Effect of non-uniform in-plane bending and edge conditions on the stability behaviour of laminated panels with and without cutouts

2020 ◽  
Author(s):  
T. Rajanna ◽  
Vinay M.L. Gowda
Keyword(s):  
Stability Behaviour ◽  
Edge Conditions ◽  
Laminated Panels ◽  
Plane Bending ◽  
The Stability

Effects of finite-rate chemistry and detailed transport on the instability of jet diffusion flames

2014 ◽  
Vol 745 ◽  
pp. 647-681 ◽  
Author(s):  
Yee Chee See ◽  
Matthias Ihme
Keyword(s):  
Transport Properties ◽  
Diffusion Flames ◽  
Diffusive Transport ◽  
Mean Flow ◽  
Stability Behaviour ◽  
Jet Diffusion Flames ◽  
One Step ◽  
The Mean ◽  
Modelling Assumptions ◽  
The Stability

AbstractLocal linear stability analysis has been shown to provide valuable information about the response of jet diffusion flames to flow-field perturbations. However, this analysis commonly relies on several modelling assumptions about the mean flow prescription, the thermo-viscous-diffusive transport properties, and the complexity and representation of the chemical reaction mechanisms. In this work, the effects of these modelling assumptions on the stability behaviour of a jet diffusion flame are systematically investigated. A flamelet formulation is combined with linear stability theory to fully account for the effects of complex transport properties and the detailed reaction chemistry on the perturbation dynamics. The model is applied to a methane–air jet diffusion flame that was experimentally investigated by Füriet al.(Proc. Combust. Inst., vol. 29, 2002, pp. 1653–1661). Detailed simulations are performed to obtain mean flow quantities, about which the stability analysis is performed. Simulation results show that the growth rate of the inviscid instability mode is insensitive to the representation of the transport properties at low frequencies, and exhibits a stronger dependence on the mean flow representation. The effects of the complexity of the reaction chemistry on the stability behaviour are investigated in the context of an adiabatic jet flame configuration. Comparisons with a detailed chemical-kinetics model show that the use of a one-step chemistry representation in combination with a simplified viscous-diffusive transport model can affect the mean flow representation and heat release location, thereby modifying the instability behaviour. This is attributed to the shift in the flame structure predicted by the one-step chemistry model, and is further exacerbated by the representation of the transport properties. A pinch-point analysis is performed to investigate the stability behaviour; it is shown that the shear-layer instability is convectively unstable, while the outer buoyancy-driven instability mode transitions from absolutely to convectively unstable in the nozzle near field, and this transition point is dependent on the Froude number.

Topological Hopf bifurcation in the plane

1983 ◽  
Vol 93 (1) ◽  
pp. 113-119
Author(s):  
Dieter Erle
Keyword(s):  
Hopf Bifurcation ◽  
Dynamical Systems ◽  
Asymptotic Stability ◽  
Stationary Point ◽  
Parameter Family ◽  
Stability Behaviour ◽  
Closed Orbits ◽  
The Stability ◽  
Image Position ◽  
Negative System

Classical bifurcation theorems for a 1 -parameter family of plane dynamical systemsassert the presence of closed orbits clustering at some distinguished parameter value (∈ = 0, say). Here, for any ∈, the origin is the only stationary point. The topological content of the mostly analytic hypotheses imposed is some change in the stability behaviour of the origin at ∈ = 0, roughly the passing of a kind of stability to a kind of instability. Topologically speaking, e.g. some of the conditions demanded are asymptotic stability of the origin for the negative system at ∈ > 0 and asymptotic stability of the origin for at ∈ < 0 (Hopf (8), Ruelle and Takens(11)) or ∈ = 0 (Chafee(2)).

On the stability of plates under combined compression and in-plane bending

1994 ◽  
Vol 53 (6) ◽  
pp. 1453-1464 ◽  
Author(s):  
O.K. Bedair ◽  
A. Sherbourne
Keyword(s):  
Plane Bending ◽  
The Stability

Comprehensive strength analysis of framed sandwich panels

1979 ◽  
Vol 6 (4) ◽  
pp. 514-522 ◽  
Author(s):  
S. Rizzo ◽  
P. Fazio
Keyword(s):  
Sandwich Panels ◽  
Strength Analysis ◽  
Local Instability ◽  
Test Programme ◽  
Thin Aluminum ◽  
Out Of Plane ◽  
Edge Conditions ◽  
Plane Bending

Local instability of thin facings in sandwich panels often leads to wrinkling at stresses lower than yield stresses. An investigation was carried out by the authors on the behaviour of the facings of rectangular sandwich panels having thin aluminum faces and styrofoam core when subjected to edgewise compression and (or) out-of-plane bending. A set of the panels had no additional reinforcement at the edges whereas others were either totally or partially reinforced with wood framing integrated along the edges. Existing formulae developed to predict these stresses were found to overestimate results obtained from a test programme conducted by the authors. New expressions are presented for wrinkling and ultimate loads for sandwich panels with various edge conditions. A comparison is made between existing and newly derived expressions.

Extending Laser Bending for the Generation of Convex Shapes

1995 ◽  
Vol 209 (6) ◽  
pp. 433-442 ◽  
Author(s):  
H Arnet ◽  
F Vollertsen
Keyword(s):  
Laser Beam ◽  
Experimental Results ◽  
Laser Bending ◽  
Stability Behaviour ◽  
Process Understanding ◽  
Bending Mechanism ◽  
The Stability

A summary about the present process understanding of the laser bending technology is given. Three different bending mechanisms are distinguished. Experimental results showing that at certain parameters an instability behaviour can occur are discussed. A bending mechanism is suggested which explains the stability behaviour. It is shown that laser bending can be extended in order to generate convex shapes, which means a bending away from the laser beam. The possibility of bending towards the laser beam or of bending away from the laser beam opens new ranges of applications, two of which are introduced in this paper.

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