1、BRITISH STANDARD BS 5350-C6: 1990 Methods of test for Adhesives Part C6: Determination of bond strength in direct tension in sandwich panels UDC 665.93:620.172.24BS5350-C6:1990 This British Standard, having been prepared under the directionof the Adhesive Standards Policy Committee, waspublished und
2、er the authorityof the Board of BSI andcomes into effect on 28 September 1990 BSI 07-1999 First published January 1981 Second edition September 1990 The following BSI references relate to the work on this standard: Committee reference ADC/9 Draft for comment 89/53399 DC ISBN 0 580 18775 6 Amendments
3、 issued since publication Amd. No. Date of issue CommentsBS5350-C6:1990 BSI 07-1999 i Contents Page Foreword ii 1 Scope 1 2 Definition 1 3 References 1 4 Principle 1 5 Apparatus 1 6 Test pieces 1 7 Conditioning and testing atmosphere 3 8 Procedure 3 9 Expression of results 3 10 Test report 3 Figure
4、1 Test assembly 2BS5350-C6:1990 ii BSI 07-1999 Foreword This Part of this British Standard has been prepared under the direction of the Adhesives Standards Policy Committee. This edition introduces technical changes but it does not reflect a full review or revision of the standard, which will be und
5、ertaken in due course. This edition differs from the previous edition in that the scope has been amended to emphasize that the test is not intended to be used for obtaining numerical design data, and the requirements concerning the conditioning and testing atmosphere have been clarified. The testing
6、 of sandwich panels by direct tension affords a method of estimating the bond strength between the core and the facing sheets of a sandwich panel. The stress applied to the adhesive is not simple tension, but contains other components, and the breaking force is not proportional to the area of the ad
7、hesive present. It is therefore necessary to standardize the procedure in order to obtain reproducibility. The test does not necessarily reflect how an adhesive would perform in service. Such design data would usually be obtained using the construction materials and configurations used in an actual
8、design. WARNING NOTE. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from the legal obligations relating to health and safety at any s
9、tage. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comp
10、rises a front cover, an inside front cover, pagesi andii, pages1 to3 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS5350-C6:1990 BSI 07-1999 1 1 Scope This Part
11、of BS 5350 describes a procedure for determining the bond strength of a flat composite sandwich panel when subjected to a tensile force. The method is applicable to any type of adhesive over a wide range of test temperatures. It is also applicable to test pieces which have been subjected to one of a
12、 variety of environmental exposures before test. This test is intended for ranking and quality control of adhesives and not for obtaining data for design purposes. NOTEThe adhesive bond strength may be greater than the cohesive strength of either the core material or the facing panels, but the test
13、may still provide useful information if the type of failure is taken into account. 2 Definition For the purposes of this Part of this British Standard, the following definition applies. sandwich panel an assembly made of a lightweight core to which sheet material has been bonded on both surfaces 3 R
14、eferences This Part makes reference to the following standards publications. BS 903, Methods of testing vulcanized rubber. BS 903-A26, Determination of hardness. BS 5214, Specification for testing machines for rubbers and plastics. BS 5214-2, Constant rate of force application machines. BS 5350, Met
15、hods of test for adhesives. BS 5350-A1, Adherend preparation. BS 5350-A2, Guide to the selection of adherend materials. BS 5350-E1, Guide to statistical analysis. 4 Principle A composite test piece, in the form of a sandwich in which two thin facing sheets are bonded by the test adhesive to a core m
16、aterial, is fixed by a secondary adhesive to a traction jig. The test piece is strained to rupture by a tensile force and the reported result is the observed force at rupture. NOTEThis method in principle can be used to test the bond to the core material alone. In this case no facing sheets are used
17、 and the core is bonded directly to the traction jig by the test adhesive. 5 Apparatus 5.1 Tensile testing machine. The machine shall comply with grade A or B of BS 5214-2, as appropriate. 5.2 Adaptors. These shall be free to swivel about the axis of the test assembly (see Figure 1). 5.3 Rigid attac
18、hment blocks, e.g. aluminium or aluminium alloy, suitable for bonding to the test piece and attaching to the adaptors (see Figure 1). 5.4 Secondary adhesive. This shall be strong enough to ensure that the tensile force shall cause failure within the adhesive under test or within the materials from w
19、hich the composite test piece is made. The secondary adhesive shall be chosen so that its use does not affect the composite test piece. 6 Test pieces 6.1 General The detailed construction of the test piece depends on the proposed use of the sandwich panel and shall be described in the test report. 6
20、.2 Adherends NOTEThe two facing sheets are normally of identical material. In order to test an adhesive, the core material shall be of a quality that gives reproducible results, e.g.expanded (foamed) polymer or a honeycomb or similar construction of metallic or non-metallic lamellar, or paper elemen
21、ts. The core shall be of uniform thickness and the faces substantially flat. When honeycomb core is used, the lamellae shall be perpendicular to the face of the test piece. NOTEWith metallic or high-strength honeycomb, the preferred thickness is 12 mm. 6.3 Dimensions The dimensions of the adherends
22、shall be reported. NOTEThe preferred dimensions are: 6.4 Preparation of test pieces Before bonding the core to the facing sheet, prepare the adherend surfaces in accordance with the recommendations of the adhesive supplier. In the absence of any such recommendations, select an appropriate procedure
23、from those specified inPartA1 of this standard. facing sheets and core 50 mm 50 mm; thickness of core 12 mm to 25 mm.BS5350-C6:1990 2 BSI 07-1999 Apply the adhesive to the adherends and make the bond in accordance with the methods recommended by the manufacturer of the adhesive or as specified by th
24、e user. In the absence of such recommendations or specifications, the procedure shall be such as to minimize bonding variations and shall be reported. The mass of adhesive used per unit area of adherend shall be closely controlled. Either prepare single test pieces, or cut test pieces from a laminat
25、ed panel of a suitable size, avoiding the edges and taking care to avoid frictional heating or mechanical damage to the bond. If a press is used to make the test piece, it shall be capable of applying an even pressure over the entire bonded area. NOTE 1The press should preferably be fitted with a ti
26、me release mechanism. In order to give a uniform distribution of pressure over the bonded area, the platens of the press shall either be parallel, or if this is impracticable, one platen shall be covered with a resilient rubber pad. NOTE 2A 10 mm thick pad of rubber of hardness approximately 45 IRHD
27、 (see BS 903-A26) has been found satisfactory on a press which applies a pressure up to 1 MPa. The preparation procedure shall be such as to minimize bonding variations. NOTE 3The use of a pneumatic or hydraulic press, hand or power operated, which can apply a pressure up to 1 MPa, is recommended. F
28、inally, bond the test piece to the attachment blocks with the secondary adhesive. NOTE 4It is normal for the attachment blocks to be reused and the surfaces are usually cleaned and re-ground between tests. Figure 1 Test assemblyBS5350-C6:1990 BSI 07-1999 3 6.5 Number of tests The number of tests dep
29、ends on the precision required (see Part E1 of this standard) and shall be stated in the test report. NOTEReliance should not be placed on fewer than five tests. 7 Conditioning and testing atmosphere As the storage conditions of the adherends and the times and environmental conditions obtaining duri
30、ng the curing, conditioning and storage of the bonded assemblies can have a substantial effect on results, either: a) the conditions shall comply with the instructions given by the manufacturer of the adhesive; or, if no conditions are specified by the manufacturer: b) the conditions for storage, cu
31、ring and conditioning of the adherends and bonded assemblies shall be 23 2 C and 50 5 % r.h. The bonded assemblies shall be stored for at least16h before testing. The times and conditions shall be stated in the test report. 8 Procedure Locate the test piece assembly in the tensile testing machine an
32、d set the machine in motion. Operate the machine so that the test piece is subject to a force which increases at a constant (i.e. steady) rate and such that the test piece is broken in a period of65 20 s. Record the force at break and the mode of failure. Results obtained on joints failing within th
33、e secondary bond line shall be discarded. 9 Expression of results Express the results of the tests as the mean of the breaking force of all the test pieces which have broken because of the failure of the adhesive under test, and give an indication of the spread of the results (e.g. the standard devi
34、ation; see Part E1 of this standard). 10 Test report The report shall state the following: a) a designation of the adhesive, giving all the information required for complete identification of the sample; b) a description of the core material, and the facing sheets and of their dimensions and pretrea
35、tment; c) the method of applying the adhesive, the mass per unit area and the open time; d) the method of making the bond, including details of the bonding pressure, temperature, relative humidity and conditioning time; e) the curing procedure and the conditioning environment; f) the temperature, re
36、lative humidity and time for which the assemblies were stored before testing; g) the rate of application of force; h) the number of assemblies tested and the mean breaking force, together with information about the spread of results; i) the type of failure for each test piece, i.e.whether adhesive,
37、cohesive or adherend, and, if applicable, the degree of coalescence of the adhesive; j) that the method of test complied with the requirements of BS 5350-C6; k) any other factor that may have affected the result.BS 5350-C6: 1990 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution
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