PRODUCT OVERVIEW

CORE
MATERIALS

www.gurit.com
GURIT CORE MATERIAL OFFERING
Gurit is a technical leader in the development and manufacture of structural core materials. Cores in
a sandwich construction are specified by designers and architects to increase stiffness and reduce
the weight of a composite structure. Gurit has a range of core materials to fit any specification or
manufacturing process. Structural core materials are offered in sheet form and with a variety of cut
patterns or finishes, tailored to customer needs or processing choice.

Gurit® Balsaflex™ END GRAIN BALSA WOOD CORE is the classic

end-grain balsa wood core, featuring very high strength to weight
ratio and is available in range of densities, thickness and format/
finish. Gurit® Balsaflex™ is approved by Germanischer Lloyd (GL) /
Det Norske Veritas (DNV).

Gurit® Corecell™ SAN STRUCTURAL FOAM

Gurit® Corecell™ is a structural foam core material using a SAN
(styrene acrylonitrile) polymer base featuring high toughness and
impact resistant characteristics. Gurit® Corecell™ has become widely
accepted for the construction of large, high performance structures
through a wide range of processing methods.

Gurit® Kerdyn™ Green THERMOPLASTIC RECYCLED FOAM CORE

Gurit® Kerdyn™ Green is an up to 100% recycled PET content
structural foam. Offering a perfect solution for application requiring a
good balance of mechanical performance, top-in-class resin uptake
performance as well as a more sustainable approach to the light weight
composite sandwich solution. With highly adaptable and recyclable
capabilities, this thermoplastic PET (polyethylene-terephthalate)
core material provides an adequate solution with a wide range of
applications and processes.

Gurit® PVC & Gurit® PVC HT CROSS-LINKED PVC FOAM

Gurit® PVC is a closed cell, cross-linked PVC (polyvinyl chloride)
foam. It provides high strength to weight ratio for all composite
applications. Other key features of Gurit® PVC include outstanding
chemical resistance, low water absorption and excellent thermal
insulation capabilities. The HT option offers high temperature
processing up to 140oC.

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 GURIT’S RANGE OF STRUCTURAL CORE MATERIALS

 
SHEAR COMPRESSION DYNAMIC PROCESSIBILITY COMPATIBILITY
FIRE,
3RD PARTY
PRODUCT MAIN FEATURES ELONGA- IMPACT SMOKE & HEAT OUT- WATER MACHIN- THERMO- PAGE
  STRENGTH MODULUS STRENGTH MODULUS FATIGUE HDT PRU RECYCLABILITY VE PE EP CERTIFICATIONS
TION RESISTANCE TOXICITY STABILITY GASSING ABSORPTION ABILITY FORMING

¬ Up to 100% recycled PET content

¬ All-purpose foam
PET

Gurit® Kerdyn™ ¬ Suitable for all sandwich applications

FR version Y Y Y ¬ DNV-GL 6
Green ¬ Superior strength & stiffness:weight
¬ Outstanding chemical resistance
¬ FR version

¬ All-purpose foam
¬ DNV-GL
¬ Suitable for all sandwich applications Self
Gurit® PVC N/A Y Y Y ¬ RINA 7
¬ Superior strength & stiffness:weight Extinguishing
¬ Lloyds Register
¬ Outstanding chemical resistance
PVC

¬ DNV-GL
Gurit® Self
¬ High temperature processing up to 140°C N/A Y Y Y ¬ RINA 7
PVC HT Extinguishing
¬ Lloyds Register

¬ Industrial grade structural foam

Gurit® ¬ Compatible with prepreg processing ¬ DNV-GL
N/A N/A Y Y Y 8
Corecell™ T ¬ Superior strength & stiffness:weight ¬ ABS
¬ Cost-effective

¬ High performance foam, ideal for marine ¬ DNV-GL

applications
SAN

¬ Lloyds Register
Gurit®
¬ High shear strength and low density N/A N/A Y Y Y ¬ BV 8
Corecell™ M
¬ Compatible with prepreg processing ¬ ABS
¬ High elongation for toughness ¬ RINA

¬ Hydrostatic Crush
Gurit®
¬ Sub-sea buoyancy foam N/A N/A Y Y Y Pressure tested to ASTM 9
Corecell™ S
D-2736
BALSA

¬ Classic wood core

Gurit® ¬ Available in typical densities & formats
N/A N/A N/A Y Y Y ¬ DNV-GL 9
Balsaflex™ ¬ Very high mechanical properties
¬ Sustainably and responsibly sourced

* Please contact your local sales representative for further information on the products.

Key: Fair Good Excellent Outstanding Key: PRU = Panel Resin Uptake VE = Vinylester PE = Polyester EP = Epoxy

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 GURIT’S RANGE OF STRUCTURAL CORE MATERIALS

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NOMINAL DENSITY HALF SHEET SIZE NOMINAL SHEET SIZE THICKNESS RANGE
DENSITY SHORT EDGE MARKING
(kg/m3) (lb/ft3) (mm) (inches) (mm) (inches) (mm) (inches)

80 Blue 80 4.99 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-200 13/64 - 7 7/12
100 Green 100 6.24 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-200 13/64 - 7 7/12
115 Black 115 7.18 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-175 13/64 - 6 57/64
135 Black Green 135 8.43 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-150 13/64 - 5 29/32
150 Orange 150 9.36 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-135 13/64 - 5 5/16
200 Black Yellow 200 12.49 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-100 13/64 - 3 15/16
250 Black Blue 250 15.61 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-80 13/64 - 3 5/32
235 Black Brown 235 14.67 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-200 13/64 - 7 7/11

Gurit® Kerdyn™ Green

300 Black Orange 300 18.73 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-80 13/64 - 3 5/32
80 FR Blue Red 80 5 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-200 13/64 - 7 7/11
115 FR Black Red 115 7.18 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-175 13/64 - 6 57/64
180 FR Brown Red 180 11.24 1005/1220 x 1220 39.5/48 x 48 1005/1220 x 2440 39.5/48 x 96 5-110 13/64 - 4 21/64

NOMINAL DENSITY HALF SHEET SIZE NOMINAL SHEET SIZE UNBONDED THICKNESS
DENSITY FOAM COLOUR
(kg/m3) (lb/ft3) (mm) (inches) (mm) (inches) (mm) (inches)

40 Azure 40 2.5 1330 x 2850 52.4 x 112.2 3-84 1/8 - 3 5/16

48 Lilac 48 3 1270 x 2730 50 x 107.5 3-80 1/8 - 3 5/32
60 Yellow 60 3.75 1150 x 2450 45.3 x 96.4 3-78 1/8 - 3 5/64
HT60 Pink 60 3.75 1120 x 2400 44.1 x 94.5 3-78 1/8 - 3 5/64
80 Green 80 5 1020 x 2180 40.2 x 85.8 3-72 1/8 - 2 53/64
HT80 Light Yellow 80 5 1005 x 2150 39.6 x 84.6 3-75 1/8 - 2 61/64
Please contact local Gurit representative
100 Red 100 6.24 950 x 2050 37.4 x 80.7 3-68 1/8 - 2 43/64
HT100 Light Orange 100 6.24 940 x 2030 37 x 79.9 3-65 1/8 - 2 9/16
130 Blue 130 8.12 850 x 1900 33.5 x 74.8 3-58 1/8 - 2 9/32

Gurit® PVC & Gurit® PVC HT

HT130 Orange 130 8.12 850 x 1900 33.5 x 74.8 3-58 1/8 - 2 9/32
200 Brown 200 12.5 750 x 1600 29.5 x 63 3-48 1/8 - 1 57/64

250 Green 250 15.6 700 x 1500 27.6 x 59 3-47 1/8 - 1 27/32

PLEASE NOTE: Maximum unbonded thicknesses can vary across Gurit sites. Please contact your local sales representative for more information.
Gurit® Kerdyn™ Green product width are depend to production sites; please check with your regional Gurit Sales contact. Kerdyn™ 300 is solely available from Gurit Tianjin production site.

NOMINAL DENSITY HALF SHEET SIZE NOMINAL SHEET SIZE UNBONDED THICKNESS
DENSITY SHORT EDGE MARKING
3 3
(kg/m ) (lb/ft ) (mm) (inches) (mm) (inches) (mm) (inches)

T400 White Green 71 4.4 1285 x 1285 50.5 x 50.5 1285 x 2605 50.5 x 102.5 3-50 1/8 - 2

T500 White Blue 94 5.9 1195 x 1220 47 x 48 1195 x 2440 47 x 96 3-40 1/8 - 1 9/16

M60 Yellow Green 65 4.1 1285 x 1285 50.5 x 50.5 1285 x 2605 50.5 x 102.5 3-50 1/8 - 2

M80 Yellow Blue 85 5.3 1220 x 1220 48 x 48 1220 x 2440 48 x 96 3-50 1/8 - 2

M100 Yellow Black 107.5 6.7 1130 x 1130 44.5 x 44.5 1130 x 2275 44.5 x 89.5 3-48 1/8 - 1 7/8
Gurit® Corecell™

M130 Yellow Pale Brown 140 8.7 1015 x 1015 40 x 40 1015 x 2045 40 x 80.5 3-44 1/8 - 1 3/4

M200 Yellow Brown 200 12.5 915 x 915 36 x 36 915 x 1830 36 x 72 3-31 1/8 - 1 1/4

S1200 Red Brown 210 13.1 890 x 890 35 x 35 890 x 1830 35 x 72 21-24 53/64 - 15/16

S1800 Red Mauve 315 19.7 785 x 785 31 x 31 785 x 1600 31 x 63 16-21 5/84 - 53/64

NOMINAL DENSITY SPECIAL SHEET (FLEXIBLE PANEL ONLY) NOMINAL SHEET SIZE UNBONDED THICKNESS
DENSITY SHORT EDGE MARKING
(kg/m3) (lb/ft3) (mm) (inches) (mm) (inches) (mm) (inches)
Gurit®
Balsaflex™

150 Written 155 9.7 1220 x 1220 48 x 48 610 x 1220 24 x 48 6.35-55 1/4 - 2

PLEASE NOTE: Maximum unbonded thicknesses can vary across Gurit sites. Please contact your local sales representative for more information.
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Gurit® Kerdyn™ Gurit® PVC &
Green Recyclable DNV-GL FR version Gurit® PVC HT High Chemical DNV-GL, Lloyds High Process
Recycled Structural Foam certified Resistance & RINA approved Temperature
All-Purpose Foam Core

¬ Up to 100% recycled PET content ¬ New Gurit PET product line ¬ Suitable for all composite sandwich applications ¬ Outstanding chemical resistance
¬ Improved mechanical properties ¬ Reduced resin uptake ¬ Superior strength and stiffness to weight ratio ¬ Excellent thermal insulation capabilities
¬ Recyclable ¬ FR version ¬ Self extinguishing ¬ High temperature resistance up to 140oC with
¬ Compatible with all types of composite manufacturing techniques Gurit® PVC HT

Gurit® Kerdyn™ Green is a new recyclable, thermoplastic foam with an improved balance of mechanical properties, enhanced resin Gurit® PVC is a closed cell, cross-linked PVC foam. It provides superior strength to weight ratio for all composite applications.
uptake performance, and good temperature resistance for a wide range of applications and production processes. Other key features of Gurit® PVC include outstanding chemical resistance, negligible water absorption, and excellent thermal insulation
capabilities. It is compatible with most common resin systems including epoxy, polyester and vinylester.

Gurit® PVC is available in a wide range of formats with all standard cut patterns and finishes possible.
TYPICAL APPLICATIONS
Gurit® Kerdyn™ is used extensively in wind turbine blades, civil and marine structures. Gurit® Kerdyn™ is available in plain sheet form. A
fire retardant version is also available with certification under review.
TYPICAL APPLICATIONS
Gurit® PVC is an all purpose core and can be used in decks, hull sides,
bulkheads, floors and wind turbine blade shells.

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Gurit® Corecell™ T High Chemical DNV-GL, ABS ap- High Process
Gurit® Corecell™ S High Water Ultra-fine High Hydrostatic
Resistance proved Temperature
Structural Foam Core Sub-sea Foam
Resistance Cell Size Crush Strength

¬ Suitable for all PVC core applications ¬ Excellent mechanical properties ¬ Sub-sea buoyancy foam ¬ Outstanding mechanical properties
¬ Outstanding chemical resistance ¬ 120oC processing ¬ Ultra-fine cell size ¬ Lower density than resin-based syntactics
¬ Ideal for resin infusion ¬ High hydrostatic crush strength and water resistance

Gurit® Corecell™ T has been developed as a technological step-change from traditional PVC and Balsa structural core. Gurit® Corecell™ T is an
Gurit® Corecell™ S has been designed specifically for use in sub-sea buoyancy applications. Its resistance to crushing means that it can withstand
outstanding core material in every application where balsa or cross-linked PVC is commonly used. High mechanical toughness and thermal stability
depths of over 900m, and its closed-cell structure gives it a high water resistance that ensures buoyancy is maintained over time. With its very high
give Gurit® Corecell™ T excellent fatigue characteristics. This reliability makes Gurit® Corecell™ T a natural replacement for cross-linked PVC or balsa
compressive strength, Gurit® Corecell™ S can also replace other materials, such as plywood, when creating high strength inserts for through-bolting
in applications where a significant service life is required.
in composite laminates.
The high temperature stability of Gurit® Corecell™ T also means that it can be used in manufacturing processes to at least 120oC / 250oF with short
durations during a cure cycle to over 150oC / 300oF. This makes it ideal for use with conventional prepregs and in some liquid infusion processes
where high resin exotherms can often be seen. Gurit® Corecell™ T is available in every resin infusion format and is compatible with polyester,
TYPICAL APPLICATIONS
vinylester and epoxy resin systems. Low resin absorption characteristics of Gurit® Corecell™ and unique knife cut formats allow for higher performing
infusions, lower resin cost and lower weight than any other structural core. Gurit® Corecell™ S has been used in a variety of demanding sub-sea
applications from buoys, civil and military submarines as well as highly
loaded marine applications units. Gurit® Corecell™ S can be supplied in
sheet form or kit-cut format. This is a Gurit special product.
TYPICAL APPLICATIONS
Ideal for applications where loads are less dynamic in nature, such as
above the waterline on yachts, on wind turbines and in mass transport.

DNV-GL, ABS,
Gurit® Corecell™ M High Chemical
BV, Lloyds, IRS & High Process Gurit® Balsaflex™ Natural and DNV-GL High strength
Resistance Temperature Sustainable certified to weight ratio
The Marine Foam RINA approved Classic Wood Core

¬ Low resin absorption ¬ Good compressive strength and stiffness ¬ High quality composite core material made from end grain balsa
¬ Highest strength to weight ratio of any structural core
¬ High temperature processing (prepreg compatible) ¬ DNV-GL, RINA, BV, Lloyds, IRS and ABS certification
¬ Natural, sustainable and responsibly sourced
¬ High shear strength & elongation – ideal for areas ¬ Suitable for prepreg, SPRINT®, infusion and
subjected to slamming loads wet lamination
Gurit® Balsaflex™ is the classic end-grain balsa wood core, featuring very high strength to weight ratio. When an application requires high-
strength and stiffness and cost effectiveness, Gurit® Balsaflex™ is a suitable solution due to a good balance between cost, properties
Gurit® Corecell™ is a structural foam core material using a SAN polymer base featuring high toughness and impact resistant characteristics. It offers and weight. Gurit® Balsaflex™ is available in a range of densities, thicknesses, formats and finishes. Gurit® Balsaflex™ is GL approved.
very reliable processing without outgassing for high quality parts. Gurit® Corecell™ M is the newest addition to the Gurit® Corecell™range and shares
the benefits of SAN chemistry common to all Gurit® Corecell™ products.

TYPICAL APPLICATIONS
Gurit® Balsaflex™ is used for wind turbine blades and nacelles, marine, automotive, truck, rail and aircraft parts. Gurit® Balsaflex™ can be
TYPICAL APPLICATIONS
supplied in sheet form or kit-cut to customer’s desired shapes.
Gurit® Corecell™ M has been developed to deliver one product for all
Marine applications. It provides a combination of high shear strength with
low density, high elongation, high temperature resistance and low resin
uptake. Gurit® Corecell™ M is the perfect choice whether your application
is slamming area or superstructure, hull or deck, using hand lamination,
infusion or prepreg.

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FINISHING FINISHING CONT’D
Complete Core Solutions Complete Core Solutions

Gurit standard product forms are described in the following tables toward faster response. Gurit can also tailor sheets to your own GURIT® GURIT® KERDYN™ GURIT®
DETAILS GURIT® PVC
specification depending on lead-time and volume - please call to discuss your requirements. Corecell™ GREEN BALSAFLEX™
PL
PL – Plain Sheet – Optimum material properties. Limited bending in-mould.

PH – Plain with Bleeder Holes – Assists air release in vacuum bag processes. PH Spacing = 50 x 50mm Spacing = 20 x 20mm Spacing = 25.4 x 25.4mm
Dia. = 1.6/2mm Dia. = 2mm Dia. = 3mm
CUTS FOR CONFORMABILITY (FOAM) (with 25 x 25 option) (with 40 x 40 option) (with 50.8 x 50.8 option)

Gurit double-cut finish is standard for Gurit® Corecell™ and Gurit® Kerdyn™ Green; and can be also considered for Gurit® PVC. Alternatives
CS Spacing = 30 x 30mm Spacing = 25.4 x 50.8mm
single-cut or the less common triple-cut can also be performed. Please be advised that cuts are dependent upon the density and Width = Knife <0.5mm / Saw 0.9/1mm Width = <0.5mm
thickness of the material. Higher density and thickness materials may need to be saw cut (0,9/1mm), rather than knife cut (0,5mm)
although the spacing will be constant. DC (TC/SC) Spacing = 30 x 30mm
N/A
Knife cuts are not visible when the sheets lie flat and these narrow knife-cuts minimize overall resin consumption compared to saw-cut core Width = <0.5mm / Saw 0.9/1mm
finishes. Maximum sheet size is half of a full-size sheet. Please contact your customer support representative for more information.
VIC Spacing = 30 x 30mm Spacing = 20 x 20mm Spacing = 19 x 19mm
SC – Single Cut – Provides flexibility in a single direction on one or both sides of a sheet. If done on both sides, the cuts intersect Width = 0.9mm Width = 2mm Width = 1mm
so no bleeder holes are necessary for vacuum bagging. Max sheet size is half of a full-size sheet. Depth = 2mm Depth = 2mm Depth = 2.5mm

DC – Double Cut – Provides flexibility in two directions on one or both sides of the sheet. If Double Cut on both sides, the intersecting VIC+PH Spacing = 20 x 20mm
cuts make DC a highly effective resin infusion medium. The cuts are not visible when the sheets lie flat and these narrow knife-cuts
Width = 2mm
minimise unnecessary resin accumulations compared to sawn core materials. As above Depth = 2mm + Spacing = As above
CS – Contour Scrim – provides optimum flexibility in two directions. Sheets are cut in squares and bonded to a glass scrim. Available on 20 x 20mm
sheets up to 25mm (0.98”) thick (dependent on density). Maximum standard sheet size is half the full sheet. Dia. = 2mm Intersection

SURFACE GROOVES FOR INFUSION (FOAM)

VIC – Vacuum Infusion Core – There are several VIC options and Gurit can customize grooving patterns and bleeder holes as required. For details regarding the maximum window of capabilities related to core type, thickness and density, please contact your local Sales Team:
For curved laminate sections, double-sided DC is very effective system for resin infusion with low weight gain. Heat-forming VIC surface www.gurit.com/contact.aspx
cut also useful for obtaining curved panels with minimal resin uptake.

Combination – Combinations of these aforementioned formats are also available.

PRODUCT FORMATS (BALSA)

Gurit® Balsaflex™ is available plain or with typical formats including perforations, grooves, contour scrim and with optional coating.

OTHER PRODUCT FORMATS

Fillet strips – Triangular edge strips to create tapered panel edge drop-offs, or stringer base fillets.
KITTING
Complete Core Solutions

Gurit has an extensive kitting capability to provide all the Gurit® Corecell™ formats in customised, numbered, ready to use, CNC machined
kits. Gurit can make comprehensive kits using either full customer drawings or their B3 SmartPac software solution. All types of core can be
supplied and machined including Gurit® Corecell™ (SAN), Gurit® PVC, Gurit® Kerdyn™ Green and Gurit® Balsaflex™.

Gurit use either 5-Axis, or 3-Axis CNC machines along with a range of semi-
automatic and manual machines to provide the optimum kitting solution depending
PL - Plain SC - Single Cut CS - Contour/Scrim upon kit complexity. Gurit has developed specific knowledge and experience on
the correct flute and clearance angles to provide optimum cutting conditions.
This allows for quick cutting to minimise cost, accurate cutting for component
dimensions and fine cutting to allow the best nesting routines so maximising yield
rates and minimising waste.

Gurit’s machining strategy for core is to develop a range of cutting techniques that
provide a cost-effective and flexible kitting solution to satisfy customer requirements.

PH - Plain/Bleeder Holes DC - Double Cut VIC - Typical VIC

10 11
SANDWICH PANEL ENGINEERING THEORY STRUCTURAL ENGINEERING WITH CORE MATERIALS
Single skin laminates, made from glass, carbon, aramid, or other fibers may be strong, but they can lack stiffness due to their relatively low Gurit’s heritage lies in engineering high performance yachts such as Americas Cup, Open 60’s and Volvo 70’s. However, over the past 30
thickness. Traditionally the stiffness of these panels has been increased by the addition of multiple frames and stiffeners, adding weight and or so years, Gurit has been involved with almost every type of marine craft including military power boats, production cruisers, and some
construction complexity. of the world’s most spectacular superyachts. Whilst Gurit is most widely recognised for its marine expertise, the team has considerable
experience in the provision of innovative engineering solutions to many different structures.
A sandwich structure consists of two high strength skins separated by a core material. Inserting a core into the laminate is a way of increa-
sing its thickness without incurring the weight penalty that comes from adding extra laminate layers. In effect the core acts like the web in an
The range of projects worked on covers any large composite structural application and includes:
I-beam, where the web provides the lightweight ‘separator’ between the load-bearing flanges. In an I-beam the flanges carry the main tensile
and compressive loads and so the web can be relatively lightweight. Core materials in a sandwich structure are similarly low in weight compared ¬ Raceboats ¬ Wind turbines ¬ Civil Engineering
to the materials in the skin laminates. ¬ Superyachts ¬ Underwater turbines ¬ Architectural features

Engineering theory shows that the failure mode of the sandwich panel can be linked to specific properties of the core material used. To show how different core materials are considered in industry, some of the challenges that designers face for superyachts and wind
energy turbine blades are discussed below.
IMPACT
SKIN WRINKLING SHEAR CRIMPING PANEL BUCKLING SHEAR FAILURE
RESISTANCE

Thickness
SUPERYACHT DESIGN
Shear elongation
Hulls
Shear modulus
The hull and deck shells of a boat provide the watertight safety cell for the crew and also the foundation to support the rig and keel. The
Shear strength
amount of pressure from the water that the hull of a yacht has to sustain varies along the length of the boat and also from the bottom
Compressive modulus to the shearline. Classification societies adopt a quasi-static analysis, which defines a hydrostatic pressure distribution. The hull bottom
panels see higher pressure than the topside panels because they are submersed deeper in the water. The pressure distribution also
decreases from the bow to the stern due to decreasing exposure to waves.

SKIN WRINKLING
Core provides insufficient out-of-plane support to
skins allowing local, independent buckling.
Occurs on panels subjected to high compressive
strains, independently of panel width.

SHEAR CRIMPING
Core shear modulus is too low to transfer loads * To avoid print through if hull topside has a
between outer laminate skins. dark colour finish

Occurs on panels subjected to high compressive ** Slamming loading is recognised by most

classification societies by giving credit for
loads, independently of panel width.
cores with a higher shear elongation
*** Thermoformability or adequate cut pattern is
required to fit pronounced curvature

PANEL BUCKLING
Decks
The panel has insufficient bending stiffness to pre-
As superyacht length increases, boats get sleeker and the fore and aft bending stiffness becomes an increasing challenge, putting
vent buckling.
decks under increased compression loads.
Occurs on wide flat panels subjected to high com-
For smaller size boats, deck stiffening tapes are added over the full width of the deck. The critical failure mode is likely to be Euler Buckling (Fig.1
pressive load (Euler buckling), or on deep panels
& 2). As boat size increases, the most common solution is to concentrate the deck tapes at the edges of the panel. This changes the critical
subjected to high shear load (Shear buckling).
failure mode from Euler Buckling of the overall side deck panel to shear crimping in way of the concentrated tapes (Fig. 3).

IMPACT RESISTANCE
Core toughness and resistance to cracking is too low
to absorb high energy slamming loads. Occurs in core
Fig. 1 Fig. 2 Fig. 3
materials with low shear elongation.

Decks also have to support water pressure and local indentation from walking loads and deck gear.
SHEAR FAILURE
Core shear strength is too low to carry shear stress.
Occurs on panels subjected to high bending loads

12
13
 In way of high point-loaded deck fittings

Where topside cosmetics are critical,

e.g. dark coloured finish, or where

Where topside cosmetics are less

For clad internal panels subjected

critical, e.g. light coloured finish

WIND ENERGY TURBINE BLADES

¬ Gurit® Kerdyn™ Green 100

where cosmetics are critical

For low weight solution and

FORWARD TOPSIDES
to light occupant loads only

¬ Gurit® Corecell™ M 100

NON-STRUCTURAL

¬ Gurit® Corecell™ M 200

¬ Gurit® Corecell™ M 60
For low weight solution

¬ Gurit® PVC 200 / 250

slamming is expected
For low cost solution

DECK FITTINGS
Material solutions developed by Gurit for manufacturers of wind turbine blades have continuously contributed to the increasing efficiency of

¬ Gurit® PVC 100

BOLLARDS &
¬ Gurit® PVC 60
PARTITIONS
wind power installations. This progress is most visible when looking at the increase of a typical blade size from 23m to over 80m+. The growing

& penetrations
dimensions create enormous challenges for wind turbine blade manufacturers as the longest blades today weigh in excess of 20 tons each.
New materials solutions were needed to keep the weight of the blades as light as possible, yet maximising their strength, stiffness and durability.

FORWARD BOTTOM SHELL

Where cosmetics are less critical,
Where cosmetics are critical, e.g.

For impact toughness in high

where cosmetics are critical
For low weight solution and
SUPERSTRUCTURE

¬ Gurit Corecell M 130

¬ Gurit® Corecell™ M 80

¬ Gurit® Corecell™ M 60

e.g. light coloured finish

slamming load region

dark coloured finish

™
¬ Gurit® PVC 80

®
**

* Thickness towards root is limited by conformity

* ** Mass towards tip generates vibration and affects loads

FORWARD LONGITUDINALS

For low weight solution and where

¬ Gurit Kerdyn Green 115
¬ Gurit Kerdyn Green 100

¬ Gurit® Corecell™ M 80
For low weight solution
For low weight solution

cosmetics are critical

For low cost solution
For low cost solution

™
™

¬ Gurit® PVC 60

¬ Gurit® PVC 80
The blade shells are manufactured using sandwich structures due to the large panel size and the requirement for good bending stiffness at
STRUCTURAL CORE MATERIAL APPLICATIONS IN SUPERYACHTS
The diagram below shows a limited range of possible options. The Gurit Engineering Team will be available to support the

SOFFITS

®
the lowest design weight. As the main requirement of the shell panels is to resist deformation under aerodynamic loading, the core‘s primary
®

function is to provide stability (resistance to buckling of the load carrying laminate) under compressive, shear and out of plane loading. Three
types of buckling failure mode can be considered:

Euler buckling: Panel bending stiffness failure - dependent on thickness and shear modulus of the core

Skin wrinkling: Local skin deformation - dependent on the shear and tensile modulus of the core and the skin thickness of the laminate
¬ Gurit Kerdyn Green 115

Shear crimping: Core failure - Shear modulus is too low to transfer the loads between the skins and especially relevant for thicker skin
For low weight solution
For low cost solution

laminates
™

¬ Gurit® PVC 80
BULKHEADS

When you consider the design of the structural shell for a wind blade the loading profile of the shell changes considerably from the root to
the tip and furthermore the blade geometry places further constraints on possible laminate configurations. Therefore, the requirements for
®

the core properties change along a shell structure.

Due to the high loads in the root section the laminate thickness is high and therefore shear crimping becomes a driving design criterion.
Therefore, balsa is widely used in these areas due to its very high shear modulus. Further outboard along the blade the loads are lower but
the strains become higher and the failure of the core is more likely to be due to skin wrinkling or panel (Euler) buckling. For this area of a
adequate material selection and suitable design for your component.

blade the thickness of the sandwich structure has much more influence to resist these failure modes and therefore a core with lower shear
Where topside cosmetics are

modulus can be used. It is also desirable to reduce weight of the panel the further you move away from the root area due to the increased
critical, e.g. dark coloured
¬ Gurit Corecell M 80

bending moment. Therefore, core density and resin uptake is a key consideration.
™

The most common cores used for wind blade manufacture are PVC followed by SAN foam as they have good properties for their density
AFT TOPSIDES

¬ Gurit® PVC 80

and are relatively competitive with respect to their cost. They also have significantly lower resin uptake characteristics than Balsa and have
higher strain capability which is useful for the transport and handling of blades after manufacture and before service life begins.
®

finish

PET has also made some progress and is now extensively used in blade design, but it does have a weight disadvantage over PVC and SAN
cores and can be too brittle for blade lifting points.
Exterior geometry provided by Warwick Yacht Design
Where cosmetics are critical, e.g. dark
Lowest cost, highest weight solution
appropriate for high traffic areas

¬ Gurit Corecell M 100/130

¬ Gurit® Kerdyn™ Green 100
¬ Gurit Kerdyn Green 115

¬ Gurit® Kerdyn™ Green 200

bolting areas e.g. engine or

For general foam-filled top

Inserted in way of through

AFT BOTTOM SHELL

¬ Gurit® Corecell™ M80
For low weight solution

For lower cost solution

For impact toughness
¬ Gurit® PVC 100/130
For low cost solution

equipment mounts
¬ Gurit® Balsaflex™

LONGITUDINAL

™
™

¬ Gurit® PVC 90

coloured finish

hat sections
ENGINE
SOLES
®

14 15
 n Gurit® Kerdyn™ Green
STRUCTURAL CORE
n Gurit® Corecell™ T

n Gurit® Balsaflex™
n Gurit® PVC
TECHNICAL INFORMATION

Shear Web

Shell
Root

Spar
For more detailed information on core materials, as well as the complete Gurit product portfolio, please visit:

4
www.gurit.com to view the following:

¬ Product Data Sheets ¬ Corporate Videos

¬ News / Case Studies ¬ Composite Guides

¬ Events Schedules ¬ Representatives Contact Details

4 ¬ Product Brochures
STRUCTURAL CORE MATERIAL APPLICATIONS IN WIND TURBINE BLADES

For pricing or other enquiries, please contact customer.support@gurit.com

3

Product Datasheets
1

www.gurit.com Case Studies

16 17
Core Bro-21-0322 www.gurit.com