The Folding of Triangulated Cylinders, Part I: Geometric Considerations

1994 ◽  
Vol 61 (4) ◽  
pp. 773-777 ◽  
Author(s):  
S. D. Guest ◽  
S. Pellegrino
Keyword(s):  
Cylindrical Shell ◽  
Design Parameters ◽  
Small Displacement ◽  
Generic Type ◽  
Folding Process ◽  
Small Strains ◽  
Biological Structures ◽  
Geometric Formulation

This study was inspired by a model of a triangulated cylindrical shell made by C. R. Calladine during an investigation of the mechanics of biological structures. The model consisted of identical triangular panels on a helical strip and had a small-displacement internal inextensional mechanism. It is shown that many triangulated cylinders broadly similar to Calladine’s model can be folded down to a compact stack of plates: only small strains, whose magnitude can be made arbitrarily small by the choice of suitable design parameters, are imposed during folding. A general geometric formulation of the problem is presented and then, assuming that the folding process is uniform, the folding properties of any triangulated cylinder of this generic type are discussed.

Large Displacements With Small Strains in Loaded Structures

1948 ◽  
Vol 15 (1) ◽  
pp. 45-48
Author(s):  
K. H. Swainger
Keyword(s):  
Exact Solution ◽  
Flat Plate ◽  
Large Class ◽  
Major Part ◽  
Flexible Structures ◽  
Elastic Cylinder ◽  
Small Displacement ◽  
Large Displacements ◽  
Physical Conditions ◽  
Small Strains

Abstract This paper considers the case of flexible structures in which displacements can be large although strains are small. The theory gives an “exact” solution in a large class of problems where the displacements are large but predictable closely from the physical conditions imposed. In this method, the major part of the displacement is “guessed,” and then a further “small” displacement calculated from equations, which are developed, to assure compatibility. As a simple but not trivial example, the generation of an elastic cylinder from a flat plate is considered to illustrate the method.

Type Classification for Horizontal Axis Tidal Turbine (HATT): An Important Step Towards Commercialisation

2014 ◽  
Author(s):  
Claudio Bittencourt ◽  
Kimon Argyriadis ◽  
Michael Steiniger
Keyword(s):  
Wind Turbines ◽  
Design Parameters ◽  
Serial Production ◽  
Generic Type ◽  
Astronomical Tide ◽  
Tidal Turbines ◽  
Type Classes ◽  
Minimum Number ◽  
Tidal Turbine ◽  
Type Classification

One key aspect of serial production is to define a set of parameters that can define the limits and conditions that product can be used. Type certification is applied to serial production such as wind turbines when the matching of the site characteristics and the turbine design conditions is summarised in a short description of the site parameters that fundamentally describes the wind conditions (energy and turbulence). This easy matching is used by all stakeholders in assessing the suitability of different turbines to a specific project development. However, type classification is also important to optimise the design, manufacturing, installation and maintenance costs by setting key parameters to production of turbines with same characteristics (scale factor). The same applies to tidal turbines. Although, at the present phase of development, serial production is not yet a main driver and designs are mainly carried out with specific sites in mind, it is useful to develop a type classification now to support generic design parameters and that can be tested for future serial production and matching sites with serial products. While for wind turbines, the set of key parameters is reasonably simple [1], for tidal there are a number of environmental conditions (for example waves, astronomical tide, current turbulence, water depth, etc), and parameters (such as hub height related to the seabed and sea surface) which must be considered within the design of a HATT, parameters which may also be utilised in the construction of generic type classes for Tidal Turbines. Thus, the identification of generic type classes for HATTs is dependent upon the ability (by conjunction of assumptions, formulations, etc.) to distil the existing extensive list of site / HATT parameters down to a minimum number of key parameters upon which a simple but robust set of generic type classes could be based. Whilst it is recognised that adjustments of type classes may be required in the future, a first approach will be presented in the DNV GL Standard for Certification of HATT developed under the ReDAPT project and it is described in detail in this paper. The ReDAPT project is commissioned and co-funded by the ETI (Energy Technologies Institute).

scholarly journals Dynamic model of closure the liner

2020 ◽  
pp. 114-122
Author(s):  
I. V. Dmytriv I. V.
Keyword(s):  
Cylindrical Shell ◽  
Modulus Of Elasticity ◽  
Mechanical Characteristics ◽  
Vacuum Pressure ◽  
Design Parameters ◽  
Radial Deformation ◽  
Central Angle ◽  
Radial Plane ◽  
Working Length ◽  
Physical And Mechanical Characteristics

Annotation Purpose. Develop analytical dependences for modeling the speed and dynamics of deformation of liner depending on its design parameters and physical and mechanical characteristics, taking into account the technological parameters of the process. Methods. Based on the system of geometric equilibrium equations for a cylindrical shell, taking into account the isotropy of the medium and the momentless stress state, the spatial action of forces and pre-tension of the liner, developed analytical equations that allow modeling the dynamics of deformation of liner in time, which allows to determine the time constant of the system “liner – milking cup”. Results. Analytical dependences of the dynamics of deformation of liner in time in the radial plane and the rate of deformation depending on its design parameters and physical and mechanical characteristics of the material are developed. Parameters for deformation simulation are: R – radius of liner, Е – modulus of elasticity, ρ – the density of the rubber material, h – thickness of liner, рн – vacuum pressure, l – the length of the active part of liner, ν – Poisson's coefficient for rubber, Fн – force of tension of liner. Depending on the central angle in the radial plane of the section, the shape of the deformation of the liner is modeled along its entire working length during the closing and opening stroke. Conclusions. The obtained dependences allow to model the dynamics of deformation of liner in the radial plane depending on its design parameters and physical and mechanical characteristics of the material. The developed analytical dependences take into account the pre-tension of the liner, vacuum pressure and allows modeling depending on the central angle in the radial plane of the rubber section. The use of the developed analytical dependences makes it possible to substantiate the main parameters that affect the process of closing and opening of the liner. The characteristic of the deformation in the cross section of the largest deformation is that the tension of the liner does not affect the deformation characteristic. This is due to the isotropy property of the cylindrical shell and the elastic isotropic properties. Keywords: liner, vacuum pressure, modulus of elasticity, radial deformation, coordinate system, tension of rubber, the cylindrical shell, the isotropic medium.

Reducing the Noise of Pressure Pulp Screen: Theory and Application

1995 ◽  
Author(s):  
Alain Berry ◽  
Rémy Oddo ◽  
Raymond Panneton ◽  
Jean Nicolas
Keyword(s):  
Cylindrical Shell ◽  
Moving Load ◽  
Paper Industry ◽  
Outer Shell ◽  
Design Parameters ◽  
Cellulose Fibres ◽  
Rotating Speed ◽  
Radiated Noise ◽  
Preliminary Study ◽  
Vibration And Sound Radiation

Abstract A pressure pulp screen is a machine used in the pulp and paper industry to remove and class cellulose fibres in paper pulp. It involves an inner perforated cylindrical basket which receives the pulp under pressure, an inner rotor with profiled blades used to clear the holes or slits of the basket, and an outer cylindrical shell. The noise radiated by the outer shell is characterized by discrete frequencies in mid- and high frequency (1–4 kHz). A preliminary study has shown that the radiated noise is due to the vibration of the perforated basket under the moving load of the rotor. This vibration is transmitted to the outer shell through various paths which were analyzed and classified. An analytical model of the vibroacoustic behavior of a cylindrical shell under a circumferentially moving load was used to establish various rotating speed regimes with respect to the vibration and sound radiation of the shell. It was shown that a circumferential modulation of the load (corresponding to the effect of holes or slits on the inner basket) leads to theoretical noise spectra similar to measured data. On the practical front, the model was used to identify significant design parameters with respect to the noise of the machine. The paths of energy transmission from the basket to the outer shell were studied and various noise reduction approaches have been investigated.

scholarly journals Characterisation of sand-steel interface shearing behaviour for the interpretation of driven pile behaviour in sands

2019 ◽  
Vol 92 ◽  
pp. 13001
Author(s):  
Tingfa Liu ◽  
Haoruo Chen ◽  
Róisín M. Buckley ◽  
V. Santiago Quinteros ◽  
Richard J. Jardine
Keyword(s):  
Effective Stress ◽  
Sandy Soils ◽  
Triaxial Tests ◽  
Design Parameters ◽  
Small Displacement ◽  
Chemical Compositions ◽  
Time Duration ◽  
Steel Piles ◽  
Interface Shearing ◽  
Shear Interface

The installation and loading of steel piles driven in sands modifies both the piles' surface topography and the characteristics of the granular materials present adjacent to the pile shaft. Large-displacement ring shear interface tests incorporating pre-conditioning stages are capable of reproducing such physical processes in the laboratory and can generate case-specific interface design parameters. This paper summarises laboratory research that characterised the interface shearing behaviour of three natural sandy soils retrieved from field test sites (Dunkirk, France; Blessington, Ireland; Larvik, SE Norway) where extensive piling studies on micro and industrial scale driven piles have been carried out. The programme examined the influences of soil characteristics (physical properties and chemical compositions), interface type (mild steel or stainless steel) and surface roughness, and highlighted the significant effects of normal effective stress level and ageing time duration. Remarkable trends of increasing interface friction angles with elevated normal effective stress levels and prolonged ageing were observed. The results from supplementary small-displacement direct shear interface tests and triaxial tests are also reported. The experiments are interpreted with reference to earlier studies to develop an overview of interface shearing characteristics between steels and sandy soils and provide important insights into the mechanisms of axial capacity increases applying to steel piles driven in sands.

scholarly journals Nonlinear Buckling Analysis of Steel Cylindrical Shell with Elliptical Cut-out Subjected to Longitudinal Compressive Load

2019 ◽  
Vol 16 (2) ◽  
pp. 6723-6737
Author(s):  
K. N. Salloomi ◽  
L. A. Sabri ◽  
Y. M. Hamad ◽  
S. Al-Sumaidae
Keyword(s):  
Cylindrical Shell ◽  
Compressive Load ◽  
Positive Influence ◽  
Buckling Load ◽  
Design Parameters ◽  
Element Analysis ◽  
Nonlinear Buckling ◽  
Geometry Design ◽  
Nonlinear Buckling Analysis ◽  
Steel Cylindrical Shell

The current paper investigates the effect of cut-out design parameters on load-bearing capacity and buckling behaviour of steel cylindrical shell using a nonlinear finite element analysis in modelling cylinder buckling under longitudinal compressive load. The effect of four geometry design parameters: shell diameter to thickness ratio, cut-out location, orientation, and size were investigated in this study. To enhance the prediction of buckling behaviour, both geometrical and material nonlinearities were considered. An ANSYS APDL code was written and tested by verifying its validity through comparison with former buckling study. The results showed that changing the cut-out location from mid-height of the cylindrical shell towards a fixed edge caused an increase in the buckling load value. Moreover, the study showed that increasing parameters such as shell thickness and cut-out orientation have a positive influence in which the buckling load value increased too. For fast design purposes, an empirical numerical based regression formula was presented for the calculation of the critical buckling load of a cylindrical shell having an elliptical cut-out.

Bistable Behavior of the Cylindrical Origami Structure With Kresling Pattern

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Cai Jianguo ◽  
Deng Xiaowei ◽  
Zhou Ya ◽  
Feng Jian ◽  
Tu Yongming
Keyword(s):  
Strain Energy ◽  
Complex Case ◽  
Small Displacement ◽  
Cyclic Symmetry ◽  
Thin Cylindrical Shell ◽  
Bistable Behavior ◽  
Limit Condition ◽  
Bistable Phenomenon ◽  
Geometric Formulation ◽  
Made In

The deployment of a cylinder based on origami with Kresling pattern, whose basic mechanisms are formed by the buckling of a thin cylindrical shell under torsional loading, is studied in this paper. The model consists of identical triangular panels with cyclic symmetry and has a small displacement internal inextensional mechanism. First, geometric formulation of the design problem is presented. Then, assuming that the deployment and folding process is uniform, the bistable behavior of the cylinder is discussed. It can be found that, during the deployment, the dimensionless strain energy increases first and then reduces to zero but followed by another sharp increase. Moreover, the limit condition of geometry parameters for the bistable phenomenon is also discussed. Finally, the bistable behavior is also studied by using numerical simulations for simple and more complex case of the cylinder with multistory. The numerical results agree well with the analytical predictions. Therefore, comparisons with finite element predictions have shown that the analytical solutions given in this paper are accurate and have validated the assumptions made in the derivations.

Shape-Morphing Space Frame (SMSF) Using Linear Bistable Elements

2015 ◽  
Author(s):  
Ahmad Alqasimi ◽  
Craig Lusk
Keyword(s):  
Cylindrical Shell ◽  
Single Layer ◽  
The Other ◽  
Design Parameters ◽  
Cylindrical Shape ◽  
Space Frame ◽  
Initial Shape ◽  
Initial Height ◽  
Shape Morphing ◽  
Space Frames

This paper presents a new concept: a Shape-Morphing Space Frame (SMSF), which is a novel application utilizing the Linear Bistable Compliant Crank-Slider Mechanism (LBCCSM). The frame’s initial shape is constructed from a single-layer grid of flexures, rigid links and LBCCSMs. The grid is bent into the space frame’s initial cylindrical shape, which can morph because of the inclusion of LBCCSMs in its structure. The design parameters consist of the frame’s initial height, its tessellation pattern (including bistable elements’ placement), its initial diameter, and the final desired shape. The method used in placing the bistable elements is a novel contribution to this work as it considers the principle stress trajectories. This paper will present two different examples of Shape-Morphing Space Frames, each starting from a cylindrical-shell space frame and morphing, one to a hyperbolic-shell space frame and the other to a spherical-shell space frame, both morphing by applying moments, which shear the cylindrical shell, and forces, which change the cylinder’s radius using Poisson’s effect.

Modal Energy Transduction of a Cylindrical Shell Laminated With a Segmented Piezoelectric Layer

2011 ◽  
Author(s):  
X. Li ◽  
K. C. Chuang ◽  
H. Li ◽  
H. S. Tzou
Keyword(s):  
Cylindrical Shell ◽  
Energy Harvesting ◽  
Energy Harvester ◽  
Piezoelectric Effect ◽  
Energy Transduction ◽  
Design Parameters ◽  
Physical Parameters ◽  
Engineering Applications ◽  
Piezoelectric Energy ◽  
Direct Piezoelectric Effect

Energy transduction between the mechanical and electric effects has been evaluated over the years. Energy harvesting based on the direct piezoelectric effect using the curvature structures is a new endeavor in engineering applications. This study focuses on energy harvesting from mechanical vibrations through a simply supported circular cylindrical shell laminated with segmented piezoelectric energy harvester patches. The voltages (or modal signals) induced by the modal strains of the piezoelectric patch due to the direct piezoelectric effect can be further converted to modal energies. Spatial distributions of the modal energies are evaluated and compared in three piezoelectric energy harvester patch sizes, and key design parameters. The objective of this study is to investigate the spatial distribution characteristic of the modal energy and evaluate the effects of energy harvester patch size and physical parameters on the generation of the modal energy. These data evaluated in this study can be used as guidelines to design the optimum piezoelectric energy harvester in practical engineering applications.

Optimal Control of Piezoelectric Laminated Parabolic Cylindrical Panels

2013 ◽  
Author(s):  
S. D. Hu ◽  
H. Li ◽  
H. S. Tzou
Keyword(s):  
Optimal Control ◽  
Cylindrical Shell ◽  
Feedback Control ◽  
Vibration Control ◽  
Control Algorithm ◽  
Damping Ratio ◽  
Design Parameters ◽  
Distributed Sensors ◽  
Control Gain ◽  
And Control

Vibration control of parabolic cylindrical shell panels by piezoelectric patches using optimal control algorithm is presented in this study. Laminated piezoelectric patches serve as distributed sensors and actuators. Dynamic behaviors and mode shape functions in three directions are obtained by the Rayleith-Ritz method. The sensing sensitivity of the piezoelectric sensor and the actuation force of the piezoelectric actuator are obtained. Feedback control gain between sensing and control signals is solved using the LQ optimal control algorithm. LQ controllers for independent modes are designed, and relative optimal control gains and control voltages are presented. Control results with respect to independent mode and optimal design parameters are evaluated in case studies. Numerical results show that the LQ optimal controller with optimal feedback control gain is effective for the vibration control of parabolic cylindrical shell panels. The damping ratio can be greatly enhanced; the maximal damping ratio reach 7.79% for mode (1,3). Studies on parametric designs suggest that relatively larger Q22 and/or smaller R results in rapider reduction of mechanical motion with more control energy cost, and vice versa. These results would provide a design reference in practical engineering.

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