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STRUCTURE EVOLUTION OF polymer CHAINS FOR NECKING FORMATION IN HIGH-SPEED FIBER SPINNING PROCESS

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chinese Journal of polymer science 2006年第1期24卷 1-11页

作者： Hong Zheng Wei Yu Hong-bin Zhang and chi-xing zhou department of polymer materials science & engineering,shanghai Jiao Tong university,shanghai 200240,china department of polymer materials science & engineering Shanghai Jiao Tong University Shanghai 200240 China

Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions, The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.

关键词： Semi-crystalline polymer Crystallization High-speed Fiber Spinning Process Conformation Finite Element Method (FEM).

A RHEOLOGICAL MODEL FOR polymer MELTS WITH INTERNAL STRUCTURE IN FLOW FIELDS

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chinese Journal of polymer science 1999年第2期17卷 151-158页

作者： chi-xing zhou department of polymeric materials science and engineering, shanghai Jiao Tong university, shanghai 200240, china 上海交通大学高分子材料科学与工程系上海

Conceptually, an imagined conformation ellipsoid is supposed to represent the shape of a polymer chain for polymer melts in flow fields and to be equivalent to the volume element in a mathematical sense in continuum mechanics. A power law dependence of shear modulus of polymer melts on detC, referred to as envelope volume, is proposed. Based on those assumptions and the non-linear relation of shear modulus, a phenomenological viscoelastic model is derived. The model is tested in simple shear flow, simple elongational flow, oscillatory shear flow, and relaxation process after flow suddenly stopped. The results show that the model works well to predict the change of internal structure and viscoelastic performance of polymer melts in flow fields.

关键词： polymer melts rheological model polymer conformation flow fields

MORPHOLOGY OF MELT SPINNING SUPERSATURATED B2 NiAl

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Acta Metallurgica Sinica(English Letters) 1996年第2期9卷 89-93页

作者： SUN Baode CHE Xiaozhou LIN Dongliang zhou Yaohe(department of materials engineering,shanghai jiaotong university,shanghai 20030,china)(department of materials science,shanghai jiaotong university,shanghai 200030,china) shanghai jiaotong Univ Shanghai China

The morphology and structure of melt spinning Ni-33.6at% Al doped with B and RE were *** results show that the alloy consists of L10 martensitic grains and L12 Ni3Al at the grain boundaries when it contains no B and *** addition of 0.11-0.31wt% B can suppress the martensitic transformation and Ni3Al separation at the boundaries,and a supersaturated B2 single phase NiAl is *** addition of 0.05wt% RE can eliminate Ni3Al precipitated at the boundaries and get complete martensite,but 0.2-0.8wt% RE addition can suppress the martensitic transformation, and supersaturated B2 single phase NiAl is *** formation mechanism of supersaturated B2 single phase NiAl has been analyzed.

关键词： NiAl supersaturate morphologl melt spinning

SEM in-situ Fracture Observation and the Reinforcing Effect of Composite SiC_p/ZA22

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Journal of materials science & Technology 2001年第6期17卷 649-652页

作者： Jun WANG, Baode SUN and Yaohe zhou School of materials science and engineering, shanghai jiaotong university, shanghai 200030, china Lining ZHANG and Feng CHEN department of materials science and engineering, Southeast university, Dept. of Mat. Sci. and Eng. Southeast Univ. Nanjing 210096 China

The strengthening effect of a Zn alloy reinforced by SiC particulate was examined. Based on the results of SEM in-situ fracture observation and stress field analysis by finite element method, it is believed that the r... 详细信息

关键词： SiC SEM in-situ Fracture Observation and the Reinforcing Effect of Composite SiC_p/ZA22

Optimal motion planning of an underactuated spacecraft using wavelet approximate method

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Progress in Natural science:materials International 2006年第8期16卷 868-873页

作者： GE Xinsheng, CHEN Liqun and LIU Yanzhu (Beijing Institute of Machinery, Beijing 100085, china department of Mechanics, shanghai university, shanghai 200072, china department of engineering Mechanics, shanghai jiaotong university, shanghai 200030, china) Beijing Institute of Machinery Beijing 100085 China department of Mechanics Shanghai University Shanghai 200072 China department ofengineering Mechanics Shanghsi Jiaotong University Shanghsi 200030 China

An optimal motion planning scheme using wavelet approximation is proposed for an underactuated spacecraft. The motion planning of an underactuated spacecraft can be formulated as an optimal control of a drift-free system. A cost functional is used to incorporate the control energy and the final state errors. The motion planning is to determine control inputs to minimize the cost functional. Using the method of wavelet, one can transform an infinite-dimensional optimal control problem to a finite-dimensional one and use Gauss-Newton algorithm to solve it for a feasible trajectory which satisfies nonholonomic constraints. The proposed scheme has been applied to a rigid spacecraft with two momentum wheels. The numerical simulation results indicate that optimal control with wavelet approximation is an effective approach to steering an underactuated spacecraft system from the initial configuration to the final configuration.

关键词： underactuated spacecraft motion planning optimal control nonholonomic constraint wavelet analysis.

Amphiphilic dendronized homopolymers

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science china Chemistry 2010年第12期53卷 2509-2519页

作者： LI Wen 1 & ZHANG AFang 1,2 1 Institute of polymers,department of materials,ETH Zurich,Wolfgang-Pauli-Str.10,8093 Zurich,Switzerland 2 department of polymer materials,College of materials science and engineering,shanghai university,shanghai 201800,china Institute of polymers Department of Materials ETH Zurich Zurich Switzerland department of polymer materials College of Materials Science and Engineering Shanghai University Shanghai China

A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are *** polymers are constructed in each repeat unit with various generations of hydrophobic 4-aminoproline and hydrophilic oligoethylene glycol (OEG)-based dendrons,and their over-all hydrophilicity is tuned by varying these dendron *** with or without the first generation of proline dendron show good water solubility at room temperature,but exhibit typical thermoresponsive behaviors at elevated temperatures as characterized by turbidity measurements using UV-vis spectroscopy,while the polymer with the secondary generation of proline dendron is not soluble in *** polymers show ordered secondary structures as evidenced by the optical rotation and circular dichroism ***,assembly of these amphiphilic homopolymers into porous films via breath figure (BF) technique is described,and polymer structures are found to show significant influence on the morphology of porous film.

关键词： amphiphilic polymer dendronized polymer dendritic macromolecule supramolecular structure

Effect of Solute Drag and Precipitate Pinning on Austenite Grain Growth in Ti-Nb Microalloyed Steels

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Journal of Iron and Steel Research International 2011年第S1期18卷 383-387页

作者： FU Li-ming 1,WANG Huan-rong 2,WANG Wei 2,SHAN Ai-dang 1 (1.School of materials science and engineering,shanghai jiaotong university,shanghai 200240,china 2.department of Structural Steels,Baosteel Research Institute,shanghai 201900,china) shanghai Jiao Tong Univ Sch Mat Sci & Engn Shanghai 200240 Peoples R China Baosteel Res Inst Dept Struct Steels Shanghai 201900 Peoples R China

A metallurgical model concerning the co-effect of the Nb solute drag and the complex carbonitride precipitates pinning is proposed to predict the recrystallization austenite grain growth of low carbon Nb-containing microalloyed *** analysis,both predicted and experimental,reveals the precipitate pinning plays a dominate role in suppressing the austenite grain growth with less Nb solute drag effect in high temperature region whereas the Nb solute drag predominates in relatively low temperature region.A factor p is suggested to assess the effectiveness of drag and *** pinning and the drag are more effective in restraining grain growth as p>0 and p<0,respectively.A low carbon Nb microalloyed steel and a kind of Ti-modified low carbon Nb steel by Ti substituting for part of Nb are employed to validate the modeling *** theoretical calculations show a good agreement with experimental results.

关键词： grain growth precipitates pinning solute drag Ti-Nb microalloyed steels

PHASE TRANSFORMATION UNIT OF BAINITIC FERRITE AND ITS SURFACE RELIEF IN LOW AND MEDIUM CARBON ALLOY STEELS

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Acta Metallurgica Sinica(English Letters) 1989年第3期2卷 161-167页

作者： YU Degang CHEN Dajun ZHENG Jinghong HE Yirong SHEN Fufa shanghai jiaotong university,shanghai,china Professor,department of materials science and engineering,shanghai jiaotong university,1954 Huashan Road,shanghai 200030,china

The lath-or plate-shaped bainitic ferrite of low and medium carbon alloy steels consists of packets of ferrite sublaths which are composed of many finer and regular ferrite *** are uniform shear growth units of bainitic phase *** carbide is precipitated from *** bainitic O-carbides are precipitated from γ-α interface or carbon-rich *** mode of arrangement of the units in ferrite sublath packet is in uni-or bi-di- *** surface relief is produced by the accumulation of uniform shear strains with all the ferrite units arranged unidirectionally in a sublath packet,while tent-shaped surface relief is formed by the integration of the uniform shear strains of two groups with ferrite units piling up in two directions and growing face to face;whereas if they grow back to back,the integra- tion will be responsible for invert-tent-shaped surface *** interface trace between two groups of ferrite units in a sublath packet is shown as“midrib”.

关键词： low and medium carbon alloy steels bainite ferrite phase transformation unit surface relief

Modeling Study of the Particle Pinning Effect on the Grain Boundary Movement

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Journal of Iron and Steel Research International 2011年第S1期18卷 342-345页

作者： WANG Xue-lun 1,FU Li-ming 2,WANG Wei 3,JIA Zhi-xin 1 (1.Rizhaosteel Technology Center,Rizhao Iron and Steel Co Ltd.Rizhao 276806,china 2.School of materials science and engineering,shanghai jiaotong university,shanghai 200240 china 3 department of Structural Steels,Baosteel Research Institute,shanghai 201900,china) Rizhao Iron & Steel Co Ltd Rizhaosteel Technol Ctr Rizhao 276806 Peoples R China shanghai Jiao Tong Univ Sch Mat Sci & Engn Shanghai 200240 Peoples R China Baosteel Res Inst Dept Struct Steels Shanghai 201900 Peoples R China

In this work,based on the classical grain boundary (GB) formula and the principle of work-energy conversion,a new physically-based model has been developed to predict the particle pinning force concerning the interaction between second phase particles (SPPs) and the moving *** effect of particles pinning on the GB movement is *** modeling results can be applied to quantitatively determine the critical numbers of SPPs required for complete pining the grain growth,such as the critical SPPs number of the unit GB area,the critical number for single grain stagnation,the critical volume fraction of particles at a given particle *** predictions are in good agreement with the experimental results by Gladman.

关键词： the second-phase particle pinning force physical-based model