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General Analytical Shakedown Solution for Structures with Kinematic Hardening Materials

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 944-953页

作者： GUO Baofeng zou zongyuan JIN Miao Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University

The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems： a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

关键词： elastic-plastic elastic shakedown kinematic hardening shakedown limit load general analytical solution

Shakedown Criterion Employing Actual Residual Stress Field and Its Application in Numerical Shakedown Analysis

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 919-927页

作者： zou zongyuan GUO Baofeng LI Yinxiao JIN Miao ZHAO Shiyan Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Chinese 91315 People's Liberation Army Troops

Construction of the static admissible residual stress field and searching the optimal field are key tasks in the shakedown analysis methods applying the static theorem. These methods always meet dimension obstacles when dealing with complex problems. In this paper, a novel shakedown criterion is proposed employing actual residual stress field based on the static shakedown theorem. The actual residual stress field used here is produced under a specified load path, which is a sequence of proportional loading and unloading from zero to all the vertices of the given load domain. This ensures that the shakedown behavior in the whole load domain can be determined based on the theorem proposed by K6nig. The shakedown criterion is then implemented in numerical shakedown analysis, The actual residual stress fields are calculated by incremental finite element elastic-plastic analysis technique for finite deformation under the specified load path with different load levels. The shakedown behavior and the shakedown limit load are determined according to the proposed criterion. The validation of the criterion is performed by a benchmark shakedown example, which is a square plate with a central hole under biaxial loading. The results are consistent with existing results in the literatures and are validated by full cyclic elastic-plastic finite element analysis. The numerical shakedown analysis applying the proposed criterion avoids processing dimension obstacles and performing full cyclic elastic-plastic analysis under arbitrary load paths which should be accounted for appearing. The effect of material model and geometric changes on shakedown behavior can he considered conveniently.

关键词： elastoplastic finite element shakedown criterion specified load path actual residual stress field

General Analytical Shakedown Analysis of a Structure Subjected to Combined Loading with Constant and Cyclic Loads

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Journal of Harbin Institute of Technology(New Series) 2017年第3期24卷 67-75页

作者： zongyuan zou Baofeng Guo Miao Jin Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of Education of China Yanshan UniversityQinhuangdao 066004 China

The shakedown behavior of structures subjected to a combined loading of constant and cyclic loads has been well *** some specified problems,shakedown limit loads have been ***,the general effect of combined loading on the structural shakedown has not yet been *** general analytic solution of the elastic shakedown limit load is thus derived for a structure subjected to combined ***'s extended static shakedown theorem for combined loading is *** stress field in equilibrium with the external constant load required in Polizzotto's extended theorem is constructed by subtracting the reference elastic stress field of the peak cyclic load from the elastic-plastic stress field of the combined constant load and peak cyclic *** shakedown condition of the stress field is then derived according to the extended *** the analytical analysis of the shakedown condition,the structural shakedown behavior under combined loading is investigated.A general solution of the shakedown limit load is then derived,and the effects of the combined loading on the shakedown behavior are *** obtained general analytical result is applied to a hollow tension specimen under constant tension and alternating torsion and a plate with a central hole under constant and cyclic *** results are consistent with the solutions reported in the literature.

关键词： elastic-plastic shakedown limit load general analytical solution combined loading

钒含量对Ti-V微合金钢CGHAZ韧性影响研究

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机械工程学报 2018年第6期54卷 146-153页

作者：邹宗园李银潇先进锻压成形技术与科学教育部重点实验室(燕山大学) 中国人民解放军91315部队

现阶段'Ti氧化物冶金+V微合金化'复合技术用于研发大线能量焊接用钢已引起人们的广泛关注,这种复合技术能够充分利用在Ti的氧化物上析出的Ti、V碳氮化物粒子诱导焊接粗晶热影响区大量针状铁素体形核,改善CGHAZ韧性。本研究从运用Thermo-... 详细信息

现阶段'Ti氧化物冶金+V微合金化'复合技术用于研发大线能量焊接用钢已引起人们的广泛关注,这种复合技术能够充分利用在Ti的氧化物上析出的Ti、V碳氮化物粒子诱导焊接粗晶热影响区大量针状铁素体形核,改善CGHAZ韧性。本研究从运用Thermo-Calc热力学软件定量计算第二相颗粒固溶析出规律入手,考察了Ti、V、O、N等元素构成的氧化及碳氮化夹杂物在诱导AF形核中的关键作用。与此同时,在研究中也利用了热力模拟试验机、力学测量设备、高倍电镜等,对V含量为0、0.05%、0.1%的Ti-V微合金钢进行大线能量焊接、力学性能测量及形貌分析。通过分析试验结果得出V元素在提高Ti-V微合金钢强度和CGHAZ韧性的一般规律,并进一步阐述了Ti-V微合金钢CGHAZ中析出夹杂物诱导AF形核机制。

关键词： Ti-V微合金钢大线能量焊接焊接粗晶热影响区夹杂物韧性

大热输入焊接用钢的焊接粗晶热影响区韧性提升方法研究

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金属学报 2017年第8期53卷 957-967页

作者：邹宗园许小奎李银潇王超燕山大学先进锻压成形技术与科学教育部重点实验室东北大学轧制技术及连轧自动化国家重点实验室中国人民解放军91315部队

通过研究焊接热影响区(HAZ)冲击功分布图,提出大热输入焊接用钢焊接粗晶热影响区(CGHAZ)韧性提升的新方法,即在峰值温度不变的条件下,将焊接CGHAZ中晶界铁素体(GBF)和大量针状铁素体(AF)组织改变成细晶热影响区(FGHAZ)多边形铁素体(PF)... 详细信息

通过研究焊接热影响区(HAZ)冲击功分布图,提出大热输入焊接用钢焊接粗晶热影响区(CGHAZ)韧性提升的新方法,即在峰值温度不变的条件下,将焊接CGHAZ中晶界铁素体(GBF)和大量针状铁素体(AF)组织改变成细晶热影响区(FGHAZ)多边形铁素体(PF)组织,并消除CGHAZ中破坏韧性的侧板条铁素体(FSP)组织。以对比Ti-V-N与Al-Ti-V-N微合金焊接用钢焊接CGHAZ组织和韧性为基础,探讨了Al-Ti-V-N钢焊接CGHAZ中PF转变条件、形核机制,认为微米级氧化夹杂物是诱导焊接CGHAZ中大量PF形核的关键,纳米级碳氮化物是拖曳、钉扎奥氏体与铁素体晶界的关键,两者的有效配合保证了焊接CGHAZ中大量PF组织生成,从而大幅提升焊接CGHAZ的低温冲击韧性。

关键词：大热输入焊接 CGHAZ AF形核 PF转变韧性

基于循环拉-压试验的混合硬化模型参数确定及模型应用

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机械工程学报 2020年第2期56卷 63-68页

作者：李群金淼邹宗园郭佳杨聪先进锻压成形技术与科学教育部重点实验室(燕山大学) 秦皇岛066004 蜂巢能源科技有限公司保定071000

材料弹塑性本构模型是影响有限元模拟精度的最重要因素,混合硬化本构模型能较准确表现材料塑性变形过程真实硬化特征,而本构模型中材料特性相关参数是否准确直接影响到有限元模拟的精度。基于Hill48各向异性屈服准则,结合Voce各向同性... 详细信息

材料弹塑性本构模型是影响有限元模拟精度的最重要因素,混合硬化本构模型能较准确表现材料塑性变形过程真实硬化特征,而本构模型中材料特性相关参数是否准确直接影响到有限元模拟的精度。基于Hill48各向异性屈服准则,结合Voce各向同性硬化模型和Armstrong-Frederic非线性随动硬化模型,建立一个考虑材料各向异性和Bauschinger效应的混合硬化弹塑性本构模型。通过循环拉伸-压缩试验,获得DC54D+ZF镀锌板的循环变形应力-应变曲线,并利用通用全局优化算法,根据单向应力状态混合硬化本构方程,准确地确定了混合硬化模型中的材料特性参数。最后,使用ABAQUS有限元软件对板材循环拉伸-压缩问题和板材过拉深筋问题进行该本构模型的适用性分析,验证了所建立的各向异性混合硬化材料本构模型的可靠性和精确性。循环拉伸-压缩试验是直接准确地获得本构模型材料参数的有效方法。

关键词：各向异性 Bauschinger效应混合硬化循环拉伸-压缩试验全局优化算法

Analyzing the Dissemination of News by Model Averaging and Subsampling

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Journal of Systems Science & Complexity 2024年第5期37卷 2104-2131页

作者： zou Jiahui School of Statistics Capital University of Economics and Business

The dissemination of news is a vital topic in management science, social science and data science. With the development of technology, the sample sizes and dimensions of digital news data increase remarkably. To alleviate the computational burden in big data, this paper proposes a method to deal with massive and moderate-dimensional data for linear regression models via combing model averaging and subsampling methodologies. The author first samples a subsample from the full data according to some special probabilities and split covariates into several groups to construct candidate models. Then, the author solves each candidate model and calculates the model-averaging weights to combine these estimators based on this subsample. Additionally, the asymptotic optimality in subsampling form is proved and the way to calculate optimal subsampling probabilities is *** author also illustrates the proposed method via simulations, which shows it takes less running time than that of the full data and generates more accurate estimations than uniform subsampling. Finally,the author applies the proposed method to analyze and predict the sharing number of news, and finds the topic, vocabulary and dissemination time are the determinants.

关键词： Asymptotic optimality dissemination of news linear regression models model averaging optimal subsampling

Image Fusion Based on Bioinspired Rattlesnake Visual Mechanism Under Lighting Environments of Day and Night Two Levels

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Journal of Bionic Engineering 2024年第3期21卷 1496-1510页

作者： Yong Wang Hongmin zou College of Communication Engineering Jilin UniversityChangchun130012China

This study,grounded in Waxman fusion method,introduces an algorithm for the fusion of visible and infrared images,tailored to a two-level lighting environment,inspired by the mathematical model of the visual receptive field of rattlesnakes and the two-mode cells'*** research presented here is segmented into three *** the first segment,we design a preprocessing module to judge the ambient light intensity and divide the lighting environment into two levels:day and *** second segment proposes two distinct network structures designed specifically for these daytime and nighttime *** the daytime images,where visible light information is predominant,we feed the ON-VIS signal and the IR-enhanced visual signal into the central excitation and surrounding suppression regions of the ON-center receptive field in the B channel,***,for nighttime images where infrared information takes precedence,the ON-IR signal and the Visual-enhanced IR signal are separately input into the central excitation and surrounding suppression regions of the ON-center receptive field in the B *** outcome is a pseudo-color fused *** third segment employs five different no-reference image quality assessment methods to evaluate the quality of thirteen sets of pseudo-color images produced by fusing infrared and visible *** images are then compared with those obtained by six other methods cited in the relevant *** empirical results indicate that this study's outcomes surpass the comparative results in terms of average gradient and spatial *** one or two sets of fused images underperformed in terms of standard deviation and entropy when compared to the control *** sets of fused images did not perform as well as the comparison in the QAB/F *** conclusion,the fused images generated through the proposed method show superior performance in terms of scene detail,visual perception,and image sharpness

关键词： Rattlesnake Visible image Infrared image Daylight Bionic

Conceptual transition from molecular to atomic: unleashing a new era in hydrogen therapy for chronic disease

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National Science Review 2024年第04期11卷 17-18页

作者： Zhigang zou Eco-materials and Renewable Energy Research Center (ERERC) Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State Microstructures and Department of PhysicsNanjing University

The dysregulated overexpression of reactive oxygen and nitrogen species (RONS)intricately links to the occurrence and development of diverse chronic diseases[1–3]. Hydrogen therapy stands out as a promising treatment methodology recognized for effectively mitigating RONS and maintaining intracellular redox equilibrium, thereby yielding therapeutic benefits [4,5].

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