General Dynamic Equations of Helical Springs With Static Solution and Experimental Verification

1987 ◽  
Vol 54 (4) ◽  
pp. 910-917 ◽  
Author(s):  
Yuyi Lin ◽  
Albert P. Pisano
Keyword(s):  
Pitch Angle ◽  
Static Solution ◽  
Dynamic Equations ◽  
Compression Force ◽  
Variable Pitch ◽  
Helical Springs ◽  
Variable Helix ◽  
Wire Cross Section ◽  
Compression Springs ◽  
General Dynamic

The general dynamic equations of helical compression springs with circular wire cross section, variable pitch angle, and variable helix radius are derived. The equations are formulated by Hamilton’s principle and a variational method. In contrast to previous studies, the effects of coil flexure bending, variable pitch angle and variable helix radius are taken into account. The general equations are shown to agree with dynamic equations found in literature when the general equations are reduced to simplified forms. For a specific helical spring and static loading, the equations are solved with both the predicted radial expansion and the predicted longitudinal spring compression force in excellent agreement with experimental data.

The Differential Geometry of the General Helix as Applied to Mechanical Springs

1988 ◽  
Vol 55 (4) ◽  
pp. 831-836 ◽  
Author(s):  
Yuyi Lin ◽  
Albert P. Pisano
Keyword(s):  
Experimental Data ◽  
Differential Geometry ◽  
Fatigue Life ◽  
Pitch Angle ◽  
Helical Spring ◽  
Variable Pitch ◽  
Helical Springs ◽  
Spring Force ◽  
Variable Helix ◽  
Curvature And Torsion

In order to improve the performance of helical springs, such as increasing the fatigue life and suppressing resonance, variable pitch angle and variable helix radius may be incorporated into the helical spring geometry. Employing the tool of differential geometry, new and complete formulae of curvature, torsion, and spring force are derived. It is shown that these formulae are more general and accurate than Kelvin’s curvature and torsion formulae, than commonly used force formulae (Wahl, 1963). Possible simplifications to the complete formulae and the corresponding errors introduced are both discussed and compared with experimental data.

Axial-mode elliptical helical antenna with variable pitch angle

2008 ◽  
Vol 44 (19) ◽  
pp. 1103 ◽  
Author(s):  
F. Yang ◽  
P. Zhang ◽  
C.-J. Guo ◽  
J.-D. Xu
Keyword(s):  
Pitch Angle ◽  
Helical Antenna ◽  
Axial Mode ◽  
Variable Pitch

Effect of the Material Types on the Fundamental Frequencies of Uniaxial Composite Conical Springs

1999 ◽  
Author(s):  
Vebil Yildirim ◽  
Erol Sancaktar ◽  
Erhan Kiral
Keyword(s):  
Transfer Matrix Method ◽  
Pitch Angle ◽  
Natural Frequencies ◽  
Axial Deformation ◽  
Helical Springs ◽  
Fundamental Frequencies ◽  
Helix Pitch ◽  
Constant Pitch ◽  
Α Helix

Abstract This paper deals with the effect of the material types (Graphite-Epoxies and Kevlar-Epoxy) on the fundamental frequencies of uniaxial constant-pitch composite conical helical springs with solid circle section and fixed-fixed ends. The transfer matrix method is used for the determination of the fundamental natural frequencies. The rotary inertia, the shear and axial deformation effects are taken into account in the solution. The free vibrational charts for each material presented in this study cover the following vibrational parameters: n (number of active turns) = 5–10, α = (helix pitch angle) = 5° and 25°, R2/R1, (minimum to maximum radii of the cylinder) = 0.1 and 0.9, and Dmax/d (maximum cylinder to wire diameters) = 5 and 15. These charts can be used for the design of uniaxial composite conical springs.

A Review on Pitch Angle Control Strategy of Variable Pitch Wind Turbines

2013 ◽  
Vol 772 ◽  
pp. 744-748 ◽  
Author(s):  
Chao Tan ◽  
Hong Hua Wang
Keyword(s):  
Wind Turbines ◽  
Pitch Angle ◽  
Sliding Mode ◽  
Integrated Control ◽  
Variable Structure ◽  
Network Control ◽  
Neural Network Control ◽  
Variable Pitch ◽  
Structure Control ◽  
Sliding Mode Variable Structure

This paper summarizes the development process of wind turbines control technology, reviews the application of traditional control, sliding mode variable structure control, H robust control, adaptive control, fuzzy control, artificial neural network control and integrated control in the pitch angle control system of variable pitch wind turbines, points out its present situation and development prospect.

Recent Developments of the Mechanism of the Hydraulic Variable-pitch Aircraft Propeller

1950 ◽  
Vol 163 (1) ◽  
pp. 111-124
Author(s):  
H. L. Milner
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Pitch Angle ◽  
Variable Pitch ◽  
Jet Propulsion ◽  
Recent Developments ◽  
Gas Turbine Power Plant ◽  
Centrifugal Action ◽  
Engine Type ◽  
Blade Element

After briefly outlining the main features of the variable-pitch propeller, this paper proceeds to describe the development of the piston-engined hydraulically operated propeller as a brake, both in the air and on the ground. Examples are given of the magnitude of the braking effort of a propeller when windmilling under controlled conditions and when in reverse pitch under power. The advent of the gas turbine, originally intended as a means of jet propulsion, opened up a new field of application for the variable-pitch propeller and this application with its attendant problems and their solution is discussed. Three types of gas-turbine power plant, together with the appropriate propeller arrangements are reviewed. These are: (1) the direct-connected turbine; (2) the compound-compressor turbine; and (3) the free-propeller turbine. Each engine requires a plurality of controllable pitch stops peculiar to the engine type, and these are described. The necessity for powerful controlling forces in maintaining the blades at any given pitch angle is made clear by consideration of the centrifugal action of a blade element, and an example of the magnitude of these forces is given for a specific case. Brief reference is made to developments in blade bearings, followed by an illustrated description of a contra-rotating propeller.

General Equations of a Helical Spring With a Cup Damper and Static Verification

1997 ◽  
Vol 119 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Ming Hsun Wu ◽  
Jing Yuan Ho ◽  
Wensyang Hsu
Keyword(s):  
Experimental Data ◽  
Pitch Angle ◽  
Equations Of Motion ◽  
Maximum Error ◽  
Dynamic Equations ◽  
Helical Spring ◽  
Static Force ◽  
Static Verification ◽  
Simulation Results ◽  
Force Displacement

In this study, we derive the general equations of motion for the helical spring with a cup damper by considering the damper’s dilation and varying pitch angle of the helical spring. These dynamic equations are simplified to correlate with previous models. The static force-displacement relation is also derived. The extra stiffness due to the damper’s dilation considered in the force-displacement relation is the first such modeling in this area. In addition, a method is presented to predict the compressing spring’s coil close length and is then verified by experimental data. Moreover, the simulation results of the static force-displacement relation are found to correspond to the experimental data. The maximum error is around 0.6 percent.

scholarly journals Kinematics of a vertical axis wind turbine with a variable pitch angle

2018 ◽  
Author(s):  
Mateusz Jakubowski ◽  
Roman Starosta ◽  
Pawel Fritzkowski
Keyword(s):  
Wind Turbine ◽  
Pitch Angle ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Variable Pitch
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