scholarly journals Efficient Visualization Method of Buckling Region in Dynamic Transient Analysis of Cable Network Structures

2020 ◽  
pp. 11-20
Author(s):  
Shoko Arita ◽  
Yasuyuki Miyazaki
Keyword(s):  
Transient Analysis ◽  
Flexible Structures ◽  
Response Analysis ◽  
Visualization Method ◽  
Membrane Element ◽  
Large Structure ◽  
Cable Network ◽  
Truss Model ◽  
Entire Structure ◽  
Truss Element

Deployable structure system using flexible members is necessary to construct a large structure in the space. The flexible members easily buckle as seen in wrinkles and slack. Therefore, it is available at designing of spacecraft to grasp when, where and how large the buckling occurs in the entire structure during the deployment. When dynamic analysis of large flexible structures which can ignore bending is conducted, the truss element and the membrane element, which do not consider the bending of an element, are often used from the viewpoint of calculation cost. Therefore, this paper proposes a comprehensive and efficient visualization method of buckling occurrence region and buckling magnitude during dynamic response analysis using the truss element to progress convenience in design. The method proposed in this paper is based on two previous studies. The proposed method is verified by a simple truss model, and an application example is shown.

A statistical study on artificially generated earthquake records

1976 ◽  
Vol 3 (1) ◽  
pp. 11-19
Author(s):  
W. K. Tso ◽  
B. P. Guru
Keyword(s):  
Statistical Study ◽  
Spectral Response ◽  
Flexible Structures ◽  
Time History ◽  
Maximum Response ◽  
Response Analysis ◽  
Seismic Region ◽  
Natural Period ◽  
Earthquake Records ◽  
Time History Response

A statistical study has been done to investigate (i) the variation of spectral responses of structures due to artificially generated earthquake records with identical statistical properties, (ii) the effect of duration of strong shaking phase of artificial earthquakes on the response of structures, and (iii) the number of earthquake records needed for time-history response analysis of a structure in a seismic region. The results indicate that the flexible structures are more sensitive to the inherent statistical variations among statistically identical earthquake records. Consequently several records must be used for time-history response analysis. A sample of eight or more records appear to provide a good estimate of mean maximum response. The duration of strong shaking can significantly affect the maximum response. Based on the results, it is suggested that for the purpose of estimating peak response, the strong shaking duration of the input earthquake motion should be at least four times the natural period of the structure. The maximum responses due to statistically identical ground motion records are observed to fit approximately the type 1 extreme value distribution. Thus, it is rationally possible to choose a design value based on the mean, standard deviation of the spectral response values and tolerable probability of exceedance.

Design Seastates for Extreme Response of Jackup Structures

1998 ◽  
Vol 120 (2) ◽  
pp. 103-108 ◽  
Author(s):  
S. R. Winterstein ◽  
R. Torhaug ◽  
S. Kumar
Keyword(s):  
Earthquake Engineering ◽  
Time Domain ◽  
Flexible Structures ◽  
Wave Model ◽  
Response Prediction ◽  
Wave Crest ◽  
Response Analysis ◽  
New Wave ◽  
Extreme Response ◽  
Wave Methods

The extreme response of a jackup structure is studied. We consider how design seastate histories can be introduced to reduce the cost of time-domain response analysis. We first identify critical wave characteristics for extreme response prediction. In quasi-static cases, the maximum wave crest height, ηmax, is shown to best explain extreme deck sway. For more flexible structures we introduce a new wave characteristic, SD, based on response spectral concepts from earthquake engineering. Finally, we show how accurate response estimates can require fewer time-domain analyses, provided design seastates are pre-selected to ensure that ηmax or SD is near its average value. With respect to standard Monte-Carlo simulation, these design seastates achieve at least a 50-percent reduction in response variability, and hence at least a fourfold savings in needed simulation cost. These results may lend insight, not only into time-domain simulation, but also into more fundamental questions of jackup behavior. They also suggest that, at least in quasi-static cases, still simpler design wave methods based on ηmax may suffice. We illustrate and evaluate some such design wave methods here (e.g., the “new wave” model and others based on Slepian theory).

Optimization Design of Cable-Frame Antennas Based on Tension Compensation Method

2014 ◽  
Vol 496-500 ◽  
pp. 797-803 ◽  
Author(s):  
Ya Li Zong ◽  
Hong Jun Cao
Keyword(s):  
Optimization Design ◽  
Flexible Structures ◽  
Mathematical Optimization ◽  
Optimization Method ◽  
Compensation Method ◽  
Surface Error ◽  
Cable Network ◽  
Mathematical Optimization Model ◽  
Stress States ◽  
Cable Nets

Tension truss reflectors are flexible structures characterized by strong geometric nonlinearities, thus the surface error and the real cable tensions of a reflector cannot be controlled efficiently to anticipant levels by their initial cable tensions. To ensure both appropriate node positions and anticipant cable tensions, an optimization method based on Tension Compensation Method is presented. First, a parameterized description of the zero-stress states of the front net and the rear net is proposed and the strategy of Tension Compensation Method is used to control the cable tensions to anticipant levels. Second, a mathematical optimization model for the cable tensions and the zero-stress state design of the cable network is established based on Tension Compensation Method with the optimization target of minimizing surface error of the reflector. Finally, the feasibility and effectiveness of the presented method are validated by some numerical examples. The results show that the cable tensions can be effectively controlled by the proposed method, and this method can generate regular zero-stress states of the cable-nets which may bring great convenience to the lofting work of the cable network.

Transient Response Analysis of Damped Rotor Systems by the Normal Mode Method

1975 ◽  
Author(s):  
A. J. Dennis ◽  
R. H. Eriksson ◽  
L. H. Seitelman
Keyword(s):  
Steady State ◽  
Normal Mode ◽  
Transient Response ◽  
Transient Analysis ◽  
Equations Of Motion ◽  
Forced Response ◽  
Mode Shapes ◽  
Response Analysis ◽  
Rotor Systems ◽  
Incremental Formulation

A method to determine the transient response of damped single or multi-shaft rotor systems is presented. The rotor systems are idealized as rotating concentrated masses connected by massless beams, discrete springs, and dampers. The springs may have piecewise constant springs rates to simulate the stiffening effect of parts coming in contact after displacement through an initial offset. Arbitrary forcing functions are allowed. The method employs an incremental formulation in which damping gyroscopic and nonlinear terms are treated as external loads which are lagged in time. The equations of motion are uncoupled by performing a normal mode expansion of the response solution in terms of the non-rotating, undamped eigenvectors and their associated eigenvalues; modes and natural frequencies are obtained from a standard Prohl analysis. An analytical solution is used for each step of the incremental analysis. This technique has been used to study the response of a number of rotor systems to the sudden application of a rotating imbalance load. The systems studied include a dual shaft model of a rig, a single-shaft case from the written literature and a large multi-line (multi-shaft) system. The transient analysis was run out to steady-state and close agreement obtained with results from an independent steady-state forced response analysis. Orthogonality relations between the mode shapes were observed to be critical to the quality of the results. It was observed that transient analysis of multi-line systems can be accurately predicted only if the higher frequency modes which are participating in the response are included in the normal mode solution.

Connections Checks of Pipe-Laying Barge Stinger System under Complex Loading Conditions

2013 ◽  
Vol 365-366 ◽  
pp. 241-244
Author(s):  
Tian Feng Zhao ◽  
Jin Long Qi ◽  
Huan Hong Zhou ◽  
Meng Lan Duan
Keyword(s):  
Mechanism Design ◽  
Structural Response ◽  
Complex Loading ◽  
Beam Element ◽  
Operating Conditions ◽  
Response Analysis ◽  
Knee Brace ◽  
Environmental Loads ◽  
Truss Model ◽  
Survival Case

Fixed stinger system hanging in the stern to implement pipeline S-lay mainly includes an A-frame, a stinger hitch section, a stinger tail section, a knee-brace and a knee-brace hitch. Expect the functional loads the stinger system may suffer environmental loads in construction area and also the inertia loads induced by barge movements. Contrasting to the design of stinger truss, connection mechanism design becomes more complicated for the unknown loads shared during the laying cases or the survival case of the barge. In this paper a set of analytical approach for connection mechanism design are proposed and demonstrated for specific operating conditions. In this approach, structural response analysis were carried out firstly using a beam-element truss model to which pipelay functional loads, environmental loads and inertia loads had been applied and the loads undertook by stinger connections were extracted. Next other connection models constructed by cell grids were enabled to predict the responses of connections under those loads extracted from the analysis results of the first step. The analysis example of this paper confirms that based on this approach more careful strength or fatigue check had been realized for the connections of fixed stinger.

Dynamic performance analysis and quantitative evaluation for ultraprecision aerostatic spindle

2019 ◽  
Vol 234 (1-2) ◽  
pp. 218-228
Author(s):  
Ruocheng Wei ◽  
Chenhui An ◽  
Zhenzhong Wang ◽  
Qiao Xu ◽  
Xiangyang Lei ◽  
...  
Keyword(s):  
Transient Analysis ◽  
Dynamic Performance ◽  
Response Analysis ◽  
Quantitative Index ◽  
Medium Frequency ◽  
Dynamic Simulations ◽  
Machined Surface ◽  
Spindle System ◽  
Aerostatic Spindle ◽  
Dynamic Performance Analysis

For optics used in high-power laser beams, high accuracy requirements in full spatial frequency must be fulfilled. Among them, the allowable root mean square value is less than 5 nm in the PSD1 band. In order to evaluate the dynamic performance of the spindle system and put forward a quantitative index, a novel accurate model of the spindle system was built and a series of dynamic simulations were performed. Harmonic response analysis reveals natural frequencies and frequency response functions. Transient analysis indicates vibration waveforms of the tool-tip. Furthermore, by analyzing surface topography, it can be found that the medium-frequency waviness in the machined surface matches the vibration waveform. Obviously, the medium-frequency waviness is generated by the modal vibration of the spindle system. So that a quantitative index for the aerostatic spindle is proposed: when the amplitude of vibration in transient analysis is smaller than 8 nm, the allowable error in the PSD1 band can be fulfilled.

Progress in high-resolution CRYO-SEM imaging of viral particles

1996 ◽  
Vol 54 ◽  
pp. 818-819
Author(s):  
Ya Chen ◽  
Geoffrey Letchworth ◽  
John White
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Structural Information ◽  
Signal To Noise Ratio ◽  
Flexible Structures ◽  
Simian Virus ◽  
Topographic Features ◽  
Viral Particles ◽  
Scanning Electron

Low-temperature high-resolution scanning electron microscopy (cryo-HRSEM) has been successfully utilized to image biological macromolecular complexes at nanometer resolution. Recently, imaging of individual viral particles such as reovirus using cryo-HRSEM or simian virus (SIV) using HRSEM, HV-STEM and AFM have been reported. Although conventional electron microscopy (e.g., negative staining, replica, embedding and section), or cryo-TEM technique are widely used in studying of the architectures of viral particles, scanning electron microscopy presents two major advantages. First, secondary electron signal of SEM represents mostly surface topographic features. The topographic details of a biological assembly can be viewed directly and will not be obscured by signals from the opposite surface or from internal structures. Second, SEM may produce high contrast and signal-to-noise ratio images. As a result of this important feature, it is capable of visualizing not only individual virus particles, but also asymmetric or flexible structures. The 2-3 nm resolution obtained using high resolution cryo-SEM made it possible to provide useful surface structural information of macromolecule complexes within cells and tissues. In this study, cryo-HRSEM is utilized to visualize the distribution of glycoproteins of a herpesvirus.

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