2023 Fiscal Year Research-status Report
ダブルネットワークゲルの大変形下における高速破壊挙動の解明
| Project/Area Number |
23KF0002
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| Research Institution | Hokkaido University |
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Principal Investigator |
グン 剣萍 北海道大学, 先端生命科学研究院, 教授 (20250417)
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| Co-Investigator(Kenkyū-buntansha) |
TIAN FUCHENG 北海道大学, 先端生命科学研究院, 外国人特別研究員
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| Project Period (FY) |
2023-04-25 – 2025-03-31
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| Keywords | Nonlinear material / Phase field model / Dynamic fracture / Supershear crack |
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| Outline of Annual Research Achievements |
At present, we have developed a dimensionless dynamic phase field model for the fracture of soft materials. Based on this model, we successfully replicated the diverse crack dynamics in quasi-2D soft materials. The captured spontaneous crack oscillations, branching, and the transition from sub-Rayleigh to supershear crack patterns align remarkably well with experimental observations. Categorizing by crack patterns, we constructed crack stability phase diagrams for three different materials, i.e., strain-stiffening, large-strain linear elastic, and strain-softening materials, in a 2D pre-strained fracture scenario. The distinct phase diagrams offer insights into why the intriguing phenomenon of crack oscillation is seldom observed in experiments. The instability wavelength is identified as a bilinear function of nonlinear scale and crack driving force, featuring an intrinsic minimum scale. The onset speed of oscillation scales linearly with the characteristic wave speed near the crack tip. Moreover, our findings also suggest the transition of cracks from sub-Rayleigh to supershear regimes in homogeneous soft materials roots in the increased local wave speed. These findings elucidate the universal laws of nonlinearity in regulating fracture dynamics. The established scaling laws for the supercritical crack oscillation, especially the relation between crack oscillation velocity and local wave speed significantly deepens our understanding of dynamic fracture in soft materials.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
We have successfully completed the tasks outlined in our research plan for the year 2023, and the relevant findings have been compiled into a manuscript currently under review. However, we have encountered some challenges in our work for the year 2024. The large-scale three-dimensional computations of the composite system underway are time-consuming, and suitable boundary conditions have yet to be determined. A significant amount of time is being devoted to testing various boundary conditions. Once an appropriate computational framework is established, subsequent computations are expected to proceed smoothly.
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| Strategy for Future Research Activity |
(1) We plan to develop a three-dimensional toughening model for composite systems. Starting from a simple linear elastic regime and expanding to a nonlinear elastic regime, we aim to utilize this model to elucidate toughening mechanisms in DN gels. Additionally, the developed model holds promise in addressing the stick-slip crack propagation in DN gels.
(2) Our previous work has indicated that crack dynamics are governed by local scales, which significantly deviates from classical fracture theories. In the upcoming research, we endeavor to establish scaling laws for these local scales.
Potential challenges may arise in numerical aspects, particularly in dealing with large-scale, nonlinear computations. We will attempt to address this issue by utilizing the open-source MOOSE framework.
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| Causes of Carryover |
学会への参加がなく、旅費の支出がありませんでした。
2024年度は海外での学会参加を予定しております。
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