Analysis of fracture mechanism of bolted joints and nail joints in LVL
| Project/Area Number |
62560174
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
林産学
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| Research Institution | Nagoya University |
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Principal Investigator |
SOBUE Nobuo Nagoya University, Faculty of Agriculture, Josyu., 農学部, 助手 (50023495)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Yasutosi Nagoya University, Faculty of Agriculture, Josyu., 農学部, 助手 (90154004)
TSUZUKI Kazuo Nagoya University, Faculty of Agriculture, Assoc. Prof., 農学部, 助教授 (60023438)
TAKEMURA Tomio Nagoya University, Faculty of Agriculture, Professor, 農学部, 教授 (90014919)
OHTA Masamitsu University of Tokyo, Faculty of Agriculture, Assoc. Prof., 農学部, 助教授 (20126006)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1988: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1987: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Laminated Veneer Lumber / Nail Joints / Bolted Joints / Fracture of Joints / 破壊 / 破壊力学 |
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| Research Abstract |
The fracture of bolted joints in LVL, Laminated Veneer Lumber, and the crack propagation during driving nails into LVL were studied.
1. The crack caused by driving nails was longer inside of materials than at surface. The crack length estimated from fracture mechanics concept using the material constants (density and fracture toughness) agreed well with that of experiments.
2. The fracture of the bolted joints subjected to shear loads (perpendicular to grain and parallel to grain), the influence of the bolt position on the ultimate load, and the measurement of the stress concentration around a bolt hole were studied. The LVL (Micro-lam; 2.0 E) of 2" by 10" lumber size were jointed by bolts of 16mm in diameter(d). The allowable bolt position for LVL based on the yield condition of LVL was given as follows: In the case of load perpendicular to grain, the allowable side distance of bolt hole and the end distance were longer than 4d-7.6d(= half of the depth of a specimen) and longer than 7d-10d, respectively. In the case of load parallel to grain, the end distance was longer than 7d. These distances were a little longer than those of the recommendation of the standard for wood.
3. The important stress concentrations around a blot hole were the tensile stress at the boundary of a bolt hole for the load perpendicular to grain and the tensile stress at the end surface for the load paralled to grain. The major fracture mode of joints was split of LVL along grain when the side and the end distances were not enough.
4. The equivalent edge crack length of the lathe-check of veneers in LVL estimated from the fracture mechanics concept was about 9 mm.
5. The acoustic emission related to the fracture modes of joints.
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Report
(3 results)
Research Products
(7 results)
