共查询到20条相似文献，搜索用时 234 毫秒
1.
The purpose of this study was to build a flexible mechanical system with a hydrostatic skeleton. The main components of this system are two type flexible bags. One is a structural bag with constant inner pressure. The other is an actuator bag with controlled inner pressure. To design the system, it was necessary to estimate both structural deformation and driving force. Nu- merical analysis of flexible bags, however, is difficult because of large nonlinear deformation. This study analyzed structural strength and driving force of flexible bags with the nonlinear finite element analysis （FEA） software ABAQUS. The stress con- centration dependency on the bag shape is described and the driving force is calculated to include the large deformation. From the analytical results, this study derives an empirical equation of driving force. The validity of the equation was confirmed by condition-changed analyses and experimental results. 相似文献
2.
SUNGWen-pei LINCheng-I SHIHMing-hsiang GOCheer-germ 《浙江大学学报(A卷英文版)》2005,6(2):132-140
In view of the recent technological development, the pursuit of safe high-precision structural designs has been the goal of most structural designers. To bridge the gap between the construction theories and the actual construction techniques, safety factors are adopted for designing the strength loading of structural members. If safety factors are too conservative, the extra building materials necessary will result in high construction cost. Thus, there has been a tendency in the construction field to derive a precise buckling load analysis model of member in order to establish accurate safety factors. A numerical analysis model, using modal analysis to acquire the dynamic function calculated by dynamic parameter to get the buckling load of member, is proposed in this paper. The fixed and simple supports around the circular plate are analyzed by this proposed method. And then, the Monte Carlo method and the normal distribution method are used for random sampling and measuring errors of numerical simulati 相似文献
3.
This paper presents a method for isolatedly solving the normal mode of vi-bration according to the uncoupling condition of vibrations inside and outside the archplane.The finite element method for curved beam elements is adopted to analyse the dy-namic characteristics of arch structures and the calculating program is made.The resultsobtained from Apple II microcomputer are compared with those from SAP5 program byan example,and are in good agreement. 相似文献
4.
HU Ying-chun LI Shang-ping 《重庆大学学报(英文版)》2007,6(3):187-191
A three-dimensional model of the uplift device of a sugarcane harvester was built up in Pro/Engineer. Simulation and evaluation of its motional and dynamic performance were performed with the automatic dynamic analysis of mechanical system (ADAMS). ANSYS program was applied to the structural analysis of the model. A finite element analytic model was built up with the bottom-up methodology and was meshed. The default Block Lanczos method was used to work out the native frequency. The results indicate that the five lower modes-the transpotaion wheel, the left holding device, the right holding device, the left cutter disk, and the right cutter disk- and displacement of vibratory type only slightly affect the process of sugarcane harvester and harvesting quality. So it is advisable that the optimization of the static intensity other than the dynamic stiffness of uplift device be executed. 相似文献
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Fundamental principles from structural dynamics, random theory and perturbation methods are adopted to develop a new response spectrum combination rule for the seismic analysis of non-classically damped systems, such as structure-damper systems. The approach, which is named the perturbation spectrum method, can provide a more accurate evaluation of a non-classically damped system＇s mean peak response in terms of the ground response spectrum. To account for the effect of non-classical damping, all elements are included in the proposed method for seismic analysis of structure, which is usually approximated by ignoring the off-diagonal elements of the modal damping matrix. Moreover, as has been adopted in the traditional Complete Quadratic Combination （CQC） method, the white noise model is also used to simplify the expressions of perturbation correlation coefficients. Finally, numerical work is performed to examine the accuracy of the proposed method by comparing the approximate results with exact ones and to demonstrate the importance of the neglected off-diagonal elements of the modal damping matrix. In the examined cases, the proposed method shows good agreement with direct time-history integration. Also, the perturbation spectrum method leads to a more efficient and economical calculation by avoiding the integral and complex operation. 相似文献
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The duct static pressure reset (DSPR) control method is a popular modern control method widely applied to variable air volume (VAV) systems of commercial buildings. In this paper, a VAV system simulation program was used to predict the system performance and zone air temperature of two kinds of layouts that were applied to a typical floor of an existing building office in Hong Kong. The position where the static pressure sensor was placed should affect the zones temperature and energy consumption. The comparison of predictions of the two kinds of layouts indicates that with the same DSPR control method the layout of the air duct might influence the fan control result and energy savings. 相似文献
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The variation of the vibration characteristics of a Huanghua pear was investigated using finite element simulations. A new image processing technique was used to obtain the unsymmetrical and un-spherical geometrical model of a pear. The vibration characteristics of this type of pear with the correlation of its behavior with geometrical configurations and material characteristics were investigated using numerical modal analysis. The results showed that the eigenfrequency increased with the increasing pear Young＇s modulus, while decreased with increasing pear density, and decreased with increasing pear volume. The results of this study provided foundation for further investigations of the physical characteristics of fruits and vegetables by using finite element simulations. 相似文献
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To improve the static and dynamic performance of hydrodynamic journal beatings, a novel bearing is developed, which is a cone-shaped hydrodynamic bearing with spiral oil wedges. The major structural feature of this bearing is the three spiral circular recesses on the beating‘s surface, leading to improved characteristics. This paper aims to develop a model for design and calculation of the geometric parameters and the oil film thickness, and to provide a theoretical analysis to the static characteristics using a f‘mite element method. Some new features are introduced. 相似文献
9.
FANG You-tong YAO Ying-ying 《浙江大学学报(A卷英文版)》2007,8(3):412-415
In this paper, a modified transient finite element (FE) algorithm for the performance analysis of magnetically levitated vehicles of electromagnetic type is presented. The algorithm incorporates the external power system and vehicle’s movement equations into FE model of transient magnetic field computation directly. Sliding interface between stationary and moving region is used during the transient analysis. The periodic boundaries are implemented in an easy way to reduce the computation scale. It is proved that this method can be used for both electro-motional static and dynamic cases. The test of a transformer and an EMS-Maglev system reveals that the method generates reasonable results at very low computational costs comparing with the transient FE analysis. 相似文献
10.
The objective of this study was to develop, as well as validate the strongly coupled method （two-way fluid structural interaction （FSI）） used to simulate the transient FSI response of the vertical axis tidal turbine （VATT） rotor, subjected to spatially varying inflow. Moreover, this study examined strategies on improving techniques used for mesh deformation that account for large displacement or deformation calculations. The blade＇s deformation for each new time step is considered in transient two-way FSI analysis, to make the design more reliable. Usually this is not considered in routine one-way FSI simulations. A rotor with four blades and 4-m diameter was modeled and numerically analyzed. We observed that two-way FSI, utilizing the strongly coupled method, was impossible for a complex model; and thereby using ANSYS-CFX and ANSYS-MECHANICAL in work bench, as given in ANSYS-WORKBENCH, helped case examples 22 and 23, by giving an error when the solution was run. To make the method possible and reduce the computational power, a novel technique was used to transfer the file in ANSYS-APDL to obtain the solution and results. Consequently, the results indicating a two-way transient FSI analysis is a time- and resource-consuming job, but with our proposed technique we can reduce the computational time. The ANSYS STRUCTURAL results also uncover that stresses and deformations have higher values for two-way FSI as compared to one-way FSI. Similarly, fluid flow CFX results for two-way FSI are closer to experimental results as compared to one-way simulation results. Additionally, this study shows that, using the proposed method we can perform coupled simulation with simple multi-node PCs （core i5）. 相似文献
11.
李远瑛 《洛阳工业高等专科学校学报》2006,16(2):19-20,61
利用有限元分析软件ANSYS对某高层建筑结构进行模态分析,建立高层建筑结构的三维模型,研究该结构的动力特性,并将计算得到结构的自振周期同经验公式比较,探讨计算高层建筑结构自振周期的影响因素,结果表明两种计算方法结果十分接近,验证了有限元分析的正确性。 相似文献
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This paper deals with the along-wind dynamic response of tall buildings passively controlled by Cross-Tensioned Spring Damper
(CTSD) mechanisms. In order to estimate the dynamic response more accurately and efficiently, the building and its CTSD controllers
were considered as a coupled non-classical damping system and a new stochastic response analysis method, complex-modal state-space
method, was proposed based on the combination of complex modes of the structural system rather than on the real-modal decomposition
as usual. As numerical examples, the displacement response of a 2-degree-of-freedom system to white-noise input is first considered
and the validity and accuracy of the proposed method are demonstrated through comparison with the exact results. The wind-induced
dynamic responses of a tall building controlled by two CTSD mechanisms are then analyzed. The calculation results showed that
the proposed method is much more appropriate and accurate than the conventional real-modal decomposition method in the analysis
of dynamic responses of passively controlled tall buildings.
Project (59478034) supported by National Natural Science Foundation of China (NSFC). 相似文献
13.
Beth M. Casey Elizabeth E. Pezaris Julie Bassi 《Learning and individual differences》2012,22(1):25-36
Two studies were conducted on block building in adolescents, assessing middle school (Study 1) and high school students (Study 2). Students were asked to build something interesting with blocks. In both samples, the same pattern of gender differences were found; boys built taller structures than girls, and balanced a larger number of blocks on a small base of upright blocks (a new measure developed for this study). Gender differences in the height of structures were fully mediated by this measure of structural balance. These findings suggest that balance elements are key to understanding gender differences in block building. In Study 2, high-school students were given a second task, requiring them to apply structural balance principles (only four upright blocks were provided on which to build), and instructing them to build a tall, complex, well-balanced structure. Gender differences again were found, suggesting that gender differences in block building may be skill-based as well as stylistic. A separate question was whether block-building characteristics at this age have any relevance to math achievement. In both studies, the measure of structural balance was the only block-building characteristic that predicted math achievement. Additional research is needed to understand the cognitive underpinnings of this new spatial measure, how malleable it is, and its further practical significance for adolescent learners. 相似文献
14.
In the structural design of tall buildings, peak factors have been widely used to predict mean extreme responses of tall buildings
under wind excitations. Vanmarcke’s peak factor is directly related to an explicit measure of structural reliability against
a Gaussian response process. We review the use of this factor for time-variant reliability design by comparing it to the conventional
Davenport’s peak factor. Based on the asymptotic theory of statistical extremes, a new closed-form peak factor, the so-called
Gamma peak factor, can be obtained for a non-Gaussian resultant response characterized by a Rayleigh distribution process.
Using the Gamma peak factor, a combined peak factor method was developed for predicting the expected maximum resultant responses
of a building undergoing lateral-torsional vibration. The effects of the standard deviation ratio of two sway components and
the inter-component correlation on the evaluation of peak resultant response were also investigated. Utilizing wind tunnel
data derived from synchronous multi-pressure measurements, we carried out a wind-induced time history response analysis of
the Commonwealth Advisory Aeronautical Research Council (CAARC) standard tall building to validate the applicability of the
Gamma peak factor to the prediction of the peak resultant acceleration. Results from the building example indicated that the
use of the Gamma peak factor enables accurate predictions to be made of the mean extreme resultant acceleration responses
for dynamic serviceability performance design of modern tall buildings. 相似文献
15.
高层建筑上部结构与地基基础共同工作分析的研究进展 总被引：1，自引：1，他引：1
黄海宏 《宁德师专学报(自然科学版)》2004,16(4):376-379
从高层建筑和地基基础共同作用的概念入手，简要地阐述了该课题在近几十年的研究发展情况．进而论述了目前高层建筑上部结构与地基基础共同工作主要采用的分析方法以及具体的实现过程，并介绍了研究所取得的成果． 相似文献
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Umary Jamal * 《东南大学学报》1998,(1)
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