ABSTRACT
By analogy with Figs. 2 and 3, Fig. 17 shows the specific stress at failure versus slenderness ratio for a commercial 125 g/m2 linerboard. The test results are obtained with an STFI short-span compression test, which can be employed with different span lengths. The trend of the curves in Fig. 17 is representative of carton board, linerboard, and corrugated medium in general. Agreement with the Euler equation Eq. (9), is shown in the long-column range down to a slenderness ratio of 300, which corresponds to a slenderness ratio of 150 in Fig. 3. This indicates an elastic buckling failure. As the span decreases, the specimen shows deviations from the Euler curve. In the intermediate-column range, elastic buckling is gradually replaced by plastic failure until a well-defined plateau is reached at slenderness ratios smaller than 20, i.e., spans shorter than six times the thickness. This plateau was identified in Fig. 2 as the short-column range, representing the compression strength of the material. It should be noted that the short-column range is much shorter for paper than for steel. The reason for this is ascribed to the nonuniform thickness of paper, which has the effect that a shorter span is required to obtain sufficient stability in the sample.
