FORD FLTM BS 105-1-2000 DETERMINATION OF FLEXURAL STRENGTH AND THE ELASTICITY MODULUS.pdf

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1、 FORD LABORATORY TEST METHOD BS 105-01 Date Action Revisions 2000 11 10 Revised Editorial no technical change A. Cockman 1994 09 19 Printed copies are uncontrolled Page 1 of 3 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF FLEXURAL STRENGTH AND THE ELASTICITY MODULUS Application Thi

2、s procedure is used to determine the flexural strength, before and after water immersion and the modulus of elasticity of cellulose fibre boards. Apparatus Required Flexural Loading Device (Figure 1) The support cylinders and the flexing mandrel must be of a width greater than the test specimen. The

3、 diameter of the flexing mandrel and that of the support cylinders must be 12.5 mm for a test specimen up to 6 mm thick, and it must be 25 mm for a test specimen 6 - 10 mm thick. Recording Device This shall be used to set up the load/deflection diagram. Micrometer Gauge Conditioning and Test Conditi

4、ons All test values indicated herein are based on material conditioned in a con trolled atmosphere of 23 +/ - 2 C and 50 +/ - 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure Original Flexural Strength 1. Cut six

5、 test specimens from the material under test, three in the longitudinal and three in the transverse direction. Note: The thickness of the specimen “a“ (see sketch) must be measured in the centre of the cellulose fibre board. The width of the specimen “b“ must be 50 mm and it must be mea sured accura

6、tely to 0.1 mm. The edges of the specimen must be clean cut and must be parallel to each other within +/ -0.4 mm. The length of the specimen “Lg“ must be approximately 50 mm greater than the distance between the lines of support “Ls“. The lat ter must be 24 x the specimen thickness “a“. FORD LABORAT

7、ORY TEST METHOD BS 105-01 Page 2 of 3 Copyright 2000, Ford Global Technologies, Inc. 2. Adjust the supports of the loading fixture to the correct span for the thickness of the boards “Ls“ and place the specimen on the support cylinders midway between the supports. The smooth side must face th e flex

8、ing mandrel. 3. Apply the load at a uniform rate in the middle of the supported span, until fracture takes place. Record the breaking - load (P) in newtons. The break must occur within 30 - 45 seconds. Evaluation The flexural strength in MPa is th en computed according to the following formula: Flex

9、ural Strength in MPa = P x 3L s / (2b x a) Where: P = Breaking Load in N. L s = Supported Span in mm. a = Thickness of the test specimen in mm, measured in the middle of the supported span. b = Wid th of the test specimen in mm. Flexural Strength After Water Immersion The specimens shall be immersed

10、 for 24 hours in distilled water at 20 +/ - 2 C and must be tested immediately afterwards as described under paragraphs 1 to 3. Note: Measure thickness before water immersion. Determination of the Elasticity Modulus When each test is completed, the force/deflection diagram must be recorded. For this

11、 purpose the deflection “f“ must be measured in the middle of the supported span, if possible until the mo ment of fracture, using a suitable micrometer gauge to an accuracy of 0.01 mm. The force (load) must be applied gradually in steps, such that at least six readings are taken before one third of

12、 the total (breaking) load is applied. FORD LABORATORY TEST METHOD BS 105-01 Page 3 of 3 Copyright 2000, Ford Global Technologies, Inc. Evaluation The modulu s of elasticity is related to the gradient of the straight section of the force/deflection curve and it shall be computed as follows: E = Modu

13、lus in MPa = P/d x L S /(4b x a) P = Force (Load) in N as indicated in the straight section of the force/defl ection curve. d = The deflection (expressed in mm) which corresponds to the Force P. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and hand ling in its facilities. Figure 1