Formation of high aspect ratio wrinkles and ridges on elastic bilayers with small thickness contrast

Soft Matter ◽  
2018 ◽  
Vol 14 (42) ◽  
pp. 8545-8551 ◽  
Author(s):  
Anesia Auguste ◽  
Jiawei Yang ◽  
Lihua Jin ◽  
Dayong Chen ◽  
Zhigang Suo ◽  
...  
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Period Doubling ◽  
Finite Element Simulations ◽  
Regular Pattern ◽  
High Modulus ◽  
Soft Substrate ◽  
Small Thickness ◽  
Secondary Bifurcations

An elastic bilayer composed of a stiff film bonded to a soft substrate forms wrinkles under compression. Experiments and finite element simulations reveal that at small thickness contrast, secondary bifurcations such as period doubling are delayed, providing access to high aspect ratio wrinkles. For high modulus contrast, the periodic wrinkles can evolve into a regular pattern of ridges with even higher aspect ratio.

The Analyse on Stiffness Model of 3-PPSR Flexible Parallel Robot

2014 ◽  
Vol 716-717 ◽  
pp. 1643-1647
Author(s):  
Yu Liang Luan ◽  
Wei Bin Rong ◽  
Li Ning Sun
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Parallel Robot ◽  
Force Balance ◽  
Element Analysis ◽  
Flexible Hinge ◽  
Stiffness Model ◽  
The Finite Element Analysis ◽  
The Mathematical Model

In order to achieve greater workspace motion, it’s designed a high aspect ratio 3-PPSR flexible parallel robot, driven by a piezoelectric motor, connected by flexible hinges, which has the advantages of simple structure, non singular, seamless, high motion precision. Because of the stiffness of the system directly affecting the motion accuracy, load bearing performance, according to the characteristics of high aspect ratio flexible hinge, It’s established the mathematical model of flexible hinge through finite element method. Using method of integral stiffness, conbined coordination equation with force balance equation, the flexible stiffness model of system is obtained. Finally, through using Ansys, it’s confirmed the validity of the theoretical model by comparing of the theoretical stiffness model results with the finite element analysis of the model results, to provide a reliable guarantee for optimization and analysis of kinematics and dynamics of flexible parallel robot.

Predicting the Young’s modulus of intercalated and exfoliated polymer/clay nanocomposites

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Vadoud Molajavadi ◽  
Hamid Garmabi
Keyword(s):  
Aspect Ratio ◽  
Young’S Modulus ◽  
Surface Area ◽  
High Aspect Ratio ◽  
Young's Modulus ◽  
Clay Nanocomposites ◽  
High Modulus ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
New Equation

AbstractThe Halpin-Tsai equations were used for the composites with low level content of reinforcements, which contain lamellar shape, high modulus and high aspect ratio. These characteristics of reinforcements were taken into consideration to simplify the Halpin-Tsai equations. The effect of different parameters on the longitudinal Young’s modulus of well aligned polymer/clay nanocomposites was investigated for both exfoliated and intercalated microstructures. It was shown that the applied simplification had negligible effect on the prediction of the Halpin-Tsai model. For the intercalated structures with a high number of platelets per stack (n), increase in the gallery spacing did not influence the predicted modulus values. In an intercalated structure, the surface area of a stack, as the interface of fillermatrix, is n times lower than that of the exfoliated state. By considering the effect of the degree of exfoliation in the proposed model, a new equation was developed to predict the modulus enhancement in the nanocomposites filled with Montmorillonite (MMT). The theoretical predictions were supported by the experimental results.

Aircraft Configuration Improvement Study from Aerodynamic and Structure Standpoints

2015 ◽  
Vol 798 ◽  
pp. 565-570
Author(s):  
Luciano Magno Fragola Barbosa ◽  
Ricardo Luiz Utsch de Freitas Pinto ◽  
Bernardo Oliveira Hargreaves
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Load Distribution ◽  
Structural Deformation ◽  
Load Factor ◽  
Aircraft Wing ◽  
Induced Drag ◽  
Vertical Displacements ◽  
Lifting Line

In this work improvements on the geometry of a high aspect ratio aircraft wing are studied, in order to reduce the wing in-flight deformation, without changing the drag of the aircraft and without increasing the structural weight. For this, from a reference rectangular wing, one new wing with elliptical planform has been defined; and comparative analyses of loads and structural deformation have been made for the wings considered: the original rectangular wing and the new corresponding elliptical wing. The aerodynamic analysis is based on the lifting line approach. A computer routine is made by the authors based on this approach, to obtain both induced drag values and the load distribution of the two wings, the original one and the corresponding elliptical. Based on the loads, spars for the two wings have been defined, and in order to evaluate the vertical displacements in flight, a finite element routine have been used. The main result of this study is the comparison of the deformation of wings considered, subjected to the same load factor, and for the same aircraft mass. The results obtained are encouraging for further developments using the present methodology.

scholarly journals Finite element simulation of fracture in a restored premolar tooth using high aspect ratio elements

2018 ◽  
Vol 34 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Maryam Ramezani ◽  
Estevam Barbosa de Las Casas ◽  
Cláudia Machado de Almeida Mattos ◽  
Osvaldo Luís Manzoli ◽  
Eduardo Alexandre Rodrigues
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Finite Element Simulation ◽  
High Aspect Ratio ◽  
Element Simulation

scholarly journals Nonlinear Reduced Order Model for Aeroelastic Static Deformations of Cantilevered Rectangular High Aspect Ratio Wing Model

2019 ◽  
Vol 9 (1) ◽  
pp. 924-930
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Reduced Order Model ◽  
Order Model ◽  
Torsional Mode ◽  
Linear Solution ◽  
Reduced Order ◽  
Wing Model ◽  
Bending Mode

The paper is motivated by the increasing interest in the use of high aspect ratio (HAR) wings to utilize its aerodynamic properties to gain better endurance. Nevertheless, the drawback of the issue is that with increment in the aspect ratio of the wing, the geometric nonlinearity gains more significance hence the linear solution is no longer acceptable. Even though, a number of nonlinear solution package are available in the market, but the solution is a very time consuming process. Hence, to help reduce the complexity of the nonlinear aeroelastic analysis, a Combined Model/Finite Element (CMFE) technique is employed to develop a Nonlinear Reduced Order Model (NROM) which describe the nonlinearity of the HAR wing from a solution of nonlinear static analysis for a range of prescribed loading cases. Three loading types were considered for the production of the NROM of which the force subjected to the wing model was normalized to follow the normal mode of the wing model. The three loading types are of the first bending mode, the first torsional mode and a combination of the first bending and torsional modes. The NROM equations are then developed utilizing the backward regression method. In order to verify the NROM equation accuracy with respect to the results obtained from the finite element analysis (FEA) software, the comparisons are made in terms of mean error and standard deviation of the error. The results indicate the NROM developed using a combination of the first bending mode and first torsional mode of the wing model has better accuracy than the NROM developed with the modes individually. The NROM also portrays greater accuracy when developed using the data due to the load from the first bending and the first torsional mode.

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