scholarly journals Effect of Geometric Nonlinearity on Membrane Roof Stability in Air Flow

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Weiju Song ◽  
Jun Xu ◽  
Xiaowei Wang ◽  
Changjiang Liu
Keyword(s):  
Geometric Nonlinearity ◽  
Geometrical Nonlinearity ◽  
Reference Value ◽  
Single Mode ◽  
Small Mass ◽  
Wind Load ◽  
Strong Wind ◽  
Membrane Structures ◽  
Open Structures ◽  
High Flexibility

Membrane materials are widely used in construction engineering with small mass and high flexibility, which presents strong geometric nonlinearity in vibration. In this paper, an improved multiscale perturbation method is used to solve the aerostatics stability of membrane roofs on closed and open structures by quantifying the effect of geometric nonlinearity on the single-mode aeroelastic instability wind velocity. Results show that the critical wind velocities of two models are smaller when the geometrical nonlinearity of the membrane material is neglected. In addition, under normal wind load, the influence of geometrical nonlinearity of the membrane on the aerodynamic stability of the roof can be neglected. However, under strong wind load, when the roof deformation reaches 3% of the span, the influence of geometric nonlinearity should be considered and the influence increases with the decrease of transverse and downwind span of the membrane roof. The results obtained in this paper have an important theoretical reference value for the design membrane structures.

Probabilistic Fatigue Damage Analysis of Long Span Suspension Bridge Due to Wind Induced Buffeting

2020 ◽  
Vol 980 ◽  
pp. 275-281
Author(s):  
Hu Jun
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Time History ◽  
Suspension Bridge ◽  
Wind Load ◽  
Strong Wind ◽  
Fatigue Reliability ◽  
Long Span ◽  
Fatigue Damage Analysis ◽  
Fluctuating Wind

In order to consider the fluctuating wind load induced fatigue problem of long span suspension bridge, fatigue reliability formula is modified by assuming the fatigue life is accord with the weibull distribution. Based on the accurate bridge buffeting analysis of time history, the stress time history of components of a suspension bridge in east sea China is simulated, and then the fatigue damages and reliabilities are calculated. The results indicate that the main cables and hangers have enough fatigue reliability under the fluctuating wind load, the fatigue failure will not occur; the stiffening girder has larger fatigue damage, under 40 / (m.s-1) mean wind speed action, the girder of mid-support section’s average fatigue life is only 3.103 years, so the girder’s damage under strong wind action should be taken seriously.

Optimal Vibration Control of Membrane Structures with In-Plane Polyvinylidene Fluoride Actuators

2020 ◽  
Vol 20 (08) ◽  
pp. 2050095
Author(s):  
Yifan Lu ◽  
Qi Shao ◽  
Fei Yang ◽  
Honghao Yue ◽  
Rongqiang Liu
Keyword(s):  
Vibration Control ◽  
Polyvinylidene Fluoride ◽  
Vibration Suppression ◽  
Flexible Structures ◽  
Control Force ◽  
Membrane Structures ◽  
Optimization Criteria ◽  
High Flexibility ◽  
And Control ◽  
Actuator Placement

Different kinds of membrane structures have been proposed for future space exploration and earth observation. However, due to the low stiffness, high flexibility, and low damping properties, membrane structures are likely to generate large-amplitude (compared to the thickness) vibrations, which may lead to the degradation of their working performance. In this work, the governing equations are established at first, taking into account the modal control force induced by the polyvinylidene fluoride (PVDF) actuator. The optimal vibration control of the membrane structure is explored subsequently. A square PVDF actuator is attached on the membrane to achieve the vibration suppression. The influence of actuator position and control gains on the vibration control performance are studied. The optimal criteria for actuator placement and energy allocation are developed. Several case studies are numerically simulated to demonstrate the validity of the proposed optimization criteria. The analytical results in this study can serve as guidelines for optimal vibration control of membrane structures. Additionally, the proposed optimization criteria can be applied to active control of different flexible structures.

Wind Effect Estimation in Side by Side Offloading Operation for FLNG and LNG Carrier Ships

2012 ◽  
Author(s):  
Toshifumi Fujiwara ◽  
Kazuhiro Yukawa ◽  
Hiroshi Sato ◽  
Kazuhisa Otsubo ◽  
Tomoki Taniguchi
Keyword(s):  
Interaction Effect ◽  
Wind Wave ◽  
Estimation Method ◽  
Deep Ocean ◽  
Wind Load ◽  
Shielding Effect ◽  
Wind Effect ◽  
Strong Wind ◽  
Closed Area ◽  
Capability Evaluation

Liquid Natural Gas resource development is often conducted worldwide. Recently the drilling area has gradually expanded from shallow sea area to the deep ocean. A Floating LNG facility (FLNG) and a LNG carrier ship (LNG) are assumed to operate in the open sea expected to wind, wave and current. In this situation, an operational capability evaluation of the LNG would be needed to grasp the operational weather limitation. The effect of each weather element, i.e. wind, wave and current, giving manoeuvring effect to ships, is expected to assess exactly as external loads. In such a situation, wind interaction effect under the operating condition that a FLNG and a LNG are in same closed area is not clearly understood. This paper treats and proposes one estimation method of wind load for the operation of side-by-side offloading including interaction effect of a FLNG and a LNG. The proposed wind load estimation method based on the wind tunnel experiments represents the shielding effect of the LNG behind the FLNG. Operational assessment on ship manoeuvring under strong wind is calculated using the proposed wind load method in the final stage.

scholarly journals Analysis of Wind-Induced Vibration of a Spoke-Wise Cable–Membrane Structure

2020 ◽  
Vol 8 (8) ◽  
pp. 603
Author(s):  
Hua Huang ◽  
Yaoqiang Xian ◽  
Wei Zhang ◽  
Mengxue Guo ◽  
Kun Yang ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Dynamic Behavior ◽  
Damage Assessment ◽  
Membrane Structure ◽  
Aerospace Industry ◽  
Time History ◽  
Wind Load ◽  
Membrane Structures ◽  
Wind Resistance ◽  
Wind Induced Vibration

Lightweight cable–membrane structures can span large distances and undertake aesthetically pleasing shapes. They are widely used for roofs and modern structural canopies and in the aerospace industry for large on-board antenna reflectors that are to be deployed in space. This paper studies a wind-induced vibration under different cable stress relaxation conditions based on the wind load time-history to obtain the dynamic behavior of such a structure. Particularly, the focus is put upon its wind resistance in the event of stress relaxation. This research can provide an important reference for the design of wind resistance, damage assessment, and emergency maintenance for the spoke-wise cable–membrane structure (SCMS).

scholarly journals GEOMETRICAL NONLINEARITY ANALYSIS OF THE STEEL NETWORK ARCH BRIDGES / PLIENINŲ TINKLINIŲ ARKINIŲ TILTŲ GEOMETRINIO NETIESIŠKUMO VERTINIMAS

2016 ◽  
Vol 8 (5) ◽  
pp. 490-494
Author(s):  
Sigutė Žilėnaitė
Keyword(s):  
Geometric Nonlinearity ◽  
Geometrical Nonlinearity ◽  
Compressive Force ◽  
Work Conditions ◽  
Geometrical Factor ◽  
Principal Behavior ◽  
New Construction ◽  
Arch Bridges ◽  
The Individual ◽  
The City

Arch bridges are one of the popular, oldest and graceful bridges which are being built in zones of the city and out of the city. However arches becomes especially sensitive to their buckling response due to dominated compressive force in the arch. In order to ensure stability conditions of the individual arch and arch bridges, it is estimated not just geometrical factor of arch, residual stress, work conditions, geometric imperfections but geometrical nonlinearity too. Geometric nonlinearity especially dominates in many times static indeterminable systems such as network arch bridges. However there are a few represents of estimation of geometric nonlinearity of the new construction form of the arch bridges created in a middle of 20th century. This paper represents estimation of geometric nonlinearity with numerical method of the steel arch bridges with vertical hangers and network arch bridges. There are determined stress-strain law and principal behavior of the steel network arch bridges under symmetric and asymmetric pedestrian loadings. Arkiniai tiltai – vieni populiariausių, seniausių ir grakščiausių tiltų, statomų miesto ir užmiesčio zonose. Tačiau dėl dominuojančios ašinės gniuždymo jėgos arkos tampa ypač jautrios stabilumo praradimui. Siekiant užtikrinti pavienių arkų ir arkinių tiltų pastovumo sąlygas, vertinami ne tik arkos geometriniai rodikliai, darbo stadijos, pradiniai įtempiai, geometriniai netobulumai, bet ir netiesinė konstrukcijos elgsena. Geometrinis netiesiškumas ypač dominuoja daug kartų statiškai neišsprendžiamose sistemose, tokiose kaip tinkliniai arkiniai tiltai. Tačiau šios XX a. viduryje atsiradusios naujos arkinių tiltų konstrukcinės formos geometrinio netiesiškumo vertinimas pateiktas minimaliai. Straipsnyje pateikiamas plieninių arkinių tiltų su vertikaliomis pakabomis ir tinklinių arkinių tiltų geometrinio netiesiškumo vertinimas skaitiniais metodais. Nustatomas plieninių tinklinių arkinių tiltų įtempių-deformacijų būvis ir esminiai elgsenos ypatumai, veikiant simetrine ir asimetrine pėsčiųjų apkrovomis.

scholarly journals Particle morphology of medusavirus inside and outside the cells reveals a new maturation process of giant viruses

2021 ◽  
Author(s):  
Ryoto Watanabe ◽  
Chihong Song ◽  
Yoko Kayama ◽  
Masaharu Takemura ◽  
Kazuyoshi Murata
Keyword(s):  
Electron Microscopy ◽  
Intracellular Localization ◽  
Particle Morphology ◽  
Host Cells ◽  
Maturation Process ◽  
Membrane Structures ◽  
Viral Dna ◽  
Internal Membrane ◽  
Open Structures ◽  
Giant Viruses

Medusavirus, a giant virus, is phylogenetically closer to eukaryotes than the other giant viruses and has been recently classified as an independent species. However, details of its morphology and maturation process in host cells remain unclear. Here, we investigated the particle morphology of medusavirus inside and outside infected cells using conventional transmission electron microscopy (C-TEM) and cryo-electron microscopy (cryo-EM). The C-TEM of amoeba infected with the medusavirus showed four types of particles: empty, DNA-full, and the corresponding intermediates. Time-dependent changes in the proportion and following intracellular localization of these particles suggested a new maturation process for the medusavirus. Empty particles and viral DNAs were produced independently in the cytoplasm and nucleus, respectively, and only empty particles located near the nucleus incorporated the viral DNA into the capsid. All four types of particles were also found outside the cells. The cryo-EM of these particles showed that the intact capsid structure, covered with three different types of spikes, was conserved among all particle types, although with minor size-related differences. The internal membrane exhibited a structural array similar to that of the capsid, interacted closely with the capsid, and displayed open membrane structures in the empty and empty-intermediate particles. This result suggests that the open structures in the internal membrane are used for an exchange of scaffold proteins and viral DNA during the maturation process. This new model of the maturation process of medusavirus provides insight into the structural and behavioral diversity of giant viruses.

scholarly journals Wind-Load Response and Evacuation Efficiency Analysis of Marine Evacuation Inflatable Slide

2019 ◽  
Vol 10 (1) ◽  
pp. 21
Author(s):  
Fankai Kong ◽  
Hengxu Liu ◽  
Binghan Wang ◽  
Huaqiu Ding ◽  
Zhen Jiang ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Wind Load ◽  
Membrane Structures ◽  
Double Standards ◽  
Wind Resistance ◽  
Wind Speeds ◽  
Load Response ◽  
The Stability ◽  
Dangerous Condition ◽  
The Ideal

Flexible inflatable membrane structure has the characteristics of light weight, large span, and small stiffness, and it is very sensitive to wind load. Aiming at the dynamic response of marine evacuation inflatable slides under complex and changeable wind loads at sea, the response law of the inflatable slide under different wind directions, wind speeds, and internal pressure conditions is studied by using fluid–solid coupling theory. The most dangerous conditions of evacuation system installation and the ideal internal pressure of the inflatable slide meeting the stability requirements are deduced. The LS-DYNA module is used to simulate the inflation process of the slide. The evacuation sliding is rationally simplified. By changing the inflatable internal pressure of the slide, the variation law of displacement, deformation, and sliding speed of the slide is obtained, and the optimal inflation internal pressure satisfying the evacuation efficiency requirement is obtained. The results show that the inflow wind direction angle of 30° is the most dangerous condition for slideway installation, and the internal pressure of 4000 Pa is the ideal internal pressure to meet the double standards of stability and evacuation efficiency. The numerical results obtained are valuable for analyzing wind resistance of offshore inflatable membrane structures and their practical design and application in evacuation systems.

Geometrically Nonlinear Calculation of Trailing rod designs. Part 1. Calculation of flexible threads

10.12737/335 ◽  
2013 ◽  
Vol 1 (1) ◽  
pp. 7-17
Author(s):  
Андрей Свентиков
Keyword(s):  
Linear Model ◽  
Geometric Nonlinearity ◽  
Geometrical Nonlinearity ◽  
Constant Load ◽  
Geometrically Nonlinear ◽  
Flexible Rods ◽  
Nonlinear Matrix ◽  
Current Value ◽  
Special Case ◽  
Matrix Calculation

Is treated geometrically nonlinear matrix calculation core construction with the use of flexible threads. The first part is devoted to the study the major calculation dependencies of flexible threads. It is established that the geometric nonlinearity of flexible rods depends on the cube of the ratio of the calculation in a zero-offsets end stabilize relations to its current value. Also found that the constructive nonlinearity is a special case of geometrical nonlinearity and depends on the degree of impact on the VDS of flexible thread load on its own weight. It is found that the preliminary adjustment of the length of flexible rods leads to the increase of the share of the stresses of constant load and, accordingly, to the approximation of the nature of the work of these elements into a linear model.

Optimization of Bridge Windbreak on High-Speed Railway through Strong Wind Area

2012 ◽  
Vol 452-453 ◽  
pp. 1518-1521 ◽  
Author(s):  
Ling Ling Zhou ◽  
Xi Feng Liang ◽  
Ming Zhi Yang ◽  
Sha Huang
Keyword(s):  
Protective Effect ◽  
Wind Velocity ◽  
High Speed ◽  
Wind Load ◽  
Aerodynamic Load ◽  
Strong Wind ◽  
High Speed Railway ◽  
Overturning Moment ◽  
Catenary System ◽  
Self Gravity

Based on 3-d, uncompressible onflow model with steady N-S equation and the k-epsilon double equation, aerodymic characteristics of EMU and windbreaks on bridge under cross wind were studied numerically, the results show: (1) compared to no windbreak, EMU overturning moment was decreased 50% by setting general windbreak , 75% by setting ventilated windbreak; ventilated windbreak’s protective effect on train and pantograph-catenary system is better especially when H≥2.5m ; (2) aerodynamic load on ventilated windbreak is far lower than general windbreak; (3)the higher cross-wind velocity is, the more aerodynamic load decreased when setting ventilated windbreak. Besides, ventilated windbreak’s leak form could significantly reduce bridge’s self gravity and wind load, improve wind break ability and EMU operation safety.

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