August 27, 2025
Title: Bending Stiffness, Four Point Method
This procedure specifies the method of determining the bending stiffness, also called flexural rigidity, in the machine and cross directions, of corrugated board using four-point loading. The procedure may also be used for solid boards and paperboard. The method is applicable to boards with a bending stiffness of 0.5 – 200 Nm (4.4 – 1770 lbf • in.).
Fig. 1. The four-point test configuration (testing corrugated fiberboard in machine direction). Fig. legends: F = force; h = moment arm; l = free span; δB = deflection; r = rotation axis; P = clamping pressure; s = clamping length.
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Date of Publication: May 29, 2025
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