1、AECMA PREN*bObL 95 1012311 OOL007L 483 AECMA STANDARD NORME AECMA AECMA NORM prEN 6061 Edition PI November 1995 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - 8-1200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICs : Descriptors : ENGLISH VERSION A
2、erospace series Fibre reinforced plastics Test met hod Determination of sandwich flexural strength 4 point bending Srie arospatiale Luft- und Raumfahrt Mthode dessai Prfverfahren Matires plastiques renforces de fibres Dtermination de la contrainte de flexion dune poutre sandwich sur 4 appuis Faserve
3、rstrkte Kunststoffe Bestimmung der Biegefestigkeit von Kernverbunden 4-Punkt Biegeversuch This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA-Members. It has
4、been technically approved by the experts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without
5、 re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. Not
6、a - Extra copies can be supplied by B.N.A.E. - Technopolis 54 - 199, rue Jean-Jacques Rousseau - 921 38 ISSY-LES-MOULINEAUX CEDEX AIBITFG Chairman I Edition approved for publication Comments should be sent within six months after the date of Dublication to 1995-11-30 AECMA Gulledelle 94 B-1200 BRUXE
7、LLES Mr K. Schneider aecrna 199 AECMA PRENwbObL 95 = LOL23LL OOL0072 3LT = Page 2 prEN 6061 : 1995 Contents list 1 5 6 7 8 9 10 Scope Normative references Definitions Principle of the method Designation of the method Apparatus Test specimen Procedure Presentation of the results Test report AECMA PRE
8、N*bObL 95 LOL23Ll OOL0073 256 Page 3 prEN 6061 : 1995 I Scope This standard specifies the procedure to determine the flexural ultimate load and the deflection of sandwich components with fiber reinforced plastic skins. The specimen is designed to fail in one of the faces. This standard does not give
9、 any directions necessary to meet health and safety requirements. It is the responsibility of the user of this standard to consult and establish appropriate health and safety precautions. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other
10、publications. These normatives references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or r
11、evesion. For undated references, the latest edition of the publication referred to applies. EN 2374 Aerospace series Glass fiber reinforced moulding and sandwich composites Production of test panels EN 2489 Aerospace series Fibre reinforced plastics Determination of the action of liquid chemicals )
12、EN 2565 EN 2743 EN 2823 Aerospace series Preparation of carbon fibre reinforced resin panels for test purposes I Aerospace series Reinforced plastics Standard procedures for conditioning prior to testing ) Aerospace series Fibre reinforced plastics Test method for the determination of the effect of
13、exposure to humid atmosphere on physical and mechanical characteristics Parameters for conditioning and testing I 3 Definitions 3.1 Sandwich panels Integrated panels of light weight and high stiffness/strength, containing a core, shear loadedin thickness direction to which high strength/stiff skins
14、are bonded carrying in plane compression and tension loading. Sandwich panels show a big variety of materials for skins and core and manufacturing techniques. 3.2 Ultimate load Maximum load applied in the flexural test. 3.3 Deflection The deflection is the displacement of the center of the specimen
15、relative to the outer steel cylinder during the test. I Published as AECMA Prestandard at the date of publication of this standard AECMA PRENxhOhL 95 I1012311 0010074 192 = Page 4 prEN 6061 : 1995 4 Principle of the method A sandwich beam composed of two composite face sheets separated by a sufficie
16、ntly deep core is loaded in a four point bending jig until failure. Facing, core materials and specimen size as well as jig dimensions are selected to obtain failure of one of the faces. Ultimate load and load versus displacement are recorded. 5 Designation of the method The designation of the metho
17、d shall be drawn up as Description block I Identity block Sandwich flexural test 4 point bending Number of this standard I 6 Apparatus 6.1 Testing machine, accurate to within 1 %, in the load range used, capable of operating at a crosshead speed of 12 mm/min. 6.2 Flat face micrometer accurate to the
18、 nearest 0,Ol mm. 6.3 Vernier caliper accurate to the nearest 0,l mm. 6.4 Dial Test Indicator (DTI) having 0,Ol mm graduations or equivalent linear voltage displacement transducer (LVDT). 6.5 Temperature chamber applied to the testing machine covering the needed test temperatures with an accuracy of
19、 -t 3OC. 6.6 Temperature measuring equipment accurate to f 0,2OC at the applied test temperature. 6.7 Moisture chamber covering the requirements of EN 2743 and EN 2823, if required. 7 Test specimen 7.1 Test specimen description The test specimen shall be a rectangular beam cut from a sandwich panel
20、prepared in accordance with 7.2. Standard dimensions are given in figure 1. In order to determine the ultimate strength of a sandwich face, it is necessary, depending on the facing materials and lay-ups, to select an adequate span length so that a moment sufficiently high to obtain failure is genera
21、ted at a load that can be carried by the core in shear. AECIA PRENxbObl 95 m 1012311 0010075 O29 m Page 5 prEN 6061 : 1995 This span length S (see figure 1 I can be determined according to the following : 2xaxt s2 + 100 KXT where : S is the span length, in millimetres U is the estimated strength of
22、the critical skin, in MPa T is the allowable shear strength of the core, as far as possible, the core shall be oriented into the specimen in order to have the higher shear strength (ribbon in the longitudinal direction for hexagonal honeycomb), in MPa K is a factor ensuring failure in the sandwich s
23、kins (K = 0.75) t is the thickness of the critical skin, in millimetres The core shall be deep enough to avoid a too large deflection of the specimen at failure (the higher the strength of the skins, the deeper the core should be). The test specimen shall have sides parallel within 0,l mm. The facin
24、g and core materials shall be defined by the specification invoking the test. 7.2 Test panel preparation Test panel to be cut into specimens shall be in accordance with the designed specimens of 7.1. The panel dimensions shall be sufficient for the number of test specimen required and an edge cut-of
25、f of 2 30 mm all around. The thickness variation of a panel shall be within 10,2 mm unless otherwise specified, the sandwich faces shall be parallel within 0,l mm. All information about preparation of the panels, bagging for curing, cure cycles, equipments, etc. shall be provided by the specificatio
26、n invoking the test. In case secondary bonding is used cured laminates for the skins shall be prepared in accordance with EN 2374 and EN 2565 as far as applicable. 7.3 Number of test specimens Five specimens shall be tested per test condition, except when otherwise specified in the invoking specif i
27、cation. 8 Procedure 8.1 Ageing of specimen Tests after immersion shall be in accordance with EN 2489, open core edges shall be sealed when specified. Tests after exposure to humid atmosphere shall be in accordance with EN 2823. 8.2 Conditioning The storage and testing of the as-cured specimens (see
28、EN 2743) shall be carried out at (23 +_ 2)OC, (50 & 51% relative humidity in accordance with EN 2743. Aged specimens shall be tested directly after the ageing procedure, a maximum of 8 hours at (23 -c 2)OC is allowed. AECMA PREN*bObL 95 = LOLZ31L OOLOOb Tb5 Page 6 prEN 6061 : 1995 8.3 Determination
29、of dimensions Measure and record before ageingkesting the thickness and width to the nearest 0,Ol mm and 0,l mm respectively of the specimen. Use for the thickness the micrometer (see 6.2) and for the width the vernier caliper (see 6.3). Five thickness measurements for each specimen are required at
30、the supports, at the loading points and in the middle. 8.4 Testing Place test specimen symmetrically on the supports according to figure 1, assure that the right face will be loaded in compression. Alignment of the test specimen in the test machine shall be as accurate as possible, in order to avoid
31、 introducing any secondary loads. Work scale of the testing machine shall be selected in such a way that the loads obtained throughout the test are comprised within 10% to 90% of the scale. The load shall be applied at a constant crosshead speed of 12 mm/min until failure occurs. Load versus deflect
32、ion readings shall be recorded in the middle of the specimen using the apparatus defined in 6.4. Record the maximum load carried by the specimen during the test (ultimate load). Record the failure mode and its location relative to the center of each specimen. The required failure mode should be obse
33、rved, any other failure mode shall lead to investigations and it has to be decided whether it shall be taken in consideration for the test results. 8.5 Elevated and sub-zero temperature tests Apply a thermocouple (see 6.6) on the top skin as close as possible to centre of the specimen and seal the t
34、hermocouple from the surrounding air by using suitable material, like vacuum bag sealant. After a dry specimen has reached a temperature of 2OC below the required elevated temperature or 2OC above the required sub-zero temperature, the specimen shall be maintained at the obtained condition for 5 min
35、utes prior to testing. The procedure for aged specimen shall be in accordance with EN 2823. 9 Presentation of the results 9.1 Ultimate load Ultimate loads shall be presented taking into account the regulations of 8.4 concerning failure mode. 9.2 Deflection Maximum deflection or/and specific deflecti
36、on (D) at a given load shall be presented in accordance with the requirements of the relevant specification invoking the test. AECMA PREN*:bObL 95 LOL23LL OOLOO 9TL m Page 7 prEN 6061 : 1995 10 Test report The test report shall refer to this standard and shall include the following. 1 O. 1 Complete
37、identification of the materiai tested, including at least : material designation, manufacturer/supplier, batch number, roll number, fibre areal weight, filament count, processing details. 1 0.2 All details regarding panel and specimen preparation (faces stacking sequence, honeycomb identification .
38、10.3 Dimensions of the specimens. 10.4 Ageing and/or further treatment (e.g. core edge sealing) prior to the testing, conditioning. 10.5 Date of test, facility and identification of individuals performing the tests. 10.6 Equipment and test parameters used including span measurement. 10.7 Load deflec
39、tion curves. 10.8 Individual test results, failure mode and calculations. 10.9 Any incident which may have affected the results and any deviation from this standard. AECMA PREN*bObL 95 = 101231L 0010078 838 Page 8 prEN 6061 : 1995 top skin (see 7.1) compressive bottom skin (see 7.1) tensile steel cy
40、linder length 2 76 0 15 I h- typically 120 mm to allow for deflection Tolerance 1 mm All dimensions in mm unless otherwise specified S :Span L : Length :S+50mm H : Core height See also 7.1 : to be determined in accordance with 7.1 : to be determined by the specification invoking the test Range : 8 I H I 30 (mm) Ratio : Hr 10 xt Figure 1 : Specimen and test fixture
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