Influence of in-plane and out-of-plane stiffness on the stability of free-edge gridshells: A parametric analysis

2018 ◽  
Vol 131 ◽  
pp. 755-768 ◽  
Author(s):  
Fiammetta Venuti ◽  
Luca Bruno
Keyword(s):  
Parametric Analysis ◽  
Free Edge ◽  
Out Of Plane ◽  
The Stability

scholarly journals Parametric Instability of a Traveling Plate Partially Supported by a Laterally Moving Elastic Foundation

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
V. Kartik ◽  
J. A. Wickert
Keyword(s):  
Data Storage ◽  
Parametric Instability ◽  
Primary Resonance ◽  
Free Edge ◽  
Moving Plate ◽  
Torsional Mode ◽  
Plane Vibration ◽  
Out Of Plane ◽  
Axially Moving ◽  
The Stability

The parametric excitation of an axially moving plate is examined in an application where a partial foundation moves in the plane of the plate and in a direction orthogonal to the plate’s transport. The stability of the plate’s out-of-plane vibration is of interest in a magnetic tape data storage application where the read/write head is substantially narrower than the tape’s width and is repositioned during track-following maneuvers. In this case, the model’s equation of motion has time-dependent coefficients, and vibration is excited both parametrically and by direct forcing. The parametric instability of out-of-plane vibration is analyzed by using the Floquet theory for finite values of the foundation’s range of motion. For a relatively soft foundation, vibration is excited preferentially at the primary resonance of the plate’s fundamental torsional mode. As the foundation’s stiffness increases, multiple primary and combination resonances occur, and they dominate the plate’s stability; small islands, however, do exist within unstable zones of the frequency-amplitude parameter space for which vibration is marginally stable. The plate’s and foundation’s geometry, the foundation’s stiffness, and the excitation’s amplitude and frequency can be selected in order to reduce undesirable vibration that occurs along the plate’s free edge.

Parametric Instability of a Traveling Plate Partially Supported by a Laterally-Moving Foundation

2007 ◽  
Author(s):  
V. Kartik ◽  
J. A. Wickert
Keyword(s):  
Data Storage ◽  
Parametric Instability ◽  
Primary Resonance ◽  
Free Edge ◽  
Moving Plate ◽  
Torsional Mode ◽  
Plane Vibration ◽  
Out Of Plane ◽  
Axially Moving ◽  
The Stability

The parametric excitation of an axially-moving plate is examined in an application where a partial foundation moves in the plane of the plate and in a direction orthogonal to the plate’s transport. The stability of the plate’s out-of-plane vibration is of interest in a magnetic tape data storage application where the read/write head is substantially narrower than the tape’s width, and is repositioned during track following maneuvers. In this case, the model’s equation of motion has time-dependent coefficients, and vibration is excited both parametrically and by direct forcing. The parametric instability of out-of-plane vibration is analyzed by using the Floquet theory for finite values of the foundation’s range of motion. For a relatively soft foundation, vibration is excited preferentially at the primary resonance of the plate’s fundamental torsional mode. As the foundation’s stiffness increases, multiple primary and combination resonances occur, and they dominate the plate’s stability; small islands, however, do exist within unstable zones of the frequency-amplitude parameter space for which vibration is marginally stable. The plate’s and foundation’s geometry, the foundation’s stiffness, and the excitation’s amplitude and frequency can be selected in order to reduce undesirable vibration that occurs along the plate’s free edge.

Edge Buckling of Imperfectly Guided Webs

1998 ◽  
Vol 120 (2) ◽  
pp. 346-352 ◽  
Author(s):  
A. V. Lakshmikumaran ◽  
J. A. Wickert
Keyword(s):  
Plane Deformation ◽  
Free Edge ◽  
Laboratory Measurements ◽  
Angular Misalignment ◽  
Web Handling ◽  
State Of Stress ◽  
Out Of Plane ◽  
Metal Processing ◽  
The Stability ◽  
The Web

Web handling is germane to a diverse set of industries, including paper, polymer, textile, and sheet metal processing. Angular misalignment of the guides used to position a web in its transport system generates non-uniform in-plane forces that can result in transverse buckling of the web, even for misalignments as small as a fraction of a degree. In this paper, the state of stress, the associated in-plane deformation, out-of-plane vibration, and stability of webs with misaligned guides are investigated experimentally and theoretically. The onset of edge buckling, in which transverse corrugations are present along an entire free edge or are localized near a guide, is governed by the stability of a relatively high mode of the nominally aligned web. Two models of common web transport components—termed “free sliding” and “edge guided” —are developed and discussed in the light of laboratory measurements for predicting and bounding critical buckling angles.

scholarly journals Out-of-plane local mechanism analysis with finite element method

2021 ◽  
Vol 8 (1) ◽  
pp. 130-136
Author(s):  
Roberto Spagnuolo
Keyword(s):  
Finite Element ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Mechanism Analysis ◽  
Fem Method ◽  
Local Mechanism ◽  
Out Of Plane ◽  
Smeared Crack ◽  
The Stability ◽  
No Tension Material

Abstract The stability check of masonry structures is a debated problem in Italy that poses serious problems for its extensive use. Indeed, the danger of out of plane collapse of masonry walls, which is one of the more challenging to evaluate, is traditionally addressed not using finite element models (FEM). The power of FEM is not properly used and some simplified method are preferred. In this paper the use of the thrust surface is suggested. This concept allows to to evaluate the eccentricity of the membrane stresses using the FEM method. For this purpose a sophisticated, layered, finite element with a no-tension material is used. To model a no-tension material we used the smeared crack method as it is not mesh-dependent and it is well known since the early ’80 in an ASCE Report [1]. The described element has been implemented by the author in the program Nòlian by Softing.

Retuning the actuator proportional–integral–derivative controller of spinning missiles

2016 ◽  
Vol 231 (14) ◽  
pp. 2594-2602 ◽  
Author(s):  
Wei Zhou ◽  
Shuxing Yang ◽  
Liangyu Zhao
Keyword(s):  
Angular Motion ◽  
Proportional Integral Derivative ◽  
Proportional Integral Derivative Controller ◽  
Proportional Integral ◽  
Out Of Plane ◽  
Integral Element ◽  
The Stability ◽  
Proportional Derivative Controller

The hinge moment acting on the actuator will cause an out-of-plane moment, which is a destabilizing factor to the angular motion of spinning missiles. A new tuning criterion for the actuator controller is proposed to decrease the out-of-plane moment. It is noted that the integral element does not decrease the out-of-plane moment. A carefully designed proportional–derivative controller with some compromises can ensure the stability of the missile and provide good performance for the actuator.

scholarly journals Implications of free-edge effect at thin plain-woven carbon fiber reinforced plastic laminates with out-of-plane waviness under cyclic loading

2021 ◽  
pp. 002199832110417
Author(s):  
Lukas Heinzlmeier ◽  
Stefan Sieberer ◽  
Christoph Kralovec ◽  
Martin Schagerl
Keyword(s):  
Carbon Fiber ◽  
Edge Effect ◽  
Fatigue Testing ◽  
Free Edge ◽  
Numerical Calculations ◽  
Carbon Fiber Reinforced Plastic ◽  
Damage Initiation ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Out Of Plane

The onset of damage caused by the free-edge effect in plain-woven carbon fiber reinforced plastic (CFRP) specimens with an out-of-plane waviness under tension-tension fatigue loading is investigated. Numerical calculations show that interlaminar and intralaminar stresses close to the out-of-plane waviness are higher than the equivalent stresses at the surrounding edge regions. Using submodels, the influence of the chosen out-of-plane waviness can be better assessed. The free-edge effect of the considered specimens, which originates from stress gradients between plies of different orientation, is altered by the change in the stress field caused by the out-of-plane waviness. Large interlaminar stresses between plies of the same orientation are obtained, which contrasts with existing literature. In experimental fatigue testing it is found that cracks at the free edge appeared at the predicted locations, and after reaching crack saturation, in regions close to the out-of-plane waviness, interlaminar and intralaminar stresses lead to additional cracks along the whole free edges. The experimental tests are supported by a three dimensional image correlation system (3D-DIC), a thermal-imager and a digital photographic camera, which allows detailed examination of selected areas. Visual observation during fatigue testing and post-mortem inspection show good agreement between experimental data and numerical calculations in relation to the location of the damage initiation. As a result, out-of-plane waviness at free edges must be considered as an additional significant fatigue damage initiation location in laminate analysis.

Stability Coefficient of Interlocking Compressed Earth Block Masonry under Axial Compression

2020 ◽  
Author(s):  
Tianya Wang ◽  
Yihong Wang ◽  
Guiyuan Zeng ◽  
Jianxiong Zhang ◽  
Dan Shi
Keyword(s):  
Compressive Strength ◽  
Axial Compression ◽  
Design Guidelines ◽  
Stability Coefficient ◽  
Strength Failure ◽  
Compressed Earth Block ◽  
Out Of Plane ◽  
The Stability ◽  
Earth Block ◽  
Plane Deformations

To investigate the effects of the height-thickness ratio (β) on the mechanical properties and stability coefficients (φs) of interlocking compressed earth block (ICEB) masonry members under axial compression, four groups of specimens with different β of 3.75, 6.75, 11.25, and 14.25 were tested, thereby assessing their stress process, failure mode, compressive strength, and in- and out-of-plane deformations. All the specimens underwent brittle failure under axial compression: the compressive strength was found to decrease in a range from 5.6% to 43% with increasing β, whereas the initial stacking defects and the in- and out-of-plane deformations increased. The specimens became less stable, and we noticed that the overall damage was caused by strength failure and not instability failures. Because the stability coefficient of ICEB-based masonry components cannot be calculated as those of more conventional brickwork, we combined our results with well-established masonry design guidelines and derived an interlocking improvement coefficient.

Numerical Modeling and Parametric Analysis of Multiplanar CHS KT-Joints with K-Plane Overlap and Out-of-Plane Gap

2011 ◽  
Vol 94-96 ◽  
pp. 575-582
Author(s):  
Jian Dong Sun ◽  
Jun Li Lv ◽  
Tao Du ◽  
Yang Xian Li
Keyword(s):  
Numerical Modeling ◽  
Parametric Analysis ◽  
Element Model ◽  
Ultimate Capacity ◽  
Dimensional Parameter ◽  
International Convention ◽  
Out Of Plane ◽  
Dimensional Parameters ◽  
Test Result ◽  
Good Agreement

A finite element model simulating the experiment on multiplanar unstiffened CHS KT joints with K-plane overlapped and out-of-plane not (KT-IPOv joints), with the background of Suzhou International Convention & Exhibition Center, was advanced and validated by comparing failure mode and the ultimate capacity with experimental results, which is shown to be in good agreement with the test result. Using this model, the effect of non-dimensional parameters on ultimate capacity of KT-IPOv joints were studied, and resistance comparison between multiplanar KT-IPOv joints and uniplanar overlapped K-joints was carried out. The results of FE parametric Analysis conclude that multiplanar parameter ζ t, τT and βT have not significant influence on the ultimate strength; the effect of non-dimensional parameter βK, τK, γ, Ov on the resistance of multiplanar KT-IPOv joints has the same as that of uniplanar overlapped K-joints; the strength of multiplanar KT-IPOv joints have been not significantly influenced by the configuration with the brace inside T-plane which it is not subjected to force; it is suitable and feasiable that ultimate capacities of KT-IPOv joints predicted by formula of uniplanar K-joints.

Equilibrium, photophysical, photochemical and quantum chemical examination of anionic mercury(I) porphyrins

2009 ◽  
Vol 13 (08n09) ◽  
pp. 910-926 ◽  
Author(s):  
Zsolt Valicsek ◽  
György Lendvay ◽  
Ottó Horváth
Keyword(s):  
Quantum Chemical ◽  
Structural Data ◽  
Free Base ◽  
Chemical Examination ◽  
Distorted Structure ◽  
Out Of Plane ◽  
The Stability ◽  
Nitrogen Bonds ◽  
Small Charge ◽  
Soret Absorption

Hg22+ ion and 5,10,15,20-tetrakis(parasulphonato-phenyl)porphyrin anion can form 2:1 (2 clusters:1 porphyrin) and 2:2 complexes, while the formation of the 1:1 species is not observable: it is only an intermediate, similarly to the cases of other large metal ions of small charge-density. The differences between mercury(I) and mercury(II) porphyrins in the composition of monoporphyrins (2:1 vs. 1:1), in the stability and the Soret absorption based on the arrangement of 2:2 complexes (asymmetric vs. probably symmetric sandwich-structure), in the kinetic behavior (molecularities and the special dimerization of HgIIP4-), in the product of the photoinduced dissociations of 2:2 bisporphyrins (free-base ligand vs. 1:1 complex) can prove that no mercury(II) porphyrins can form due to the possible disproportion of dimercury(I) ions. However, the similarities in the absorption, photophysical and photochemical features (also to other out-of-plane metalloporphyrins) suggest that the out-of-plane position of metal center and the distorted structure of complexes may be responsible for these common properties, the so-called sitting-atop characteristics. Moreover, the calculated structural data of the theoretically studied 1:1 mercury(I) porphyrin are very similar to those of Hg II P as a consequence of the charge separation in the cluster based on the strength of metal-nitrogen bonds. In the case of the 2:2 species, neither the increased distance (because of the Hg-Hg bond), nor the absence of 45° rotation of the two ligands can significantly modify the π-π interaction because its both measured and calculated absorption spectra are similar to those of Hg II2 P 2.

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