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1. Objective
The objective with this chapter is to give requirements for the raw-materials used in structural parts of
the craft and to define the mechanical properties to be used in the structural dimensioning
2. References
The presentation in this chapter is based on the following international standards:
- ISO 12215.1:2000 - Hull construction and scantlings - Part 1: Materials:
Thermosetting resins, glass-fibre reinforcement, reference laminate.
- ISO 12215-2:2002 - Hull construction and scantlings - Part 2: Materials:
Core materials for sandwich construction, embedded materials
- ISO 12215-5:2008 - Hull construction and scantlings -- Part 5: Design
pressures for monohulls, design stresses, scantlings determination
3. Documentation
To verify the compliance with the requirements in this chapter,
the following documentation is needed:
- Datasheets or similar of the used raw-materials
- Testreports of mechanical properties
4. Resins
4.1 Resins used in structural components shall meet the requirements of ISO 12215-1 as "Type A" resin
4.2 Resin additives such as agents for adjusting tixotrophy or filling, shall be compatible with the resin.
5. Fibre reinforcement
5.1 Fibre reinforcements used in structural components shall meet the requirements of ISO 12215-1.
6. Compability of fibres with resin
6.1. There shall be documentation to show, that materials are suitable for the application in question
and for the anticipated environmental conditions.
6.2. The fibre reinforcement shall have a seizing which is compatible with the laminating resin.
6.3. Orthophtalic resin must not be used with powder bounded chopped strand mat.
7. Mechanical properties of laminates
7.1 The following requirements concern glass/polyester laminates if not stated otherwise.
Requirements for other materials shall be determined according to ISO 12215-5.
Glassfibre reinforced laminates shall fulfill the following minimum propertiest:
- Ultimate tension stress sT = 80 MPa
- Tensile modulus ET = 6350 MPa
- Ultimate bending stress sB = 135 MPa
- Flexural modulus EB = 5200 MPa
- Ultimate shear stress in the plane of the laminate tXY
= 50 MPa
- Ultimate interlaminar shear stress tXZ
ja tYZ = 15 MPa
7.2 Mechanical properties for the hull shell shall be determined by testing according to paragraph 8
or by calculation using the method in paragraph 9.
8. Determination of mechanical properties by testing
8.1 When the mechanical properties of laminates are determined by testing, the specimen shall be
produced using the same production processes and -parameters as when manufacturing the craft itself
8.2 The relevant parameters shall be determined in the both main directions of the laminate.
Unidirectional laminates shall be tested in one direction only. The laminates shall be tested without
gel- or topcoat.
8.3 The tensile stress and -modulus shall be determined according to ISO 527-1 ja ISO 527-4.
8.4 Compressive stress shall be determined according to ASTM D3410
8.5 The bending stress and modulus shall be determined according to ISO 178. When measuring bending strength, the
outer surface (=the outside of the hull) shall be in tension..
8.6 Shear stress shall be determined according to ASTM D 4255.
8.7 The average results for each tested property shall meet the requirements in 6.1.
No single value shall be less than 80% of the average value..
9. Determination of mechanical properties by a nominal fibre content
9.1 The mechanical properties of laminates may also be determined on the basis of a
nominal fibre content which is a function of the used reinforcement products and the manufacturing process.
9.2 Nominal fibre content
The nominal fibre content, Y, which is expressed in percent by weight, shall
be taken as follows. The formulae are valid for laminates reinforced by glassfibre. For other fibre types
the nominal fibre content shall be determined according to ISO 12215-5.
- Chopped strand mat (CSM) laminates Y= 30%
- CSM / woven rowing laminates Y= 46-18∙R,
where R = proportion of CSM
- Multidirectional laminate Y= 50%
- Unidirectional laminates Y= 55%
9.3 Mechanical properties
The mechanical properties of laminates is determined from Figure 9.1...9.6 based on the nominal fibre
content. The figures apply to laminates reinforced by chopped strand mat and/or balanced woven rowing and
for unidirectional laminates. The mechanical properties for "Double Bias" (±45o
fabrics) and multiaxial fabrics shall be determined according to ISO 12215-5.
Requirements from paragraph 12 shall be met when acquiring values from figures 9.1...9.6.
When assessing the compliance according to Chapter 10, the laminate thickness requirements shall be converted to
reinforcement area mass using Figure 9.8
10.
Sandwich core materials
10.1 Sandwich core materials in structural components of the craft shall meet the
requirements of ISO 12215-2 "Grade 1."
11. Mechanical properties of sandwich core materials
Unless samples has been tested from the actual batch used for the craft in question, the mechanical
properties of sandwich core materials shall be determined on the basis of the material, the elongation
to break and the density of the material using Figures 9.8...9.11 mukaan.
12. Values to be used for scantling determination
12.1 The values used for scantling detemination depend on the level of production control.
12.2 If the mechanical properties have been determined by testing, and the tested laminates correspond to the laminate for
the structural part in question, the values to be used for scantling determination are:
- For tensile-, compressive-, bending- and shear strength, 90% of the average value obtained in the
tests or the average value minus two standard deviations, whichever is less, shall be used;
- For the modulus, the average value obtained from the test shall be used.
12.3 If no testing has been carried out, but the fibre content is regularly monitored in the production, the values
determined according to paragraph 8 are to be used without further correction for scantling determination.
12.4 If no testing has been carried out and no monitoring of fibre content during production is done, the values determined
according to paragraph 8 are to be multiplied by 0,8 for scantling determination.
12.5 For sandwich core materials, the values obtained from paragraph 11 shall be used without further correction.
13. Adhesives
13.1 Adhesives to be used in structural components are to be developed for the combination of materials in question..
13.2 For the purpose of bonding sandwich faces to the core, adhesives developed for shall be used. Alternatively,
shop-made adhesives of the same resin type that is used for lamination may be used.
14. Other materials
14.1. Plywood shall be water resistant type and its adhesives shall meet the requirements from WBP
standard B.S. 6566 part 8. 14.2. Embedded materials such as reinforcements for fittings etc shall
meet the requirements in ISO 12215-3.
Figure 9.1. Ultimate tensile stress for chopped strand mat/woven rowing laminates and unidirectional laminates as a
function of nominal fibre content.
Figure 9.2. Ultimate compressive stress for chopped strand mat/woven rowing laminates and unidirectional
laminates as a function of nominal fibre content.
Figure 9.3. Ultimate bending stress for chopped strand mat/woven rowing laminates and unidirectional laminates
as a function of nominal fibre content.
Figure 9.4. Modulus of elasticity for chopped strand mat/woven rowing laminates and unidirectional laminates
as a function of nominal fibre content.
Figure 9.5. Ultimate shear stress in the plane of the laminate for chopped strand mat/woven rowing laminates as
a function of nominal fibre content.
Figure 9.6. Ultimate interlaminar shear stress for chopped strand mat/woven rowing as a function
of nominal fibre content.
Figure 9.7. Reinforcement area mass as a function of fibre content
Figure 9.8. Ultimate shear stress for structural polymer foams as a function of density.
Figure 9.9. Shear modulus for structural polymer foams as a function of density.
Figure 9.10. Shear modulus for balsa as a function of density.
Figure 9.11. Ultimate compressive stress for core materials as a function of density.
Figure 9.12. Ultimate compressive stress for balsa as a function of density.
Figure 9.13. Compressive modulus for structural polymer foams as a function of density.
Figure 9.14. Compressive modulus for balsa as a function of density.
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