| Project/Area Number |
16560068
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Nagoya University |
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Principal Investigator |
TANAKA Eiichi Nagoya University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (00111831)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUNO Koji Nagoya University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (80335075)
YAMAMOTO Sota Nagoya University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (80293653)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Biomechanics / Bone / Mechanical properties / Constitutive model / Automobile simulation / Injury evaluation of lower extremity / 構成式モデル / 動的負荷 / 損傷 |
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| Research Abstract |
We formulated a new constitutive model of bone to facilitate an accurate prediction of fracture pattern under dynamic conditions. The model describes anisotropy of deformation and strength, asymmetric properties for tension and compression, inelastic deformation and damage evolution, and strain-rate dependency of afore-mentioned characteristics. The total strain is divided into elastic and inelastic parts. The elastic part is modeled as a transversely isotropic material with strain-rate dependent elastic moduli. The inelastic part is described by a framework of viscoplastic flow theory with an equipotential surface of Tsai-Wu criterion. The effects of damage were taken into account by an isotropic damage variable and its evolution equation. The introduction of isotropic and kinematic hardening variables was also discussed to describe loading-unloading and cyclic test results.
To evaluate the effects of damage on mechanical properties of bone we performed repetitive compressive tests. The results showed that there was no difference between the initial elastic moduli in the loading and unloading process. We also discussed the adequacy of Carter-Hayes model on the elastic modulus-strain rate relationship in low strain-rate range.
Finally we developed an algorithm to implement the proposed model to FE code LS-DYNA. We confirmed the adequacy of the implementation by comparing FE calculation results using a single cubic element for simple tension or compression process and the corresponding calculation results by direct use of the constitutive model. We performed a parametric study for cases of axial impact to ankle joint by use of the proposed model and a conventional model. We found that the proposed model gave better predictions on the location, severity, and pattern of fracture than the ordinary model.
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