纸和纸板 弯曲韧性的测定 共振法

[中文适用范围]： 本文件规定了使用共振法测定弯曲刚度的方法。 该方法仅给出每个测试试件的单个结果，尽管一般来说，弯曲刚度值可能取决于材料的哪个表面形成由弯曲力产生的圆弧的内表面。 使用这种方法可以测量多种纸张和纸板的弯曲刚度。 然而，对于某些材料，例如下面列出的材料，测量的数值将与 3.1 中定义的弯曲刚度不严格相同： a) 多层纸和板，其中各层在测试期间可以单独移动； b) 有明显卷曲的纸和纸板，尤其是卷曲轴位于试件长度方向时； c) 一些克重低于40g/m2左右的软纸。 此方法不适用于瓦楞纸板。 [外文原描述]： ISO 5629:2017 specifies a method for the determination of bending stiffness using the resonance method. This method gives only a single result for each test piece tested, although in general, bending stiffness values may depend on which surface of the material forms the inner surface of the arc resulting from bending forces. The bending stiffness of a very wide range of papers and boards can be measured using this method. However, for some materials, such as those listed below, the measured numerical values will not be strictly identical with bending stiffness as defined in 3.1: a) multi-ply papers and boards in which the component plies can move separately during a test; b) papers and boards with appreciable curl, especially if the axis of the curl is in the long direction of the test piece; c) some soft papers with grammage below about 40 g/m2. This method is not applicable to corrugated boards.