Estimation of Bending Characteristics of Creased White-Coated Paperboard Subjected to In-Plane Compressive Load Using V-Block Fixtures

Shigeru Nagasawa, Quyet Tran Xuan, and Weerayut Jina

Nagaoka University of Technology, Japan

Abstract: This research work deals with the development of simple evaluation method of creasing characteristics of coated paperboard. The recent-developed testing device (CST, crease stress tester) is able to control the bending rotation speed of the creased part of a worksheet and its sleeping time at a specified angle position. Although the CST is a high grade equipment and useful for analyzing the bending characteristics, while the cost performance of equipment for simply having assurance of crease stiffness is another problem. The authors have developed a simple evaluation method for knowing the creasing characteristics on a folded line of paperboard, which is subjected to an in-plane compressive load by using a set of V-block fixtures. Through the bending experiment of creased paperboard, the proposed V-Block based estimation method has been compared with some analysis results based on the CST, and its effectiveness was revealed. The primary results were as follows: (1) The buckling strength as the maximum compressive load is characterized with respect to the nominal shear strain (normalized scoring depth of crease). (2) The transitional point as variation tendency of compressive load (by the V-Block) well coincides to the disappearance of peak bending moment of CST. (3) The equivalent bending moment of V-Block well coincides to the CST based bending moment resistance when choosing a certain large folding angle. (4) The proposed V-Block method can be effectively used for a certain large range of folding angle.

Key words: bending moment, folding strength, de-lamination, shearing, buckling, simple evaluation technique