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Journal of Wuhan University of Technology(Materials Science) 2008年第5期23卷 625-631页

作者： ZHANG Yunqing GUO Zhiying DONG Xianghuai li dequn National Die and Mold CAD Engineering Research Center Shanghai Jiaotong UniversityShanghai 200030China

Tensile properties of automotive needlepunched carpets made up of two layers of different materials （a fabric layer and a foam layer） in their thermoforming temperatures ranges with or without heat dispersion were discussed. Effects of forming temperature, extensile speed and fiber orientation on the tensile properties were studied based on an orthogonal experiment design. The experimental results show that automotive carpets are rate-dependent anisotropic materials and more strongly depend on forming temperature than the extensile speed and fiber orientation. Furthermore, contributions of the fabric layer and the foam layer to the overall tensile performance were investigated by comparing the tensile results of single fabric layer with those of the overall carpet. Both the fabric layer and the foam layer show positive effects on the overall tensile strength which is the combination of the two layers＇ tensile strength and independent of temperature, extensile speed and fiber orientation On the other hand, their influences on the overall deformation are relatively complicated.

关键词： automotive needlepunched carpet mechanical behavior formability

Intelligent methods for the process parameter determination of plastic injection molding

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Frontiers of Mechanical Engineering 2018年第1期13卷 85-95页

作者： Huang GAO Yun ZHANG Xundao ZHOU dequn li State Key Laboratory of Material Processing and Die & MouldTechnology Huazhong University of Science and Technology Wuhan430074 China

Injection molding is one of the most widely used material processing methods in producing plastic products with complex geometries and high precision. The determination of process parameters is important in obtaining qualified products and maintaining product quality. This article reviews the recent studies and developments of the intelligent methods applied in the process parameter determination of injection molding. These intelligent methods are classified into three categories： Case-based reasoning methods, expert sys- tem-based methods, and data fitting and optimization methods. A framework of process parameter determination is proposed after comprehensive discussions. Finally, the conclusions and future research topics are discussed.

关键词： injection molding intelligent methods,process parameters optimization

Three-dimensional numerical simulation for plastic injection-compression molding

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Frontiers of Mechanical Engineering 2018年第1期13卷 74-84页

作者： Yun ZHANG Wenjie YU Junjie liANG Jianlin LANG dequn li State Key Laboratory of Material Processing and Die & MoldTechnology Huazhong University of Science and Technology Wuhan430074 China Beijing Institute of Aeronautical Materials Beijing 100095 China

Compared with conventional injection mold- ing, injection-compression molding can mold optical parts with higher precision and lower flow residual stress. However, the melt flow process in a closed cavity becomes more complex because of the moving cavity boundary during compression and the nonlinear problems caused by non-Newtonian polymer melt. In this study, a 3D simulation method was developed for injection-compres- sion molding. In this method, arbitrary Lagrangian- Eulerian was introduced to model the moving-boundary flow problem in the compression stage. The non-New- tonian characteristics and compressibility of the polymer melt were considered. The melt flow and pressure distribution in the cavity were investigated by using the proposed simulation method and compared with those of injection molding. Results reveal that the fountain flow effect becomes significant when the cavity thickness increases during compression. The back flow also plays an important role in the flow pattem and redistribution of cavity pressure. The discrepancy in pressures at different points along the flow path is complicated rather than monotonically decreased in injection molding.

关键词： injection-compression molding simulation,injection molding melt flow cavity pressure

Special issue： Near-net shaping technology

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Frontiers of Mechanical Engineering 2018年第1期13卷 1-2页

作者： dequn li Dongming GUO Qingxue HUANG Yanchun LOU State Key Laboratory of Material Processing and Die & Mold Technology Huazhong University of Science and Technology Wuhan 430074 China Key Laboratory for Precision & Non-traditional Machining of Ministry of Education Dalian University of Technology Dalian 116024 China Heavy Machinery Engineering Research Center of Education Ministry Taiyuan University of Science and Technology Taiyuan 030024 China Shenyang Research Institute of Foundry Shenyang 110022 China

Near-net shaping is an efficient, economical and environmentally-friendly approach to manufacture products which are very close to the final shape, reducing the need for surface finishing. It has become more and more important to use raw materials and energy in an optimal way. Near-net shaping technology has attracted increasing attention in both academic and industrial communities, especially in China, because China has become the world＇s largest regional market for main material forming methods, such as casting, forging and injection molding. The main objective of this special issue in Frontiers of Mechanical Engineering is to bring together the leading ideas, experience and research results of academic scientists and researchers on various aspects of near-net shaping technology. This special issue contains eleven papers contributed by prestigious experts from different countries, including four reviews and seven research articles. These papers cover a broad area of the near-net shaping technology,

关键词： Injection molding casting-forging Material forming raw material Forged Energy sources Casting Surface finish

STRESS ANALYSIS OF INJECTION MOLDED PARTS IN POST-FILliNG STAGE

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Chinese Journal of Mechanical Engineering 2000年第1期13卷 41-46页

作者： Jiang Tao Chen Xing li dequn (National Key ho of Plastic Simulation & Molding Technology Huazhong University of Science & Technology) 华中科技大学塑性成形模拟及模具技术国家重点实验室湖北武汉

The linear isothermo-viscoelastic constitutive equation is established according to the principle of viscoelastic mechanics. Given the boundary conditions of the temperature field, the linear thermo-viscoelastic constitutive equation is established acording to the analysis of the thermorheologically simple. The stress analysis model is constructed on the base of some reasonable hypotheses which consider the restraint conditions of mold and the characteristics of injection molding in the post-filling stage. The mathematical model is calculated by the finite difference method. The results can help to predict the warpage of plastic products.

关键词： Injection molding Stress analysis Thermo-viscoelastic Laplace transform

Modeling and simulation of heat transfer for glass bulb mold

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Progress in Natural Science:Materials International 2005年第7期15卷 650-655页

作者： ZHOU Huamin and li dequn (State Key Laboratory of Mold & Die Technology, Huazhong University of Science and Technology, Wuhan 430074, China) State Key Laboratory of Mold and Die Technology Huazhong University of Science and Technology Wuhan 430074 China

Cooling system design in glass bulb pressing operation can greatly affect the productivity and the quality of the final product. The concept of cyclic-averaged steady temperature field is proposed in modeling. Heat transfer in the mold region is considered to be a cyclic-steady, three-dimensional conduction; heat transfer within the glass melt region is treated as a transient, one-dimensional conduction; heat exchange between the cooling system surface and coolant is treated as a steady heat convection. A hybrid model consisting of a three-dimensional boundary element method for the mold region and a finite-difference method with a variable mesh for the melt region is used for numerical simulation. Compared with the experimental data, the numerical model developed here is computationally efficient and sufficiently accurate.

关键词： glass bulb mold numerical simulation boundary element method cyclic-averaged steady temperature field.

Modeling and simulation of residual stresses during glass bulb pressing process

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Science China(Technological Sciences) 2007年第1期50卷 103-117页

作者： ZHOU HuaMin, XI GuoDong & li dequn State Key Laboratory of Plastic Forming Simulation and Mold & Die Technology, Huazhong University of Science and Technology, Wuhan 430074 State Key Laboratory of Plastic Forming Simulation and Mold & Die Technology Huazhong University of Science and Technology Wuhan China

The residual stresses accumulated in the forming process have great effects on the product quality of the glass bulb. Based on the characteristics analysis of glass bulb forming, a mathematical model has been established for calculating residual stresses of glass pressing process. The material is assumed as thermorheologically simple thermoviscoelastic material, and the flow-induced stress is neglected. The consequences of equilibrium and compatibility equations are discussed in detail, and the boundary conditions are specified for various stages of the forming process. The numerical solution is based on the theory of thin layers, combined with finite difference method in the time and layer difference in the thickness direction. The presented model and solution method could easily be extended to general pressing process of glass, and applied to problems relative to glass pressing, providing extensive reference values. Keywords glass bulb - residual stresses - mathematical modeling - numerical simulation - theory of thin layers Supported by the National Natural Science Foundation of China (Grant No. 50205011), and the Program for New Century Excellent Talents in University (Grant No. NCET-04-0718)

关键词： glass bulb residual stresses mathematical modeling numerical simulation theory of thin layers

塑料注射成型工艺参数优化的模糊规则网络模型

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机械工程学报 2022年第20期58卷 206-220页

作者：郭飞汪汝健张云周华民李德群哈尔滨工业大学金属精密热加工国家级重点实验室哈尔滨150001 华中科技大学材料成形与模具技术国家重点实验室武汉430074

注射成型是塑料产品成型的最主要工艺,工艺参数是影响成型产品外观、尺寸与性能的关键因素之一。工艺参数的设置与优化属于弱理论、强经验的问题,迫切需要发展科学化、系统化的方法。针对产品缺陷修正中人工经验依赖性强的问题,构建知... 详细信息

注射成型是塑料产品成型的最主要工艺,工艺参数是影响成型产品外观、尺寸与性能的关键因素之一。工艺参数的设置与优化属于弱理论、强经验的问题,迫切需要发展科学化、系统化的方法。针对产品缺陷修正中人工经验依赖性强的问题,构建知识的统一模糊化规则形式,建立工艺优化知识表示和推理于一体的Takagi-Sugeno-Kang(TSK)模糊规则网络模型。进一步,提出从工艺数据集自动发现工艺参数优化规则的学习方法,采用Dropout策略与Bagging集成学习策略缓解高维工艺数据下工艺知识库增长出现的规则数量爆炸等问题。分析了模糊规则网络参数、结构对知识表示和推理的影响,建立模型的参数学习与结构优化的双重进化方法。提出基于经验回放的工艺数据增量学习方法,建立数据的增量学习策略。在注射成型工艺数据集上的结果表明,模型的规则数量和长度降低了50%,具有高可解释性以及增量学习稳定性。

关键词：注射成型工艺参数优化模糊规则网络

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税收优惠公平竞争审查标准优化研究

学术论坛 2024年第3期47卷 56-65页

作者：郑德群中国人民大学法学院北京100872

根据什么标准治理税收优惠措施是我国建设全国统一大市场中的难题。税收优惠措施名目繁多,很难从立法层面对它们进行统一规范,合法标准对税收优惠措施治理并不具有普适性。由建立全国统一大市场和公平竞争环境目标所决定,税收优惠措施... 详细信息

根据什么标准治理税收优惠措施是我国建设全国统一大市场中的难题。税收优惠措施名目繁多,很难从立法层面对它们进行统一规范,合法标准对税收优惠措施治理并不具有普适性。由建立全国统一大市场和公平竞争环境目标所决定,税收优惠措施公平竞争审查应采取非歧视标准。鉴于比较是歧视界定的基本方法,对税收优惠措施进行歧视性审查必须有客观可比情形存在,客观可比情形应根据税式支出优惠措施的目的及其所属税制的性质或结构来进行确定,税式支出优惠措施所属税制是税收优惠措施赖以依存的基准税制,因此税收优惠公平竞争审查之非歧视标准涉及基准税制、税式支出优惠措施和客观可比情形三个要素。

关键词：税收优惠公平竞争审查合法标准非歧视标准

GLS/GGLS/SUPG在三维注射成形充填模拟中的应用

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化工学报 2010年第2期61卷 510-515页

作者：李阳严波赵朋李德群华中科技大学材料成形与模具技术国家重点实验室湖北武汉430074 上海交通大学塑性成形工程系上海200030

塑料注射成形充填模拟中,采用GLS(Galerkin/least-squares)法能实现速度、压力同次插值时稳定地求解速度场、压力场,在能量场方程的求解中采用GGLS(Galerkin gradient least-squares)/SUPG(streamline upwind/Petrov-Galerkin)法能得到稳定的温度场数值解,其中SUPG法抑制对流占优导致的数值震荡问题,GGLS法消除由于小扩散系数造成的虚假温度升高。由GLS法、GGLS/SUPG法建立的速度、压力、温度求解的稳定有限元计算格式,实现了对注射成形充填模拟。模拟结果表明,采用GGLS法,温度场模拟结果更加合理,由GGLS/SUPG法获得了充填过程中稳定、准确的温度场,并采用GLS法正确地模拟了熔体速度、压力及流动前沿。

关键词：注射成形 GLS GGLS SUPG 温度场