composites also provide the ability to “design the material” by combining fibers and resins in different ways and by placing the fibers along preferred orientations following loading and stress paths, thus reducing the weight-tostrength and weight-to-stiffness ratios.

Further, composites facilitate the manufacture of seamless, complex shapes for better hydrodynamic performance and stealth characteristics. Composites can be more easily draped over round surfaces while sheet metals cannot. They also enable part consolidation and part count reduction using resin transfer molding or co-curing of large assemblies at once, without the need for riveting or joining small parts together, thus reducing manufacturing cycle times and costs.

Composites also offer some valuable mechanical properties, including better fatigue resistance and less sensitivity to crack propagation than aluminium and other metals; enhanced acoustic transparency for improved sonar transmission (for instance, in the bow dome); and reduced lifetime and maintenance costs compared to metallic structures.

This photo shows the dividing line between where composites (top) and metal (the hull) have been used on this class 212 submarine. Oddly in the photo the red, white and blue bunting does not suggest it is a 212 for the German Navy or a 212-Todaro for Italy.  TKMS/HDW is using Fibersim to design and manufacture the complete upper deck, keel covers, tower sail fairings, propeller blades and rudders. (Photo courtesy SIEMENS.)
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HDW [part of TKMS] is using Fibersim to design and manufacture a variety of glass fiber and carbon fiber outfitting parts...TKMS is using Fibersim to design and manufacture the complete upper deck, keel covers, tower sail fairings, propeller blades and rudders. “Fibersim takes a lot of the worry out of the process by enabling us to capture many more details of the final composite layups...” complete upper deck, keel covers, tower sail fairings, propeller blades and rudders. In the near future, TKMS expects to extend the use of Fibersim to include the design of structural parts, starting with a new, lighter weight storage rack for torpedoes.

“Fibersim enables us to do a faster conversion from metal to composites, and minimizes the risk by verifying information before it ever gets to the manufacturing floor”.
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2.  SAAB may have its own composite material section.

[Pete comment - although SAAB buying 
GKN Aerospace’s Applied Composites AB Business may be more SAAB-aircraft oriented than marine.

SAAB certainly has an extensive marine composites capability, as seen in the Visby corvettes. a capability which would extend to the A26 submarines.]

Maybe SAAB and Naval Group could send comments with some details of their submarine composites?
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3.
 
ADifferent types of composites include:

-  Glass/carbon fiber reinforced plastic/polymer (GFRP/CFRP) and

Fiber reinforced metal (FRM) Metal matrix composite (MMC) for pressure hulls seems to be difficult.
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PETE COMMENT

The percentage (by weight) of composites in submarines is likely to increase across submarine makers and their country customers. 

Composites in pressure hulls (hitherto Steel or Titanium monopolies) may be possible in the future.

11 comments:

Anonymous said...

FRP is non-magnetic material.

retortPouch said...

That's a 212 I think, not a 214.

That said, 214s probably employ composites too. The 218sg certainly does.

Anonymous said...

Hi Pete,

There exist 2 articles about the Visby class corvettes (in Swedish unfortunately) the first one includes the composites and a second one they are from 2014 so things as happen like RBS15 has been added but more is coming.

And Saab just got Saab Signs Two Contracts for Next Generation Corvettes for Sweden

"Saab and the Swedish Defence Materiel Administration, (FMV), have signed two agreements concerning the next generation of surface ships and corvettes. A Product Definition Phase for the Mid-Life Upgrades (MLU) of five Visby-class corvettes, as well as a Product Definition Phase for the next generation; Visby Generation 2 corvettes."

And Saab has delivered composite superstructures to Singapore and India.

/Kjell

Pete said...

MHalblaub, on February 17, 2021 at 9:00 AM, commented/asked:

Another topic: steel hull vs. diamagnetic stell hull.
How often does a Diesel only submarine have to snorkel? This is independent of battery type. A submarine can stay submerged for a longer period with better batteries but then has to snorkel for a longer period.
---------------------------

Pete's response:

Hi MHalblaub

How often does a Diesel only submarine snorkel - depends on the submarine, mission, degree of discretion required and Captain's preferences.

Often subs could snorkel every 2 days, but they may snort every day to keep their batteries topped up for unforseen emergencies eg:

- need to move fully submerged at 18 knots for 3 hours after torpedoing a ship or other quick tactical movement,

OR

- unusual need to stay fully submerged for 3 days to escape searching subs/surface ships/or aircraft.

Many other considerations.

Regards

Pete

Pete said...

Hi retortPouch

Yes the photo looks like a 212 to me to.

2 things:

1. Its Siemens calling it a 214

and

2. the bunting is red, white and blue. Nothing like the German (212A) or Italian (212A Todaro) flags.

But I suspect that when Siemens translated their article from German to English Siemens mistranscribed what is clearly a 212 into a "214". I've altered caption to "212".

Yes very likely 214s and 218s use composites.

Regards

Pete

Anonymous said...


In Type 214 submarine, metal hydride cylinders are installed on the lower outside of the pressure hull, thermally insulated, and covered by FRP panels.

Kjell said...

Hi Pete,

You can also counteract the magnetic field that part of the talk starts att 9:20 in the video.

/Kjell

MHalblaub said...

Dear Pete,

the colours seen in the photo are of Schleswig-Holstein, the state where the submarine was built.

Regards,
MHalblaub

Pete said...

Thanks /Kjell

For your February 18 comment.

This presentation "How to build an invisible submarine - Saab at Infoshare 2018" at https://youtu.be/ZPkYbFq8KLk 9:20-11:00

describes very well how to minimise magnet signature.

Regards

Pete

Pete said...

Thanks MHalblaub [at February 20, 2021]

For cracking the (non-national bunting flag) code.

The 212A's surronding bunting indeed represents the red, white and blue flag of https://en.wikipedia.org/wiki/Flag_of_Schleswig-Holstein where the 212A sub was built.

Interesting how that flag has gone in and out of official acceptance so much.

Regards

Pete

Pete said...

Thanks /Kjell [your February 17, 2021 at 8:28 AM]

The Visby class corvettes clearly have a “a carbon fiber reinforced sandwich construction” very stealthy shape for low radar signature, multi-coloured camouflage, large gun, missiles and torpedos.

Very different from Australia’s far less stealthy https://en.wikipedia.org/wiki/Arafura-class_offshore_patrol_vessel with a 40mm gun, .50 calibre machine guns and a UAV.

Regards

Pete