Compressive and Torsional Instability of Sandwich Cylinders

2009 ◽  
pp. 56-56-14 ◽  
Author(s):  
George Gerard
Keyword(s):  
Torsional Instability

The Third Bosporus Bridge — the Aerodynamic Stability of the Steel Segments During the Lifting

2019 ◽  
Author(s):  
Vincent de Ville de Goyet ◽  
Yves Duchêne
Keyword(s):  
Vertical Axis ◽  
Longitudinal Axis ◽  
The Black Sea ◽  
Span Length ◽  
Geometrical Configuration ◽  
Aerodynamic Stability ◽  
The Third ◽  
The North ◽  
Torsional Instability ◽  
Main Cables

<p>The Third Bosporus Bridge is a suspendion bridge with a main span length of 1 408 m and a total length of 2 408 m located at the north of Istanbul near the Black Sea.</p><p>The main span is partially suspended at the pylons by stiffening cables and at the main cables with vertical hangers (Fig.1‐2). The deck is 58.8 m wide. But contrary to a classical arrangement, the transversal distance between the vertical hangers, in the suspended zone, is only 13.50 m. Due to this geometrical configuration of the vertical hangers, it was necessary to verify the risk of aeroelastic instabilities of steel segments of the deck during its lifting: risk of a torsional instability around the longitudinal axis but also around the vertical axis. Countermeasures have been proposed and adopted to suppress these risks.</p>

A Nonlinear Analysis of the Wahl–Fischer Torsional Instability

2020 ◽  
Vol 88 (2) ◽  
Author(s):  
E. F. Infante ◽  
S. Doughty
Keyword(s):  
Large Amplitude ◽  
Linear Analysis ◽  
Mathematical Explanation ◽  
Nonlinear Methods ◽  
Strongly Nonlinear ◽  
Instability Problem ◽  
Torsional Instability ◽  
Mechanical Devices ◽  
Trans Asme ◽  
Nonlinear Nature

Abstract This is an extension to a previous study of the Wahl–Fischer torsional instability problem (Infante and Doughty, “An Old Problem Reconsidered: The Wahl–Fischer Torsional Instability Problem”, J. Appl. Mech. Trans. ASME, 2020, 87(10), p. 101004). There, we provided a mathematical explanation of the reasons for the existence of torsional oscillations observed in numerical simulations and in actual mechanical devices such as the exhaust fan system studied by Wahl and Fischer. That explanation was mostly based on linear analysis. This paper presents an additional mathematical explanation of the nature and form of the large self-excited oscillations, due to the strongly nonlinear nature of the system and the large amplitude of these oscillations. Because the oscillations are large, their study requires the use of nonlinear methods.

scholarly journals On the variation of longitudinal and torsional frequencies in a partially hinged rectangular plate

2017 ◽  
Vol 24 (1) ◽  
pp. 63-87 ◽  
Author(s):  
Elvise Berchio ◽  
Davide Buoso ◽  
Filippo Gazzola
Keyword(s):  
Rectangular Plate ◽  
Normal Modes ◽  
Torsional Instability

We consider a partially hinged rectangular plate and its normal modes. There are two families of modes, longitudinal and torsional. We study the variation of the corresponding eigenvalues under domain deformations. We investigate the possibility of finding a shape functional able to quantify the torsional instability of the plate, namely how prone is the plate to transform longitudinal oscillations into torsional ones. This functional should obey several rules coming from both theoretical and practical evidences. We show that a simple functional obeying all the required rules does not exist and that the functionals available in literature are not reliable.

Torsional Instability in Hysteretic Structures

1985 ◽  
Vol 111 (4) ◽  
pp. 512-528 ◽  
Author(s):  
O. A. Pekau ◽  
Pradip K. Syamal
Keyword(s):  
Torsional Instability
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