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Transactions of Nonferrous Metals Society of China 2022年第6期32卷 1805-1821页

作者： Hiromi NAGAUMI Jian QIN Cheng-bin YU Xiao-guo WANG Lin-sheng WANG High Performance Metal Structural Materials Research Institute Soochow UniversitySuzhou 215021China Shagang School of Iron and Steel Soochow UniversitySuzhou 215021China College of Agricultural Engineering Shanxi Agricultural UniversityTaigu 030801China Press Metal International Ltd. Foshan 528000China

The microstructural evolution of AA6061 and Mn-bearing Al-Mg-Si-Cu alloys was studied by compression tests that were carried out between 300 and 500 °C with a wide range of strain rates. Compared to the AA6061 alloy, the large amount of α-Al(MnFeCr)Si dispersoids in the Mn-bearing alloy yielded a significant increase in the flow stress under all deformation conditions. The effects of the deformation parameters on the evolution of the microstructure were studied using electronic backscatter diffraction measurements. The predominant softening mechanism of both alloys was dynamic recovery. The presence of α dispersoids in Mn-bearing alloys effectively refined the size of substructures with misorientation angles in the range of 2°-5°, which retarded the dynamic recovery. To predict the subgrain size under various deformation conditions, the threshold stresses that were caused by α dispersoids were calculated by the modified Orowan equation and incorporated into a conventional constitutive equation. The subgrain size that was predicted by the modified constitutive equation showed satisfactory agreement with the experimental measurements.

关键词： Al-Mg-Si alloy hot deformation α-Al(MnFeCr)Si dispersoids substructure dynamic softening threshold stress Z parameter

MODAL TEST AND ANALYSIS OF CANTILEVER BEAM WITH TIP MASS

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Acta Mechanica Sinica 2002年第4期18卷 407-413页

作者：肖世富杜强陈滨刘才山向荣山周为华徐友钜徐有刚 Southwest Institute of Structural Mechanics P.O.Box 919-401Mianyang 621900China Department of Mechanics & Engineering Science Peking UniversityBeijing 100871China

The phenomenon of dynamic stiffening is a research field of general interest for flexible multi-body *** fact,there are not only dynamic stiffening but also dynamic softening phenomenon in the flexible multi-body *** this paper,a non-linear dynamic model and its linearization characteristic equations of a cantilever beam with tip mass in the centrifugal field are established by adopting the general Hamilton Variational ***,the problems of the dynamic stiffening and the dynamic softening are studied by using numerical ***, the modal test is carried out on our *** numerical results show that the system stiffness will be strengthened when the centrifugal tension force acts on the beam (*** dynamic stiffening).However,the system stiffness will be weakened when the centrifugal compression force acts on the beam (*** dynamic softening). Furthermore,the equilibrium position of the system will lose its stability when the inertial force reaches a critical *** theoretical analysis,we find that this phenomenon comes from the effect of dynamic softening resulting from the centrifugal compression *** test results verify the above conclusions and confirm that both dynamic stiffening and softening phenomena exist in flexible multi-body systems.

关键词： flexible multibody system centrifugal field inertial force dynamic stiffening dynamic softening

Hot deformation behavior and constitutive modeling of Q345E alloy steel under hot compression

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Journal of Central South University 2017年第2期24卷 284-295页

作者：钱东升彭亚亚邓加东 School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China School of Automotive Engineering Wuhan University of Technology Wuhan 430070 China Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan 430070 China State Key Laboratory of Materials Processing and Die & Mould Technology Wuhan 430070 China

Q345E as one of typical low alloy steels is widely used in manufacturing basic components in many fields because of its eminent formability under elevated temperature. In this work, the deformation behavior of Q345E steel was investigated by hot compression experiments on Gleeble-3500 thermo-mechanical simulator with the temperature ranging from 850 ℃ to 1150 ℃ and strain rate ranging from 0.01 s-1 to 10 s-1. The experimental results indicate that dynamic softening of Q345E benefits from increasing deformation temperature and decreasing strain rate. The mathematical relationship between dynamic softening degree and deformation conditions is established to predict the dynamic softening degree quantitatively, which is further proved by some optical microstructures of Q345E. In addition, the experimental results also reveal that the stress level decreases with increasing deformation temperature and decreasing strain rate. The constitutive equation for flow stress of Q345E is formulated by Arrihenius equation and the modified Zener-Hollomon parameter considering the compensation of both strain and strain rate. The flow stress values predicted by the constitutive equation agree well with the experimental values, realizing the accurate prediction of the flow stress of Q345E steel under hot deformation.

关键词： hot deformation behavior dynamic softening flow stress constitutive model

dynamically softened substrate regulates malignancy of breast tumor cells

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Science China Materials 2021年第10期64卷 2580-2592页

作者： Mi Hu Xu Li Wei-Pin Huang Deng-Feng Hu Ke-Feng Ren Jian Ji MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province Sir Run Run Shaw HospitalZhejiang UniversityHangzhou 310016China

It has long been hypothesized that an increase in the extracellular matrix(ECM)stiffness mechanoactivates malignant phenotypes of breast tumor cells by regulating an array of processes underlying cancer *** the contribution of substrate stiffening to drive malignant phenotype traits and other biological functions of a tumor is increasingly understood,the functional role of substrate softening on breast cancer cellular responses has rarely been ***,we employed matrix metalloproteinase(MMP)-sensitive film to perform assays to explore the consequences of lowering stiffness on the biological behaviors of breast cancer cell *** demonstrated that cells underwent dramatic changes in migration,cellular conjunction,and expression of malignance-associated proteins and genes when the substrate stiffness *** on RNA sequencing and analysis,we found that hub genes including TP53,CCND1,MYC,CTNNB1,and YAP were validated to play central parts in regulating stiffness-dependent cellular manner ***,through visualization of differentially expressed genes(DEGs),cells on dynamically softened substrate appeared less influenced by transfer to tissue culture polystyrene(TCPS).These results suggest substrates with decreasing stiffness could normalize breast tumor malignant phenotype and help cells store the mechanical memory of the consequential weaker malignance.

关键词： substrate stiffness dynamic softening breast tumor cell malignance normalization

dynamic BEHAVIOR OF THIN RECTANGULAR PLATE ATTACHED TO MOVING RIGID

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Applied Mathematics and Mechanics(English Edition) 2006年第4期27卷 555-566页

作者：肖世富陈滨 Southwest Institute of Structural Mechanics P. O. Box 919-401 Mianyang 621900Sichuan ProvinceP. R. China Department of Mechanics and Engineering Science Peking University Beijing 100871P. R. China

A nonlinear dynamic model of a thin rectangular plate attached to a moving rigid was established by employing the general Hamilton＇s variational principle. Based on the new model, it is proved theoretically that both phenomena of dynamic stiffening and dynamic softening can occur in the plate when the rigid undergoes different large overall motions including overall translational and rotary motions. It was also proved that dynamic softening effect even can make the trivial equilibrium of the plate lose its stability through bifurcation. Assumed modes method was employed to validate the theoretical result and analyze the approximately critical bifurcation value and the postbuckling equilibria.

关键词： flexible multi-body system dynamic stiffening dynamic softening stability bifurcation post-buckling