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Forming limit Stress Diagram Prediction of Aluminum Alloy 5052 Based on GTN Model Parameters Determined by In Situ Tensile Test

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Chinese Journal of Aeronautics 2011年第3期24卷 378-386页

作者： HE Min li fuguo WANG Zhigang School of Materials Science and Engineering Northwestern Polytechnical University Xi 'an 710072 China Department of Mechanical Science and Engineering Xuzhou Institute of Technology Xuzhou 221008 China Department of Aircraft Structure Design and Research the First Aircraft Institute Aviation Industry Corporation of China Xi 'an 710089 China

The conventional forming limit diagram （FLD） is described as a plot of major strain versus minor strain. However, FLD is dependent on forming history and strain path. In the present study, a forming limit stress-based diagram （FLSD） has been adopted to predict the fracture limit of aluminum alloy （AA） 5052-O1 sheet. Nakazima test is simulated by plastic constitutive formula derived from the modified Gurson-Tvergaard-Needleman （GTN） model. An in situ tensile test with scanning electron microscope （SEM） is proposed to determine the parameters in GTN model. The damage evolution is observed and recorded, and the parameters of GTN model are identified through counting void fraction at three damage stages of AA5052-O 1. According to the experimental results, the original void volume fraction, the volume fraction of potential nucleated voids, the critical void volume fraction, the void volume fraction at the final failure of material are assigned as 0.002 918, 0.024 9, 0.030 103, 0.048 54, respectively. The stress and strain are obtained at the last loading step before crack. FLSD and FLD of AA5052-O 1 are plotted. Compared with the experimental Nakazima test and uniaxial tensile test, the predicted results show a good agreement. The parameters determined by in situ tensile test can be applied to the research of the forming limit for ductile metals.

关键词： forming limit stress diagram GTN model in situ tensile test void damage aluminum alloy 5052-O1 sheet metal forming

一种基于等温多塑性变形机制耦合的数值模拟方法

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稀有金属材料与工程 2011年第5期40卷 778-783页

作者：蔡军李付国西北工业大学陕西西安710072

以TC4合金等温锻造为例,提出一种基于多塑性变形机制耦合的数值模拟方法。通过对等温锻造过程中塑性变形机制的研究和对应变速率敏感指数以及TC4合金动态再结晶的分析,建立材料常规塑性变形、超塑性变形和蠕变变形的判据。并依据多塑性... 详细信息

以TC4合金等温锻造为例,提出一种基于多塑性变形机制耦合的数值模拟方法。通过对等温锻造过程中塑性变形机制的研究和对应变速率敏感指数以及TC4合金动态再结晶的分析,建立材料常规塑性变形、超塑性变形和蠕变变形的判据。并依据多塑性变形机制判据来确定坯料内部各单元的实时塑性变形机制,同时采用相应的本构方程,使模拟结果更符合实际情况,从而能真实反映航空难变形材料的等温锻造工艺过程:普通塑性变形、超塑性变形和等温保压充填模具过程等。模拟结果表明,变形材料并非处于单一塑性变形机制,而是多种变形机制相互协调,并且随着变形的进行,材料各单元的变形机制也随之改变。等温锻造过程中,上述机制的改变与材料的动态再结晶密切相关。

关键词：等温锻造 TC4合金多塑性变形机制耦合分析数值模拟

颗粒团聚对Al基SiC颗粒增强复合材料的流变形为影响(英文)

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稀有金属材料与工程 2010年第9期39卷 1525-1531页

作者：张鹏李付国 NW Polytech Univ Sch Mat Sci & Engn Xian 710072 Peoples R China

基于微观组织的有限元分析模型,研究颗粒团聚对Al基SiC颗粒增强金属基复合材料流变行为的影响。通过建立的3种增强颗粒分布的胞元模型(一个团聚现象、两个团聚现象和随机分布),分析讨论基体和增强颗粒中的等效应力和等效应变的分布规律... 详细信息

基于微观组织的有限元分析模型,研究颗粒团聚对Al基SiC颗粒增强金属基复合材料流变行为的影响。通过建立的3种增强颗粒分布的胞元模型(一个团聚现象、两个团聚现象和随机分布),分析讨论基体和增强颗粒中的等效应力和等效应变的分布规律,以此为基础,获得3种颗粒分布模型下的SiC颗粒增强Al基复合材料的应力应变曲线。结果表明:颗粒增强金属基复合材料的流变行为和力学响应与增强颗粒的分布非常敏感,但在弹性变形阶段这种影响就相对较弱。从增强颗粒的最大主应力分布来看,颗粒团聚增加了SiC颗粒开裂的概率。从基体的静水应力分布来看,颗粒团聚将促进早期的界面脱粘和在韧性基体中形成微空洞。

关键词：颗粒团聚 SiC颗粒增强复合材料变形 Metal Matrix Composites 颗粒增强金属基复合材料增强颗粒应力分布 effective stress metal matrix composites finite element analysis particle distribution mechanical response elastic deformation maximum principal 团聚现象流变行为颗粒分布 three 有限元分析模型 results

Single-cell transcriptomic atlas of goat ovarian aging

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Journal of Animal Science and Biotechnology 2024年第1期15卷 146-161页

作者： Dejun Xu Shuaifei Song fuguo Wang Yawen li Ziyuan li Hui Yao Yongju Zhao Zhongquan Zhao Chongqing Key Laboratory of Herbivore Science College of Animal Science and TechnologySouthwest UniversityChongqing 400715China

Background The ovaries are one of the first organs that undergo degenerative changes earlier in the aging process,and ovarian aging is shown by a decrease in the number and quality of ***,little is known about the molecular mechanisms of female age-related fertility decline in different types of ovarian cells during aging,especially in ***,the aim of this study was to reveal the mechanisms driving ovarian aging in goats at single-cell *** For the first time,we surveyed the single-cell transcriptomic landscape of over 27,000 ovarian cells from newborn,young and aging goats,and identified nine ovarian cell types with distinct gene-expression *** enrichment analysis showed that ovarian cell types were involved in their own unique biological processes,such as Wnt beta-catenin signalling was enriched in germ cells,whereas ovarian steroidogenesis was enriched in granulosa cells(GCs).Further analysis showed that ovarian aging was linked to GCs-specific changes in the antioxidant system,oxidative phosphorylation,and ***,we identified a series of dynamic genes,such as AMH,CRABP2,THBS1 and TIMP1,which determined the fate of ***,FOXO1,SOX4,and HIF1A were identified as significant regulons that instructed the differentiation of GCs in a distinct manner during ovarian *** This study revealed a comprehensive aging-associated transcriptomic atlas characterizing the cell typespecific mechanisms during ovarian aging at the single-cell level and offers new diagnostic biomarkers and potential therapeutic targets for age-related goat ovarian diseases.

关键词： Goat Granulosa cells Ovarian aging Single-cell transcriptomic

Simulation of rice grain breakage process based on Tavares UFRJ model

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PARTICUOLOGY 2024年第10期93卷 65-74页

作者： Shen, Shaohang Ji, Shouyu Zhao, Dan Han, Yanlong li, Hao Sun, Ze li, Zhuozhuang li, Anqi Feng, Wenyu Fei, Jiaming Jia, fuguo li, Yang Northeast Agr Univ Coll Engn Harbin 150030 Peoples R China Northeast Agr Univ Sch Water Conservancy & Civil Engn Harbin 150030 Peoples R China Northeast Agr Univ Coll Food Sci Harbin 150030 Peoples R China

Understanding the breakage characteristics of rice grains is an important means to reduce rice breakage rate. However, the dynamic breakage mechanism of rice grain is unclear due to the lack of a reasonable breakage model. In this study, the uniaxial compression test and drop weight test of single rice were carried out, the breakage model of rice grain was constructed, the reliability of rice model was verified by the experiment and simulation results. The results showed that the fracture energy distribution of rice can be obtained by uniaxial compression test, the specific fracture energy of rice accords with a lognormal distribution, and the median specific fracture energy of rice is 479.75 J/kg. The damage accumulation coefficient and fragment size distribution of rice can be acquired by drop test, the result of damage accumulation coefficient of rice was 4.3. Rice grain breakage mainly occurs in the milling section of the vertical circulation rice mill. (c) 2024 Published by Elsevier B.V. on behalf of Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences.

关键词： Rice breakage mechanism Discrete element method Parameter calibration PARTICLE FRACTURE DESIGN VARIABLES DEM

SiC颗粒增强Al基复合材料的动态再结晶模型

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稀有金属材料与工程 2010年第7期39卷 1166-1170页

作者：张鹏李付国西北工业大学陕西西安710072

采用Gleeble-1500热模拟试验机研究15%SiC颗粒增强铝基复合材料在温度为713～773K、应变速率为0.001～1s-1的热变形行为,并建立热变形本构方程;同时采用Quantiment-500型自动图形分析仪测量该材料的动态再结晶晶粒尺寸。在研究中,以试... 详细信息

采用Gleeble-1500热模拟试验机研究15%SiC颗粒增强铝基复合材料在温度为713～773K、应变速率为0.001～1s-1的热变形行为,并建立热变形本构方程;同时采用Quantiment-500型自动图形分析仪测量该材料的动态再结晶晶粒尺寸。在研究中,以试验数据为基础,建立θ-σ和θ/-σ–σ曲线,从而进一步获得动态再结晶的临界应变和稳态应变,并通过试验数据的回归分析,建立动态再结晶的临界应变模型和稳态应变模型,并在此基础上,获得所研究材料的动态再结晶图。

关键词： SiC颗粒增强Al基复合材料动态再结晶临界应变

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镦粗成形工艺的类等势场分析法

西北工业大学学报 2006年第5期24卷 672-676页

作者：肖军李付国李超西北工业大学材料学院陕西西安710072

以镦粗成形工艺为例提出了一种新的适用于实时控制的快速模型构建方法。通过对镦粗件初始形状和终了形状电极的缩放,形成一个完整的静电场,并获得按照一定规律渐变的介于2个导体形状之间的等势线。根据其分布规律确定出坯料内部的流线... 详细信息

以镦粗成形工艺为例提出了一种新的适用于实时控制的快速模型构建方法。通过对镦粗件初始形状和终了形状电极的缩放,形成一个完整的静电场,并获得按照一定规律渐变的介于2个导体形状之间的等势线。根据其分布规律确定出坯料内部的流线和等势线以及坯料内部质点的流动情况,进行了相关场变量的分析计算,最后将计算结果与有限元法分析结果进行了比较,分析表明,该方法可行、计算结果可靠、计算过程快捷。

关键词：镦粗等势线模拟静电场

An Acoustic Discrimination Method for Impact Load Based on Artificial Neural Network

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An Acoustic Discrimination Method for Impact Load Based on A...

作者： Zhenhan Wang li Ma Qianru Zhan Qinghua li fuguo li Honors College Northwestern Polytechnical University State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical University School of Materials Science and Engineering Northwestern Polytechnical University

In order to meet the engineering requirements of non-contact measurement of impact load and realize the intelligent identification of its characteristic parameters,this paper attempts to establish a method to analyze and learn the audio characteristics generated by accidental loads,such as impact and explosion,and to identify the impact load characteristics in *** method,which is based on energy conservation,momentum conservation and strokes law,used p-norm in mathematics to extract the basic characteristics of impact load,and the frequency analysis to find the inevitable connection between the audio characteristics impulseinduced and the impact load *** last,"Acoustic Discrimination for Impact Load Identification（ADII）" by adopting the functions of artificial neural networks about learning,categorization and generalization was implemented.

关键词： Impact load characteristic identification acoustic discrimination artificial neural network

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延性金属材料损伤变量的实验表征方法研究

稀有金属材料与工程 2011年第11期40卷 2022-2025页

作者：陈波李付国何敏西北工业大学陕西西安710072

基于微观损伤的宏观表征,采用各种实验方法对延性金属塑性变形过程中的宏观损伤变量进行表征。通过预拉伸变形的方法制备了6种不同真应变条件下的拉伸试样,并基于微小材料压缩试验机(MCT-W501)对不同预变形试样的压缩试验结果,分别采用... 详细信息

基于微观损伤的宏观表征,采用各种实验方法对延性金属塑性变形过程中的宏观损伤变量进行表征。通过预拉伸变形的方法制备了6种不同真应变条件下的拉伸试样,并基于微小材料压缩试验机(MCT-W501)对不同预变形试样的压缩试验结果,分别采用显微硬度、弹性模量、韧性指标和电阻率等指标归一化表征了金属材料的韧性损伤,并就损伤变量的变化规律及所代表的物理含义进行分析讨论。结果表明:综合应用上述各损伤表征量并构造等效损伤曲线,能真实反映与解释延性金属材料的实际损伤过程。

关键词：韧性损伤延性金属实验表征