Effects of Flexural and Mass Axes Position of Simple Rectangular Wing on Flutter Speed

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
A. Daniel Antony ◽  
M. Gopalsamy ◽  
K. Pavithra ◽  
R. Dinesh Babu
Keyword(s):  
Coupling Effect ◽  
Aircraft Design ◽  
Analytical Tool ◽  
Flutter Speed ◽  
Eigen Value ◽  
Elastic Forces ◽  
Flutter Analysis ◽  
Eigen Values ◽  
Wing Structure ◽  
Classical Flutter

The flexibility of the modern aircraft structures paves the way for the study of aero elasticity during the verification procedures of aircraft design and stability. The structures of wing will cautiously vibrate, either linearly or non-linearly due to the coupling effect between the aerodynamic, inertial and elastic forces of the wing structure, so the designing of aircraft involves two major aero elastic considerations such as wing torsional divergence and flutter. However, flutter problems are considered from the field of dynamic stability, the modal representation of flutter analysis is done by setting up the lifting surface as a linear ordinary differential equation, then changed to Eigen values and further stability analysis has been done. In order to complete the flutter analysis as an analytical tool, two important aerodynamic theories are taken into account and we identified and solved the classical flutter derivatives by using Eigen value method and also the position of flexural and mass axis of the simple rectangular wing on flutter speed has been analysed.

scholarly journals Verification of Flutter Method for the Purposes of Building a Very Flexible Wing Generative Model

2020 ◽  
Author(s):  
Kamil Zenowicz ◽  
Wojciech Skarka
Keyword(s):  
Preliminary Analysis ◽  
Aircraft Design ◽  
Generative Model ◽  
Structure Stability ◽  
Resistance Force ◽  
Flexible Wing ◽  
Flutter Analysis ◽  
Flight Parameters ◽  
Wing Structure ◽  
Calculation Software

First step of aircraft design is calculation of initial parameters, based on assumptions determining flight parameters which designed aircraft should meet. During these calculations, it is possible to pre-detect structure instability called a flutter. These calculations are made based on the geometric parameters assumed in the first conceptual drawings of the flying vehicle. Assumed masses and speeds allow for preliminary analysis of forces acting on the structure. The next step is to determine the displacements and deformations occurring in the structure of the aircraft in different phases of flight and under different conditions. The article presents all the stages of wing analysis for a proposed stratospheric drone with a highly flexible wing structure. This analysis, after integration with CAD software, will allow for the preparation of a comprehensive generative model. The basic assumptions of the designed aircraft are: flight altitude, wings area, very extended or unlimited flight time, approximate flight speed, climbing time, hull parameters, rudder size and placement, wing profile and mass of the structure. These assumptions made it possible to carry out a preliminary analysis of loads, wing pressure distribution, lift force and total resistance force. The goal of the research is to develop a methodology of preliminary flutter analysis which can be easily integrated in the form of calculation backgound for generative model. This methodology has been developed to determine displacements, structure stability and critical vibration frequencies. CAD software after integration with constantly optimizing calculation software will allow the generation of optimal shape and structure rigidity for given initial assumptions.

scholarly journals Numerical Calculation of Energy Eigen-values of the Hydrogen Negative Ion in the 2p^2 Configuration by Using the Variational Method

2020 ◽  
Vol 24 (1) ◽  
pp. 30
Author(s):  
Yosef Robertus Utomo ◽  
Guntur Maruto ◽  
Agung Bambang Setio Utomo ◽  
Pekik Nurwantoro ◽  
Sholihun Sholihun
Keyword(s):  
Numerical Calculation ◽  
Variational Method ◽  
Trial Function ◽  
Hydrogen Molecule ◽  
Negative Ion ◽  
Multipole Moments ◽  
A Value ◽  
Eigen Value ◽  
Eigen Values ◽  
Electric Multipole Moments

Calculation of energy eigen value of hydrogen negative ion (H − ) in 2p^2 configuration using the method of variation functions has been done. A work on H − can lead to calculations of electric multipole moments of a hydrogen molecule. The trial function is a linear combination of 8 expansion terms each of which is related to the Chandrasekhar’s basis. This work produces a series of 7 energy eigen values which converges to a value of −0.2468 whereas the value of this convergence is expected to be −0.2523. This deviation from the expected value is mainly due to the elimination of interelectronic distance (u) coordinate. The values of the exponent parameters used in this work contribute also to this deviation. This variational method will be applied to the construction of some energy eigen functions of Hv2 .

Identification of kinematic chains and distinct mechanisms using extended adjacency matrix

2007 ◽  
Vol 221 (1) ◽  
pp. 81-88 ◽  
Author(s):  
A Mohammad ◽  
R A Khan ◽  
V P Agrawal
Keyword(s):  
Adjacency Matrix ◽  
Kinematic Chain ◽  
Theoretic Approach ◽  
Kinematic Chains ◽  
Graph Theoretic ◽  
The Past ◽  
Graph Theoretic Approach ◽  
The Family ◽  
Eigen Value ◽  
Eigen Values

Development of the methods for generating distinct mechanisms derived from a given family of kinematic chains has been persued by a number of researchers in the past, as the distinct kinematic structures provide distinct performance characteristics. A new method is proposed to identify the distinct mechanisms derived from a given kinematic chain in this paper. Kinematic chains and their derived mechanisms are represented in the form of an extended adjacency matrix [EA] using the graph theoretic approach. Two structural invariants derived from the eigen spectrum of the [EA] matrix are the sum of absolute eigen values EA∑ and maximum absolute eigen value EAmax. These invariants are used as the composite identification number of a kinematic chain and mechanism and are tested to identify the all-distinct mechanisms derived from the family of 1-F kinematic chains up to 10 links. The identification of distinct kinematic chains and their mechanisms is necessary to select the best possible mechanism for the specified task at the conceptual stage of design.

A Discussion about Finite Element Analysis of Aircraft Wing Structure

2012 ◽  
Vol 532-533 ◽  
pp. 427-430
Author(s):  
Wei Tao Zhao ◽  
Tian Jun Yu ◽  
Yi Yang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aircraft Design ◽  
Element Model ◽  
Aircraft Wing ◽  
Element Analysis ◽  
Actual Structure ◽  
Shear Plate ◽  
Wing Structure ◽  
Lifting Surfaces

One of the most significant components of aircraft design is the wing, the wings are the main lifting surfaces that support the airplane in flight. The structures of wings must have enough strength and rigidity to ensure the safe of the aircraft. Usually, the displacements of the structures are calculated by using finite element method. But it is very difficult to select a reasonable finite element model to approximate the actual structure. In this study, two models are adopted to calculate the displacements of the wing structure. The first is a model of rod and shear plate, the second is a model of beam and shell. The disadvantages and advantages of two models are discussed. As seen from the comparison with the test date, two models proposed are both feasible to analyze the wing structure.

An Aero-Thermo-Elasticity Method Applied on the Supersonic Aircraft Model

2012 ◽  
Vol 215-216 ◽  
pp. 438-442 ◽  
Author(s):  
Hong Tang ◽  
Guo Guang Chen ◽  
Hui Zhu He
Keyword(s):  
Structural Dynamics ◽  
Thermal Deformation ◽  
Aircraft Design ◽  
Ride Quality ◽  
Supersonic Aircraft ◽  
Flutter Speed ◽  
Unsteady Aerodynamic ◽  
Aeroelastic Analysis ◽  
Computational Structural Dynamics ◽  
Analytical Tools

Coupling between the vibration frequencies and the unsteady aerodynamic will reduce the flutter speed and ride quality through the aerodynamic heat transfer. As the flight speed improved, the aeroelastic analysis has become an essential means of aircraft design. The method of aero-thermo-elastic (ATE) analysis is coupled with aircraft aeroelastic analysis and thermal deformation, and is more realistic reflection of the actual flight of the aircraft. In this paper, an ATE analysis of aircraft adopted by computational fluid dynamics/computational structural dynamics (CFD/CSD) methods, and compared with the traditional analysis, to provide analytical tools for the supersonic aircraft design.

Evaluation of classical flutter analysis for the prediction of limit cycle oscillations

1997 ◽  
Author(s):  
Charles Denegri, Jr. ◽  
Malcolm Cutchins ◽  
Charles Denegri, Jr. ◽  
Malcolm Cutchins
Keyword(s):  
Limit Cycle ◽  
Limit Cycle Oscillations ◽  
Flutter Analysis ◽  
Classical Flutter

Eigen function and corresponding eigen values of charge carriers in V-grooves quantum wires with variable width

2016 ◽  
Vol 30 (17) ◽  
pp. 1650103
Author(s):  
Ali Hossein Mohammad Zaheri
Keyword(s):  
Effective Potential ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Wave Functions ◽  
Charge Carriers ◽  
Energy Spectra ◽  
Eigen Value ◽  
Eigen Values ◽  
Interface Geometry ◽  
Good Agreement

In this work, we have calculated analytically the energy spectra of electrons and holes in V-grooves quantum wires. To modify wire structure, we have used the equations which suggested in the work of Inoshita et al. We introduce a new effective potential scheme which is applicable and matchable with actual interface geometry of this groove of ridge quantum wires. By applying this effective potential and considering a suitable transformed coordinate that allows the decoupling of the two-dimensional wave functions, we have calculated eigen values of the charge carriers in three states as well as the wave functions. We found that by increasing the curvature at the top of quantum wire [Formula: see text] the energy eigen value decreases. Our results are in good agreement with the earlier investigations.

scholarly journals PERANCANGAN AWAL SCALE MODEL GLIDER STTA-25-02_SAILPLANE

2017 ◽  
Vol 8 (2) ◽  
pp. 87
Author(s):  
Hendrix Novianto Firmansyah ◽  
Buyung Junaidin ◽  
M. Fatha Mauliadi
Keyword(s):  
Dynamic Stability ◽  
Stability Condition ◽  
Aircraft Design ◽  
Static Stability ◽  
Scale Model ◽  
Negative Slope ◽  
Preliminary Design ◽  
Short Period ◽  
Eigen Value ◽  
Significant Achievement

The knowledge and experience in aircraft design, especially for glider or sailplane are very important to have. Today, process of designing glider developed so rapidly, especially in America and Europe, one of the significant achievement is the performance aspect of glider. For example, the German-built Eta has a wingspan 30.78 m, aspect ratio 51 and wing loading 50.97 kg/m2, with glide angle of 0.8 degree and 3 km altitude, the glider able to fly 213 km in horizontal direction. Therefore, as the first step to understand the preliminary design of glider, it is important to start with designing a scale model glider STTA-25-02_Sailplane. The goals of this design are to get geometry and configuration of the glider, to obtained stability of glider and to gain performance data that meet with design requirements and objectives data (DR&O). The conclusions from the preliminary design of scale model glider STTA-25-02_Sailplane are the geometry and configuration are good, for example the achivement in performance, the minimum sink rate 0.52 m/s, the glide ratio more than 20 at a cruising speed over 13 m/s, stall speed 11.45 m/s at angle of attack 0 degree. In addition glider STTA-25-02_Sailplane has static and dynamic stability, the static stability condition is indicated by the value of trim angle is positive 1 degree, curve of Cma and Clfi has negative slope, Cnfi curve has positive slope. The dynamic stability condition is indicated by the eigen value for each mode o f movement are negative except on phugoid and spiral mode, eigen value for short period -5.7681 ± 7.0010, phugoid 0.0403 ± 1.1136, rool damping -32.6243, dutch roll -1.0468 ± 3.4891 and spiral 0.1467. Positive eigen value on phugoid and spiral mode can be solved by adding a control parameter of the controlsurfaces.

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