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Nonlinear dynamic response and stability analysis of the stapes reconstruction in human middle ear

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应用数学和力学:英文版 2023年第10期44卷 1739-1760页

作者： Lele WANG Liang WANG Yueting ZHU zhanli liu Yongtao SUN Jie WANG Hongge HAN Shuyi XIANG Huibin SHI Qian DING Department of Mechanics Tianjin UniversityTianjin 300350China Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin UniversityTianjin 300350China Department of Otolaryngology Head and Neck SurgeryTianjin Children's HospitalTianjin UniversityTianjin 300400China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Department of Otolaryngology Head and Neck Surgery Beijing Tongren HospitalCapital Medical UniversityBeijing 100730China Key Laboratory of Otolaryngology Head and Neck Surgery Ministry of EducationBeijing 100730China Beijing Engineering Research Center of Audiological Technology Beijing 100730China

Stapes fracture causes hearing loss and instability in the middle ear hearing system(MEHS). The material used in the stapes reconstruction restores stapes, but the effects of the nonlinear material parameters on the stability of the MEHS are still unknown. To address this challenge, the nonlinear dynamic response and stability of the stapes reconstruction are investigated using a multi-degree-of-freedom mechanical model. The material parameters of the implant are tentatively determined by analyzing the natural frequencies of the undamped system. The dynamical properties of the MEHS are characterized under different external excitations. The approximate solution of the MEHS near the resonant frequency is derived through the multiple-time-scale method(MTSM). The results show that the nonlinear stiffness of the material has little influence on the MEHS in the healthy state, but it causes resonant phenomena between the ossicle and the implant in the pathological state.

关键词： crus fracture of stapes stapes reconstruction dynamic analysis bifurcation analysis multiple-time-scale method(MTSM)

A Crystal Plasticity Model with Irradiation Effect for the Mechanical Behavior of FCC Metals

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Acta Mechanica Solida Sinica 2019年第6期32卷 675-687页

作者： Jnnfeng Nie Yunpeng liu Pandong Lin Qihao Xie zhanli liu Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Minis try of EducationTsinghua UniversityBeijing 100084China Applied Mechanics Lab. School of Aerospace EngineeringTsinghua UniversityBeijing 100084China Data Science and Information Technology Research Center Tsinghua-Berkeley Shenzhen InstituteShenzhen 518055China

In this paper,a crystal plasticity model considering the irradiation effect based on the thermal activation theory is established.The evolutions of screw dislocations,edge dislocations,and stacking fault tetrahedrals(SFTs)(induced by irradiation)are included into the model.The interactions between dislocations and irradiation-induced SFTs are also considered.The constitutive model is numerically implemented on the ABAQUS platform through UMAT subroutine and applied to study the irradiation effect on the mechanical behavior of pure copper.The mechanical properties of single and polycrystalline copper are studied,and the simulation results show that the constitutive model can properly predict the mechanical behavior of irradiated pure copper.Especially for polycrystalline copper,the simulation results are in good agreement with the experimental data.

关键词： Crystal plasticity Irradiation effect Uniaxial tension Dislocation FCC crystal

On the material constants measurement method of a fluid-saturated transversely isotropic poroelastic medium

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 69-75页

作者： Yue Gao zhanli liu Zhuo Zhuang Keh-Chih Hwang AML Department of Engineering Mechanics Tsinghua University Center for Mechanics and Materials Tsinghua University

The fluid-saturated transversely isotropic poroelastic medium could be widely found in nature, e.g., the sedimentary rocks underground. To determine the eight independent material constants for the transversely isotropic poroelastic medium, a series of tests are discussed. Two undrained tests and one drained test are suggested as a set of tests of the least amount. For the verification purpose, two additional drained tests are also introduced as an option. The atmospheric dried test is discussed as a replacement of the traditional infiltrated drained test to save the time waiting for an equilibrium state. Some microscopic material constants, i.e.,the unjacketed bulk coefficients, the porosity, and the compressibility of porous fluid, are measurable but unnecessary to determine the independent material constants of a poroelastic medium.

关键词： poroelastic constitutive model material constants measurement transversely isotropic medium

Theoretical aspects of selecting repeated unit cell model in micromechanical analysis using displacement-based finite element method

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Chinese Journal of Aeronautics 2017年第4期30卷 1417-1426页

作者： Lijun GAO Chengyu WANG zhanli liu Zhuo ZHUANG Department of Engineering Mechanics School of Aerospace Engineering Tsinghua University Beo'ing 100084 China

Repeated Unit Cell（RUC）is a useful tool in micromechanical analysis of composites using Displacement-based Finite Element（DFE）method,and merely applying Periodic Displacement Boundary Conditions（PDBCs）to RUC is almost a standard practice to conduct such analysis.Two basic questions arising from this practice are whether Periodic Traction Boundary Conditions（PTBCs,also known as traction continuity conditions）are guaranteed and whether the solution is independent of selection of RUCs.This paper presents the theoretical aspects to tackle these questions,which unify the strong form,weak form and DFE method of the micromechanical problem together.Specifically,the solution’s independence of selection of RUCs is dealt with on the strong form side,PTBCs are derived from the weak form as natural boundary conditions,and the validity of merely applying PDBCs in micromechanical Finite Element（FE）analysis is proved by referring to its intrinsic connection to the strong form and weak form.Key points in the theoretical aspects are demonstrated by illustrative examples,and the merits of setting micromechanical FE analysis under the background of a clear theoretical framework are highlighted in the efficient selection of RUCs for Uni Directional（UD）fiber-reinforced composites.

关键词： Finite element method Micromechanics of composites Periodic boundary condition Repeated unit cell Theoretical aspect Traction continuity

Study on interaction between induced and natural fractures by extended finite element method

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Science China(Physics,Mechanics & Astronomy) 2017年第2期60卷 24-37页

作者： DanDan Xu zhanli liu Zhuo Zhuang QingLei Zeng Tao Wang School of Aerospace Engineering Tsinghua University Beijing 100084 China

Fracking is one of the kernel technologies in the remarkable shale gas revolution. The extended finite element method is used in this paper to numerically investigate the interaction between hydraulic and natural fractures, which is an important issue of the enigmatic fracture network formation in fracking. The criteria which control the opening of natural fracture and crossing of hydraulic fracture are tentatively presented. Influence factors on the interaction process are systematically analyzed, which include the approach angle, anisotropy of in-situ stress and fluid pressure profile.

关键词：相互作用天然裂缝有限元法诱导压力剖面水力压裂裂缝网络水力裂缝

XFEM modeling of hydraulic fracture in porous rocks with natural fractures

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Science China(Physics,Mechanics & Astronomy) 2017年第8期60卷 45-59页

作者： Tao Wang zhanli liu QingLei Zeng Yue Gao Zhuo Zhuang Applied Mechanics Lab. School of Aerospace Engineering Tsinghua University

Hydraulic fracture(HF) in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method(XFEM) coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures(NFs). In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex fracture network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk(KGD) model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.

关键词：天然裂缝性多孔岩石水力压裂 Biot固结理论流体流动岩石渗透率多孔介质耦合模型

Recent advances in the extended finite element method (XFEM) and isogeometric analysis (IGA)

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Science China(Physics,Mechanics & Astronomy) 2016年第12期59卷 80-81页

作者： DanDan Xu zhanli liu Zhuo Zhuang School of Aerospace Engineering Tsinghua University

The finite element method (FEM) is one of the most popular and efficient methods for computational modeling in scientific research and engineering [1-3]. To expand its application to more complex problems, lots of new FEM-based methods have been developed in recent decades. One major achievement is the significantly improvement on the flexibility

关键词： XFEM IGA Recent advances in the extended finite element method and isogeometric analysis

ANALYTICAL AND NUMERICAL INVESTIGATIONS OF TWO SPECIAL CLASSES OF GENERALIZED CONTINUUM MEDIA

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Acta Mechanica Solida Sinica 2011年第4期24卷 326-339页

作者： Zhaohui Zhang zhanli liu Yuan Gao Junfang Nie Zhuo Zhuang Department of Engineering Mechanics School of AerospaceTsinghua UniversityBeijing 100084China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China Naval Academy of Armament Beijing 100073China

In this paper,the micromorphic theory and the second gradient theory are proposedwhere the micromorphic model can be reduced to the second gradient model with the vanishing relative deformation between macrodeformation gradient and microdeformation.Analytical solutions for the simple shear problem in the case of a general small strain isotropic elasticity micromorphic model and the second gradient model are presented,respectively.Besides,uniaxial tension of a constrained layer with two different boundary conditions is also analytically solved.Finally,the micromorphic theory is implemented numerically within a two-dimensional plane strain finite element framework by developing two isoparametric elements.

关键词： micromorphic second gradient boundary layer size effect finite element

灌溉水温与施氮量对滴灌棉田土壤水热及棉花生长和产量的影响

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中国农业科学 2024年第2期57卷 319-335页

作者：何静王振华刘健马占利温越石河子大学水利建筑工程学院/现代节水灌溉兵团重点实验室/农业农村部西北绿洲节水农业重点实验室

【目的】探究膜下滴灌棉田土壤水热环境和棉花生长对灌溉水温与施氮量的响应机理，旨在确定北疆滴灌棉花合理的灌溉水温和施氮量。【方法】以新陆早42号棉花为试验材料，设置4个灌溉水温：15℃(T0)、20℃(T1)、25℃(T2)和30℃(T3);3个... 详细信息

【目的】探究膜下滴灌棉田土壤水热环境和棉花生长对灌溉水温与施氮量的响应机理，旨在确定北疆滴灌棉花合理的灌溉水温和施氮量。【方法】以新陆早42号棉花为试验材料，设置4个灌溉水温：15℃(T0)、20℃(T1)、25℃(T2)和30℃(T3);3个施氮水平：250 kg·hm-2(F1)、300 kg·hm-2(F2)和350 kg·hm-2(F3)，采用双因素完全随机试验设计。分析不同灌溉水温条件下施氮量对棉田土壤水热环境、棉花生长、产量和水氮利用效率的影响。【结果】常规灌溉水温与低氮处理降低土壤温度，抑制棉花生长，单株铃数降低并导致籽棉产量下降。适宜的灌溉水温和施氮量可以改善土壤水热环境，促进棉花生长发育，提高籽棉产量和水氮利用效率。与15℃常规灌溉水温相比，增温灌溉显著提高了土壤温度0.58—3.30℃，土壤储水量降低1.2%—7.2%，土壤呼吸速率显著提高5.7%—28.0%；随灌溉水温升高，棉花株高、叶面积指数及地上部干物质积累量先增高后降低，在灌溉水温为25℃时达最大。随施氮量增加，土壤储水量降低3.3%—6.7%，土壤呼吸速率显著提高3.6%—9.5%，棉花株高增加3.2%—4.9%，叶面积指数显著增加5.8%—11.0%，地上部干物质积累量显著增加1.2%—2.2%，均在施氮量为350 kg·hm-2时达最大。水分利用效率、氮肥偏生产力及籽棉产量随灌溉水温升高均先增加后减少，随施氮量增加分别表现为增加、减少、增加的趋势。通径分析表明，土壤温度对籽棉产量直接作用最大，而施氮量通过促进棉花生长对籽棉产量间接作用最大。籽棉产量与水分利用效率均在T2F2处理达到最大值，分别为6 652.3 kg·hm-2、1.17 kg·m-3，且T2F2处理的氮肥偏生产力(22.17 kg·kg-1)显著大于T2F3处理(18.80 kg·kg-1)。【结论】综合考虑灌溉水温与施氮量对土壤温度，土壤呼吸速率，棉花生长、产量及水氮利用效率的影响，推荐北疆棉区适宜灌溉水温为25℃，施氮量为300 kg·hm-2。

关键词：膜下滴灌棉花灌溉水温氮肥产量水肥利用效率北疆