曲げ荷重を受けたI-214ポプラ/集成材の実験と数値解析

Experimental and Numerical Analysis of Mixed I-214 Poplar/ Laminated Timber Subjected to Bending Loadings.

• Francisco J Rescalvo
• Cristian Timbolmas
• Rafael Bravo
• Antolino Gallego

抄録

ポプラのような成長の早い低品位種の木材の構造利用は、エンジニアリング製品の開発を通じて、木材バリューチェーンにおける現在の課題の一つとなっている。本研究では、外層にパイン材を用いた混合集成材と内層にポプラ材を用いた混合集成材の挙動を定性的に比較検討した。制御レイアウトには単種ポプラとパイン集成材を用いた。調査は、破壊的な4点曲げ試験と、有限要素数値モデル、平行軸定理に基づく半解析モデル、音響共鳴試験の3つの非破壊的手法を用いて行った。その結果、実験結果と数値計算結果は良好な一致が得られた。試験したサンプル数は少ないが，結果は，積層材の内層に低級材としてポプラを使用することが，松の良好な機械的特性を維持したまま木材の軽量化を図るための有望な技術であることを示している．同様に，実験的測定と数値解析の両方でせん断弾性率を使用する必要性が示唆され，混成材の場合の非破壊等級付けのための振動方法を再構築する必要性が示唆された．

The structural use of timber coming from fast growing and low-grade species such as poplar is one of the current challenges in the wood value chains, through the development of engineering products. In this work, a qualitative comparison of the behavior of mixed glued laminated timber made of pine in their outer layers and of poplar in their inner layers is shown and discussed. Single-species poplar and pine laminated timber have been used as control layouts. The investigation includes destructive four-point bending tests and three non-destructive methodologies: finite elements numerical model; semi-analytical model based on the Parallel Axes theorem and acoustic resonance testing. An excellent agreement between experimental and numerical results is obtained. Although few number of samples have been tested, the results indicate that the use of poplar as a low-grade species in the inner layers of the laminated timber can be a promising technology to decrease the weight of the timber maintaining the good mechanical properties of pine. Likewise, the need for the use of the shear modulus in both experimental measurements and numerical analysis is suggested, as well as the need to reformulate the vibration methodology for non-destructive grading in the case of mixed timber.