Investigation of Discrete Out-of-Plane Waviness in Composite Wind Turbine Blades Using Ultrasonic Nondestructive Evaluation

2011 ◽  
Author(s):  
Sunil Kishore Chakrapani ◽  
Vinay Dayal ◽  
Daniel Barnard ◽  
David Hsu
Keyword(s):  
Aspect Ratio ◽  
Nondestructive Evaluation ◽  
Wind Turbine ◽  
High Frequency ◽  
Turbine Blades ◽  
Element Model ◽  
Wind Turbine Blades ◽  
Out Of Plane ◽  
Process Detection ◽  
Air Coupled Ultrasonics

With the need for larger and more efficient wind turbine blades, thicker composite sections are manufactured and waviness becomes difficult to control. Thus, there is a need for more effective and field implementable NDE. In this paper we propose a method of detection and quantification of waviness in composite wind turbine blades using ultrasonics. By employing air coupled ultrasonics to facilitate faster and easier scans, we formulated a two step process. Detection was performed with single sided air coupled ultrasonics, and characterization was performed with the help of high frequency contact probes. Severity of the wave was defined with the help of aspect ratio, and several samples with different aspect ratio waves were made. A finite element model for wave propagation in wavy composites was developed, and compared with the experimental results.

scholarly journals Scalable Wind Turbine Blades nondestructive evaluation using different types of sensors

2018 ◽  
Vol 444 ◽  
pp. 022006
Author(s):  
N Iftimie ◽  
R Steigmann ◽  
G S Dobrescu ◽  
N A Danila ◽  
A Savin ◽  
...  
Keyword(s):  
Nondestructive Evaluation ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Different Types

scholarly journals Experimental Investigation of Finite Aspect Ratio Cylindrical Bodies for Accelerated Wind Applications

Fluids ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 25 ◽  
Author(s):  
Michael Parker ◽  
Douglas Bohl
Keyword(s):  
Aspect Ratio ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Cylindrical Body ◽  
Turbine Rotor ◽  
Flow Speed ◽  
The Body ◽  
Rotor Blades ◽  
Wind Turbine Blades ◽  
Smooth Cylinder

The placement of a cylindrical body in a flow alters the velocity and pressure fields resulting in a local increase in the flow speed near the body. This interaction is of interest as wind turbine rotor blades could be placed in the area of increased wind speed to enhance energy harvesting. In this work the aerodynamic performance of two short aspect ratio (AR = 0.93) cylindrical bodies was evaluated for potential use in “accelerated wind” applications. The first cylinder was smooth with a constant diameter. The diameter of the second cylinder varied periodically along the span forming channels, or corrugations, where wind turbine blades could be placed. Experiments were performed for Reynolds numbers ranging from 1 × 105 to 9 × 105. Pressure distributions showed that the smooth cylinder had lower minimum pressure coefficients and delayed separation compared to the corrugated cylinder. Velocity profiles showed that the corrugated cylinder had lower peak speeds, a less uniform profile, and lower kinetic energy flux when compared to the smooth cylinder. It was concluded that the smooth cylinder had significantly better potential performance in accelerated wind applications than the corrugated cylinder.

Elastic Field and Frequency Variation in Extendable Wind Turbine Blades

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Jeswin John ◽  
Donald W. Radford ◽  
Subhas Karan Venayagamoorthy ◽  
Paul R. Heyliger
Keyword(s):  
Wind Turbine ◽  
Maximum Stress ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Elastic Field ◽  
Element Model ◽  
Frequency Variation ◽  
Wind Turbine Blades ◽  
Length Changes ◽  
Representative Material

The behaviors of tip displacement, maximum stress, and natural frequency of vibration as a function of blade length are investigated for extendable wind turbine blades. A three-dimensional linear elasticity finite-element model of the blade is used along with a typical profile and representative material properties. The quasi-linear response and free vibration behavior are investigated for a sequence of blade geometries. These estimates are intended to give approximate measures of expected changes in the elastic and dynamic field as the operating length changes and provide preliminary guidelines for this novel class of structure.

Automated Composite Fabric Layup for Wind Turbine Blades

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Siqi Zhu ◽  
Corey J. Magnussen ◽  
Emily L. Judd ◽  
Matthew C. Frank ◽  
Frank E. Peters
Keyword(s):  
Wind Turbine ◽  
Plane Deformation ◽  
Turbine Blades ◽  
Three Dimensional ◽  
3D Models ◽  
New Method ◽  
Two Dimensional ◽  
Wind Turbine Blades ◽  
Out Of Plane ◽  
Fiberglass Fabric

This work presents an automated fabric layup solution based on a new method to deform fiberglass fabric, referred to as shifting, for the layup of noncrimp fabric (NCF) plies. The shifting method is intended for fabric with tows only in 0 deg (warp) and 90 deg (weft) directions, where the fabric is sequentially constrained and then rotated through a deformation angle to approximate curvature. Shifting is conducted in a two-dimensional (2D) plane, making the process easy to control and automate, but can be applied for fabric placement in three-dimensional (3D) models, either directly or after a ply kitting process and then manually placed. Preliminary tests have been conducted to evaluate the physical plausibility of the shifting method. Layup tests show that shifting can deposit fabric accurately and repeatedly while avoiding out-of-plane deformation.

Quick Method for Aeroelastic and Finite Element Modeling of Wind Turbine Blades

2014 ◽  
Author(s):  
Jeffrey Bennett ◽  
Robert Bitsche ◽  
Kim Branner ◽  
Taeseong Kim
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wind Turbine ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Element Model ◽  
Wind Turbine Blades ◽  
Quick Method ◽  
Cross Sectional ◽  
Aeroelastic Simulations

In this paper a quick method for modeling composite wind turbine blades is developed for aeroelastic simulations and finite element analyses. The method reduces the time to model a wind turbine blade by automating the creation of a shell finite element model and running it through a cross-sectional analysis tool in order to obtain cross-sectional properties for the aeroelastic simulations. The method utilizes detailed user inputs of the structural layup and aerodynamic profile including ply thickness, orientation, material properties and airfoils to create the models. After the process is complete the user has two models of the same blade, one for performing a structural finite element model analysis and one for aeroelastic simulations. Here, the method is implemented and applied to reverse engineer a structural layup for the NREL 5MW reference blade. The model is verified by comparing natural frequencies to the reference blade. Further, the application to aeroelastic and structural evaluations is demonstrated. Aeroelastic analyses are performed, and predicted fatigue loads are presented. Extreme loads from the aeroelastic simulations are extracted and applied onto the blade for a structural evaluation of the blade strength. Results show that the structural properties and natural frequencies of the developed 5MW blade match well with the reference blade, however the structural analysis found excessive strain at 16% span in the spare caps that would cause the blade to fail.

Out-of-Plane Nonlinear Dynamic Analysis of Wind Turbine Blades

2014 ◽  
Author(s):  
Venkatanarayanan Ramakrishnan ◽  
Brian F. Feeny
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Nonlinear Dynamic Analysis ◽  
Single Mode ◽  
Equation Of Motion ◽  
Wind Turbine Blades ◽  
Blade Vibration ◽  
Premature Failure ◽  
Lagrange Formulation ◽  
Out Of Plane

In this work, the out-of-plane equation of motion of a wind turbine blade modeled as a beam is developed using the Lagrange formulation. The modeling of aerodynamic loads is done with the blade element momentum theory. The equation of motion has combined effects of parametric and direct excitations and is reduced to a single mode. Perturbation analysis based on previous work shows how various terms affect the steady-state responses near resonance. Numerical simulations using parameters from a real turbine, reveal that these resonance become critical as the blades increase in size. The out-of-plane vibration model shows resonances that would not be expected by blade designers without analysis and modeling techniques presented in this work. The influence of these superharmonic blade vibration responses on the increased loads on the gearbox components would provide insight into premature failure of wind turbine blades and gearboxes.

scholarly journals Damage Identification of Wind Turbine Blades Using Piezoelectric Transducers

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Seong-Won Choi ◽  
Kevin M. Farinholt ◽  
Stuart G. Taylor ◽  
Abraham Light-Marquez ◽  
Gyuhae Park
Keyword(s):  
Wind Turbine ◽  
High Frequency ◽  
Structural Integrity ◽  
Damage Identification ◽  
Turbine Blades ◽  
Piezoelectric Transducers ◽  
Detection Capability ◽  
Wind Turbine Blades ◽  
Sensors And Actuators ◽  
Active Sensors

This paper presents the experimental results of active-sensing structural health monitoring (SHM) techniques, which utilize piezoelectric transducers as sensors and actuators, for determining the structural integrity of wind turbine blades. Specifically, Lamb wave propagations and frequency response functions at high frequency ranges are used to estimate the condition of wind turbine blades. For experiments, a 1 m section of a CX-100 blade is used. The goal of this study is to assess and compare the performance of each method in identifying incipient damage with a consideration given to field deployability. Overall, these methods yielded a sufficient damage detection capability to warrant further investigation. This paper also summarizes the SHM results of a full-scale fatigue test of a 9 m CX-100 blade using piezoelectric active sensors. This paper outlines considerations needed to design such SHM systems, experimental procedures and results, and additional issues that can be used as guidelines for future investigations.

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