Stress analysis under the surface compression for SCP medium (semi-chemical medium) in fiberboards which are shown as semi-elliptic and sinusoidal waves is considered. Then relations between stress distributions and shapes of SCP medium are discussed, and strength efficiencies (strength per mass of the corrugated sheet) Efe and Efs for elliptic and sinusoidal waves are discussed from results of the analysis. Obtained results are as follows :
(1) Lateral weight Woe in SCP medium of the elliptic wave under the constant surface compression is smaller than lateral weight Woe in the sinusoidal wave. Ratio of Woe/Woe is about 0.7. Woe and Woe decrease with the increment of thickness T of SCP medium.
(2) Maximum values (σemax for elliptic wave, σemax for sinusoidal wave) of their absolute stresses are on inner surfaces of contact positions with kraft liner. Ratio of/σemax/σemax is about 1.6 and increases with the increment of wave length L. Maximal values of absolute stresses for elliptic and sinusoidal waves of SCP medium occur at 7 L/32 and L/6 from their contact positions along the machine direction.
(3) In range ρ (radius of curvature at the top of SCP medium) >T/2 (T : thickness of the medium), σemax decreases with the increment of T. Initially σemax decreases, then increases with increments of L and wave height h. In the range ρ> T/2, Efe and Efs increase and decrease with increases of T, L and h.