EN 15190:2007

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Structural adhesives - Test methods for assessing long term durability of bonded metallic structuresVWUXNWXUAdhésifs structuraux - Méthodes d'essai pour évaluer la durabilité a long terme des structures métalliques colléesStrukturklebstoffe - Prüfverfahren zur Bewertung der Langzeitbeständigkeit geklebter metallischer StrukturenTa slovenski standard je istoveten z:EN 15190:2007SIST EN 15190:2007en,fr,de83.180LepilaAdhesivesICS:SLOVENSKI
STANDARDSIST EN 15190:200701-november-2007

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15190August 2007ICS 83.180 English VersionStructural adhesives - Test methods for assessing long termdurability of bonded metallic structuresAdhésifs structuraux - Méthodes d'essai pour évaluer ladurabilité à long terme des structures métalliques colléesStrukturklebstoffe - Prüfverfahren zur Bewertung derLangzeitbeständigkeit geklebter metallischer StrukturenThis European Standard was approved by CEN on 24 June 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15190:2007: E

Knowledge of the long-term durability of bonded joints is useful for product development and material selection.
Furthermore, it has been shown that the relationship between cyclic mode I strain energy release rate and crack growth rate is independent of geometry and load application.
This allows the materials characterisation data measured from RDCB testing to be applied directly to other joined metallic structures, and therefore the data are useful for establishing design allowable criteria used in their life assessment.

1 Scope 1.1 This standard specifies test procedures for determining the long-term durability of an adhesive system subjected to environmental and fatigue loads. The procedures are based upon measurement of the crack growth rate and the resistance to crack propagation through the adhesive layer in double cantilever beam type specimens under an applied mode I opening cycling loading. 1.2 The test specimens consist of rectangular metal substrates bonded together with a pre-starter crack in the bondline. For testing joints consisting of relatively thin sheets of metallic substrates the specimen needs to be structurally reinforced by adding layers of compatible material to the back of each adherend substrate in order to prevent permanent deformation, usually referred to as reinforced double cantilever beam (RDCB) test specimen. 1.3 For brevity, the standard relates to testing RDCB specimens, which are essentially more complex in manufacturing than standard double cantilever beam (DCB) specimens. However, the standard allows also for use of single substrate double cantilever beam specimens when the substrate material is available in sufficient thickness. 1.4 The test method has been proven to be particularly sensitive in finding weaknesses within certain adhesive systems and is recommended as a scientific tool to study adhesion properties.
This test method may be used to determine: - The fatigue crack growth rate as a function of the mode I strain energy release rate; - The threshold values for negligible crack growth; - The effects of other environmental factors (temperature and/or humidity cycling); - The mode I (peel or crack opening) failure mode of the adhesive joint (cohesive, interfacial, near-surface …). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 923:2005, Adhesives – Terms and definitions EN 13887, Structural Adhesives - Guidelines for surface preparation of metals and plastics prior to adhesive bonding EN ISO 9142, Adhesives - Guide to the selection of standard laboratory ageing conditions for testing bonded joints (ISO 9142:2003) ISO 15024, Fibre-reinforced plastic composites — Determination of mode I interlaminar fracture toughness, GIc, for unidirectionally reinforced materials 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 923:2005 and the following apply.

mode I crack opening crack opening mode due to a load applied perpendicular to the plane of crack growth using a reinforced double cantilever beam specimen as shown in Figure 1 3.2
number of fatigue cycles, N (cycles)
cycle count during a fatigue test 3.3
crack length, a (mm)
crack length measured from the loading point to the crack tip 3.4 initial crack length, ao (mm)
manufactured crack length before the test 3.5
fatigue crack growth rate, da/dN (mm/cycle) increase of the crack length per fatigue cycle 3.6
strain energy release rate, G (J/m2) loss of strain energy, dU, in the test specimen per unit of specimen width for an infinitesimal increase in crack length, da, for a crack growing under a constant displacement. In mathematical form,
aUbGdd0001= (1) where: U
total elastic strain energy in the test specimen (mJ) b
specimen width (mm) a
crack length (mm) 3.7
displacement, δδδδ (mm)
distance between the load points 3.8
fatigue loading ratio, R
ratio of the minimum load to the peak load within a load cycle 3.9
maximum mode I cyclic strain energy release rate, G(Imax) (J/m2) value of G at peak load during the fatigue cycle 3.10
strain energy release rate threshold, Gth (J/m2)
value of G at which fatigue crack growth becomes negligible (approach zero).
This is typically at measured crack growth rates between 10 -6mm/cycle and 10-7 mm/cycle. 3.11
peak load, Pmax (N) maximum load applied during a dynamic load cycle

displacement divided by load during the loading cycle applied to the RDCB specimen, at a given crack length 3.13
maximum displacement, /max(mm)
maximum test piece displacement at the peak load, i.e. Pmax x C, for any given crack length 3.14
compliance calibration constant, m (mm-2/3 . N-1/3)
slope of the linear fit relationship between the cube root of the test piece compliance, C (y-axis) and crack length, a (x-axis) 3.15 compliance calibration constant, ∆∆∆∆ (mm) x-axis intercept, determined from the extrapolation of the linear fit (between C1/3 and a) to the point where C1/3 equals zero 3.16
test piece width, b (mm)
4-point average of test piece width, measured along the length of the RDCB test piece 3.17
Paris Law constants, A and B for the Paris Law relationship: da/dN = A(G)B applied to the log-log plot of G(Imax) versus da/dN 3.18 projected ‘threshold’, G|10-6 (J/m2) projected value of GI(max) at a crack growth rate of 10-6 mm/cycle, using the Paris Law relationship: da/dN = AGB 3.19 projected ‘threshold’, G|10-7 (J/m2) projected value of GImax at a crack growth rate of 10-7 mm/cycle, using the Paris Law relationship: da/dN = AGB

Metallic adherends
Adhesive
Reinforcement bars
PTFE inserts NOTE The 3,2 mm diameter holes are for the use with 3 mm pins to apply the load Key 1 Centre line 2 Reinforcement 3 Substrate (thickness as required) 4 Reinforcement Figure 1 — RDCB Specimen dimensions and configuration 4 Principle 4.1 A reinforced double cantilever beam (RDCB) test specimen (see Figure 1) is tested to determine a compliance relationship with the crack length, the rate of crack growth at ambient and elevated temperature and the effect of imposing a hostile environment.
For the fatigue characterisation the RDCB is cycled between a minimum and maximum displacement, δmin, and δmax, at a specified frequency. For linear elasticity and small deflections the displacement ratio, δmin/δmax, is identical to the fatigue loading ratio, R.
The rate of growth of the crack per fatigue cycle is recorded along with the corresponding mode I cyclic strain energy release rate, for example the maximum value, G(Imax).
The test is run until the crack growth rate reduces to a slow rate or nominally a threshold value, Gth. The test is conducted at ambient temperature, elevated temperature, and both elevated temperature and humidity to determine any degradation in wet adhesion.
Combinations of environmental factors can also be applied, to determine their effects on either crack growth behaviour or crack initiation.
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