Concept for a Bistable Composite Twisting Structure

2011 ◽  
Author(s):  
Xavier Lachenal ◽  
Stephen Daynes ◽  
Paul Weaver
Keyword(s):  
Strain Energy ◽  
Energy Levels ◽  
Bending Moment ◽  
Vertical Axis ◽  
Element Model ◽  
Torsional Stiffness ◽  
Design Parameters ◽  
Reinforced Plastic ◽  
Potential Applications ◽  
Carbon Fibre Reinforced Plastic

A novel type of morphing twisting structure capable of large deformations is investigated. The structure consists of two flanges subject to a uniform distributed bending moment along their length and joined to introduce two stable twisted configurations. These equilibria are positioned symmetrically with regards to the vertical axis of the device and the structure can be twisted between these configurations by a snap-through action. By tailoring the design parameters of the structure, different twist angles and snap-through moments can be achieved. An analytical model and finite element model (FEM) are presented. A prototype made of carbon-fibre reinforced plastic (CFRP) was manufactured and tested. Agreement in terms of angle of twist, axial force and stiffness is found. Moreover, comparison between the two models confirms their validity in terms of snap-through moment, torsional stiffness and strain energy levels. The influence of the lay-up employed and design parameter is also investigated. Potential applications include deployable and morphing structures.

10 kw Vertical Axis Wind Turbine Spindle Design and Optimization

2014 ◽  
Vol 487 ◽  
pp. 429-434 ◽  
Author(s):  
Qiao Mei Li ◽  
Yang Cao ◽  
Guo Qing Wu ◽  
Xing Hua Chen ◽  
Yan Hua Cao
Keyword(s):  
Wind Turbine ◽  
Vibration Mode ◽  
Vertical Axis ◽  
Element Model ◽  
High Load ◽  
Design Parameters ◽  
Vertical Axis Wind Turbine ◽  
Dead Weight ◽  
Design And Optimization ◽  
The Finite Element Model

The spindle of a 10 kw vertical axis wind turbine is designed in this paper, and the relevant geometric parameters is given, and build the geometry of the finite element model. Calculation of the spindle under wind load and dead weight , and analyse the spindle Von Mess stress, deformation nephogram, and give the former six order vibration mode of the spindle. Through the analysis, Then the design parameters of the spindle are optimized. and the optimized structure of spindle has been got. optimized spindle is in lower quality, more satisfy the requirement of wind turbine running under high load at the same time .

Accurate Characterization of Torsional Stiffness of Flexible Disk Couplings

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Alex Francis ◽  
Ilya Avdeev ◽  
Joseph Hamann ◽  
Sundar Ananthasivan
Keyword(s):  
Power Systems ◽  
Experimental Validation ◽  
Natural Frequencies ◽  
Element Model ◽  
Torsional Stiffness ◽  
Design Parameters ◽  
Torsional Coupling ◽  
Flexible Disk ◽  
High Degree

Flexible torsional couplings are used primarily to transmit power between rotating components in industrial power systems, including turbomachinery, while allowing for small amounts of misalignment that may otherwise lead to equipment failure. The torsional coupling lumped characteristics, such as torsional- and flexural stiffness, as well as natural frequencies of vibration are important for design of the entire power system and, therefore, must be calculated or computed with a high degree of accuracy. In this paper, we compare theoretical-, computational-, and experimental methods of characterizing torsional stiffness of a family of metallic disk type flexible couplings. We demonstrate the sensitivity of torsional stiffness to various design parameters and characterization assumptions, including boundary conditions, level of model detail, and material properties of the coupling's components. We also develop a full 3D parametric finite element model of the coupling and report on its experimental validation.

Calibration of the material parameters of a CFRP laminate for numerical simulations

2019 ◽  
Vol 54 (17) ◽  
pp. 2313-2326
Author(s):  
A Gilioli ◽  
A Manes ◽  
M Giglio
Keyword(s):  
Tensile Test ◽  
Element Model ◽  
Tensile Tests ◽  
Bending Test ◽  
Three Point Bending ◽  
Reinforced Plastic ◽  
Short Beam ◽  
Explicit Solver ◽  
Carbon Fibre Reinforced Plastic ◽  
Stress Patterns

The aim of present paper is to show a procedure to calibrate mechanical properties to be used in a finite element model for a carbon fibre-reinforced plastic laminate that use solid elements. A reduced experimental programme including tensile test, tensile test on specimen with a central hole, three-point bending test and three-point bending test on short beam test were carried out. Every test was numerically reproduced by means of an explicit solver. Properties are determined from the tensile test and unmodified for the other load scenarios which are used as validation benchmarks. Finally, it is demonstrated that the properties determined with the simple tensile tests can guarantee accurate results when adopted to simulate much more complicated stress patterns.

Influences of Beam-Arch Combination Bridge Structure Arrangement on Mechanical Characteristics

2011 ◽  
Vol 243-249 ◽  
pp. 1707-1710
Author(s):  
Ri Chen Ji ◽  
Yue Zhen Xu ◽  
Ying Zhe Sun
Keyword(s):  
Mechanical Characteristics ◽  
Bending Moment ◽  
Element Model ◽  
Structure Design ◽  
Design Parameters ◽  
Bridge Structure ◽  
Basic Frequency ◽  
Calculation Results ◽  
Practical Engineering ◽  
The Finite Element Model

For the arrangement of suspender and arch rib in the combination of beam and arch bridge, the finite element model is established according to the background of practical engineering. The influence of the variations of structure design parameters on structure characteristics of the static and dynamic is analyzed. The calculation results show that the different layout of suspender has small effect on the axial force variations of tie beam and arch rib, but has bigger influence on the bending moment of partial section. The structural transverse basic frequency augments with increase of arch rib leaning-angle, the vertical and twisting basic frequency is larger when the leaning suspender and netted suspender are used. The arrangement of suspender and arch rib should be optimized in the design of similar bridge.

scholarly journals Detailed Parametric Investigation and Optimization of a Composite Wing with High Aspect Ratio

2019 ◽  
Vol 2019 ◽  
pp. 1-27 ◽  
Author(s):  
Yu-shan Meng ◽  
Li Yan ◽  
Wei Huang ◽  
Tian-tian Zhang
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Bending Moment ◽  
Element Model ◽  
Torsional Stiffness ◽  
Final Thickness ◽  
Maximum Deformation ◽  
Component Size ◽  
Deformation Problem ◽  
Large Deformation Problem

The large deformation problem of the wing with high aspect ratio cannot be avoided due to the large bending moment and poor torsional stiffness. The wing design follows the following procedure; firstly, the design indexes of high aspect ratio wing are preliminarily formulated referring to some parameters of the Predator UAV. Then, the aerodynamic analysis of the wing is performed, and the stress cloud diagram is obtained. Next, the finite element model of the wing is designed, and the static analysis is conducted in the ANSYS ACP module, and the unreasonable component size is changed. An appropriate thickness which is 12 mm is selected as the final thickness of the wing. Then, the analysis of laying methods of skin structure is conducted. Finally, the composite structure is proved to reduce the maximum deformation and maximum stress effectively compared with the metal wing.

Concept for a Deployable Wing

2014 ◽  
Author(s):  
Xavier Lachenal ◽  
Paul M. Weaver ◽  
Alberto Pirrera
Keyword(s):  
Bending Moment ◽  
Element Model ◽  
Unmanned Aircraft ◽  
Bending Test ◽  
Radius Of Curvature ◽  
Glass Fiber Reinforced Plastic ◽  
Glass Fiber Reinforced ◽  
Reinforced Plastic ◽  
Extended Position ◽  
Brazier Effect

A concept for a novel folding wing is presented, which, using the Brazier effect, can snap from a stable, extended position to a folded configuration. A wing typical of size used in an unmanned aircraft vehicle (UAV) is examined, including manufacturing aspects as well as an analytical and a finite element model (FEM) of the structure. The wing is simply made of a glass fiber reinforced plastic (GFRP) skin stiffened by ribs at regular intervals. At the mid-span location, a cut-out is made in the leading and trailing edge in order to allow the pressure and suction sides of the wing to collapse inward when folding occurs (due to Brazier effect). The analytical model draws upon work from Brazier to predict the maximum bending moment the folding section can withstand before buckling. A FEM, using a quasi-static analysis and requiring a contact definition to allow the wing surfaces to meet, reproduces with accuracy the folding pattern seen on the prototype. A bending test of the demonstrator confirmed the validity of the models in terms of bending stiffness, bending snap through and folding radius of curvature.

Torsional Analysis of a Steel Cord-Rubber Tire Belt Structure

1996 ◽  
Vol 24 (4) ◽  
pp. 339-348 ◽  
Author(s):  
R. M. V. Pidaparti
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Rubber Belt ◽  
Steel Cord ◽  
Torsional Analysis

Abstract A three-dimensional (3D) beam finite element model was developed to investigate the torsional stiffness of a twisted steel-reinforced cord-rubber belt structure. The present 3D beam element takes into account the coupled extension, bending, and twisting deformations characteristic of the complex behavior of cord-rubber composite structures. The extension-twisting coupling due to the twisted nature of the cords was also considered in the finite element model. The results of torsional stiffness obtained from the finite element analysis for twisted cords and the two-ply steel cord-rubber belt structure are compared to the experimental data and other alternate solutions available in the literature. The effects of cord orientation, anisotropy, and rubber core surrounding the twisted cords on the torsional stiffness properties are presented and discussed.

Aerodynamic and aeroacoustic performance investigations on modified H-rotor Darrieus wind turbine

2021 ◽  
pp. 0309524X2110039
Author(s):  
Amgad Dessoky ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
3D Models ◽  
Power Coefficient ◽  
Design Parameters ◽  
Second Phase ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes

The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplished with such enhancement. The studies are carried out in two phases; the first phase is a parametric 2D CFD simulation employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach to optimize the design parameters of the guide-vanes. The second phase is a 3D CFD simulation of the full turbine using a higher-order numerical scheme and a hybrid RANS/LES (DDES) method. The guide-vanes show a superior power augmentation, about 42% increase in the power coefficient at λ = 2.75, with a slightly noisy operation and completely change the signal directivity. A remarkable difference in power coefficient is observed between 2D and 3D models at the high-speed ratios stems from the 3D effect. As a result, a 3D simulation of the capped Darrieus turbine is carried out, and then a noise assessment of such configuration is assessed. The results show a 20% increase in power coefficient by using the cap, without significant change in the noise signal.

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