担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Laminated wood-based materials have been widely developed, and the laminating process and adhesive itself have been reported to enhance performance beyond the sum of the individual layers' performance. This phenomenon is particularly notable under loads applied in the "edge-wise direction", where each layer bears stress collectively. These combined effects are referred to as the "adhesive effect". Strength under partial compressive loads is critical in timber engineering, as partial compressive stress generates complex stress distributions influenced by boundary conditions. The adhesive effect may also be impacted by these conditions. The aim of this study was to quantitatively and directly evaluate the adhesive effect under partial and full compressive loads using various parameters. The strength of laminated veneer lumber (LVL) with adhesive was compared to that of simply layered veneers without adhesive to assess the adhesive effect. Three mechanisms contributing to the adhesive effect were proposed: Mechanism I, caused by the deformation of the adhesive layer independently from the veneers; Mechanism II, resulting from the adhesive impregnating the veneers; and Mechanism III, arising from the reinforcement provided by adjacent veneers. The results suggested the following: (i) Mechanism I had minimal impact, as the fiber direction and the presence of additional length showed strong and slight effects on the adhesive effect, respectively; (ii) Mechanism II contributed to preventing crack propagation and altering the relationships among mechanical properties, with its effectiveness increasing as the adhesive weight increased; and (iii) Mechanism III functioned as a crossband effect, reinforcing weaknesses caused by the slope of the grain and the angle of the annual rings.

DOI： 10.1186/s10086-025-02195-z

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その他リンク： https://link.springer.com/article/10.1186/s10086-025-02195-z/fulltext.html

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Although embedment properties are vital to timber engineering, the behavior and strain distributions in wood-based panels have not been clarified in detail. Our early studies suggested four possible causes of failure behavior and strain distribution: (i) two types of failure behavior (in-plane and out-of-plane failure); (ii) enlargement of the stress-spreading range with increasing load step; (iii) reduction of the stress-spreading range (normalized by dowel diameter) with increasing dowel diameter; and (iv) preferential stress spreading in the vertical and horizontal directions along the strong and weak-axis specifications, respectively. However, these hypotheses were not supported by actual observations. The present study aims to observe and clarify the surface strain distribution via digital image correlation and the internal failure behavior via computed tomography scanning. Most results of the wood-based panel specimens (plywood and oriented strand board) did not contradict the above hypotheses. The failure behaviors of plywood and oriented strand board are likely determined by the direction of the veneer fibers and the layer’s position, respectively. Within the strong axial layer of plywood, fibers on both sides of the dowel were densified by fibers dissociated immediately above the dowel, whereas the weak axial layer in plywood was deformed like a timber under partial compression perpendicular to the grain. In contrast, oriented strand board under an embedding stress exhibited a circularly distributed strain and a dispersed void area in its outer layer. Densification was observed only in the inner layer.

DOI： 10.1186/s10086-023-02113-1

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その他リンク： https://link.springer.com/article/10.1186/s10086-023-02113-1/fulltext.html

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Embedment properties are vital to timber structural designs, and many types of wood-based structural panels have been developed for diverse uses. Comprehensive and systematic studies regarding the embedment properties of wood-based structural panels are limited. In this study, a jig that allows the observation of fracture processes is developed, and a monotonic tensile embedment test is conducted on plywood, oriented strandboard (both strong and weak axes), particleboard, medium density fiberboard, and hardboard. The parameters used in the test are the dowel diameter, pilot hole size, and end and edge distances. The effects of these parameters on the embedment properties (i.e., the failure mode, ductility, maximum stress, and yield stress) are discussed comprehensively. The failure mode is determined by the edge distance. At a sufficient edge distance, ductile failure occurs, and the load is maintained until the remaining end distance reaches a certain value. The maximum stress and yield stress are analyzed quantitatively via standardized multiple regression analysis. The results suggest the following: (i) The ratio of the in-plane strength to the internal bond strength is related to the failure behavior; (ii) the dowel diameter, fiber direction, and load levels affect the stress spread pattern of the embedment pressure.

DOI： 10.1186/s10086-023-02093-2

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その他リンク： https://link.springer.com/article/10.1186/s10086-023-02093-2/fulltext.html

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担当区分：筆頭著者  

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担当区分：筆頭著者   出版者・発行元：World Conference On Timber Engineering 2025  

DOI： 10.52202/080513-0199

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