ISO INTERNATIONAL STANDARD 16978 First edition 2003-07-01 Wood-basedpanelsDeterminationof modulus of elasticity in bending and of bending strength Panneauxabasedebois-Determinationdumoduled'élasticiteen flexionetdela résistancealaflexion Reference number ISO 16978:2003(E) ISO @ISO2003 Copyright Intemational Organization for Standardization without license from IHS Not for Resale ISO16978:2003(E) Foreword IsO (the International Organization for Standardization)is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has been non-governmental, in liaison with IsO, also take part in the work. IsO collaborates closely y with the InternationalElectrotechnicalCommission(lEC)onallmattersofelectrotechnicalstandardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval byatleast 75%of thememberbodies casting avote Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO16978wasprepared byTechnical CommitteeISO/TC 89,Wood-basedpanels. ISO16978isbasedonISO9429andEuropeanStandardEN310. ii Copyrahtlitematlinal Organizaon tor standardzation rights reserved arda Not for Resale INTERNATIONAL STANDARD ISO16978:2003(E) Wood-based panels Determination of modulus of elasticity in bending and of bending strength 1 Scope This International Standard specifies a method for determining the apparent modulus of elasticity and bending strength of wood-based panels in flatwise bending. 2 Normativereferences references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Iso9424,Wood-basedpanels-Determinationofdimensionsoftestpieces Iso 16999,Wood-based panelsSampling and cutting of test pieces Principle The modulus of elasticity in bending and bending strength are determined by applying a load to the centre of a test piece supported at two points. The modulus of elasticity is calculated by using the slope of the linear region of the load-deflection curve; the value calculated is the apparent modulus, not the true modulus, because the test method includes shear as well as bending. The bending strength of each test piece is calculated by determining the ratio of the bending moment M, at the maximum load Fmax, to the moment of its full cross-section. 4 Apparatus 4.1 Measuring instruments, as specified in ISO 9424. 4.2 Testing apparatus, having the following essential components (see Figure 1) 4.2.1 Two parallel, cylindrical, roller-bearing supports, of length exceeding the width of the test piece and of (10 ± 0,5) mm diameter for panels of nominal thickness ≤ 6 mm and of diameter (15 ± 0,5) mm for panels of nominal thickness > 6 mm. The distance between the supports shall be adjustable. 4.2.2 Cylindrical loading head, of the same length and (10 ± 0,5) mm in diameter for panels of nominal thickness ≤ 6 mm, and (30 ±0,5)mm in diameter for panels of nominal thickness > 6 mm, placed parallel to the supports and equidistantfromthem. Copyrahtntemationalorganizaontostandardzationrights reserved Not for Resale ISO16978:2003(E) Dimensions in millimetres @d, (1/ 2 11 12 Key test piece ≥20 t 1 F load 12 = 1 + 50 thickness of the test piece d, =①dz=10 ± 0,5for t≤6 ①d,=30±0,5;①d,=15±0,5for t>6 NOTE Alternative arrangements may be used if a valid correlation to the specified arrangement can be proven. Figure1-Arrangementofthebendingapparatus 4.2.3