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Novel Mobility Formula for Parallel Mechanisms Expressed with Mobility of General Link Group

Chinese Journal of Mechanical Engineering 2013年第6期26卷 1082-1090页

作者： ZHANG Yitong LU Wenjuan MU Dejun YANG Yandong ZHANG Lijie ZENG Daxing Key Laboratory of Parallel Robot and Mechatronic System Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University

The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new formulae have been presented, however these formulae can hardly intuitively reflect general link group＇s restrictions on output member and its influences on independence of output parameters, which is premise to the judgment of the properties of mobility. Towards the problem to reveal the intrinsic relationship between the degree of freedom（DOF） of a mechanism, the link group, and the dimension of output parameters, also to avoid determination of virtual constraint, based on the new concepts of the ＂DOF of general link group＂ and ＂node parameters＂, a new formula in the calculation of the mobility of mechanisms is presented that is expressed with DOFs of the general link groups and rank of motion parameters of base point of the output link. It is named GOM（mobility of groups and output parameter） formula. On the basis of new concepts of＂effective parameters＂ and ＂invalid parameters＂, a rule is put forward for solving the DOF of mechanisms with invalid parameters by GOM formula, that is, the base point parameters are the subset of effective parameters of link group. Thereafter, several examples are enumerated and the results coincide with the prototype data, which proves the validity of the proposed formula. Meanwhile, it is obtained that the necessary and sufficient condition for the judgment of output parameters independence is that each of the DOF of the link group is not less than zero. The proposed formula which is simple in calculation provides theoretical basis for the judgment of independence of output parameters and provides references for type synthesis of novel parallel mechanisms with independence requirements of their output parameters.

关键词： parallel mechanism degree of freedom general link group output parameters

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Concurrently bioprinted scaffolds with autologous bone and allogeneic BMSCs promote bone regeneration through native BMSC recruitment

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Bio-Design and Manufacturing 2025年第1期8卷 85-99,I0042,I0043页

作者： Yu Huan Hongqing Chen Dezhi Zhou Xin He Sanzhong Li Xiuquan Wu Bo Jia Yanan Dou Xiaowei Fei Shuang Wu Zhou Fei Tao Xu Fei Fei Department of Neurosurgery Xijing HospitalAir Force Medical UniversityXi’an 710032China Department of Neurosurgery General Hospital of Northern Theater CommandShenyang 110840China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationDepartment of Mechanical EngineeringTsinghua UniversityBeijing 100084China Department of Precision Medicine and Healthcare Tsinghua Berkeley Shenzhen InstituteShenzhen 518055China Center for Bio-intelligent Manufacturing and Living Matter Bioprinting Research Institute of Tsinghua University in ShenzhenShenzhen 518057China Department of Ophthalmology Xijing HospitalAir Force Medical UniversityXi’an 710032China

Autologous bone marrow-derived mesenchymal stem cells(BMSCs)have been shown to promote osteogenesis;however,the effects of allogeneic BMSCs(allo-BMSCs)on bone regeneration remain ***,we explored the bone regeneration promotion effect of allo-BMSCs in 3D-printed autologous bone particle(ABP)***,we concurrently printed scaffolds with polycaprolactone,ABPs,and allo-BMSCs for appropriate support,providing bioactive factors and seed cells to promote *** vitro studies showed that ABP scaffolds promoted allo-BMSC osteogenic *** vivo studies revealed that the implantation of scaffolds loaded with ABPs and allo-BMSCs into canine skull defects for nine months promoted *** experiments suggested that only a small portion of implanted allo-BMSCs survived and differentiated into vascular endothelial cells,chondrocytes,and *** implanted allo-BMSCs released stromal cell-derived factor 1 through paracrine signaling to recruit native BMSCs into the defect,promoting bone *** study contributes to our understanding of allo-BMSCs,providing information relevant to their future application.

关键词： Concurrent 3D bioprinting Cranioplasty Autologous bone particles Allogeneic mesenchymal stem cells Recruitment

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On the strain and strain-rate hardenability of additively manufactured austenitic stainless steels

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Materials Science and Engineering: A 2025年 939卷

作者： Kong, Decheng Xu, Xuexu Ni, Xiaoqing Zhu, Guoliang Dong, Chaofang Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and Technology University of Science and Technology Beijing Beijing100083 China Research and Application Center of Additive Manufacturing Materials Shanghai Research Institute of Materials Co. Ltd. Shanghai200437 China

Dislocation cells (DCs) are peculiar substructures frequently observed in plastically deformed (PD) and additively manufactured (AM) metals and alloys, and the latter typically exhibit visible elemental segregation along the DC boundaries. This work comparatively analyzes the DC effects on the strain-hardening and strain-rate hardening capabilities of PD and AM austenitic stainless steels (ASSs). The findings suggest that the presence of Cr/Mo-decorated DCs contributes to superior yield strength and admirable mechanical stability for AM ASSs. However, the high critical stress required for deformation twinning leads to a decreased twinning ability, resulting in lower strain hardening capability for AM ASSs compared to PD counterparts. Additionally, micron-sized DCs significantly enhance the strain-rate hardening capability of the AM parts by reducing the dislocation-free path. The inherent DC substructure of these AM materials demonstrates promising energy-absorption performance under extreme-speed deformation conditions, particularly combined with intricate structural design advantages. © 2025 Elsevier B.V.

关键词： Austenitic stainless steel

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Determination of Elastoplastic Mechanical Properties of the Weld and Heat Affected Zone Metals in Tailor-Welded Blanks by Nanoindentation Test

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 911-918页

作者： MA Xiangdong GUAN Yingping YANG Liu Key Laboratory of Advanced Forming & Stamping Technology and Science of Ministry of Education Yanshan University

The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

关键词： tailor-welded blanks elastoplastic mechanical properties nanoindentation test Erichsen cupping test

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Static Recrystallization Behavior of 316LN Austenitic Stainless Steel

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Journal of Iron and Steel Research International 2013年第11期20卷 67-72页

作者： JIN Miao LU Bo LIU Xin-gang GUO Huan JI Hai-peng GUO Bao-feng Key Laboratory of Advanced Forging and Stamping Technology and Science of Ministry of Education Yanshan University

The static recrystallization of 316LN austenitic stainless steel was studied by double-pass hot compression tests on a Gleeble 3500 thermomechanical simulator. The specimens were compressed at the deformation tempera- tures of 950, 1050, 1150 ℃, strain rates of 0.01, 0.1, 1 s^- 1, strains of 0.1, 0.15, 0.2, and intervals of 1-100 s. The results show that the volume fraction of static recrystallization of 316LN increases with the increase of deforma- tion temperature, strain rate, strain and interval, which indicates that static recrystallization occurs easily under the conditions of higher deformation temperature, higher strain rate and larger strain. Deformation temperature has sig- nificant influence on static recrystallization of 316LN. The volume fraction of static recrystallization could easily reach 1000% at higher deformation temperatures. By microstructure analysis, it can be concluded that the larger the volume fraction of static recrystallization, the more obvious the grain refinement. The static recrystallization activation energy of 317 882 J/mol and the exponent n of 0.46 were obtained. The static recrystallization kinetics was established. The predicted volume fraction of static recrystallization is in good agreement with the experimental results.

关键词： static recrystallization austenitic stainless steel hot deformation

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An Iterative Compensation Algorithm for Springback Control in Plane Deformation and Its Application

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 212-223页

作者： Rui Ma Chunge Wang Ruixue Zhai Jun Zhao Key Laboratory of Advanced Forging & Stamping Technology and ScienceMinistry of Education of China Yanshan University College of Mechanical Engineering Yanshan University College of Mechanical and Energy Engineering Ningbo Institute of Technology Zhejiang University Key Laboratory of Roll Forming Technology Research

In order to solve the springback problem in sheet metal forming, the trial and error method is a widely used method in the factory, which is time-consuming and costly for its non-direction and non-quantitative. Finite element simulation is an e ective method to predict the springback of complex shape parts, but its precision is sensitive to the simulation model, particularly material model and boundary conditions. In this paper, the simple iterative method is introduced to establish the iterative compensation algorithm, and the convergence criterion of iterative parameters is put forward. In addition, the new algorithm is applied to the V-free bending and stretch-bending processes, and the convergence of curvature and bending angle is proved theoretically and verified experimentally. At the same time,the iterative compensation experiments for plane bending show that, the new method can predict the next compensaantido tnh ev atlaureg ebta cseurdv oatnu trhe ew sitphri tnhgeb earcrko ro fo fe laecshs ttehsat,n s0 o. 5 th%a ta rteh eo btatraigneet db aefntedri n2 g-3 a nitgelrea tiwoitnhs.t Thhei se rrreosre aorf clhe sps rtohpaons e±s 0 a.1%new iterative compensation algorithm to predict springback in sheet metal forming process, where each compensation value depends only on the iteration parameter di erence before and after springback for the same forming process of same material.

关键词： Springback control Iterative compensation algorithm Convergence criterion V-free bending Stretchbending

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Calibration of discrete element parameters and FEM-DEM coupling analysis for solid granules medium deep drawing forming

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Powder technology 2025年 463卷

作者： Haiwei Shi Changcai Zhao Bing Du Guoyi Shen Hengkai Ren Key Laboratory of Advanced Forging & Stamping Technology and Science (YanShan University) Ministry of Education of China Qinhuangdao 066004 China

To analyze the internal interactions of solid granules medium (SGM) and their interactions with sheet metal during the SGM deep drawing forming process, the discrete element method (DEM) is used for the SGM, and the finite element method (FEM) is employed for the sheet metal. A new FEM-DEM coupling method is developed based on the force conservation principle. To address the issues of circularity and deformation under high pressure present in the SGM, the rolling resistance linear (RRL) model is applied. A high-precision inversion method utilizing the back propagation neural network-particle swarm optimization (BP-PSO) algorithm is proposed to enhance the efficiency of DEM parameter calibration. The SGM deep drawing forming process is conducted and compared with the simulation results of the FEM-DEM coupling model, which confirms the accuracy of the coupling model. This model analyzes force transmission and flow of the granules, efficiently visualizing interactions during the forming process.

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Heat shock behavior of permanent die during non-solid near-net forming process

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中国有色金属学会会刊：英文版 2009年第S3期19卷 795-801页

作者：张密兰单忠德邢书明姜超许应 State Key Laboratory of Advanced Forming Technologyand Equipment Advanced Manufacture Technology CenterChina Academy of Machinery Science and Technology School of Mechanical and Engineering University of Science and Technology Beijing State Key Laboratory of Advanced Forming Technology and Equipment Advanced Manufacture Technology CenterChina Academy of Machinery Science and Technology School of Mechanical Electronic and Control EngineeringBeijing Jiaotong University State Key Laboratory of Advanced Forming Technology and Equipment Advanced Manufacture Technology CenterChina Academy of Machinery Scienceand Technology

Heat shocks caused by alloy melt and coat spraying are the main reason of die plastic deformation and early fracture. Based on theoretical analysis of heat shock phenomenon, two characteristic parameters of die damage caused by heat shock were proposed, which are heat shock plastic deformation index (HSPI) and heat shock crack index (HSCI). The effect of heat shock on die plastic deformation and fracture behaviors was described quantitatively by these two parameters. HSPI represents approaching of heat shock stress to die yield stress. Plastic deformation will happen on a die if this index reaches 1. HSCI represents approaching of heat shock stress to die tensile strength. Die fracture will happen if this index reaches 1. According to theoretical analysis of heat transfer, theoretical models of HSPI and HSCI were established. It is found that, the smaller the interfacial thermal resistance (ITR) is, the higher the pouring temperature and die temperature are before heat shock, and the greater the HSPI and HSCI are, which can be fitted as exponential curves, linear and cubic curves.

关键词： non-solid near-net forming die heat shock heat shock plastic deformation index heat shock crack index

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Effects of combined rolling process on microstructure and wear resistance of 301 stainless steel strips

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Tribology International 2025年 210卷

作者： Lian, Junjie Zhao, Weidong Ma, Linan Liao, Xi Jiang, Zhengyi Zhao, Jingwei College of Mechanical Engineering Taiyuan University of Technology Taiyuan030024 China Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment Ministry of Education Taiyuan030024 China National Key Laboratory of Metal Forming Technology and Heavy Equipment Ministry of Science and Technology Taiyuan030024 China School of Mechanical Engineering Taiyuan University of Science and Technology Taiyuan030024 China Shanxi Taigang Stainless Steel Precision Strip Co. Ltd Taiyuan030006 China School of Mechanical Materials Biomedical and Mechatronic Engineering University of Wollongong NSW2522 Australia

In this paper, a combined rolling process (CRP) with pre-textured and flat rolls was used to improve the wear resistance of 301 stainless steel (SS) thin strips. The findings indicate that the wear resistance of the SS strip after CRP is significantly enhanced by constructing surface textures, inducing grain refinement, work hardening and the generation of compressive residual stress. The lowest wear rate is obtained after 10 passes of pre-textured rolling, which is 58.28 % lower than that of the as-received material. However, when the cumulative rolling deformation exceeds a certain degree, the wear damage of the SS thin strip is accelerated by forming microcracks and surface defects. © 2025

关键词： Strain hardening

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Modeling and simulation of 3D topographies of slot milled walls and floor surface considering slot bi-sided wall constraints

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Journal of Manufacturing Processes 2025年 149卷 241-257页

作者： Wenjun Lyu Zhanqiang Liu Bing Wang Yukui Cai Xiaoliang Liang Liangliang Li School of Mechanical Engineering Shandong University Jinan 250061 PR China State Key Laboratory for High-end Equipment and Advanced Technology of Metal Forming Shandong University Jinan 250061 PR China Key Laboratory of High-efficiency and Clean Mechanical Manufacture of Ministry of Education Jinan 250061 PR China Key National Demonstration Center for Experimental Mechanical Engineering Education Jinan 250061 PR China School of Mechanical Electrical & Information Engineering Shandong University Weihai 264209 PR China Shenyang Aircraft Corporation Shenyang 110850 PR China

The deflection of long-cantilever length milling cutter significantly influences both surface morphology and dimensional precision during milling operations. Three surfaces are formed concurrently, including two walls and one floor surface in the one-pass slot milling operation. The cutting tool-edges concurrently make contacts with the floor surface and bi-sided walls of the slot. The bi-sided walls of the slot impose complex contact constraints on the cutting tool-edges, and the loaded force situation of the milling cutter is complex. The application of cantilever beam theory for calculating cutter deflection in planar milling is no longer applicable to one-pass slot milling. This study proposes a novel predictive framework for surface morphology in one-pass slot milling operations, incorporating time-dependent tool deflection. Firstly, the contact and force between cutting tool-edges and slot bi-sided walls and floor surface were analyzed. Secondly, the milling tool deflection models were proposed accounting for varying contact conditions of the cutting tool-edges with the slot bi-sided walls. The universal methodology for calculating tool deflection, applicable to various milling tool deflection models, has been developed. Then, the time-dependent milling force during one-pass slot milling was derived by considering time-dependent tool deflection. Numerical calculations were performed on the instantaneous cutter deflection. Finally, the bi-sided walls and floor surface topographies of slot milling were simulated and reconstructed by accounting for milling parameters, tool installation errors, random wear errors of milling tool, time-dependent milling forces and tool deflection. This framework can be embedded as a functional module in smart machining centers, enabling prediction and control of surface characteristics and dimensional accuracy.

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