期刊文献+
共找到390篇文章
< 1 2 20 >
每页显示 20 50 100
A pseudo-coupled numerical approach for stability analysis of frozen soil slopes based on finite element limit analysis method 被引量:4
1
作者 Xi Chen JianKun Liu +3 位作者 Yuan Feng Xu Li YaHu Tian JianHong Fang 《Research in Cold and Arid Regions》 CSCD 2013年第4期478-487,共10页
To simplify the stability analysis of frozen soil slope, a pseudo-coupled numerical approach is developed. In this approach, the coupled heat transfer and water flow in frozen soils are simulated first, and based on t... To simplify the stability analysis of frozen soil slope, a pseudo-coupled numerical approach is developed. In this approach, the coupled heat transfer and water flow in frozen soils are simulated first, and based on the computed thermal-hydro field, the stability of frozen soil slope is evaluated. Although the shear strength for frozen soil is very complicated and is usually represented by a nonlinear MC failure criterion, a simple linear MC yield criterion is utilized. In this method, the internal friction angle is expressed as a function of volumetric ice content and the cohesion is fitted as a simple bilinear expression of Tand volumetric water content. To assess slope stability, the limit analysis is employed in conjunction with the recently developed a-section search algorithm. A frozen soil slope example is used to examine the proposed pseudo-coupled numerical approach, and numerical studies validate its effectiveness. Based on numerical results, it is seen that slope stability may be remarkably influenced by warming air (or grotmd surface) temperature. With increasing ground surface temperature, slope stability indicated by FOS may reduce to 1.0, implying that wanning air temperature could be a trigger of frozen soil slope failure. 展开更多
关键词 frozen soil slope stability pseudo-coupled thermo-hydro-mechanical analysis finite element limit analysis
下载PDF
Nonconforming <i>H</i><sup>1</sup>-Galerkin Mixed Finite Element Method for Pseudo-Hyperbolic Equations
2
作者 Yadong Zhang Yuqi Niu Dongwei Shi 《American Journal of Computational Mathematics》 2012年第4期269-273,共5页
Based on H1-Galerkin mixed finite element method with nonconforming quasi-Wilson element, a numerical approximate scheme is established for pseudo-hyperbolic equations under arbitrary quadrilateral meshes. The corresp... Based on H1-Galerkin mixed finite element method with nonconforming quasi-Wilson element, a numerical approximate scheme is established for pseudo-hyperbolic equations under arbitrary quadrilateral meshes. The corresponding optimal order error estimate is derived by the interpolation technique instead of the generalized elliptic projection which is necessary for classical error estimates of finite element analysis. 展开更多
关键词 pseudo-Hyperbolic Equation NONCONFORMING H1-Galerkin Mixed Finite element Error Estimate
下载PDF
基于中国剩余定理的NFC安全认证算法 被引量:1
3
作者 邹同浩 《计算机应用与软件》 北大核心 2024年第1期322-327,共6页
针对近场通信技术在应用中出现的安全隐患问题,给出一种基于中国剩余定理的算法。算法利用中国剩余定理实现对传送信息进行加密,中国剩余定理基于数学中大素数分解难题,使得攻击者无法进行破解;所有信息加密过程中混入随机数,用于保证... 针对近场通信技术在应用中出现的安全隐患问题,给出一种基于中国剩余定理的算法。算法利用中国剩余定理实现对传送信息进行加密,中国剩余定理基于数学中大素数分解难题,使得攻击者无法进行破解;所有信息加密过程中混入随机数,用于保证消息的新鲜性;算法在进行信息更新时采用伪随机函数计算,因伪随机函数具备的单向性,使得攻击者无法分析出有用隐私信息。将不同算法对比安全分析,表明该算法能够抵抗重放攻击、异步攻击等多种攻击。通过性能角度及仿真实验对多个算法进行分析,结果表明该算法计算时间复杂度低于其他算法。 展开更多
关键词 近场通信 中国剩余定理 伪随机函数 大素数 安全认证 GNY逻辑形式化分析
下载PDF
壁式钢管混凝土柱-钢梁嵌入式双侧板节点抗震性能研究及设计建议
4
作者 李露 郝际平 +3 位作者 薛强 樊春雷 黄育琪 杜智洋 《建筑结构》 北大核心 2024年第6期1-9,共9页
以壁式钢管混凝土柱-钢梁嵌入式双侧板节点为研究对象,进行两个足尺试件的拟静力试验,分析节点的破坏模式、滞回曲线、骨架曲线,并研究节点承载力、延性、耗能能力和刚度退化等指标。试验结果表明:试件破坏模式分别为侧板外梁端形成塑... 以壁式钢管混凝土柱-钢梁嵌入式双侧板节点为研究对象,进行两个足尺试件的拟静力试验,分析节点的破坏模式、滞回曲线、骨架曲线,并研究节点承载力、延性、耗能能力和刚度退化等指标。试验结果表明:试件破坏模式分别为侧板外梁端形成塑性铰、节点核心区侧板开裂及轻微鼓曲;试件滞回曲线稳定饱满,曲线呈现梭形,试件延性系数为3.11~3.53,等效黏滞阻尼系数大于0.4,具有良好的耗能能力;刚度退化较稳定,具备较好的抗侧能力。在验证有限元模型合理的基础上,通过有限元变参分析此类节点的滞回性能,结果表明:增加侧板厚度或侧板外伸长度可提高嵌入式双侧板节点的承载力及延性。最后结合试验和有限元变参分析结果,针对此类节点提出设计建议。 展开更多
关键词 壁式钢管混凝土柱 嵌入式双侧板节点 拟静力试验 抗震性能 有限元变参分析
下载PDF
元素引发对Na_(2)CO_(3)胁迫下膜荚黄芪种子萌发的影响
5
作者 尹琦翔 刘霞 《东北师大学报(自然科学版)》 CAS 北大核心 2024年第3期111-120,共10页
为研究元素引发对Na_(2)CO_(3)胁迫下膜荚黄芪种子及幼苗生长的影响,以膜荚黄芪种子为研究对象,利用2×10^(-2)mol/L浓度的Na_(2)CO_(3)溶液提供胁迫环境,使用B,Si,Fe,Zn_(4)种元素处理胁迫下的种子,测定了种子的发芽指标、幼苗的... 为研究元素引发对Na_(2)CO_(3)胁迫下膜荚黄芪种子及幼苗生长的影响,以膜荚黄芪种子为研究对象,利用2×10^(-2)mol/L浓度的Na_(2)CO_(3)溶液提供胁迫环境,使用B,Si,Fe,Zn_(4)种元素处理胁迫下的种子,测定了种子的发芽指标、幼苗的生物量、叶绿素含量、渗透调节物质含量和抗氧化酶活力.结果表明:3×10^(-5)mol/L的B元素、6.5×10^(-5)mol/L的Si元素、1.8×10^(-4)mol/L的Fe元素和1.2×10^(-4)mol/L的Zn元素对种子及幼苗的生长发育促进效果显著,可缓解Na_(2)CO_(3)对植物的胁迫作用、提高种子发芽率、增加幼苗生物量的积累、增强幼苗的光合作用、提高幼苗的抗氧化能力.引发浓度较低时,对种子及幼苗生长的促进效果不显著,引发浓度较高时则会抑制种子及幼苗生长. 展开更多
关键词 膜荚黄芪 Na_(2)CO_(3)胁迫 元素 种子引发
下载PDF
装配式开孔不锈钢防屈曲支撑抗震性能试验研究
6
作者 陈磊 王东升 +1 位作者 孙治国 钱辉 《工程力学》 EI CSCD 北大核心 2024年第7期226-238,共13页
为提升沿海工程结构中耗能构件的耐久性能,提出了装配式不锈钢防屈曲支撑(BRBs),分别采用奥氏体S304和双相型S2205不锈钢作为内芯板。对内芯板和外约束板进行开孔设计,实现定点耗能的同时方便震后对BRBs的损伤情况进行观察。通过拟静力... 为提升沿海工程结构中耗能构件的耐久性能,提出了装配式不锈钢防屈曲支撑(BRBs),分别采用奥氏体S304和双相型S2205不锈钢作为内芯板。对内芯板和外约束板进行开孔设计,实现定点耗能的同时方便震后对BRBs的损伤情况进行观察。通过拟静力试验分析了不同材质BRBs的滞回特性及抗震性能,并采用ABAQUS对试验进行了模拟。结果表明:设计的装配式开孔一字形BRBs,结构形式简单,整体稳定性好。不同材质BRBs的屈服后硬化程度差异较大,建议对奥氏体S304不锈钢BRBs刚度因子取0.1,双相型S2205不锈钢BRBs刚度因子取0.02。两种不锈钢BRBs的等效粘滞阻尼比在L/100位移幅值下为0.4左右,均表现出了良好的耗能能力。在相同加载位移幅值下,奥氏体S304和双相型S2205不锈钢BRBs,与屈服强度分别相近的Q235和Q550普通钢BRBs相比,在低周疲劳寿命、塑性变形能力和总耗能等方面都分别远高于后者,具有更优的抗震性能。拟合得到的内芯板循环本构参数能够描述BRBs的滞回特性,采用的建模方法能够兼顾计算精度和计算效率。 展开更多
关键词 防屈曲支撑 不锈钢 拟静力试验 抗震性能 有限元分析
下载PDF
内嵌加劲耗能钢板的箱形钢墩柱拟静力试验及数值分析
7
作者 孙德畅 张海龙 +3 位作者 严丰佐 饶武斌 韩雪 李海锋 《建筑钢结构进展》 CSCD 北大核心 2024年第1期1-9,共9页
地震作用下钢桥墩根部易发生屈曲破坏且震后难以快速修复。基于可恢复功能理念与钢桥墩的受力特征,提出一种具备震后易恢复功能的新型箱型钢桥墩。此新型桥墩通过设置可更换的加劲耗能壁板以增强结构的耗能与变形能力,且震后能够快捷更... 地震作用下钢桥墩根部易发生屈曲破坏且震后难以快速修复。基于可恢复功能理念与钢桥墩的受力特征,提出一种具备震后易恢复功能的新型箱型钢桥墩。此新型桥墩通过设置可更换的加劲耗能壁板以增强结构的耗能与变形能力,且震后能够快捷更换受损的耗能壁板以恢复桥墩力学性能。为研究设置加劲耗能壁板的箱型钢墩柱的抗震性能,选取耗能壁板上加劲肋的布置形式、轴压比及耗能板强度等作为影响参数进行拟静力试验,且通过有限元数值模拟,综合探讨此类新型试件在地震作用下的力学性能;并对比分析新型桥墩的受力特点和破坏机理,为此类钢墩柱的数值仿真提供理论基础。结果表明,增设内嵌耗能钢板后,试件的抗震性能得到较大改善;提高耗能板强度后,试件的水平承载力得到较大提高,但其延性与变形能力下降;有限元模拟结果验证了新型钢桥墩良好的抗震性能。在试验研究、理论分析与数值仿真的基础上提出此类新型钢桥墩承载力建议公式,并应用试验结果验证了公式的准确性。 展开更多
关键词 钢墩柱 加劲耗能钢板 有限元模拟 拟静力试验 抗震性能
下载PDF
微量元素在油菜种子引发中的调控作用及实用性
8
作者 邓凤玲 李春生 顾建伟 《湖北农业科学》 2024年第6期5-11,21,共8页
为了提高油菜(Brassica napus L.)种子活力以增强种子萌发和幼苗阶段的抗逆性,试验通过响应面分析方法对不同微量元素组合间效应进行比较分析,得出对油菜种子活力提升效果最佳的元素组合,并进一步验证了该组合对不同油菜品种生长发育和... 为了提高油菜(Brassica napus L.)种子活力以增强种子萌发和幼苗阶段的抗逆性,试验通过响应面分析方法对不同微量元素组合间效应进行比较分析,得出对油菜种子活力提升效果最佳的元素组合,并进一步验证了该组合对不同油菜品种生长发育和最终产量的影响。结果表明,Se(5.0 mg/L)、B(5.0 mg/L)、Zn(100.0 mg/L)、Mo(1.0 mg/L)对油菜种子萌发均具有明显的促进作用;响应面分析得出最佳微量元素配比组合为Se(6.7 mg/L)+B(7.5 mg/L)+Zn(82.3 mg/L)+Mo(4.6 mg/L),在此配比组合处理下,幼苗期可溶性蛋白质的累积量提高且幼苗的抗逆性也有明显增强;不同品种中的应用试验证明该配比组合处理可显著提高其单株产量(P<0.05)。 展开更多
关键词 油菜(Brassica napus L.) 种子引发 种子活力 微量元素 产量
下载PDF
弹载芯片在强冲击环境下的损伤边界
9
作者 王磊 刘振亭 +2 位作者 刘星 马生荣 朱天社 《探测与控制学报》 CSCD 北大核心 2024年第2期94-100,共7页
针对弹载芯片结构在强机械冲击环境下冲击响应谱损伤边界不确定和不准确的问题,将芯片等效为单自由度无阻尼系统并进行冲击响应分析,建立结构应力响应与伪速度冲击响应谱之间的联系;对弹载芯片结构在不同频率范围内冲击载荷下的响应进... 针对弹载芯片结构在强机械冲击环境下冲击响应谱损伤边界不确定和不准确的问题,将芯片等效为单自由度无阻尼系统并进行冲击响应分析,建立结构应力响应与伪速度冲击响应谱之间的联系;对弹载芯片结构在不同频率范围内冲击载荷下的响应进行分析,构造损伤边界并通过临界加速度信号对冲击响应谱损伤边界进行修正;采用有限元仿真软件对冲击载荷下的弹载芯片结构进行仿真分析,结果表明,临界应力值与修正后损伤边界符合较好。研究结果可以为集成电路在强机械冲击环境下的可靠性设计和失效分析提供理论依据。 展开更多
关键词 弹载芯片 强机械冲击环境 伪速度冲击响应谱 损伤边界 有限元仿真
下载PDF
型钢高强混凝土柱破坏模式与变形特征研究
10
作者 孙悦 朱伟庆 +1 位作者 贾金青 龙刚 《内蒙古工业大学学报(自然科学版)》 2024年第4期351-359,共9页
开展了4根不同轴压比和箍筋间距的型钢高强混凝土(SRHC)柱的拟静力试验,分析了不同设计参数时SRHC柱的破坏模式的差异。采用有限元软件建立了SRHC柱的有限元模型,在此基础上分析了不同破坏模式时SRHC柱的变形特征以及各设计参数的影响... 开展了4根不同轴压比和箍筋间距的型钢高强混凝土(SRHC)柱的拟静力试验,分析了不同设计参数时SRHC柱的破坏模式的差异。采用有限元软件建立了SRHC柱的有限元模型,在此基础上分析了不同破坏模式时SRHC柱的变形特征以及各设计参数的影响。研究结果表明:剪跨比为3.0的SRHC柱在往复加载初期均表现为以弯曲破坏为主,但轴压比较大或箍筋间距较大的SRHC柱最终发生弯剪破坏。发生弯曲破坏的SRHC柱的滞回曲线更加饱满,骨架曲线下降段更平缓,位移延性系数和极限弹塑性位移角更大,变形能力更强。对于发生弯剪破坏的SRHC柱,轴力更大或箍筋间距更大时,滞回曲线的耗能面积更小,强度和刚度退化更明显,骨架曲线下降段更陡峭,位移延性系数和极限弹塑性位移角更小,变形能力更差。当破坏模式不同时,弯曲变形和剪切变形占总变形的比例也有所不同,发生弯剪破坏的SRHC柱的剪切变形占比较发生弯曲破坏时更大。 展开更多
关键词 型钢高强混凝土柱 破坏模式 变形特征 拟静力试验 有限元模型
下载PDF
预制系梁与柱式墩连接节点力学性能分析
11
作者 孟祥勇 王海军 武加强 《建筑技术开发》 2024年第6期128-131,共4页
我国西部地区地形多为高山峡谷,桥梁下部结构多采用带系梁的双柱式桥墩作为受力构件,为了研究预制钢系梁和混凝土现浇系梁与柱式墩连接位置的节点受力性能,设置了3种类型系梁,利用ABAQUS软件建立有限元模型,进行拟静力试验。通过在盖梁... 我国西部地区地形多为高山峡谷,桥梁下部结构多采用带系梁的双柱式桥墩作为受力构件,为了研究预制钢系梁和混凝土现浇系梁与柱式墩连接位置的节点受力性能,设置了3种类型系梁,利用ABAQUS软件建立有限元模型,进行拟静力试验。通过在盖梁中心施加竖向荷载和水平往复位移,从6个方面研究预制钢系梁和混凝土现浇系梁与双柱式桥墩的节点受力性能。结果表明:混凝土现浇系梁的抵抗变形能力和耗能能力略强于钢材预制系梁,而钢材预制系梁可以更好地减缓刚度退化和抵抗变形,减小地震产生的破坏。 展开更多
关键词 预制系梁 双柱墩 拟静力试验 有限元分析
下载PDF
型钢混凝土剪力墙抗震性能研究
12
作者 王中强 龚莉闳 《重庆建筑》 2024年第10期45-47,51,共4页
为研究型钢混凝土剪力墙结构的抗震性能,应用ABAQUS有限元分析软件建立了普通剪力墙SRC-0、内置于剪力墙暗柱内的模型SRC-1、内置与墙身的模型SRC-V和SRC-X。在低周往复作用下,分析了不同内置形式之间的抗震性能差异。结果表明,内置型... 为研究型钢混凝土剪力墙结构的抗震性能,应用ABAQUS有限元分析软件建立了普通剪力墙SRC-0、内置于剪力墙暗柱内的模型SRC-1、内置与墙身的模型SRC-V和SRC-X。在低周往复作用下,分析了不同内置形式之间的抗震性能差异。结果表明,内置型钢混凝土剪力墙初始刚度得到提升,极限承载能力相比于对照组SRC-0均有不同程度的提高,抗侧移能力和耗能能力得到一定程度的提升,内置型钢明显改善了普通剪力墙的抗震性能。 展开更多
关键词 型钢剪力墙 有限元 拟静力分析 抗震性能
下载PDF
A RECOGNITION OF SIMPLE GROUPS PSL(3,q) BY THEIR ELEMENT ORDERS 被引量:2
13
作者 M.R.Darafsheh A.R.Moghaddamfar A.R.Zokayi 《Acta Mathematica Scientia》 SCIE CSCD 2004年第1期45-51,共7页
For any group G, denote byπe(G) the set of orders of elements in G. Given a finite group G, let h(πe (G)) be the number of isomorphism classes of finite groups with the same set πe(G) of element orders. A group G i... For any group G, denote byπe(G) the set of orders of elements in G. Given a finite group G, let h(πe (G)) be the number of isomorphism classes of finite groups with the same set πe(G) of element orders. A group G is called k-recognizable if h(πe(G)) = k <∞, otherwise G is called non-recognizable. Also a 1-recognizable group is called a recognizable (or characterizable) group. In this paper the authors show that the simple groups PSL(3,q), where 3 < q≡±2 (mod 5) and (6, (q-1)/2) = 1, are recognizable. 展开更多
关键词 element order prime graph projective special linear group
下载PDF
An improved pseudo-static method for seismic resistant design of underground structures 被引量:4
14
作者 刘如山 石宏彬 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2006年第2期189-193,共5页
This paper describes a commonly used pseudo-static method in seismic resistant design of the cross section of underground structures. Based on dynamic theory and the vibration characteristics of underground structures... This paper describes a commonly used pseudo-static method in seismic resistant design of the cross section of underground structures. Based on dynamic theory and the vibration characteristics of underground structures, the sources of errors when using this method are analyzed. The traditional seismic motion loading approach is replaced by a method in which a one-dimensional soil layer response stress is differentiated and then converted into seismic live loads. To validate the improved method, a comparison of analytical results is conducted for internal forces under earthquake shaking of a typical shallow embedded box-shaped subway station structure using four methods: the response displacement method, finite element response acceleration method, the finite element dynamic analysis method and the improved pseudo-static calculation method. It is shown that the improved finite element pseudo-static method proposed in this paper provides an effective tool for the seismic design of underground structures. The evaluation yields results close to those obtained by the finite element dynamic analysis method, and shows that the improved finite element pseudo-static method provides a higher degree of precision. 展开更多
关键词 underground structures seismic design finite element method pseudo-static method dynamic analysis method
下载PDF
2.5-D modeling of cross-hole electromagnetic measurement by nite element method 被引量:3
15
作者 Shen Jinsong Sun Wenbo 《Petroleum Science》 SCIE CAS CSCD 2008年第2期126-134,共9页
A finite element method is developed for simulating frequency domain electromagnetic responses due to a dipole source in the 2-D conductive structures. Computing costs are considerably minimized by reducing the full t... A finite element method is developed for simulating frequency domain electromagnetic responses due to a dipole source in the 2-D conductive structures. Computing costs are considerably minimized by reducing the full three-dimensional problem to a series of two-dimensional problems. This is accomplished by transforming the problem into y-wave number (Ky) domain using Fourier transform and the y-axis is parallel to the structural strike. In the Ky domain, two coupled partial differential equations for magnetic field Hy and electric field Ey are derived. For a specific value of Ky, the coupled equations are solved by the finite element method with isoparametric elements in the x-z plane. Application of the inverse Fourier transform to the Ky, domain provides the electric and magnetic fields in real space. The equations derived can be applied to general complex two-dimensional structures containing either electric or magnetic dipole source in any direction. In the modeling of the electromagnetic measurement, we adopted a pseudo-delta function to distribute the dipole source current and circumvent the problem of singularity at the source point. Moreover, the suggested method used isoparametric finite elements to accommodate the complex subsurface formation. For the large scale linear system derived from the discretization of the Maxwell's equations, several iterative solvers were used and compared to select the optimal one. A quantitative test of accuracy was presented which compared the finite element results with analytic solutions for a dipole source in homogeneous space for different ranges and different wave numbers Ky. to validate the addressed the effects of the distribution range τ of the homogeneous medium. code and check its effectiveness. In addition, we pseudo-delta function on the numerical results in 展开更多
关键词 2.5-D electromagnetic modeling frequency domain isoparametric finite element pseudo-delta function
下载PDF
Pseudo-beam method for compressive buckling characteristics analysis of space inflatable load-carrying structures 被引量:1
16
作者 Changguo Wang Huifeng Tan Xingwen Du Center for Composite Materials,Harbin Institute of Technology, 150001 Harbin, China 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2009年第5期659-668,共10页
This paper extends Le van's work to the case of nonlinear problem and the complicated configuration. The wrinkling stress distribution and the pressure effects are also included in our analysis. Pseudo-beam method is... This paper extends Le van's work to the case of nonlinear problem and the complicated configuration. The wrinkling stress distribution and the pressure effects are also included in our analysis. Pseudo-beam method is presented based on the inflatable beam theory to model the inflatable structures as a set of inflatable beam elements with a prestressed state. In this method, the discretized nonlinear equations are given based upon the virtual work principle with a 3-node Timoshenko's beam model. Finite element simulation is performed by using a 3-node BEAM189 element incorporating ANSYS nonlinear program. The pressure effect is equivalent included in our method by modifying beam element cross-section parameters related to pressure. A benchmark example, the bending case of an inflatable cantilever beam, is performed to verify the accuracy of our proposed method. The comparisons reveal that the numerical results obtained with our method are close to open published analytical and membrane finite element results. The method is then used to evaluate the whole buckling and the loadcarrying characteristics of an inflatable support frame subjected to a compression force. The wrinkling stress and region characteristics are also shown in the end. This method gives better convergence characteristics, and requires much less computation time. It is very effective to deal with the whole load-carrying ability analytical problems for large scale inflatable structures with complex configuration. 展开更多
关键词 Inflatable structure - pseudo-beam method Inflatable beam theory Nonlinear buckling finite element
下载PDF
Continuous finite element methods for Hamiltonian systems
17
作者 汤琼 陈传淼 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第8期1071-1080,共10页
By applying the continuous finite element methods of ordinary differential equations, the linear element methods are proved having second-order pseudo-symplectic scheme and the quadratic element methods are proved hav... By applying the continuous finite element methods of ordinary differential equations, the linear element methods are proved having second-order pseudo-symplectic scheme and the quadratic element methods are proved having third-order pseudo- symplectic scheme respectively for general Hamiltonian systems, and they both keep energy conservative. The finite element methods are proved to be symplectic as well as energy conservative for linear Hamiltonian systems. The numerical results are in agree-ment with theory. 展开更多
关键词 Hamiltonian systems continuous finite element methods pseudo-symplectic energy conservation
下载PDF
C^*代数上pseudo DMP逆的研究
18
作者 付石琴 曹彦 《成都工业学院学报》 2020年第3期47-50,共4页
在条件a=abb^(1,3)、bc=ca,b^*c=ca*及ab=ba下研究pseudo DMP逆及dual pseudo DMP逆在C^*代数上特征及反序。同时,根据m-EP元素的定义与性质,探讨C^*代数上pseudo DMP逆、dual pseudo DMP逆和Moore-Penrose逆的关系。
关键词 pseudo DMP逆 dual pseudo DMP逆 EP元素 C^*代数
下载PDF
ANALYSIS ON PSEUDO-STEADY INDENTATION CREEP
19
作者 Hidenari Takagi Ming Dao Masami Fujiwara 《Acta Mechanica Solida Sinica》 SCIE EI 2008年第4期283-288,共6页
Theoretical analysis and finite element (FE) simulation have been carried out for a constant specific load rate (CSLR) indentation creep test. Analytical results indicate that both the representative stress and th... Theoretical analysis and finite element (FE) simulation have been carried out for a constant specific load rate (CSLR) indentation creep test. Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover, the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate underneath the indenter evolve with geometrical self-similarity. This suggests that pseudo-steady indentation creep occurs in the region beneath the indenter. The representative points in the region are defined as the ones with the equivalent stress equal to the representative stress. In addition, it is revealed that the proportionality between indentation strain rate and equivalent plastic strain rate holds at the representative points during the pseudo-steady indentation creep of a power law material. A control volume (CV) beneath the indenter, which governs the indenter velocity, is identified. The size of the CV at the indented surface is approximately 2.5 times the size of the impression. The stress exponent for creep can be obtained from the pseudosteady indentation creep data. These results demonstrate that the CSLR testing technique can be used to evaluate creep parameters with the same accuracy as conventional uniaxial creep tests. 展开更多
关键词 indentation creep finite element method conical indenter geometrical self-similarity pseudo-steady state control volume stress exponent
下载PDF
有限元法中单元划分优化及约束反力求解策略
20
作者 张国智 《新乡学院学报》 2023年第9期42-45,共4页
针对复杂形状问题的有限元的单元优化及速解,研究了有限元法中单元划分优化及约束反力求解策略。在分析对象的几何形状的基础上,提出了将物体划分为由若干个全等图形和相似图形的单元优化划分方法,并给出了二维典型单元的单元刚度矩阵... 针对复杂形状问题的有限元的单元优化及速解,研究了有限元法中单元划分优化及约束反力求解策略。在分析对象的几何形状的基础上,提出了将物体划分为由若干个全等图形和相似图形的单元优化划分方法,并给出了二维典型单元的单元刚度矩阵的计算公式。同时,针对基于刚性有限元法快速求解约束反力的问题,提出了基于整体刚度矩阵伪逆直接求解约束反力的方法。对典型复杂零件的单元划分的结果表明,单元刚度矩阵计算量减少了83%。对机床支撑筋板螺栓设计的计算结果表明,基于整体刚度矩阵伪逆直接求解约束反力可快速、精确实现螺栓的设计。将提出的单元优化划分方法和直接求解约束反力的求解方法有机结合,可有效提高有限元的计算效率和计算精度。 展开更多
关键词 单元划分优化 全等图形 相似图形 刚性有限元法 伪逆 筋板 螺栓
下载PDF
上一页 1 2 20 下一页 到第
使用帮助 返回顶部