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Effect of rotationally accelerated shot peening on the microstructure and mechanical behavior of a metastableβtitanium alloy

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Journal of Materials science & technology 2021年第16期75卷 27-38页

作者： Xinkai Ma Zhuo Chen Dongling Zhong SNLuo Lei Xiao Wenjie Lu Shanglin Zhang Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China National Key Laboratory of Reactor System Design Technology Nuclear Power Institute of ChinaChengdu 610041China

Microstructural evolution and deformation mechanism of a metastableβalloy(Ti-10 V-2 Fe-3 Al)processed by rotationally accelerated shot peening(RASP)were systematically investigated with optical microscopy,X-ray diffraction,electron backscatter diffraction and transmission electron *** gradient hierarchical microstructures(gradients inα″martensite andβphase,and hierarchical twins range from the nanoscale to microscale)can be fabricated by RASP via changing the shot peening *** hardening behavior and tensile mechanical properties of gradient hierarchical microstructure were systematically *** deformation twinning systems of{112}α″and{130}<310>α″in the kinkedα″martensite were revealed during the tensile *** was found that stress-induced martensitic transformation,twinnedα″martensite and the related dynamic grain refinement contribute to hardness and work hardening *** improvement of strength and ductility of the metastableα″titanium alloy can be achieved by introducing a gradient hierarchical microstructure.

关键词： Titanium alloys Gradient hierarchical microstructure α″martensite Rotationally accelerated shot peening Mechanical behavior

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Enhancing Mechanical Properties and Microstructure Evolution of Hybrid Az61-5sic-0.5cnts Composite During Equal Channel Angular Pressing

SSRN

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SSRN 2024年

作者： Zhou, Mingyang Zhao, Yanli Sun, Dan Long, Ziyao Gen, Laiyao Fan, Lingling Gao, Shixin Xin, Yong Quan, Gaofeng Gupta, Manoj Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China School of Mechanical Engineering Chengdu University Chengdu Sichuan610106 China School of Materials Science and Engineering Southwest Jiaotong University Chengdu610031 China 9 Engineering Drive 1 Singapore117576 Singapore

Equal channel angular pressing (ECAP) is one of widely used severe plastic deformation methods for improving performance of metallic materials. In this work, the effects of the ECAP on the microstructural evolution and mechanical properties of the AZ61-5SiC-0.5CNTs composite were studied systematically. The results revealed that ECAP can effectively reduce the porosity of the AZ61-5SiC-0.5CNTs composite, refine grains, weaken basal texture, and promote the further dispersion of CNTs, which can optimize the microstructure of the composite. However, the large shear effect of ECAP also leads to the destruction of the structural integrity of the CNTs and thus reduces the strengthening effect. Due to the combined effects of grain refinement, porosity changes, texture evolution, and structural damage of CNTs, the composites reached the highest strength after 2 ECAP passes at 250 °C. The yield and tensile strengths were increased to 383 MPa (+11.0%) and 445 MPa (+8.0%), respectively, while the elongation was marginally reduced, but remained around 6%. © 2024, The Authors. All rights reserved.

关键词： Equal channel angular pressing

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Evolution of Heuristics: Towards Efficient Automatic Algorithm design Using Large Language Model

arXiv

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arXiv 2024年

作者： Liu, Fei Tong, Xialiang Yuan, Mingxuan Lin, Xi Luo, Fu Wang, Zhenkun Lu, Zhichao Zhang, Qingfu Department of Computer Science City University of Hong Kong Hong Kong Huawei Noah’s Ark Lab China School of System Design and Intelligent Manufacturing Southern University of Science and Technology China

Heuristics are widely used for dealing with complex search and optimization problems. However, manual design of heuristics can be often very labour extensive and requires rich working experience and knowledge. This paper proposes Evolution of Heuristic (EoH), a novel evolutionary paradigm that leverages both Large Language Models (LLMs) and Evolutionary Computation (EC) methods for Automatic Heuristic design (AHD). EoH represents the ideas of heuristics in natural language, termed thoughts. They are then translated into executable codes by LLMs. The evolution of both thoughts and codes in an evolutionary search framework makes it very effective and efficient for generating high-performance heuristics. Experiments on three widely studied combinatorial optimization benchmark problems demonstrate that EoH outperforms commonly used handcrafted heuristics and other recent AHD methods including FunSearch. Particularly, the heuristic produced by EoH with a low computational budget (in terms of the number of queries to LLMs) significantly outperforms widely-used human hand-crafted baseline algorithms for the online bin packing problem. Copyright © 2024, The Authors. All rights reserved.

关键词： Combinatorial optimization

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Study on flow modes of open natural circulation with low height difference under low power conditions

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International Journal of Advanced Nuclear reactor design and technology 2020年 2卷 10-14页

作者： Yi, Li Jianchuang, Sun Hang, Peng Cheng, Xiang Quan, Biao Cao, Xiaxin Jian, Zhou Ming, Ding Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin150001 China

Open natural circulation systems are widely applied in the field of energy and chemical industries. Under some special conditions, open natural circulation systems with low height difference need to be applied, but research on this type of systems is not sufficient. In this paper, the flow modes of sucha natural circulation system were experimentally studied at low power level by adopting steam heating. In addition, the flow modes and physical phenomena of the natural circulation system were analyzed in detail under different heating power conditions. It is found that there are four flow modes at different power levels in the natural circulation system due to the influence of non-condensable gas and subcooled boiling. The inlet and outlet temperatures of heating section are analyzed in different flow modes. The result shows that the outlet temperature of heating section can be used as a judgment criterion for different flow modes. © 2019

关键词： Chemical industry

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STUDY ON AUTOMATIC DEPRESSURIZATON system OF SMR

STUDY ON AUTOMATIC DEPRESSURIZATON SYSTEM OF SMR

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2020 International Topical Meeting on Advances in Thermal Hydraulics, ATH 2020

作者： Yin, Shasha Sun, Yan Li, Yi Yang, Hongfa Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu China

ISBN: (纸本)9780894487774

Small modular reactor (SMR) is highly cared and researched by people all over the world. There are many differences during reactor operating between the small modular reactor and the traditional large-scale pressurized water reactor, because of the differences in structure and design issues for both reactors. This means that more and better research especially on SMR will be needed. The continued improvements in designing conception of SMR, the research of SMR get to be more in depth and detail. Passive safety system is commonly accepted in the present study, and developed into an indispensable system for the advance nuclear reactor. However, automatic depressurization system (ADS) as an important part of a passive safety system also is a unique system compared with conventional PWR. So ADS system is worthy of comprehensive and in-depth study. In this paper, the severe accident analysis model was established based on the design characteristics of the small modular nuclear. Then, the severe accident process, the thermalhydraulic phenomena and the system safety were researched. Then, based on the results of the severe accident process for SMR, analyze the depressurization capability of ADS system during a station blackout initiated severe accident in SMR, and analysis the effect on accident process. Finally, this paper proposed the optimization and improvement of the automatic depressurization system (ADS). The results of this study are the necessary foundations for the development of small modular reactor severe accident prevention and mitigation measures. © ATH 2020 - International Topical Meeting on Advances in Thermal *** rights reserved.

关键词： Pressurized water reactors

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Study on Uniaxial Tension and Cyclic Deformation Behavior of TA16 at Room Temperature and High Temperature

Study on Uniaxial Tension and Cyclic Deformation Behavior of...

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作者： Shao, Xuejiao Juan, Du kuang, Linyuan Lu, Yuechuan Lu, Jiang Yu, Mingda Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

TA16 is a new type of titanium alloy material, which is widely used in pipeline systems of aerospace, ship and nuclear reactor with high temperature and high pressure. In this paper, the basic mechanical properties and cyclic deformation characteristics of TA16 were obtained by uniaxial tensile test and cyclic loading test at room temperature and high temperature. The Chaboche constitutive model can reasonably describe the cyclic plastic cumulative effect of materials and is provided in ANSYS which is a commercial finite element analysis software. The constitutive model of Chaboche presents a very important evolution criterion of follow-up hardening for ratchet simulation. Based on steady cyclic stress-strain curves which is got by strain control at different temperatures, the material parameters of Chaboche model are obtained by least multiplication fitting for TA16 at room and high temperatures. The constitutive model can used in elastic and elastic finite element analysis of TA16 materials. The experiment results show that TA16 exhibits slight cyclic softening under symmetrical strain cycles, and obvious ratcheting behavior under asymmetric stress cycles. When ratcheting strain of the structure reaches a certain saturation state, plastic accumulation will lead to accidental damage of the structure and lead to serious consequences. The stable cyclic stress-strain curves of TA16 at room temperature and high temperature are simulated by Chaboche model. The simulation results are in good agreement with the experimental results, which provides the basic data for the finite element simulation of cyclic deformation behavior of TA16 titanium alloy structure. © Springer Nature Switzerland AG 2020.

关键词： Constitutive models

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A simplified two-node coarse-mesh finite difference method for pin-wise calculation with SP3

A simplified two-node coarse-mesh finite difference method f...

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2020 International Conference on Physics of reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020

作者： Zhao, Wenbo Yu, Yingrui Chai, Xiaoming Ning, Zhonghao Zhang, Bin Cai, Yun Liu, Kun Peng, Xingjie Yu, Junchong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

ISBN: (纸本)9781713827245

For accurate and efficient pin-by-pin core calculation of SP3 equations, a simplified two-node Coarse Mesh Finite Difference (CMFD) method with the nonlinear iterative strategy is proposed. In this study, the two-node method is only used for discretization of Laplace operator of the 0th moment in the first equation, while the fine mesh finite difference (FMFD) is used for the 2nd moment flux and the second equation. In the two-node problem, transverse flux is expanded to second-order Legendre polynomials. In addition, the associated transverse leakage is approximated with flat distribution. Then the current coupling coefficients are updated in nonlinear iterations. The generalized eigenvalue problem from CMFD is solved using Jacobi-Davidson method. A protype code CORCA-PIN is developed. FMFD scheme is implemented in CORCA-PIN as well. The 2D KAIST 3A benchmark problem and extended 3D problem, which are cell homogenized problems with strong absorber, are tested. Numerical results show that the solution of the simplified two-node method with 1×1 mesh per cell has comparable accuracy of FMFD with 4×4 meshes per cell, but cost less time. The method is suitable for whole core pin-wise calculation. © The Authors, published by EDP sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://***/licenses/by/4.0/).

关键词： Nonlinear equations

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Structure topology optimization design and shock resistance study on nuclear power safety DCS cast aluminum cabinet

Structure topology optimization design and shock resistance ...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Dongwei, Wang Mingxing, Liu Xiao, Wu Hao, Yan Zhiqiang, Wu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

ISBN: (纸本)9780791883761

Offshore floating nuclear power plant (FNPP) is characterized by its small and mobility, which is not only able to provide safe and efficient electric energy to remote islands, but to the oil and gas platforms. The safety digital control system (DCS) cabinet, as a carrier for the electronic devices, plays a significant role in ensuring the normal operation of the nuclear power plant. To satisfy the requirements of cabinet used in the sea environment, such as well rigidity, shock load resistance, good seal and corrosion resistance, etc, more and more attention is focused on the cast aluminum cabinet. However, the cast aluminum structure may cause larger weight of cabinet, which inevitability affects the mobility of cabinet, and increases the carried load of ship as well. Therefore, seeking for an effective approach to design a light weight cast aluminum cabinet for the offshore FNPP is definitely necessary. In this work, a frame of cast aluminum cabinet with lightweight is obtained successfully via structure topology optimization design, it is found that the weight of the frame can be reduced to 50% after optimization iterations. Subsequently, the natural frequency of the optimized cast aluminum cabinet is calculated by using ABAQUS, it is seen that the first mode frequency of the frame is beyond 30 Hz, which can meet the basic stiffness requirement. Accordingly, dynamic design analysis method (DDAM) is performed to verify the ability of the optimized cast aluminum cabinet in resisting sudden shock load, and the shock response characteristics of the cabinet are determined. Numerical results support that the optimized frame of cabinet possesses good resistance to high level shock. However, for the assembled cast aluminum cabinet, the vertical shock circumstance turns out to be the most critical condition, high stress and deformation regions occurs at the bracket and column. Reinforcements are proposed to make the bracket stiffer in this shock loading condition. Copyri

关键词： Finite element method

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Theoretical exploration of heat transfer characteristics of liquid metals

Theoretical exploration of heat transfer characteristics of ...

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2020 Transactions of the American Nuclear Society, ANS 2020

作者： Shen, Yaou Peng, Shinian Yan, Mingyu Zhang, Yu Deng, Jian Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

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Research on thermal diffusion coefficient calculation for subchannels with spacer grid using CFD methodology 14

Research on thermal diffusion coefficient calculation for su...

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Chen, Xi Du, Sijia Liu, Yu Qian, Libo Liu, Lili Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Thermal Diffusion Coefficient (TDC) is one of the most important parameters in subchannel analysis codes. Abundant research results demonstrate that TDC is mainly determined by the structures of fuel assembly, especially by the mixing vanes of spacer grids. Traditionally, TDC is acquired by thermal-hydraulic tests. However, hydraulic tests cost a great deal of money and need long time, and it's impossible to test every grid design. Another new way to obtain coefficients economically and fast is really needed for decades. Recently, with great development of Computational Fluid Dynamics, CFD has been validated as an analysis method for nuclear engineering, especially for single phase calculation. This paper established CFD methodology in TDC calculation for a 5x5 rod bundle with spacer grids. Firstly, CFD simulations were carried out to get sunchannel exit temperature including different conditions, such as different temperature, pressure, and flow rate. Then subchannel code CORTH was used to make subchannel analysis with varied TDC. Finally, we compared the TDC using CFD method with that come from tests, and validation results show that the methodology was right. In conclusion, the feasibility of TDC calculation methodology is preliminarily validated, which provided references for developments and design of new fuel assemblies. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Computational fluid dynamics

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