scholarly journals Modeling and analysis of high aspect ratio wing considering random structural parameters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bangsheng Fu ◽  
Ya Yang ◽  
Hui Qi ◽  
Jiangtao Xu ◽  
Shaobo Wang
Keyword(s):  
Elastic Modulus ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Structural Parameters ◽  
Torsional Stiffness ◽  
Statistical Characteristics ◽  
Modeling And Analysis ◽  
One Dimensional ◽  
Advanced Composite Materials ◽  
Aeroelastic Model

AbstractWith the application of advanced composite materials in High-Aspect-Ratio wings (HARW), the randomness of structural parameters, such as elastic modulus and Poisson's ratio, is enhanced. Hence, in order to explore the whole picture of aeroelastic problems, it is of great significance to study the role of random structural parameters in aeroelastic problems. In this paper, the dynamic response of flexible HARW considering random structural parameters is analyzed. An aeroelastic model of a one-dimensional cantilevered Euler–Bernoulli beam considering aerodynamic forces acting on the wing is established based on Hamilton's principle. Adopted the idea of simplifying calculation, the effect of random structural parameters is analyzed. Then, considering the elastic modulus and torsional stiffness as continuously one-dimensional random field functions, and discretized by local method. The first and second order recursive stochastic nonlinear finite element equations of wing are derived by using perturbation method. Based on it, statistical expression of aeroelastic effects of the wing is derived. Monte Carlo method is adopted to verify the effectiveness of the method. Numerical simulations indicate that the method proposed can well mirror the statistical characteristics of aeroelastic response.

Framework to model neutral particle flux in convex high aspect ratio structures using one-dimensional radiosity

2017 ◽  
Vol 128 ◽  
pp. 141-147 ◽  
Author(s):  
Paul Manstetten ◽  
Lado Filipovic ◽  
Andreas Hössinger ◽  
Josef Weinbub ◽  
Siegfried Selberherr
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Particle Flux ◽  
Neutral Particle ◽  
One Dimensional

scholarly journals Numerical Analysis and Experimental Study on Fabrication of High Aspect Ratio Tapered Ultrafine Holes by Over-Growth Electroforming Process

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 824
Author(s):  
Yunyan Zhang ◽  
Pingmei Ming ◽  
Runqing Li ◽  
Ge Qin ◽  
Xinmin Zhang ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Structural Parameters ◽  
Geometric Shape ◽  
High Tech ◽  
Shape Evolution ◽  
Metallic Plate ◽  
Electroforming Process ◽  
Photoresist Film ◽  
The Relationship

High aspect ratio (HAR) ultrafine tapered holes (diameter ≤5 μm; AR ≥5) are the most important elements for some high-tech perforated metallic products, but they are very difficult to manufacture. Therefore, this paper proposes a nontraditional over-growth electroforming process. The formation mechanism of the HAR ultrafine tapered holes is investigated, and the factors controlling the geometric shape evolution are analyzed numerically. It was found that the geometric shape and dimensions of the holes are highly dependent on the diameter and thickness of the photoresist film patterns, but are hardly affected by the spacing between two neighboring patterns; the achievable diameter for a given hole depth becomes small with the increasing pattern diameter, but it becomes big with the increasing pattern thickness. These correlations can be well interpreted by the established two empirical equations that characterize the relationship between the minimum orifice of the tapered hole and the structural parameters of the photoresist film patterns previously formed on the substrate. Application of the fabricated 1500 tapered holes with 3-μm diameter and 17-AR as the nozzles of the medical precision nebulizer is also examined. The studies show that the over-growth electroforming process is highly applicable in fabricating the perforated metallic plate with HAR ultrafine tapered holes.

scholarly journals Strong and Reversible Adhesion of Interlocked 3D-Microarchitectures

Coatings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 48 ◽  
Author(s):  
Minho Seong ◽  
Hyun-Ha Park ◽  
Insol Hwang ◽  
Hoon Eui Jeong
Keyword(s):  
Aspect Ratio ◽  
Structural Stability ◽  
High Aspect Ratio ◽  
Three Dimensional ◽  
Normal Direction ◽  
One Dimensional ◽  
Reversible Adhesion ◽  
Adhesion Behavior ◽  
Organic Nanomaterials ◽  
Good Agreement

Diverse physical interlocking devices have recently been developed based on one-dimensional (1D), high-aspect-ratio inorganic and organic nanomaterials. Although these 1D nanomaterial-based interlocking devices can provide reliable and repeatable shear adhesion, their adhesion in the normal direction is typically very weak. In addition, the high-aspect-ratio, slender structures are mechanically less durable. In this study, we demonstrate a highly flexible and robust interlocking system that exhibits strong and reversible adhesion based on physical interlocking between three-dimensional (3D) microscale architectures. The 3D microstructures have protruding tips on their cylindrical stems, which enable tight mechanical binding between the microstructures. Based on the unique 3D architectures, the interlocking adhesives exhibit remarkable adhesion strengths in both the normal and shear directions. In addition, their adhesion is highly reversible due to the robust mechanical and structural stability of the microstructures. An analytical model is proposed to explain the measured adhesion behavior, which is in good agreement with the experimental results.

scholarly journals Mechanically Improved and Multifunctional CFRP Enabled by Resins with High Concentrations Epoxy-Functionalized Fluorographene Fillers

2021 ◽  
Author(s):  
Junhua Wei
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Elastic Modulus ◽  
Carbon Fiber ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Reinforcing Particles ◽  
Thermoset Resin ◽  
High Concentrations ◽  
Carbon Based

To meet the maximum potential of the mechanical properties of carbon fiber reinforced plastics (CFRP), stress transfer between the carbon fibers through the polymer matrix must be improved. A recent promising approach reportedly used reinforcing particles as fillers dispersed in the resin. Carbon based fillers are an excellent candidate for such reinforcing particles due to their intrinsically high mechanical properties, structure and chemical nature similar to carbon fiber and high aspect ratio. They have shown great potential in increasing the strength, elastic modulus and other mechanical properties of interest of CFRPs. However, a percolation threshold of ~1% of the carbon-based particle concentration in the base resin has generally been reported, beyond which the mechanical properties deteriorate due to particle agglomeration. As a result, the potential for further increase of the mechanical properties of CFRPs with carbon-based fillers is limited. We report a significant increase in the strength and elastic modulus of CFRPs, achieved with a novel reinforced thermoset resin that contains high loadings of epoxy-reacted fluorographene (ERFG) fillers. We found that the improvement in mechanical performance of CFRPs was correlated with increase in ERFG loading in the resin. Using a novel thermoset resin containing 10 wt% ERFG filler, CFRPs fabricated by wet layup technique with twill weaves showed a 19.6% and 17.7% increase in the elastic modulus and tensile strength respectively. In addition, because of graphene’s high thermal conductivity and high aspect ratio, the novel resin enhanced CFRPs possessed 59.3% higher through-plane thermal conductivity and an 81-fold reduction in the hydrogen permeability. The results of this study demonstrate that high loadings of functionalized particles dispersed in the resin is a viable path towards fabrication of improved, high-performance CFRP parts and systems.

scholarly journals Effect of Stiffness on Flutter of Composite Wings with High Aspect Ratio

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shengjun Qiao ◽  
Jin Jiao ◽  
Yingge Ni ◽  
Han Chen ◽  
Xing Liu
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Limit Cycle Oscillation ◽  
Spanwise Direction ◽  
Aerodynamic Loads ◽  
Thin Walled Structures ◽  
Computational Fluid Dynamics Cfd ◽  
Cycle Oscillation

High aspect ratio wing (HARW) structures will deform greatly under aerodynamic loads, and changes in the stiffness will have a great impact on the flutter characteristics of such wings. Based on this, this paper presents an effective method to determine the effect of the stiffness on the flutter characteristics of HARWs. Based on the calculation theory of the mechanical profile of thin-walled structures, the torsional stiffness and bending stiffness of the wing are obtained through calculation. We use the fluid-structure coupling method to analyze the flutter characteristics of the wing, and we use our research results based on the corotational (CR) method to perform structural calculations. The load is calculated using a computational fluid dynamics (CFD) solver. The results show that, compared with the original wing, when the bending stiffness and torsional stiffness of the wing along the spanwise direction increase by 8.28% and 5.22%, respectively, the amplitude of the flutter decreases by approximately 30%. Increasing the stiffness in the range of 0.4 to 0.6 Mach has a greater impact on the flutter critical velocity, which increases by 12.03%. The greater the aircraft’s flight speed is, the more severe the stiffness affects the wing limit cycle oscillation (LCO) amplitude.

Loss of Stiffness in a Heated Wing: An Inequality

1963 ◽  
Vol 67 (627) ◽  
pp. 191-191 ◽  
Author(s):  
E. H. Mansfield
Keyword(s):  
Aspect Ratio ◽  
Present Author ◽  
Thermal Stresses ◽  
Torsional Stiffness ◽  
Flexural Stiffness ◽  
One Dimensional ◽  
Low Aspect Ratio ◽  
The One ◽  
Proportional Reduction ◽  
Number Of Authors

The loss of torsional or flexural stiffness due to thermal stresses in a thin solid wing is now well known and has been considered by a number of authors, e.g. Dryden and Duberg, Vosteen and Fuller, Bisplinghoff, Hoff, Budiansky and Mayers, Argyris, and the present author. Exact analyses are available only for the “one-dimensional” case of a wing of infinite aspect ratio with arbitrary chordwise distribution of wing thickness and temperature. The loss of stiffness in a similar wing of finite aspect ratio is not as great and, in particular, the proportional reduction in flexural stiffness in a low aspect ratio wing will tend to be less than the proportional reduction in torsional stiffness.

pH Controlled Synthesis of High Aspect-Ratio Gold Nanorods

2008 ◽  
Vol 8 (11) ◽  
pp. 5708-5714 ◽  
Author(s):  
Qingshan Wei ◽  
Jian Ji ◽  
Jiacong Shen
Keyword(s):  
Aspect Ratio ◽  
Gold Nanorods ◽  
High Aspect Ratio ◽  
Cetyltrimethylammonium Bromide ◽  
Slow Growth ◽  
Ph Value ◽  
Building Blocks ◽  
Gold Nanospheres ◽  
One Dimensional ◽  
Growth Ph

Here we report the two-step synthesis of high aspect-ratio gold nanorods via combining low pH growth and higher cetyltrimethylammonium bromide concentration. The approach is motivated by the "slow growth principle," which has been demonstrated recently as a effective protocol to prepare high aspect-ratio one-dimensional nanostructures. When the pH value of the growth solution gradually decreased, the growth rate of nanorods was significantly decreased and a continuous morphological changing from uniform monodisperse gold nanospheres to extraordinary long gold nanorods occured. By simultaneously decreasing the growth pH and increasing the concentration of cetyltrimethylammonium bromide, the length of gold nanorods could be further elongated to above 2 μm with large aspect-ratio of above 80. This kind of high aspect-ratio gold nanorods could be excellent building blocks for optical or electrical nanodevices in future.

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