期刊文献+
共找到17篇文章
< 1 >
每页显示 20 50 100
Topology optimization of 3D structures with design-dependent loads 被引量:1
1
作者 Hui Zhang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第5期767-775,共9页
Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A bou... Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A boundary search scheme is proposed for 3D problems, by means of which the load surface can be identified effectively and efficiently, and the difficulties arising in other approaches can be overcome. The load surfaces are made up of the boundaries of finite elements and the loads can be directly applied to corresponding element nodes, which leads to great convenience in the application of this method. Finally, the effectiveness and efficiency of the proposed method is validated by several numerical examples. 展开更多
关键词 Design-dependent loads Topology optimization 3D structures - load surface Pressure loading
下载PDF
Progressive collapse resisting capacity of reinforced concrete load bearing wall structures 被引量:1
2
作者 Alireza Rahai Alireza Shahin Farzad Hatami 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2730-2738,共9页
Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthqu... Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the "load factor" parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure. 展开更多
关键词 reinforced concrete(RC) load bearing wall structure progressive collapse fiber sections nonlinear analysis load factor method
下载PDF
An improved model for predicting effective Young's modulus of the twisted structure under cyclic loading:taking into account the untwisting effect
3
作者 Hexin Cui Donghua Yue +1 位作者 Xingyi Zhang Youhe Zhou 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2018年第2期132-136,共5页
Twist structures have diverse applications, ranging from dragline, electrical cable, and intelligent structure. Among these applications, tension deformation can't be avoided during the fabrication and working proces... Twist structures have diverse applications, ranging from dragline, electrical cable, and intelligent structure. Among these applications, tension deformation can't be avoided during the fabrication and working processes, which often leads to the twist structure rotation (called untwisting effect) and twist pitch increasing. As a consequence, this untwisting behavior has a large effect on the effective Young's modulus. In this paper, we present an improved model based on the classical Costello's theory to predict the effective Young's modulus of the basic structure, twisted by three same copper strands under cyclic loading. Series of experiments were carried out to verify the present model taking into account the untwisting effect. The experimental results have better agreements with the presented model than the common Costello's model. 展开更多
关键词 Twist structure Young's modulus Cyclic loading Untwisting effect
下载PDF
Hot Spot in Materials with Structural Defects under High Shear Loading Rates 被引量:1
4
作者 S. G.Psakhie K.P.Zolnikov and D. Yu.Saraev (Institute of Strength Physics and Materials Science, Russian Academy of Sciences, Siberian Branch,Akademicheskii pr.2/1, 634021 Tomsk, Russia) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1998年第1期72-74,共3页
The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopo... The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopotential theory Solitary waves were generated in the sample under mechanical loading. Their interaction with the vacancy complexes was shown to be able to initiate hot spot in that local region of the complexes. Some parameters of the hot spot as well as solitary waves were calculated. The initiation of the hot spot is accompanied with sufficient local structural relaxation. 展开更多
关键词 REV Hot Spot in Materials with Structural Defects under High Shear loading Rates
下载PDF
Seawater Corrosion Fatigue of Welded Joints Under Random Variable Amplitude Loading
5
作者 Xue, Yinian Xu, Jilin +1 位作者 Li, Yanping Li, He 《China Ocean Engineering》 SCIE EI 1993年第2期139-146,共8页
Offshore platforms are always subjected to wave action which is random variable amplitude cyclic loading. In order to simulate the stressing condition at the 'hot spot' of the tubular joints and the marine env... Offshore platforms are always subjected to wave action which is random variable amplitude cyclic loading. In order to simulate the stressing condition at the 'hot spot' of the tubular joints and the marine environment, random variable amplitude fatigue tests have been carried out on welded plate joints in sea water. The tests have been conducted under the conditions of loading frequency of 0.2 Hz/, stress ratio of -1, seawater temperature of about 20°C and cathodic protection with the potential about -850 mV, SCE. The test results have been compared with the seawater corrosion fatigue life under constant amplitude loading. Miner's linear cumulative damage summation rule has been used to predict the corrosion fatigue life under variable amplitude loading. The predicted life is in good agreement with the test data. 展开更多
关键词 Cathodic protection Corrosion fatigue Failure (mechanical) Fatigue testing Joints (structural components) Offshore structures Production platforms Seawater Stresses Structural loads Water waves WELDS
下载PDF
Application of Digital Image Correlation and Geodetic Displacement Measuring Methods to Monitor Water Dam Behavior under Dynamic Load
6
作者 Janina Zaczek-Peplinska Maria Elzbieta Kowalska +1 位作者 Krzysztof Malowany MarcinMalesa 《Journal of Civil Engineering and Architecture》 2015年第12期1496-1505,共10页
This paper presents experiment results of the measurement conducted at the Roznew Dam power plant. For a course of starting and operating of turbo-plants, downstream face of the dam was monitored in relation to its ev... This paper presents experiment results of the measurement conducted at the Roznew Dam power plant. For a course of starting and operating of turbo-plants, downstream face of the dam was monitored in relation to its eventual displacements on direction parallel to the construction axis. For the purpose of the experiment, geodetic measurement techniques and 2D DIC (digital image correlation) method (utilizing photographs of the object recorded with digital camera) were compared with regard to credibility, efficiency and accuracy. The vertical and horizontal displacements were monitored by tachometers measurements. The deformations in x-axis and y-axis on the wall surface was monitored by 2D DIC. It has been noticed that 2D DIC method is a surface method, continuous--not discreet. It allows for continuous observations of surface deformations, which is not possible in case of tachemetric measurements. Despite many advantages, the 2D DIC method lacks unambiguous evaluation of precision and relevance of designated displacements, which is rather significant for possibilities of utilization in technical control of large engineered objects. It should be also marked that the tachometric method is more reliable but is more laborious. Research of this type might comprise additional element for the assessment of the influence of dynamic loads, such as activating turbine water flow, onto the overall condition of the surveyed structure. 展开更多
关键词 Hydrotechnical structure structure dynamic load engineering object displacement geodetic displacement measurements.digital image correlation.
下载PDF
Observer-Based Disturbance Accommodation Control Strategy for Useful Lifetime Control and Structural Load Mitigation of Wind Turbines
7
作者 Rutendo Goboza Jackson Githu Njiri James Kuria Kimotho 《Journal of Power and Energy Engineering》 2022年第7期31-55,共25页
Wind turbines undergo degradation due to various factors which induce stress, thereby leading to fatigue damage to various wind turbine components. In addition, the current increase in demand for electrical power has ... Wind turbines undergo degradation due to various factors which induce stress, thereby leading to fatigue damage to various wind turbine components. In addition, the current increase in demand for electrical power has led to the development of large wind turbines, which result in increased structural loads, therefore, increasing the possibility of early failure due to fatigue load. This paper proposes a proportional integral observer (PI-Observer) based disturbance accommodation controller (DAC) with individual pitch control (IPC) for load mitigation to reduce components’ damage and ensure the wind turbine is operational for the expected lifetime. The results indicate a reduction in blades’ bending moments with a standard deviation of 15.9%, which positively impacts several other wind turbine subsystems. Therefore, the lifetime control strategy demonstrates effective structural load mitigation without compromise on power generation, thus, achieving a nominal lifetime control to inhibit premature failure. 展开更多
关键词 Disturbance Accommodation Control Individual Pitch Control Lifetime Control Structural load Mitigation
下载PDF
EFFECTS OF SPLITTER BLADES ON THE LAW OF INNER FLOW WITHIN CENTRIFUGAL PUMP IMPELLER 被引量:16
8
作者 YUAN Shouqi ZHANG Jinfeng YUAN Jianping HE Youshi FU Yuedeng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2007年第5期59-63,共5页
Analysis on the inner flow field of a centrifugal pump impeller with splitter blades is carfled out by numerical simulation. Based on this analysis, the principle of increasing pump head and efficiency are discussed. ... Analysis on the inner flow field of a centrifugal pump impeller with splitter blades is carfled out by numerical simulation. Based on this analysis, the principle of increasing pump head and efficiency are discussed. New results are obtained from the analysis of turbulence kinetic energy and relative velocity distribution: Firstly, unreasonable length or deviation design of the splitter blades may cause great turbulent fluctuation in impeller channel, which has a great effect on the stability of impeller outlet flow; Secondly, it is found that the occurrence of flow separation can be decreased or delayed with splitter blades from the analysis of blade loading; Thirdly, the effect of splitter blades on reforming the structure of "jet-wake" is explained from the relative velocity distribution at different flow cross-sections, which shows the flow process in the impeller. The inner flow analysis verifies the results of performance tests results and the PIV test. 展开更多
关键词 Centrifugal pump Splitter blades Turbulent kinetic energy structure of "jet-wake"Blade loading
下载PDF
Stiffeners layout design of thin-walled structures with constraints on multi-fastener joint loads 被引量:6
9
作者 Jie HOU Jihong ZHU +2 位作者 Fei HE Weihong ZHANG Wenjie GUO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2017年第4期1441-1450,共10页
The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are consider... The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are considered simultaneously. On one hand, the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners. On the other hand, the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface. It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation. The effects of the extended method with two different constraints are highlighted by typical numerical examples. Compared with the standard topology optimization, the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level. 展开更多
关键词 Joint load constraint Manufacturing constraint Stiffeners Thin-walled structures Topology optimization
原文传递
Perturbation Analysis of the Attached Water Mass Effect on Offshore Platform Dynamic Response
10
作者 Chu, Liangcheng Qu, Naisi +1 位作者 Guo, Yonggang Lu, Min 《China Ocean Engineering》 SCIE EI 1993年第4期369-382,共14页
Theoretically speaking, it is impossible to make the differential equation of motion uncoupled for the natural modes of a system in consideration of the attached water. The hydro-elastic structure is equal to the non-... Theoretically speaking, it is impossible to make the differential equation of motion uncoupled for the natural modes of a system in consideration of the attached water. The hydro-elastic structure is equal to the non-proportional damping system. In this paper a perturbation analysis method is put forward. The structure motion equation is strictly solved mathematically, and the non-proportional damping problem is transformed into a series of proportional damping ones in the superposition form. The paper also presents the calculation formula of the dynamic response of the structure being subjected to harmonic and arbitrary load. The convergence of the proposed method is also studied in this paper, and the corresponding convergence conditions are given. Finally, the proposed method is used to analyze the displacement response of a real offshore platform. The calculation results show that this method has the characteristics of high accuracy and fast convergence. 展开更多
关键词 Convergence of numerical methods DAMPING Dynamic response Equations of motion Mathematical models Perturbation techniques Structural analysis Structural loads WATER
下载PDF
Regression Formulations for the Stress at Hot Spot of Multiplanar Tubular DT Joints
11
作者 Chen, Tieyun Zhang, Huiyuan 《China Ocean Engineering》 SCIE EI 1993年第1期1-20,共20页
Stress concentration analysis of multiplanar tubular DT joints plays an important role in the fatigue design of offshore platforms. A semi-analytic method for stress analysis under the condition of any loads is briefl... Stress concentration analysis of multiplanar tubular DT joints plays an important role in the fatigue design of offshore platforms. A semi-analytic method for stress analysis under the condition of any loads is briefly introduced in the paper. Nineteen multiplanar tubular DT joints with one of two braces of the same dimension subjected to axial loads and out- of- plane bending moments are computed for parametric stress analysis by using the present method. The influence of geometrical parameters on the stresses of multiplanar tubular DT joints is discussed and compared with corresponding uniplanar T joints. The regression formulae for the stress at hot spot of multiplanar DT joints are found by modification of SCF of corresponding uniplanar T joints. The parametric formulae for the maximum stress by superposition. Finally, the influences of stiffening effect and load-interaction effect on the maximum stress of DT joints are discussed. 展开更多
关键词 Bending (deformation) Finite element method Joints (structural components) Offshore structures Regression analysis Structural loads
下载PDF
Static response of a layered magneto-electro-elastic half-space structure under circular surface loading
12
作者 Jiangyi Chen Junhong Guo 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2017年第2期145-153,共9页
A cylindrical system of vector functions, the stiffness matrix method and the corresponding recursive algorithm are proposed to investigate the static response of transversely isotropic,layered magneto-electro-elastic... A cylindrical system of vector functions, the stiffness matrix method and the corresponding recursive algorithm are proposed to investigate the static response of transversely isotropic,layered magneto-electro-elastic(MEE) structures over a homogeneous half-space substrate subjected to circular surface loading. In terms of the system of vector functions, we expand the extended displacements and stresses, and deduce two sets of ordinary differential equations, which are related to the expansion coeficients. The solution to one of the two sets of these ordinary differential equations can be evaluated by using the stiffness matrix method and the corresponding recursive algorithm. These expansion coeficients are then integrated by adaptive Gaussian quadrature to obtain the displacements and stresses in the physical domain. Two types of surface loads, mechanical pressure and electric loading,are considered in the numerical examples. The calculated results show that the proposed technique is stable and effective in analyzing the layered half-space MEE structures under surface loading. 展开更多
关键词 Magneto-electro-elastic material Layered and half-space structure Stiffness matrix method System of vector functions Surface loading
原文传递
VERIFICATION AND COMPARISON OF FORMULAS FOR BED LOAD TRANSPORT 被引量:3
13
作者 Wang, X.K. Li, D.X. +1 位作者 Qu, Z.S. Wang, D.C. 《Journal of Hydrodynamics》 SCIE EI CSCD 2001年第1期8-11,共4页
Several typical formulas for bed load transport are examined based on field data. It is concluded that the Einstein formula provides good estimates for the bed load transport rate while other ones predict much lower t... Several typical formulas for bed load transport are examined based on field data. It is concluded that the Einstein formula provides good estimates for the bed load transport rate while other ones predict much lower transport rates. The main reason for the under-prediction is that Dp, the effective diameter of particles, is too large as a representative diameter of the bed material for gravel streams with partially movable bed. Performance of these formulas can be significantly improved if D35 is adopted instead of Dp. 展开更多
关键词 loads (forces) Structural loads
原文传递
Synthesis of hollow and mesoporous structured NaYF4:Yb,Er upconversion luminescent nanoparticles for targeted drug delivery 被引量:6
14
作者 梁旭华 樊君 +5 位作者 王永波 赵艳艳 靳如意 孙涛 程敏 王学军 《Journal of Rare Earths》 SCIE EI CAS CSCD 2017年第5期419-429,共11页
In this paper, we demonstrated a one-step template-free strategy to fabricate a hollow mesoporous structured NaY F4:Yb,Er nanoparticles with excellent upconversion luminescence. Folic acid(FA), a commonly used canc... In this paper, we demonstrated a one-step template-free strategy to fabricate a hollow mesoporous structured NaY F4:Yb,Er nanoparticles with excellent upconversion luminescence. Folic acid(FA), a commonly used cancer-targeting agent, was conjugated on the surface of the nanoparticles based on the presence of free amine groups, which were labeled as NaY F4:Yb,Er-FA HMUCNPs. The properties were extensively studied, which indicated the obtained samples showed a typical hollow mesoporous structure and excellent upconversion luminescence that were useful for cell imaging and drug delivery. The L929 cells viability, hemolysis assay and coagulation test demonstrated good biocompatibility of the samples. The anti-cancer drug doxorubicin hydrochloride(DOX) storage/release properties were demonstrated to be pH-responsive, in which, the drug release might be beneficial at the reduced pH for targeted release and controlled therapy. Moreover, it was found that DOX-loaded NaY F4:Yb,Er-FA HMUCNPs exhibited greater cytotoxicity to KB cells than free DOX due to the specific cell uptake by KB cells via folate receptor-mediate endocytosis. Therefore, the multifunctional nanoparticles combining upconversion luminescent property and hollow mesoporous structure have potential for simultaneous targeted anti-cancer drug delivery and cell imaging. 展开更多
关键词 hollow luminescent structured template luminescence targeted fabricate loaded coagulation conjugated
原文传递
Aerodynamic and structural characteristics of helicopter rotor in circling flight
15
作者 Xu ZHOU Xiayang ZHANG +1 位作者 Bo WANG Qijun ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第12期282-296,共15页
To investigate the distinct properties of the helicopter rotors during circling flight,the aerodynamic and dynamic models for the main rotor are established considering the trim conditions and the flight parameters of... To investigate the distinct properties of the helicopter rotors during circling flight,the aerodynamic and dynamic models for the main rotor are established considering the trim conditions and the flight parameters of helicopters.The free wake method is introduced to compute the unsteady aerodynamic loads of the rotor characterized by distortions of rotor wakes,and the modal superposition method is used to predict the overall structural loads of the rotor.The effectiveness of the aerodynamic and the structural methods is verified by comparison with the experimental results,whereby the influences of circling direction,radius,and velocity are evaluated in both aerodynamic and dynamic aspects.The results demonstrate that the circling condition makes a great difference to the performance of rotor vortex,as well as the unsteady aerodynamic loads.With the decrease of the circling radius or the increment of the circling velocity,the thrust of the main rotor increases apparently to balance the inertial force.Meanwhile,the harmonics of aerodynamic loads in rotor disc change severely and an evident aerodynamic load shock appears at high-order components,which further causes a shift-of-peak-phase bending moment in the flap dimension.Moreover,the advancing side of blade experiences second blade/vortex interaction,whose intensity has a distinct enhancement as the circling radius decreases with the motion of vortexes. 展开更多
关键词 Aerodynamic load Circling state Free wake method Modal superposition method Structural load
原文传递
A Mathematical Model for Helicopter Comprehensive Analysis 被引量:5
16
作者 李攀 陈仁良 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2010年第3期320-326,共7页
This article presents a new mathematical model for helicopter comprehensive analysis with the features of flexibility and mathematical simplicity. The model synthesizes the rigid fuselage motion model with 6 degrees o... This article presents a new mathematical model for helicopter comprehensive analysis with the features of flexibility and mathematical simplicity. The model synthesizes the rigid fuselage motion model with 6 degrees of freedom,coupled flap-lag-torsion elastic rotor blade motion model,unsteady aerodynamics model with dynamic stall and high order generalized dynamic wake model. A new blade structural operator with implicit form is formulated,and the components of the blade structure model are independent of each other so that it is convenient to change or handle any component of blade structure without changing the others. What is more,the entire model is developed in a strict state-space form to simplify the comprehensive analysis. Finally,the UH-60 helicopter is taken as an example to predict the blade natural characteristics,the trim characteristics including controls and fuselage attitudes as well as the airloads at blade section under the flight conditions of high speed with moderate thrust and high thrust with moderate speed. The results are compared with UH-60 flight test data and those predicted by two well-known comprehensive codes. The validity of the model presented in this article is verified. 展开更多
关键词 helicopters rotors structural loads aerodynamic loads dynamic stall
原文传递
Longitudinal connection effect on initial support steel frames in tunnels--Take the traffic tunnels as examples 被引量:2
17
作者 Kaimeng Ma Jichun Zhang +2 位作者 Junru Zhang Zhiyong Wang Jimeng Feng 《Underground Space》 SCIE EI 2022年第4期608-622,共15页
Most tunnel projects are designed with cross-sectional loads,and the inhomogeneity of the longitudinal forces is ignored.In theory,such a support structure can resist large loads,but in practice,large deformation,conc... Most tunnel projects are designed with cross-sectional loads,and the inhomogeneity of the longitudinal forces is ignored.In theory,such a support structure can resist large loads,but in practice,large deformation,concrete cracking,steel frame distortion,and other phenomena often occur in tunnels under poor surrounding rock conditions.Hence,the longitudinal stability of the tunnel must be considered.In this study,the mechanism of longitudinal connecting ribs(LCRs)of tunnels was investigated through element tests,theoretical analyses,and numerical simulations,and the effect of the LCRs was evaluated experimentally.The applicability of the constitutive relations and boundary conditions of the numerical model was verified.The instability mode of the steel frame reflecting the longitudinal stress gradient of the tunnel was analyzed,and the longitudinal surrounding rock pressure and the verified numerical model were applied to analyze the LCR using the load structure method.The results indicate the following:(1)LCRs can effectively improve the ultimate bearing capacity and stability of a structure and reduce the area and degree of damage;(2)Two types of instability modes occur in tunnel steel frames,and the main factor is bending failure caused by the axial force;(3)The distance sensitivity of the LCR in the tunnel is higher than the stiffness sensitivity.For large deformations of tunnels,double rows of rebars with a spacing of less than 1.5 m should be used as longitudinal connections. 展开更多
关键词 TUNNEL Longitudinal connecting ribs load structure method Optimization design EXPERIMENT
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部