BS 4370-4-1991 Methods of test for rigid cellular materials - Method 14 - Determination of flexural properties《硬质微孔材料试验方法 第4部分 方法14 弯曲性能测定》.pdf

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1、BRITISH STANDARD BS4370-4: 1991 Methods of test for Rigid cellular materials Part4: Method14. Determination of flexural propertiesBS4370-4:1991 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Policy Committee, was published underthe authority of th

2、e Standards Board and comes intoeffect on 31 October1991 BSI06-1999 The following BSI references relate to the work on this standard: Committee reference PRM/24 Draft for comment86/38575 DC ISBN0 580 20124 4 Committees responsible for this British Standard The preparation of this British Standard wa

3、s entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/24, upon which the following bodies were represented: British Plastics Federation British Railways Board British Rigid Urethane Foam Manufacturers Association British Rubber Manufacturers Association

4、 Ltd. Department of the Environment (Building Research Establishment) Furniture Industry Research Association Furniture, Timber and Allied Trades Union Ministry of Defence National Bed Federation Limited Phenolic Foam Manufacturers Association RAPRA Technology Ltd. Society of British Aerospace Compa

5、nies Limited Amendments issued since publication Amd. No. Date CommentsBS4370-4:1991 BSI 06-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Apparatus 1 3 Test specimen 1 4 Number of specimens 1 5 Conditioning 1 6 Procedure 1 7 Calculation of results 1 8 Test re

6、port 2 Figure 1 Typical force-deformation diagram 2 Publication(s) referred to Inside back coverBS4370-4:1991 ii BSI 06-1999 Foreword This Part of BS4370 has been prepared under the direction of the Plastics and Rubber Standards Policy Committee from a draft submitted by the British Plastics Federat

7、ion. The method which is related to ISO1209-2 “Cellular plastics, rigid Flexural tests Part2: Determination of flexural properties” is intended to apply to rigid cellular products of polymeric origin, but it is not necessarily suitable for testing rigid cellular materials of inorganic origin. It is

8、designed to determine the modulus of elasticity in flexure of the materials when subjected to three point loading. Where fracture of the test specimen occurs at strains not exceeding5% and in the absence of crushing of the material at the loading nose and supports, the flexural strength may also be

9、determined. The specimen length to thickness ratio is much larger than the value used in method4 of BS4370-1, used for measuring cross-breaking strength, and thus the strength in flexure determined by this method will normally differ significantly from the cross-breaking strength obtained from metho

10、d4. Attention is drawn to other Parts of BS4370 dealing with other properties of rigid cellular materials. Part1: Method1 Measurement of dimensions Method2 Determination of apparent density Method3 Compression test Method4 Cross-breaking strength test Method5 Dimensional stability test; Part2: Metho

11、d6 Determination of shear strength and shear modulus Method7 Measurement of thermal conductivity Method8 Measurement of water vapour transmission Method9 Determination of tensile strength Method10 Determination of the volume percentage of closed cells; Part3: Method11 Withdrawn Method12 Determinatio

12、n of friability Method13 Determination of the coefficient of linear thermal expansion at low temperatures. 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 St

13、andard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorpora

14、ted. This will be indicated in the amendment table on theinside front cover.BS4370-4:1991 BSI 06-1999 1 1 Scope This Part of BS4370 describes a method to determine the modulus of elasticity and strength in flexure of rigid cellular material of polymeric origin, but it is not necessarily suitable for

15、 rigid cellular material of inorganic origin. Where a fracture occurs in the lower surface of the specimen at a low tensile strain, i.e.less than5% strain, and in the absence of crushing of the specimen at the loading nose or supports, the method provides a means of determining the flexural strength

16、. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Apparatus 2.1 Universal testing machine, capable of operating at a constant rate of movement of the moveable head and complying with grade0.5 of BS1610-2. The machine shall include a device for s

17、imultaneous recording of force and the corresponding deformation. 2.2 Fixed test specimen supports, consisting essentially of two parallel cylindrical supporting edges set300 2mm apart in the same horizontal plane, each having an edge radius of151mm. The length of the supports shall be greater than

18、the width of the test specimen. 2.3 Cylindrical test specimen loading head, having the same dimensions as the supports. The loading head shall be located centrally between the supports with its line of contact parallel with those of the supports. The loading head shall be rigidly attached to the mov

19、able head of the test machine. 3 Test specimen The test specimen shall be a rectangular parallelopiped representative of the bulk material without skins or moulded surfaces, with the following dimensions: The test specimen shall be cut without deformation from the original cellular structure. Plying

20、 up of test specimens is not permissible. NOTEWhen test specimens less than the standard thickness need to be tested, the results obtained will not necessarily be comparable with those obtained on standard specimens. 4 Number of specimens A set of three test specimens shall be tested. 5 Conditioning

21、 The test specimens shall be conditioned at23 2 C and505%r.h. for not less than16h. The test shall be carried out at a temperature of23 2 C immediately after conditioning. 6 Procedure Determine the dimensions of the test specimens in accordance with method1 of BS4370. Place the test specimen symmetr

22、ically upon the supports and apply an increasing force by the loading head moving at201mm/min. Record the force/deformation curve and draw a tangent to the steepest part of the curve (seeFigure 1). Stop the test either when fracture of the test specimen occurs or when the tensile strain in the lower

23、 surface reaches0.05. NOTEWith the standard test specimen and loading arrangements the tensile strain in the lower surface is at0.05 when the deflection reaches30mm. Inspect the test specimen for any sign of crushing. If any crushing is found do not calculate a flexural strength value. 7 Calculation

24、 of results The modulus of elasticity in flexure, E (in kPa), is given by the expression where The flexural strength, R (in kPa), is given by the expression where 350 10 mm in length 50 1 mm in width 25 0.5 mm in thickness F T is the force (in kN); x T is the corresponding deformation (in mm); L is

25、the span (in mm); b is the test specimen width (in mm); d is the test specimen thickness (in mm). F R is the maximum force applied (in kN); L is the span (in mm); b is the test specimen width (in mm); d is the test specimen thickness (in mm). E L 3 F T 10 6 4bd 3 x T - = R 1.5F R L 10 6 bd 2 - =BS43

26、70-4:1991 2 BSI 06-1999 8 Test report The test report shall include the following information: a) the description and identity of the material; b) the individual values of modulus of elasticity (in kPa), and dimensions of the test specimen if other than standard; c) the individual values of flexural

27、 strength (inkPa), if determined, and dimensions of the test specimen if other than standard; d) the arithmetic mean of the test results expressed as modulus of elasticity in flexure (inkPa); e) if determined, the mean flexural strength (inkPa); f) any other deviations from the test procedure; g) th

28、e method used, i.e.method14 of BS4370-4:1991. Figure 1 Typical force-deformation diagramBS4370-4:1991 BSI 06-1999 Publication(s) referred to BS1610, Materials testing machines and force verification equipment. BS1610-2, Specification for the grading of equipment used for the verification of the forc

29、es applied by materials testing machines. BS4370, Methods of test for rigid cellular materials. BS4370-1, Methods1 to5. BS4370-2, Methods6 to10 1) . BS4370-3, Methods12 and13 1) . ISO1209, Cellular plastics, rigid Flexural tests 1) . ISO1209-2, Determination of flexural properties 1) . 1) Referred t

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