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Fundamental strengthening mechanisms of ordered gradient nanotwinned metals

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Nano Research 2023年第11期16卷 12430-12437页

作者： Zhao Cheng lei lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Ordered structures with functional units offer the potential for enhanced performance in metallic *** these structures,gradient nanotwinned(GNT)microstructures demonstrate excellent *** paper provides a comprehensive review of the current state-of-the-art studies on GNT structures,encompassing various aspects such as design strategies,mechanical properties characterization,spatially gradient strain evolution analysis,and the significant role of geometrically necessary dislocations(GNDs).The primary objective is to systematically unravel the fundamental strengthening mechanisms by gaining an in-depth understanding of the deformation behavior of nanotwinned *** this work,we aim to contribute to the broader field of materials science by consolidating knowledge and providing insights for the development of novel metallic materials with enhanced properties and tailored performance characteristics.

关键词： metallic material ordered design nanotwin units trans-scale strengthening mechanisms

Size effect of deformation nanotwin bundles on their strengthening and toughening in heterogeneous nanostructured Cu

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Science China(Technological Sciences) 2021年第1期64卷 23-31页

作者： YOU ZeSheng luO ShuSen lu lei Herbert Gleiter Institute of Nanoscience Nanjing University of Science and TechnologyNanjing 210094China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Herein, we fabricated a heterogeneous nanostructured Cu with deformation nanotwin bundles(NTBs) embedded in a matrix of nanograins by means of dynamic plastic deformation at liquid nitrogen temperature. We conducted fracture mechanical measurements to investigate the effect of longitudinal length of the NTBs on their strengthening and toughening. Results suggest that an increase in the NTB length had a marginal influence on the tensile strength;however, it remarkably promoted both fracture initiation toughness and crack growth toughness. Longer NTBs are more effective not only in intrinsically enhancing crack tip plasticity by suppressing the strain localization and void nucleation but also in serving as crack bridges behind the crack front to extrinsically resist the fracture by shielding the crack tip.

关键词： fracture toughness nanotwins J-integral size effect toughening mechanism

Numerical Modeling of the Compression Process of Elastic Open-cell Foams

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Chinese Journal of Aeronautics 2007年第3期20卷 215-222页

作者： ZHANG Jia-lei lu Zi-xing Institute of Solid Mechanics Beijing University of Aeronautics and Astronautics Beijing 100083 China

The random models of open-cell foams that can reflect the actual cell geometrical properties are constructed with the Voronoi technique. The compression process of elastic open-cell foams is simulated with the nonlinear calculation module of finite element analysis program. In order to get the general results applicable to this kind of materials, the dimensionless compressive stress is used and the stress-strain curves of foam models with different geometrical properties are obtained. Then, the influences of open-cell geometrical properties, including the shape of strut cross section, relative density and cell shape irregularity, on the compressive nonlinear mechani- cal performance are analyzed. In addition, the numerical results are compared with the predicted results of cubic staggering model. Nu- merical results indicate that the simulated results reflect the compressive process of foams quite well and the geometrical properties of cell have significant influences on the nonlinear mechanical behavior of foams.

关键词： Voronoi technique open-cell foam nonlinear compressive stress

Tire Dynamics Modeling Method Based on Rapid Test Method

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Chinese Journal of Mechanical Engineering 2020年第6期33卷 228-237页

作者： Dang lu lei lu Haidong Wu Wei Wang Manyi Lv State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun130025China General R&D Institute of China Department Experiment Unit FAW Group Co.LTDChangchun130013China

Combined with the tire dynamics theoretical model,a rapid test method to obtain tire lateral and longitudinal both steady-state and transient characteristics only based on the tire quasi-steady-state test results is *** steady state data extraction,the test time of the rapid test method is half that of the conventional test *** transient tire characteristics the rapid test method omits the traditional tire test *** the mean time the accuracy of the two method is much *** rapid test method is explained theoretically and the test process is *** key parameters of tire are extracted and the comparison is made between rapid test and traditional test *** result show that the identification accuracy based on the rapid test method is almost equal to the accuracy of the conventional ***,the heat generated during the rapid test method and that generated during the conventional test are calculated *** comparison shows that the heat generated during the rapid test is much smaller than the heat generated during the conventional test *** benefits to the reduction of tire wear and the consistency of test ***,it can be concluded that the fast test method can efficiently,accurately and energy-efficiently measure the steady-state and transient characteristics of the tire.

关键词： Tire dynamics modeling Rapid test method Tire steady-state and transient characteristics Identificationof tire characteristics parameterg

Weak Solutions to the Cahn–Hilliard Equation with Degenerate Diffusion Mobility in R^N

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Acta Mathematica Sinica,English Series 2019年第10期35卷 1629-1654页

作者： Ji Hui WU lei lu College of Mathematics Physics and StatisticsShanghai University of Engineering ScienceShanghai 201620P.R.China College of Sciences Shanghai UniversityShanghai 200444P.R.China College of Mechanical Engineering Beijing University of TechnologyBeijing 100124P.R.China

This paper is concerned with a popular form of Cahn-Hilliard equation which plays an important role in understanding the evolution of phase separation. We get the existence and regularity of a weak solution to nonlinear parabolic, fourth order Cahn-Hilliard equation with degenerate mobility M(u)= u^m(1-u)^m which is allowed to vanish at 0 and 1. The existence and regularity of weak solutions to the degenerate Cahn-Hilliard equation are obtained by getting the limits of Cahn-Hilliard equation with non-degenerate mobility. We explore the initial value problem with compact support and obtain the local non-negative result. Further, the above derivation process is also suitable for the viscous Cahn–Hilliard equation with degenerate mobility.

关键词： Degenerate non-degenerate viscous convergence

Tensile Properties of Cu with Deformation Twins Induced by SMAT

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Journal of Materials Science & Technology 2006年第6期22卷 789-792页

作者： Jinyu GUO Ke WANG lei lu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

High density nano-scale deformation twins were introduced in the surface layer of Cu sample by means of surface mechanical attrition treatment （SMAT） at room temperature. The Cu sample with deformation twins shows a yield strength of about 470 MPa in tension tests. The significant strengthening may be attributed to the effective inhibition of slip dislocations by abundant twin boundaries.

关键词： Copper Surface mechanical attrition treatment (SMAT) Deformation twins Strengthening

Effect of work hardening discrepancy on strengthening of laminated Cu/CuZn alloys

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Journal of Materials Science & Technology 2022年第8期103卷 67-72页

作者： Zheng Cao Zhao Cheng Wei Xu lei lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

To clarify the work hardening discrepancy effect on the strengthening of laminated metals,we designed two laminated Cu/Cu4Zn and Cu/Cu32Zn samples with different layer ***/Cu4Zn has larger work hardening discrepancy between two constituent layers relative to Cu/Cu32Zn,but the yield strengths of two Cu Zn constituents are *** tensile results suggest Cu/Cu4Zn with larger work hardening discrepancy exhibits a significant strengthening at early deformation stage while Cu/Cu32Zn possesses a better *** underlying mechanisms for the strengthening effect are attributed to more geometrically necessary dislocations accumulated at interfaces and severer strain localization due to the larger work hardening discrepancy.

关键词： Laminated Cu/Cu alloys Work hardening Strengthening Interfacial affected zone Strain localization

Deformation and fracture mechanisms of nanotwinned metals

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National Science Review 2017年第4期4卷 519-521页

作者： Zesheng You lei lu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Herbert Gleiter Institute of Nanoscience Nanjing University of Science and Technology

Nanotwinned(NT)metal represents a unique hierarchical nanostructured material,with a large number of highly organized nanoscale twins embedded within micro-or submicro-sized *** boundaries(TBs)are effective barriers b... 详细信息

关键词： In TB Deformation and fracture mechanisms of nanotwinned metals

Improved time-optimal B-spline feedrate scheduling for NURBS tool paths in CNC machining

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Advances in Manufacturing 2023年第1期11卷 111-129页

作者： Yang Li Fu-Sheng Liang lei lu Cheng Fan School of Mechanic Engineering Northeast Electric Power UniversityJilin132012JilinPeople’s Republic of China Jiangsu Provincial Key Laboratory of Advanced Robotics and Collaborative Innovation Center of Suzhou Nano Science and Technology College of Mechanical and Electrical EngineeringSoochow UniversitySuzhou215021JiangsuPeople’s Republic of China

Feedrate scheduling in computer numerical control(CNC)machining is of great importance to fully develop the capabilities of machine tools while maintaining the motion stability of each *** and time-optimal feedrate scheduling plays a critical role in improving the machining efficiency and precision of complex surfaces considering the irregular curvature characteristics of tool paths and the limited drive capacities of machine *** study develops a general feedrate scheduling method for non-uniform rational B-splines(NURBS)tool paths in CNC machining aiming at minimizing the total machining time without sacrificing the smoothness of feed *** feedrate profile is represented by a B-spline curve to flexibly adapt to the frequent acceleration and deceleration requirements of machining along complex tool *** time-optimal B-spline feedrate is produced by continuously increasing the control points sequentially from zero positions in the bidirectional scanning and sampling *** required number of knots for the time-optimal B-spline feedrate can be determined using a progressive knot insertion *** improve the computational efficiency,the B-spline feedrate profile is divided into a series of independent segments and the computation in each segment can be performed *** proposed feedrate scheduling method is capable of dealing with not only the geometry constraints but also high-order drive constraints for any complex tool path with little computational *** and machining experiments are conducted to verify the effectiveness and superiorities of the proposed method.

关键词： B-spline feedrate Non-uniform rational B-splines(NURBS)tool path Knot insertion Bidirectional scanning Computer numerical control(CNC)machining