Elastic Buckling of Infinitely Long Trapezoidally Corrugated Plates in Shear

1978 ◽  
Vol 45 (3) ◽  
pp. 579-582 ◽  
Author(s):  
D. Perel ◽  
C. Libove
Keyword(s):  
Flat Plate ◽  
Energy Method ◽  
Orthotropic Plate ◽  
Plate Theory ◽  
Elastic Buckling ◽  
Flat Plates ◽  
Buckling Loads ◽  
Plate Elements ◽  
Corrugated Plates

Buckling loads are calculated for a class of infinitely long trapezoidally corrugated plates under uniform in-plane edge shear. This class consists of corrugated plates in which all interior plate elements are of equal width, with the end elements clamped. The energy method is used as the basis of analysis, which considers the corrugated plate as a nonplanar assemblage of flat plates. Buckling loads calculated using this method are compared to those obtained by using orthotropic plate theory, which represents the corrugated plate by an orthotropic flat plate. The comparison shows significant differences in predicted buckling loads.

Experimental Analysis of Rudder Contribution to Roll Damping

2008 ◽  
Author(s):  
Ali Etebari ◽  
Paisan Atsavapranee ◽  
Christopher Bassler ◽  
Jason Carneal
Keyword(s):  
Flat Plate ◽  
Plate Theory ◽  
Added Mass ◽  
Sine Wave ◽  
Plate Model ◽  
Flat Plates ◽  
Roll Damping ◽  
Clear Trend ◽  
Current Effort ◽  
Drag And Lift

Measuring and modeling the forces on the appendages of surface ships is important for understanding roll-damping and validating numerical simulations. In recent years, Atsavapranee et al (2007) showed that the bilge keel damping component can be modeled using the flat plate theory established by Keulegan and Carpenter (1958). This model treats the bilge keels as a flat plate that generates viscous damping, as well as added mass. The model comes as an improvement to models used in computational codes used for predicting roll damping, due to the fact that the added mass component is significant. In this study, uncoupled roll motion is investigated to quantify the rudder forces on a fully appended DTMB model #5415 with instrumented appendages at Froude numbers of 0 and 0.138. The objective of the current effort is to decompose the rudder force into its steady, symmetric, and antisymmetric components using Fourier analysis. In the force analysis the rudders are treated as flat plates for the Fr = 0 tests, using the model described by Keulegan and Carpenter (1958). The drag and lift forces are consistent with the flat plate model. The anti-symmetric term, however, does not show a clear trend. For a flat plate model, the anti-symmetric term should resemble a negative sine wave with respect to roll. However, the rudders represent a higher aspect ratio flat plate, and thus require a modification to the added mass formulation. Furthermore, during a normal roll period they tend to interact with the free surface, which can lead to wave damping, which should resemble a positive sine wave with respect to roll. Thus, the two components of the anti-symmetric portion of the signal are superimposed upon one another. In an attempt to decouple these two components, the added mass was artificially removed from the antisymmetric component of the force. This paper will detail the methods used to model the rudder forces for both the standstill and positive Froude number cases.

Buckling of Simply Supported Plates Tapered in Planform

1956 ◽  
Vol 23 (2) ◽  
pp. 207-213
Author(s):  
Bertram Klein
Keyword(s):  
Elastic Buckling ◽  
Axial Loads ◽  
Flat Plates ◽  
Buckling Loads ◽  
Simply Supported ◽  
Shear Loads ◽  
Limiting Case ◽  
The Given

Abstract Design curves are presented for determining the elastic buckling loads of simply supported flat plates of isosceles trapezoidal planform and loaded in compression along the parallel edges. Shear loads are assumed to act along the sloping edges so that any ratio of axial loads may act along the parallel edges of the given plate. Isosceles triangular plates are included as a special limiting case, and the range of the values of the various geometric and load parameters presented in the curves is considered large enough to cover practically all conditions of the type treated which are encountered in practice.

Bending, Buckling and Vibration of Orthotropic Plate-Beam Structures

1968 ◽  
Vol 12 (04) ◽  
pp. 249-268 ◽  
Author(s):  
C. S. Smith
Keyword(s):  
Orthotropic Plate ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Elastic Buckling ◽  
Lateral Loads ◽  
Orthotropic Plates ◽  
Approximate Methods ◽  
Buckling Loads ◽  
Natural Frequencies And Modes ◽  
Modes Of Vibration

A method is described of estimating elastic deflections and stresses in systems of interconnected rectangular orthotropic plates and single-direction beams, under distributed or concentrated lateral loads combined with compressive or tensile stresses applied either normal to or in the direction of the beams. The effects of initial deformation of beams and plates are included. Elastic buckling loads and modes and natural frequencies and modes of vibration may be computed. The methods described have been incorporated in a family of FORTRAN IV computer programs which are used to obtain a number of illustrative solutions, including:(/) deflections and stresses in an orthogonally stiffened, three-dimensional ship compartment; these are compared with results computed by an alternative finite element method; (//) buckling loads and modes and natural frequencies and modes of vibration for a typical deck structure; these are compared with results calculated by more approximate methods commonly used in design.

Delamination of Laminate Plates

2014 ◽  
Vol 969 ◽  
pp. 97-100 ◽  
Author(s):  
Eva Kormaníková
Keyword(s):  
Finite Element Analysis ◽  
Mixed Mode ◽  
Plate Theory ◽  
Laminate Plate ◽  
Element Analysis ◽  
Interface Elements ◽  
First Order ◽  
Plate Elements ◽  
Interface Modeling ◽  
Shear Deformable

The paper deals with numerical modeling of delamination of laminate plate consists of unidirectional fiber reinforced layers. The methodology adopts the first-order shear laminate plate theory and fracture and contact mechanics. There are described sublaminate modeling and delamination modeling by the help of finite element analysis. With the interface modeling there is calculated the energy release rate along the lamination front. Numerical results are given for mixed mode delamination problems by implementing the method in a 2D finite analysis, which utilizes shear deformable plate elements and interface elements. Numerical example is done by the commercial ANSYS code.

scholarly journals A Combined Energy Method for Flutter Instability Analysis of Weakly Damped Panels in Supersonic Airflow

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1090
Author(s):  
Xiaochen Wang ◽  
Zhichun Yang ◽  
Guiwei Zhang ◽  
Xinwei Xu
Keyword(s):  
Energy Balance ◽  
Energy Method ◽  
Plate Theory ◽  
Dynamic Pressure ◽  
Physical Nature ◽  
Aeroelastic System ◽  
Dissipation Energy ◽  
Supersonic Airflow ◽  
Flutter Instability ◽  
Modal Damping

A combined energy method is proposed to investigate the flutter instability characteristics of weakly damped panels in the supersonic airflow. Based on the small damping assumption, the motion governing partial differential equation (PDE) of the panel aeroelastic system, is built by adopting the first-order piston theory and von Karman large deflection plate theory. Then by applying the Galerkin procedure, the PDE is discretized into a set of coupled ordinary differential equations, and the system reduced order model (ROM) with two degrees of freedom is obtained. Considering that the panel aeroelastic system is non-conservative in the physical nature, and assuming that the panel exhibits a single period oscillation on the flutter occurrence, the non-conservative energy balance principle is applied to the linearized ROM within one single oscillation period. The obtained result shows that the ROM modal coordinate amplitudes ratio is regulated by the modal damping coefficients ratio, though each modal damping coefficient is small. Furthermore, as the total damping dissipation energy can be eliminated due to its smallness, the He’s energy balance method is applied to the undamped ROM, therefore the critical non-dimensional dynamic pressure on the flutter instability occurrence, and the oscillation circular frequency amplitude relationship (linear and nonlinear form) are derived. In addition, the damping destabilization paradoxical influence on the system flutter instability is investigated. The accuracy and efficiency of the proposed method are validated by comparing the results with that obtained by using Routh Hurwitz criteria.

Flush probe studies of plasma flow over a flat plate: theory

1979 ◽  
Vol 12 (10) ◽  
pp. 1685-1697 ◽  
Author(s):  
C R Giles ◽  
R M Clements ◽  
P R Smy
Keyword(s):  
Flat Plate ◽  
Plasma Flow ◽  
Plate Theory

scholarly journals A Generalized Method for Flat Plates Impact Detection and Location

2013 ◽  
Vol 543 ◽  
pp. 171-175
Author(s):  
Jose Andrés Somolinos ◽  
Rafael Morales ◽  
Carlos Morón ◽  
Alfonso Garcia
Keyword(s):  
Signal Processing ◽  
Flat Plate ◽  
Acoustic Signal ◽  
Experimental Results ◽  
Piezoelectric Sensors ◽  
Experimental Setup ◽  
Flat Plates ◽  
Impact Detection ◽  
Timing Difference

In the last years, many analyses from acoustic signal processing have been used for different applications. In most cases, these sensor systems are based on the determination of times of flight for signals from every transducer. This paper presents a flat plate generalization method for impact detection and location over linear links or bars-based structures. The use of three piezoelectric sensors allow to achieve the position and impact time while the use of additional sensors lets cover a larger area of detection and avoid wrong timing difference measurements. An experimental setup and some experimental results are briefly presented.

Experimental Study of Multiple Air Jets Impinging a Moving Flat Plate

2020 ◽  
Author(s):  
Flavia Barbosa ◽  
Senhorinha Teixeira ◽  
Carlos Costa ◽  
Filipe Marques ◽  
José Carlos Teixeira
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Jet Impingement ◽  
Plate Motion ◽  
Test Facility ◽  
Flat Plates ◽  
Target Plate ◽  
Wall Jets ◽  
Air Jets ◽  
Flow Interactions

Abstract The motion of the target plate is important in some industrial applications which apply multiple jet impingement, such as reflow soldering, drying and food processing. Multiple jet impingement is widely used due to its ability to generate high heat transfer rates over large and complex areas. This convective process is characterized by several flow interactions essentially due to adjacent jets mixing prior the impingement, wall jets collision after the impingement, as well as crossflow interactions induced by the motion of the wall jets that flow through the exits of the domain. These interactions lead to strong flow recirculation, pressure gradients and boundary layer development. However, the complexity of the flow interactions is increased with the surface motion in confined space, due to the generation of strong shear regions. These interactions can induce problems and product defects due to complicated thermal behavior and non-uniform heating or cooling, being important to fully understand the process in order to reduce time and costs. This work addresses the experimental analysis of multiple air jets impinging on a moving flat plate. The experiments are conducted on a purpose-built test facility which has been commissioned, using a 2D-PIV system. Through this technique, the flow structure and velocity profiles will be analyzed in detail. The effects of the impinging plate motion on the resulting global and local velocity profile is compared with a static flat plate. The multiple jet configuration consists on air flowing through 14 circular nozzles, at a Reynolds number of 690 and 1,380. The experiments are conducted for a nozzle-to-plate distance of 8 and a jet-to-jet spacing of 2. The target plate motion remains constant throughout the experiments and equal to 0.03 m/s. The results are compared for both stationary and moving flat plates cases and express the increased complexity of the flow due to strong interaction between jets and the target surface, which affects the heat transfer performance. The results obtained experimentally are important to clearly define this complex flow and these data can be used in future works for numerical model validation.

scholarly journals Investigation of natural frequencies of axially loaded thin-walled columns

2018 ◽  
Vol 219 ◽  
pp. 02018
Author(s):  
Łukasz Żmuda-Trzebiatowski
Keyword(s):  
Applied Load ◽  
Natural Frequencies ◽  
Elastic Buckling ◽  
Correlation Technique ◽  
Buckling Loads ◽  
Perfectly Plastic ◽  
Linear Buckling ◽  
Thin Walled ◽  
Elastic Perfectly Plastic ◽  
Flexural Torsional Buckling

The paper deals with correlation between natural frequencies of two steel thin-walled columns and the corresponding applied load. The structures are made of cold-formed lipped channel sections. The columns lengths were assumed to follow two buckling patterns – global flexural and flexural-torsional buckling. In the thicker structure two material models were considered – linearly-elastic and elastic-perfectly plastic. Numerical computations cover dynamic eigenvalue problem, linear buckling and geometrically (and materially) non-linear analysis. The correlation between squares of natural frequencies and the applied load is linear in both columns. The first natural frequencies drop to zero due to structural buckling. This method, called the Vibration Correlation Technique, allows to predict buckling loads on the basis of measured vibration frequencies of the structures. Plasticity does not affect the corresponding curves – the use of the presented technique is limited to the structures exhibiting elastic buckling behaviour.

Calculation for Elastic Global Buckling of Sandwich Plates with Ribs

2012 ◽  
Vol 188 ◽  
pp. 25-30 ◽  
Author(s):  
Qi Chao Xue ◽  
Guang Ping Zou ◽  
Ye Wu ◽  
Hai Lin Xiong ◽  
Meng Chai
Keyword(s):  
Energy Method ◽  
Sandwich Plate ◽  
Plate Theory ◽  
Sandwich Plates ◽  
Buckling Stress ◽  
Global Buckling ◽  
Simple Support ◽  
Rectangular Sandwich Plate ◽  
Two Sides ◽  
Rectangular Sandwich Plates

Based on Reissner’s sandwich plate theory, the critical globlal buckling equation of sandwich plate with ribs is deduced by energy method under simple support boundary conditions. And the critical buckling solution is obtained and discussed here. Afterwards a rectangular sandwich plate with steel faceplate and polyurthane core is taken as an example. The influence on critical global buckling stress with different inertia moments in rectangular sandwich plates are discussed. simularly the effect of the lengh ratio of two sides and the thickness of rectangular sandwich plate are also studied.

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