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民用飞机策略化气动弹性载荷方法研究
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作者 胡赞远 谭林林 《机械设计与制造工程》 2023年第12期78-82,共5页
针对现代大型民用飞机静气动弹性载荷分析的需求,建立了策略化的弹性载荷设计方法。采用工程梁法、平板面元法、高阶面元法和大变形法,并引入风洞试验或CFD气动压力数据对飞机压力分布进行修正,对某大型民用飞机进行弹性载荷分析。研究... 针对现代大型民用飞机静气动弹性载荷分析的需求,建立了策略化的弹性载荷设计方法。采用工程梁法、平板面元法、高阶面元法和大变形法,并引入风洞试验或CFD气动压力数据对飞机压力分布进行修正,对某大型民用飞机进行弹性载荷分析。研究表明:在飞机概念设计阶段,可采用工程梁法实现几十万种工况弹性载荷快速分析;在初步设计阶段,可采用优化的工程梁法和平板面元法进行几千种工况的弹性载荷分析;在详细设计阶段,可采用高阶面元法和大变形法进行几百种工况的弹性载荷分析。该策略化的静气动弹性载荷设计方法精度高、效率高,满足了大型民用飞机弹性载荷不同设计阶段需求,具有较强的工程适用性。 展开更多
关键词 工程梁 平板面元 高阶面元 大变形法 静气动弹性载荷
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应用无网格伽辽金方法分析结构大变形问题 被引量:1
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作者 陆新征 杨宁 江见鲸 《结构工程师》 2003年第z1期18-22,共5页
无单元法由于不需要复杂的网格划分,不存在网格畸变问题,因此在大变形分析领域有着广阔的应用前景.本文利用无网格伽辽金(EFGM)方法,对二维结构大变形问题进行了分析,得到了传统有限元方法所难以得到的结果.文中详细讨论了无网格伽辽金... 无单元法由于不需要复杂的网格划分,不存在网格畸变问题,因此在大变形分析领域有着广阔的应用前景.本文利用无网格伽辽金(EFGM)方法,对二维结构大变形问题进行了分析,得到了传统有限元方法所难以得到的结果.文中详细讨论了无网格伽辽金方法的基函数、权函数的选取及影响域的设定,并给出了各参数的具体取值.用计算实例说明了无网格伽辽金方法在解决结构大变形问题上的优势. 展开更多
关键词 无网格伽辽金方 大变形 无单元
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边坡稳定性弹塑性大变形有限元强度折减分析 被引量:11
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作者 张士兵 王练柱 张建 《岩石力学与工程学报》 EI CAS CSCD 北大核心 2004年第z1期4463-4467,共5页
介绍了采用更新拉格朗日法的岩土体弹塑性大变形本构方程和有限元公式的推导过程。运用弹塑性大变形有限元强度折减法分析边坡稳定性,计算程序不收敛,塑性区贯通坡体,边坡失稳。揭示了因降水引起边坡土体强度的降低是边坡发生破坏的主... 介绍了采用更新拉格朗日法的岩土体弹塑性大变形本构方程和有限元公式的推导过程。运用弹塑性大变形有限元强度折减法分析边坡稳定性,计算程序不收敛,塑性区贯通坡体,边坡失稳。揭示了因降水引起边坡土体强度的降低是边坡发生破坏的主要因素,坡体重量的增加是次要因素,为边坡治理设计提供了科学依据。 展开更多
关键词 土力学 弹塑性大变形 更新拉格朗日 强度折减
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Equal channel angular extrusion of NiTi shape memory alloy tube 被引量:3
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作者 江树勇 赵亚楠 +2 位作者 张艳秋 唐明 李春峰 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第7期2021-2028,共8页
As a new attempt, equal channel angular extrusion (ECAE) of nickel-titanium shape memory alloy (NiTi SMA) tube was investigated by means of process experiment, finite element method (FEM) and microscopy. NiTi SM... As a new attempt, equal channel angular extrusion (ECAE) of nickel-titanium shape memory alloy (NiTi SMA) tube was investigated by means of process experiment, finite element method (FEM) and microscopy. NiTi SMA tube with the steel core in it was inserted into the steel can during ECAE of NiTi SMA tube. Based on rigid-viscoplastic FEM, multiple coupled boundary conditions and multiple constitutive models were used for finite element simulation of ECAE of NiTi SMA tube, where the effective stress field, the effective strain field and the velocity field were obtained. Finite element simulation results are in good accordance with the experimental ones. Finite element simulation results reveal that the velocity field shows the minimum value in the corner of NiTi SMA tube, where severe shear deformation occurs. Microstructural observation results reveal that severe plastic deformation leads to a certain grain orientation as well as occurrence of substructures in the grain interior and dynamic recovery occurs during ECAE of NiTi SMA tube. ECAE of NiTi SMA tube provides a new approach to manufacturing ultrafine-grained NiTi SMA tube. 展开更多
关键词 NiTi tube shape memory alloy equal channel angular extrusion severe plastic deformation finite element method
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钢研总院纳米级组织的钢铁材料取得阶段性进展
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《新材料产业》 2003年第7期73-74,共2页
关键词 钢铁材料 塑性大变形法 纳米金属结构材料 不锈钢 钢铁研究总院结构材料研究所
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国内外特厚钢板生产技术及能力分析 被引量:1
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作者 刘熙章 《宽厚板》 2022年第4期7-12,共6页
围绕国内市场需求量巨大的特厚钢板,列举了国内、外钢铁企业生产特厚板时坯料准备以及钢板成形方法,概括了其优缺点,并简要介绍了工程用钢领域特厚板的品种及规格拓展情况。对比得知,国内钢铁企业在产品品种和极限厚度规格的拓展方面均... 围绕国内市场需求量巨大的特厚钢板,列举了国内、外钢铁企业生产特厚板时坯料准备以及钢板成形方法,概括了其优缺点,并简要介绍了工程用钢领域特厚板的品种及规格拓展情况。对比得知,国内钢铁企业在产品品种和极限厚度规格的拓展方面均获得重大研发成果及重点工程应用业绩,产品质量超过国外先进钢铁企业,表明我国特厚板的生产研发能力已经达到国外先进水平。 展开更多
关键词 特厚板 大变形系数轧制 锻轧
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Determination of pile failure mechanism under pullout test in loose sand 被引量:2
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作者 K.Faizi R.Kalatehjari +1 位作者 R.Nazir A.S.A.Rashid 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第4期1490-1501,共12页
Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to inves... Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to investigate the uplift resistance of piles with diameter of 5 cm and slenderness ratios of 1, 2, 3 and 4 in loose sand. Close photogrammetric technique and particle image velocimetry(PIV) were employed to observe the failure patterns due to uplift force on piles. The results show that the shear zones curve slightly outward near the ground surface. After peak resistance, the shear strain concentrates into a pair of narrow shear bands,then a flow around mechanism is formed accompanied by a reduction in the uplift resistance. The results from the laboratory tests were verified by analytical method proposed by Chattopadhyay and PLAXIS 2D and 3D finite element method software. It is found that the depth and width of the failure surface increase with the increment of the slenderness ratio. A good agreement is observed among the measured bearing capacity and obtained failure surface of the models and the results of numerical modelling. Finally, the maximum deformation of loose and dense sand respectively with densities of 25% and 75% were compared in the stage of fully removing pile. The results shows that the deformation of the soil is related to its density, therefore it depends on its dilatancy. 展开更多
关键词 pile uplift sand particle image velocimetry
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A CODEBOOK COMPENSATIVE VOICE MORPHING ALGORITHM BASED ON MAXIMUM LIKELIHOOD ESTIMATION 被引量:1
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作者 Xu Ning Yang Zhen Zhang Linhua 《Journal of Electronics(China)》 2009年第3期346-352,共7页
This paper presents an improved voice morphing algorithm based on Gaussian Mixture Model(GMM) which overcomes the traditional one in the terms of overly smoothed problems of the converted spectral and discontinuities ... This paper presents an improved voice morphing algorithm based on Gaussian Mixture Model(GMM) which overcomes the traditional one in the terms of overly smoothed problems of the converted spectral and discontinuities between frames.Firstly, a maximum likelihood estimation for the model is introduced for the alleviation of the inversion of high dimension matrixes caused by traditional conversion function.Then, in order to resolve the two problems associated with the baseline, a codebook compensation technique and a time domain medial filter are applied.The results of listening evaluations show that the quality of the speech converted by the proposed method is significantly better than that by the traditional GMM method, and the Mean Opinion Score(MOS) of the converted speech is improved from 2.5 to 3.1 and ABX score from 38% to 75%. 展开更多
关键词 Maximum-Likelihood (ML) estimation Codebook compensation Medial filter Voice morphing
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Dynamic Deformation Monitoring for Long-Span Bridges under Construction and EMD De-noising Method
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作者 Shengxiang Huang Chao Kang Wen Zhang 《Journal of Civil Engineering and Architecture》 2016年第7期853-859,共7页
Construction progress of long-span bridge is complicated and the quality control is strict. Any disadvantage during construction may potentially affect the internal forces and deck alignments after it is open to traff... Construction progress of long-span bridge is complicated and the quality control is strict. Any disadvantage during construction may potentially affect the internal forces and deck alignments after it is open to traffic. To exactly evaluate the periodic alignments, internal forces and safety, geometrical and physical monitoring are needed during construction. This study aims at the requirement of dynamic geometric monitoring during Sutong Bridge construction, and introduces the realization and observing schemes of the self-developed GPS real-time dynamic geometrical deformation monitoring system. Affected by wind load and construction circumstance, GPS (global positioning system) monitoring signal contains a variety of noise. And the useful signal can be extracted from the signal after de-noising the noises. A de-noising method based on EMD (empirical mode decomposition) model is introduced here to process the bridge dynamic monitoring data, and with the wavelet threshold de-noising method are compared. The result shows that the EMD method has good adaptability, is free from the choice of wavelet bases and the number of decomposition layer. The method is an effective de-noising method for dynamic deformation monitoring to large-span bridges. 展开更多
关键词 Long-span bridge construction period dynamic deformation monitoring empirical mode decomposition de-noising.
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Crustal Deformation Derived from GPS in the Chinese Mainland from 1991-2004
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作者 Cao Jianling Wang Hui +2 位作者 Wu Yanqiang Liu Xiaoxia Zhang Jing 《Earthquake Research in China》 CSCD 2015年第2期225-236,共12页
Based on GPS data from 1991- 2004 and the least-squares collocation method,we analyze the crustal deformation in the Chinese mainland. The results show that the first-order crustal deformation is unchanged in differen... Based on GPS data from 1991- 2004 and the least-squares collocation method,we analyze the crustal deformation in the Chinese mainland. The results show that the first-order crustal deformation is unchanged in different periods in the Chinese mainland,which reflects the background of regional tectonic activity. The strain rate is much higher in Western China,especially in the Qinghai-Tibetan Plateau and Sichuan-Yunnan area. The variations in different periods are related with seismicity of strong earthquakes during the same time. The GPS data after 2004 shows the post-seismic deformation of the 2001 Kunlun Mountains M S8. 1 earthquake. 展开更多
关键词 Chinese mainland GPS Present-day crustal deformation Least squaresCollocation
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高效愈合钢锭内部缺陷的锻造工艺设计 被引量:6
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作者 李殿中 马璇 +1 位作者 徐斌 孙明月 《金属学报》 SCIE EI CAS CSCD 北大核心 2016年第10期1199-1206,共8页
总结了宽砧径向压实工艺(WRF法),该工艺可使应变集中于钢锭中心区域,并满足孔洞闭合所需的最佳高径比条件,因此可高效愈合钢锭的中心缩孔、疏松.基于该方法,针对压机压力较小的情况,提出了单向大变形压实法.该方法通过两个道次的单方向... 总结了宽砧径向压实工艺(WRF法),该工艺可使应变集中于钢锭中心区域,并满足孔洞闭合所需的最佳高径比条件,因此可高效愈合钢锭的中心缩孔、疏松.基于该方法,针对压机压力较小的情况,提出了单向大变形压实法.该方法通过两个道次的单方向变形将坯料锻造成扁方状,可以使用小压力实现较大钢锭内缺陷的有效愈合.基于界面焊合原理,针对管板类锻件探伤合格率较低的问题,提出了管板类锻件的锻间保温锻造法.利用该方法成功进行了含缺陷管板的修复实验.以上各锻造工艺均经过工业实验验证,证明其可以顺利愈合锻件内的孔洞型缺陷,提高锻件合格率. 展开更多
关键词 孔洞闭合 宽砧径向压实 单向大变形压实 锻间保温锻造
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Three dimensional efficient meshfree simulation of large deformation failure evolution in soil medium 被引量:4
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作者 WANG DongDong LI ZhuoYa +1 位作者 LI Ling WU YouCai 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第3期573-580,共8页
An efficient Galerkin meshfree formulation for three dimensional simulation of large deformation failure evolution in soils is presented. This formulation utilizes the stabilized conforming nodal integration, where fo... An efficient Galerkin meshfree formulation for three dimensional simulation of large deformation failure evolution in soils is presented. This formulation utilizes the stabilized conforming nodal integration, where for the purpose of stability and efficiency a Lagrangian smoothing strain at nodal point is constructed and thereafter the internal energy is evaluated nodally. This formulation ensures the linear exactness, efficiency and spatial stability in a unified manner and it makes the conventional Galerkin meshfree method affordable for three dimensional simulation. The three dimensional implementation of stabilized conforming nodal integration is discussed in details. To model the failure evolution in soil medium a coupled elasto-plastic damage model is used and an objective stress integration algorithm in combination of elasto-damage predictor and plastic corrector method is employed for stress update. Two typical numerical examples are shown to demonstrate the effectiveness of the present method for modeling large deformation soil failure. 展开更多
关键词 meshfree method three dimensions stabilized conforming nodal integration failure evolution large deformation
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A New Model for Simulation of Cold Roll-Forming of Tubes by Using Spline Finite Strip Method 被引量:4
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作者 张乐乐 谭南林 刘才 《Journal of Shanghai Jiaotong university(Science)》 EI 2010年第1期70-75,共6页
A new model,called object model,for the simulation of cold roll-forming of tubes is presented.The model inherits the advantages of old models and is the embodiment of forming process that the strip is rolled step by s... A new model,called object model,for the simulation of cold roll-forming of tubes is presented.The model inherits the advantages of old models and is the embodiment of forming process that the strip is rolled step by step from feed rollers to last rolling pass.The elastic-plastic large deformation spline finite strip method based on updated Lagrangian method has been developed by improving the stiffness and transition matrix.Combined theory formulas and new analytical model,the forming process of a tube has been simulated successfully as an example.The analytical results are submitted and indicate that the proposed simulation method and new model are applicable. 展开更多
关键词 cold roll forming of tubes object model elastic-plastic deformation spline finite strip method
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