Induced Strain Actuation for Solid-State Ornithopters: Pitch and Heave Coupling

2017 ◽  
Author(s):  
Francis Hauris ◽  
Onur Bilgen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fiber Composite ◽  
Leading Edge ◽  
Theoretical Models ◽  
Element Model ◽  
Harmonic Excitation ◽  
Edge Stiffener ◽  
Modes Of Vibration ◽  
Composite Wing

This paper investigates the heaving and pitching of a wing-like parameterized cantilevered plate with a leading edge stiffener and clamp variation when actuated with a surface-bonded piezoelectric actuator. The response is analyzed using a finite element model that is validated by comparison with known analytical solutions. The validated finite-element model is subjected to a harmonic excitation parametric analysis. The parameters varied in the model are the root clamped percentage, leading edge stiffener thickness, and the aspect ratio of the plate. The model is examined at the first two Eigen frequencies. Metrics of heaving and pitching are developed using surface fitting methods and their amplitudes and phases are reported throughout the parameter space. Emphasis is placed on the interaction and coupling of the first two modes of vibration with respect to the parameters. A piezo-composite wing prototype is fabricated and actuated harmonically with a Macro-Fiber Composite actuator while leading edge stiffener thickness and root clamped percentage is varied. The resulting experimental data is used to further validate the theoretical models.

Material Constants for a Finite Element Model of the Intervertebral Disk With a Fiber Composite Annulus

1986 ◽  
Vol 108 (1) ◽  
pp. 1-11 ◽  
Author(s):  
R. L. Spilker ◽  
D. M. Jakobs ◽  
A. B. Schultz
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fiber Composite ◽  
Element Model ◽  
Intervertebral Disk ◽  
Material Constants ◽  
Reinforced Composite ◽  
Vertebral Bodies ◽  
Anisotropic Layers ◽  
Selection Of

A simple axisymmetric finite element model of a human spine segment containing two adjacent vertebrae and the intervening intervertebral disk was constructed. The model incorporated four substructures: one to represent each of the vertebral bodies, the annulus fibrosus, and the nucleus pulposus. A semi-analytic technique was used to maintain the computational economies of a two-dimensional analysis when nonaxisymmetric loads were imposed on the model. The annulus material was represented as a layered fiber-reinforced composite. This paper describes the selection of material constants to represent the anisotropic layers of the annulus. It shows that a single set of material constants can be chosen so that model predictions of gross disk behavior under compression, torsion, shear, and moment loading are in reasonable agreement with the mean and range of experimentally measured disk behaviors. It also examines the effects of varying annular material properties.

Crushing and Wet Collapse of Flowline Carcasses: A Theoretical-Experimental Approach

2010 ◽  
Author(s):  
Celso P. Pesce ◽  
Clo´vis A. Martins ◽  
Alfredo Gay Neto ◽  
Andre´ L. C. Fujarra ◽  
Fernanda C. M. Takafuji ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Yield Stress ◽  
Experimental Approach ◽  
Theoretical Models ◽  
Element Model ◽  
Experimental Results ◽  
Sensitivity Analyses ◽  
Theoretical Predictions ◽  
Equivalent Ring

The present paper brings together theoretical predictions and experimental results, comparing crushing tests results as well as carcass wet collapse tests. The theoretical models are of two kinds: (i) numerical (FE) and (ii) analytical. The first kind is a restricted 3D version of a finite element model. The second kind is based on classic assumptions of equivalent ring behavior. Discussion is made on the real yield stress value to be adopted, as well as on the pertinence of geometric hypotheses. Sensitivity analyses, regarding ovalization and helical pitch are also presented.

Large deformation mechanical modeling with bilinear stiffness for Macro-Fiber Composite bimorph based on extending mixing rules

2020 ◽  
pp. 1045389X2095125
Author(s):  
Kai-ming Hu ◽  
Hua Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Large Deformation ◽  
Composite Structures ◽  
Fiber Composite ◽  
Three Dimensional ◽  
Element Model ◽  
Fiber Composites ◽  
Mixing Rules ◽  
Macro Fiber Composite

Macro-Fiber Composite bimorph is a kind of piezoelectric actuator that allow large bending deformation. However, macro-fiber composites exhibit strong stiffness nonlinearity in their operation range, so it is difficult to accurately estimate their large deformation behavior based on a linear constitutive model. In addition, the macro-fiber composites have active and inactive parts, that significantly differ in their material sizes and properties, so it is not reasonable to consider them as uniform material. Thus, it is necessary develop an accurate modeling and analysis method for the large deformation macro-fiber composite structures. First, the mixing rules are extended to derive the three-dimensional homogenized mechanical and electrical parameters of the macro-fiber composite active part; based on these parameters, the actuation results of linear finite element model is in good agreement with the official data. Then a finite element model of the axially compressed macro-fiber composite bimorph is established, the bilinear tensile stiffness of macro-fiber composite is realized by secondary development in ANSYS. Comparison with the experimental results reveals high accuracy of the established finite element model. Thus, the developed method can be effectively used for the performance evaluation and design of the macro-fiber composite devices with large deformation.

Design and Modeling of the Fowler Flap With Adaptive Elements

Aerospace ◽  
2006 ◽  
Author(s):  
Oleksandr Kozlov
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Deformation Behaviour ◽  
Leading Edge ◽  
Element Model ◽  
High Lift ◽  
Aerodynamic Efficiency ◽  
Transport Aircraft ◽  
Sma Actuators ◽  
Active Flap

This paper describes the process of the designing of the Fowler flap with adaptive elements. Modern passenger and transport aircraft use high lift devices for take off and landing. Of great importance for the creation of high lift during take off and landing is the shape and size of the gap between wing and extended Fowler flap. To improve the deformation behaviour of the leading edge of this flap, and to improve the geometry of the gap, it was decided to use shape memory alloy (SMA) actuators in the flap structure. First, the complex finite element model of the passive flap was created and then this model was extended with active elements, which are modelling the SMA actuators. As a result, the complex finite element model of the active flap was obtained. This modelling was done using software MATLAB and a finite element model was created using software ANSYS. The main result of this work is that with help of SMA actuators integrated in the flap it was possible to influence and improve the geometry of the gap between the wing and the extended flap, resulting in the aerodynamic efficiency of this flap being increased.

Elastic-Plastic Wheel-Rail Thermal Contact on Corrugated Rails During Wheel Braking

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Yung-Chuan Chen ◽  
Sing-You Lee
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Contact Pressure ◽  
Contact Region ◽  
Thermal Contact ◽  
Maximum Shear Stress ◽  
Leading Edge ◽  
Element Model ◽  
Elastic Plastic ◽  
Peak Contact Pressure

This study uses an elastic-plastic, coupled temperature-displacement finite element model to investigate the effect of rail corrugations on the wheel-rail thermal contact stress and temperature distribution during wheel braking. The finite element model assumes that the material properties and the friction coefficient are temperature-dependent. The analysis considers various corrugation wavelengths and amplitudes and is performed over a range of braking speeds. The results indicate that the corrugated rail induces wavelike contact pressure and temperature distributions on the rail surface. The results also show that the variation in the peak contact pressure increases as the corrugation wavelength is reduced or as the corrugation amplitude is increased. Furthermore, it is found that the corrugated rail shifts the location of the peak value of the rail surface temperature toward the leading edge of the contact region. The amplitude of the temperature fluctuations reduces as the corrugation wavelength is increased or as the corrugation amplitude is reduced. Finally, a higher corrugation amplitude or a shorter corrugation wavelength causes the location of the peak maximum shear stress to shift toward the rail surface.

scholarly journals Numerical and Experimental Analysis of Umbilical Cables under Tension

2017 ◽  
Vol 26 (2) ◽  
pp. 096369351702600 ◽  
Author(s):  
Qingzhen Lu ◽  
Jinlong Chen ◽  
zhixun Yang ◽  
Yin Yuan chao ◽  
Qianjin Yue
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Inner Core ◽  
Theoretical Models ◽  
Element Model ◽  
Radial Deformation ◽  
Element Analysis ◽  
Umbilical Cable ◽  
The Finite Element Model

Umbilical cables are composite structures that consisting of metallic material and polymeric material. Analysing tension behaviour under axial loading is a key requirement to design the structure. A full three-dimensional finite element model is established in which the effect of radial deformation is given more attention. A plane finite element analysis is proposed to predict the radial stiffness of the inner core with several components. The tension behaviour of an umbilical cable is analysed by the proposed models. Tension tests of the umbilical cable were carried out. Compared with the available theoretical models in the literature, the finite element model has a satisfactory agreement with the experimental results. In addition, the finite element model is used for the assessment of the influence of the important parameters on the tension behaviour, which is helpful for the design of umbilical cable.

“In Vivo” Determination of Macroscopic Biological Material Properties

1975 ◽  
Vol 97 (4) ◽  
pp. 350-356 ◽  
Author(s):  
E. R. Garner ◽  
D. O. Blackketter
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Properties ◽  
Biological Material ◽  
Soft Tissues ◽  
Three Dimensional ◽  
Element Model ◽  
Harmonic Excitation ◽  
Analytical Technique

This paper describes an experimental-analytical technique for determining the in-vivo macroscopic biological material properties of the human forearm. The technique utilizes the experimentally determined steady-state response of the forearm to a harmonic excitation in the 100 to 1000 Hertz band and a non-symmetric three-dimensional finite element model of the forearm. The “in-vivo macroscopic material properties” were determined by adjusting the material properties of the finite element model until there was a minimum of difference between the response of the finite element and the response found experimentally in the 100 to 1000 Hertz band. Both the soft tissues and the hard tissues were modeled as viscoelastic materials.

Finite Element Modeling of the Response of Long Floating Structures Under Harmonic Excitation

1985 ◽  
Vol 107 (1) ◽  
pp. 48-53 ◽  
Author(s):  
C. Georgiadis
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Modeling ◽  
Wave Field ◽  
Element Model ◽  
Harmonic Excitation ◽  
Element Analysis ◽  
Floating Structures ◽  
Element Modeling

The response of long floating structures to a harmonic excitation is the basis for the response calculation in a short-crested wave field. This paper will present consistent formulas for obtaining the nodal loads in a finite element analysis. The accuracy of the method used is compared with the results obtained using a Rayleigh-Ritz approximation of the response with continuous eigenfunctions. The error of using an irrational finite element model is demonstrated for comparison, and to indicate to designers of similar structures the large effects which they may be overlooking.

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