GE 1.5 XLE Wind Turbine Blade Analysis with Computational Methods

for Various Composite Materials

EFSTATHIOS E.THEOTOKOGLOU, GEORGIOS XENAKIS

Department of Mechanics, Laboratory of Testing and Materials,

School of Applied Mathematical and Physical Sciences,

National Technical University of Athens,

Zografou Campus 15773, Athens,

GREECE

Abstract: - The purpose of this paper is to investigate various composite materials that have been applied in

wind turbine blades.Α computational study on a GE 1.5 XLE wind turbine blade with different composite

materials was performed. The computational evaluations from the fluent analysis have been used in order to

calculate the equivalent (Von-Mises) stress, shear stress, and displacements of a wind turbine blade. The

proposed study results in useful and interesting conclusions for the stress and displacement fields that arise in

blades with different materials and under different loading conditions.

Key Words: - Composite materials, Computational analysis, Renewable energy, Wind turbine blades, Fluent

analysis, Structural analysis

Received: January 19, 2023. Revised: March 22, 2023. Accepted: April 8, 2023. Published: May 19, 2023.

1 Introduction

In the last few years, our planet's environment has

been exponentially destroyed, the earth's population

is growing, mineral wealth is steadily diminishing,

and its management is a matter of concern to

humans and states. We consume the earth's energy

reserves without thinking about future generations.

Turning to renewable energy is essential for our

survival. Wind energy (via wind turbines) appears

as an ideal solution to the problem, [1], [2], [3], [4],

[5], [6], [7], [8], [9].

In order to use the wind turbines, we have to

improve the profit from their use. One way to

maximize profit is to optimize manufacturing. This

can be done either by improving the geometry of

the construction or its materials. Many studies have

been carried out on both cases. There are relevant

studies, [6], [7], on the geometry and the effect of

air on wind turbine blades. Another way to

optimize the geometry to avoid buckling is

presented in [10]. In terms of new materials applied

in wind turbine blades more and more research has

been done in recent years, [12], [13]. The main

component of the wind turbine that can be

improved is the blade.

During its operation, the wind turbine blade

receives complex loads of varying intensity and

orientation. In order to withstand all these loads,

manufacturers place great emphasis on the material

to be used in their manufacture. Experience has

shown that suitable materials are fibrous polymer

composites.Α detailed comparison between glass

and carbon fiber takes place in [9]. Today, the

largest range of wind turbines has E-glass

composite material as the wind turbine blade

material. However, many studies, [14], [15], [16],

[17], [18], [19], [20], [21], [22], [23], [24], [25],

[26], [27], [28], [29], [30], [31], are being carried

out to develop new, stronger, more durable, and

easily repairable materials.

Many wind turbine installations worldwide

have been studied for their failure problems. The

main problem seems to be due to fatigue on the

flaps. Fatigue blades are either repaired or replaced.

Experience from the failures of wind turbines over

the years has led to a knowledge of the design of

composite materials for their manufacture.

Manufacturers, with increased knowledge,

optimized the design of the blades and increased

their life expectancy and reliability, [2].

However, not only the failures but also the

increase in the size of the wind turbine blades

pushed the designers to change their approach to

wind turbine design. In the eighties, designers used

only static or almost static analysis. This led to

constructions with too much material or failures

after a few operating cycles. Programmable

dynamic models are now used, which simulate

unstable aerodynamic loads as well as aerosol

responses of the entire wind turbine. In addition,

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inspections, non-destructive controls as well as

maintenance programs are involved in the

production process so that designers gain thousands

of hours of experience in wind turbine operation,

[2].

Many studies on fiber development, [32],

which are stronger than E-glass fibers, have been

carried out. High-strength fibers (which are rarely

used in practice but make a promising source for

improving composites) are carbon, basalt, and

aramid fibers. Glass, carbon, and aramid are the

most common fibrous reinforcement contained in

polymer matrices. Other fibrous materials are

boron, silicon carbide, and aluminum oxide.

In this study, five different materials were

analyzed in a single wind turbine blade. These are

promising materials according to [1], ideal for wind

turbine blades. The materials to examine are E-

glass, Kevlar aramid, Solvay APC-2 / AS4 carbon

fiber, S-glass, and S-2 glass. They all have a

common polyester matrix material and as

reinforcing materials glass fibers, carbon fibers,

and aramid fibers (Table 1). In addition, all

materials are placed in the same geometry, with the

same thickness, under the same boundary

conditions. The scope of this study is to shed some

more light on the behavior of GE 1.5 XLE wind

turbine blades under different material

combinations and loading conditions in order to

improve it.

2 Materials used in This Study

Fiberglass is simply a composite of glass fibers,

continuous or discontinuous, contained in a

polymeric matrix. This type of composite material

is produced in very large quantities. The diameters

of the fibers usually range from 3 to 20 µm. Glass

is very popular as a fibrous reinforcing material for

many reasons, [3]:

• It is easily pulled from the melt on high

strength fibers.

• It is readily available and can be produced in

glass-reinforced plastic using a wide variety of

composite manufacturing techniques.

• As a fiber, it is relatively strong and when

immersed in a plastic die produces a composite

material that has very high specific strength.

• When coupled to various plastics it has a

chemical inertness, which makes the composite

useful in a wide variety of corrosive media, [3].

Carbon fibers with the chemical name “poly-

metaphenylene isophthalamides” are high

performance fibers and they are the most widely

used reinforcing agents in advanced (non-

fiberglass) polymeric matrix composites, [3]. Their

features are:

• Of all fibrous reinforcing materials, carbon

fibers have the highest specific modulus of

elasticity and the highest specific strength.

• They maintain high tensile strength and high

resistance to high temperatures. However,

oxidation at high temperatures can be a

problem.

• At room temperatures, carbon fibers are not

affected by moisture or a wide variety of

solvents, acids, and bases.

• Their fibers exhibit a range of physical and

mechanical properties enabling the composites

containing them to have specially designed

properties.

• Fiber production processes have been

developed for composites that are relatively

inexpensive and cost effective, [3].

Furthermore, aramid fibers are high strength

and high elasticity materials that were produced in

the early 1970s. They are advantageous for their

excellent values of strength ratios by weight and

are superior to those of metals. There are many

types of aramid materials. The trade names of the

two most common types are Kevlar and Nomex.

The former is classified according to its mechanical

properties in Kevlar 29, Kevlar 49, and Kevlar 149,

[3]. In this study, Kevlar 49 is used.

3 Overview of Blade Damage

Exact information on the range of wind turbine

failures is not generally available; however, studies

of composites and damage to contact points have

been conducted in recent years, [6], [7]. The static

loads and the load cycles applied to the blades are

simulated in tests and vary in different layers, fiber

layers or surfaces, compression failures, and cracks

at various points. Obviously, the failures in the

main beams and the root and acoustic layers are the

most critical. Fortunately, the composites are

durable. However, the onset of failures does not

occur on external surfaces and is not easily visible.

In addition, many cracks result from the

concentration of stresses at the ends of the length of

one layer. Still, other cracks can be found visually

but the depth of the cracking is not easily

detectable, [1].

In addition to the loads to which wind turbines

are subjected, they can be subjected to lightning,

natural disasters, or intense humidity. In some rare

cases, a bolt of lightning can cause destruction.

Wind turbine maintainers try to predict the weather

as much as possible, but at 25 years of operation, it

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is assumed that the wind turbine suffers some

disasters, [1].

Wind turbine blades are the most likely to be

exposed to lightning and usually receive a

significant number of blows during operation. Of

course, all parts of the wind turbine have a

lightning protection system. However, it is

common for burned surfaces or cracks to occur

around the point of a lightning strike, [1].

Another significant number of failures was

observed in the blades due to the rough gaseous

particles that hit and corrode the outer surfaces,

especially at the edge where the speeds are higher.

As the surface changes, the aerodynamic efficiency

of the blades was degraded and energy production

is reduced. The more the failure repaired, the

greater the damage, more time, and more methods

that are complicated are required to repair it, [1].

There is also the case of failure due to ice. At

low temperatures, ice forms on the surface of the

blades, which disturbs the balance of the

aerodynamic loads and reduce the structural fatigue

resistance, [1].

Structural failure in a wind turbine can occur in

any structural component; however, the most

common type of failure is in the rotor or the blade.

The cost of a blade corresponds to 15-20% of the

total cost of the wind turbine, and repairing is the

most expensive work that can be done. According

to them, the structural life of the blades is

considered important. In addition, the imbalance in

rotational forces due to blade failure can lead to

significant damage to the entire wind turbine

system, and to the collapse of the entire tower if no

corrective action is taken, [1].

A number of ways have been invented to detect

failures, as well as to measure displacements, either

by metering sensors or by acoustic emissions. The

types of wind turbine failures are:

• Shape damage and failure development

between cover welding and main beam flange.

• Shape damage and failure development

between the top and bottom flap weld

peripherals of the shell.

• Shape destruction and failure development

between body and face interface in sandwich

composites both externally and in main beams.

• Inner shape destruction and failure

development in laminates peripherally or in the

main beam under tensile or compressive loads.

• Rapid propagation of fiber cracks in the

periphery or main beam.

• Bending in the periphery due to shape failure or

development failure in the connection between

main beams and peripheral under compressive

loads.

• Development of cracks in layers and separation

of layers from coating, [2].

Fig. 1: Levels of wind turbine blade inspections

When designing and manufacturing wind turbine

blades various tests are performed to assess the

quality of the materials. As shown in Figure 1, the

main pyramid-shaped levels have been created. To

have the blades of an IEC 61400 wind turbine

certified, [1], they must have passed the first and

third level control, [1].

In the first level of controls, small samples of

the blade materials are subjected to tests to

determine their properties and their fatigue

resistance. These checks are usually inexpensive

and easy to execute.

In the second level of controls, larger pieces are

subjected to more complex controls. The purpose is

to verify computational models for critical details.

It is generally a more expensive procedure, which

is why it is performed less frequently.

In the third level of controls, the blades are

examined both dynamically and statically based on

the requirements of IEC 61400-23, [1]. Full-scale

tests are typically performed on one or two blades

to confirm that they meet the design specifications.

The total cost of controls at this level is very high

as it can take several months to complete. Also

important is the cost of waiting for the product to

hit the market.

In the finite element simulation work presented

by [8], it is proved that the controls at the edge of

the blades in traction forces give satisfactory

results. Failure loads as well as material failures are

identical to third-level controls.

At the moment, standard IEC 61400-23 and

DNVGL-ST-0376 quality tests are performed in

two directions, flap wise and edgewise, one

direction at a time.

During operation, the blades of wind turbines

are subjected to high dynamic loads, resulting in

many charge cycles in different directions,

centrifugal loads, various turbulences, shear

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stresses, and sudden changes in air direction. All of

the above lead to significant failures due to fatigue

in the life of the blade. The current simulations for

fatigue tests do not adequately represent the forces

and actual loads they will receive. Efforts were

made to find better controls. One method is to test

simulations for fatigue on two axes both flap wise

and edgewise. According to the study [11], the

above test is more representative and promises a

better test for the future of simulation for wind

turbine blade stresses, [1].

4 Analysis of GE 1.5XLE Wind

Turbine Blades

The aerodynamic optimal model of a wind turbine

blade corresponds to the lowest possible thickness

of the blade design. However, safety is a key

prerequisite for its design, which takes into account

unknown aspects of its loads, material degradation,

and possible flap failure. However, in many cases,

the safety factors are excessive and lead to

superstructures. In order to more precisely identify

safety factors, detailed information on the effects of

different loading conditions (high winds, humidity,

temperature changes) and parameters on the

structures of the composite materials of the blades

regarding their durability and life expectancy, are

used, [1].

The necessary information can be obtained

from computational models or theoretical studies of

the behavior of blades under different loading

conditions. For the failures, a number of analytical

and numerical methods are required. Among the

analytical methods used are models based on

residual shear stresses, generalized fiber bundle

models, failure mechanisms, and mechanism-based

models. In the models of residual shear stresses, the

equilibrium of forces assumes that shear and fiber

loads are transferred only with shear stresses. In

general, for fiber bundle models, statistical fiber

strength models and different loading conditions

are applied. According to previous analyses, the

aim is to simulate the failure of composite wind

turbines, [1].

Most often problems are solved using the finite

element method, in which the integrals and

differential equations are calculated describing the

material deformations and their microstructure

based on the discretization of the bodies and the

approximation of the equations. Complex models

of wind turbine blades, even with degraded

materials, are in the direction of significant analysis

through the above methods, [1].

In this study, we analyze the GE 1.5XLE wind

turbine blades through the finite element method

using at first the ANSYS Fluent program, [5]. The

method adopted is the Computational Fluid

Dynamics (CFD). The solution arose from the

ANSYS 19.2 Workbench software package. Taking

into consideration Computer Aided Engineering

(CAE) design, simulation, analysis, and processing

results, Fluid Fluent and Static Structural, [5], have

been used.

The model was manufactured and solved in

two parts. First, the Fluent was solved, and then the

Structural. The first model was developed to solve

aerodynamic loads on the flap and the second

through the calculated loads to determine the

stresses on the flap and its displacements. The

second model was analyzed for five materials.

These are E-Glass Fiber, Generic, Solvay APC-2 /

AS4 PEEK Plus Carbon Fiber Reinforced

Unidirectional Tape, DuPont™ Kevlar® 49

Aramid Fiber, S-Glass Fiber, Generic and S-2

Glass Fiber, Generic. We consider all five materials

to be macroscopical isotropic, as they have the

same stress values for random directions. The

properties of the materials are presented in Table 1,

[4]. The work was inspired by a first study by

Sebastian Lachance-Barrett, and Robert Zhang

Professor of wind energy at Cornell University in

New York, [4]. The GE 1.5XLE wind turbine

model was manufactured by General Electric. It

produces 1500 kW and it operates in minimum

winds of 3.5 m/s and a maximum of 20 m/s. It has a

wind resistance of up to 52.5 m/s. Its rotor has a

diameter of 82.5 meters and covers a surface of

5346 m2. It has three blades with a maximum blade

speed of 18.7 U/min. It consists of composite

material with glass fibers.

4.1 Fluent Analysis

The main equations that are used are continuity

equations and Navier-Stokes equations. These

equations are given below:

 Conservation of mass:

0p

t



  

ur

(1)

 Conservation of momentum (Navier-

Stokes):

   

2p

p



       

   

r r r

r

uu ω u ω ω r

t

(2)

Where  is the relative velocity,the angular

velocity and the deviatoric stress tensor. Also,

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the Coriolis force appears as and the

centripetal acceleration asin the Navier-

Stokes equation. In solving Ansys Fluent, [5], we

start with the additional terms framed at angular

velocity=-2k.

Finally, it is used the Reynolds averaged form

of continuity and momentum and also the model

with the SST k-omega turbulence to complete the

set of equations.

We only run 1/3 in hypothetical periodic loads:

   

11

, , 120 ; 1,2,3r r n n



  uu

(3)

Fig. 2: By taking into account 1/3 of the problem

   

11

, , 120 ; 1, 2,3r r n n



  vv

(4)

 

11

,240 120 1 ,120rrvv

(5)

 

11

,240 120 2 ,0rrvv

(6)

   

2 2 2

, , 120 ; 1,2,3r r n n



  vv

(7)

 

22

,1800 120 1 ,0rrvv

(8)

The above equations prove that the flow velocity

distribution at angles 0 and 120 degrees is the

same. If θ1 represents one of the boundary

conditions for 1/3 and θ2 the other boundary

condition, then󰇛 󰇜 󰇛 󰇜

Boundary conditions in the fluid region are:

1) Inlet (Figure 4): Velocity of 15 m/s

with turbulent intensity of 5% and

turbulent viscosity ratio of 10.

2) Outlet: Pressure 1atm.

3) Blade: No slip.

4) Side Boundaries: Periodic.

The fluent solver, [5], converts the above

differential equations (1) and (2) into a set of

algebraic equations. The conversion of these

algebraic equations gives the values (u, v, p, ω) for

each element of the total finite element mesh. Near

the flap, we have considered a very fine finite

element mesh for better accuracy of the results. The

finite element mesh-estimated at about 400,000

triangular and tetrahedral elements (Figure 3). The

matrices created are large in volume but considered

much spared as matrices. Ansys, [5], uses a

pressure-based solvent. The geometry of the wind

turbine was taken from the Cornell University

website, [4].

We first observe the fluid (air) in Figure 2,

which occupies the bulk volume and encloses one

wind turbine blade. The fluid domain is conical in

shape with a short radius of 120 m and a long

radius of 240 m. Its length is 270 m and the fluid

flows from the short beam to the long beam.

Fig. 3: Total finite element mesh

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Fig. 4: Various parts that separate the fluid for

boundary conditions.

As boundary conditions for speed entry have

considered the Inlet sections and the Inlet Top on

the Z-axis (Figure 4). A negative speed of 15 m/s

on the Z-axis entered. The vortex intensity was 5%

and the degree of viscosity was 10. As an outlet, it

is obtained a section, which has an outlet pressure

equal to atmospheric pressure. In addition, we have

considered period_1 and period_2 to be interface

points, not walls since we have taken 1/3 of

geometry. Finally, the type of interior (Figure 4)

was included in the fluid section.

With the initial calculations in the pre-analysis,

a speed of 88.48 m/s is expected at the ends of the

blades and our fluent exported a speed of 88.33

m/s, a result satisfactory for our model (Figure 5).

Fig. 5: Air velocity profile with streamline on the

blades

Figure 6 shows the wind speed profile from the

inlet (inlet) and also from the outlet. Initially, at the

entrance, there is a speed of 15m/s, an expected

result. Observing behind the blade there is a speed

reduction, which indicates correct behavior.

Finally, some orange lines around the rotation of

the blades indicate a higher speed, which also

indicates a correct solution.

Fig. 6: Air velocity profile

Examine the pressures vertically along the

blade on the x-axis (Figure 7). We notice that the

maximum pressures are located at the top of the

blade which is an expected result.

Fig. 7: Pressure around a blade

Then in the next two Figures (Figure 8 and

Figure 9) we have a look at the pressure profile on

the wind turbine, from the back and the front. As

expected, the pressure on the front is greater than

on the back.

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Fig. 8: Pressure profile from the back of the blades

Fig. 9: Pressure profile from the front of the blades

If the shape of the velocity vector is compared

with the pressure vector, the results give the

expected shape from the buoyancy and the rear of

the blade (Figure 10).

Fig. 10: Speed and pressure around a blade

Another important problem is the solution

convergence from the finite element results related

to the number of iterations performed. In Figure 11,

the behavior of the solution is presented at 3,000

iterations. As we can see, the residuals do not

change much after 1,500 iterations. Therefore,

1,500 iterations are the ideal number to get the right

results.

Fig. 11: Solution at 3000 iterations

4.2 Structural Analysis

The structural analysis includes the static study of

the blade. The pressure on the blade is calculated

using the results from the fluent study (section 4.1)

and then the stresses and displacements fields are

calculated. The blade consists of an outer surface

and an inner beam (Figure 12).

Fig. 12: Separation of the blade into the beam and

outer surface

The mathematical model that was used for

static analysis is based on Shell theory. This is an

extension of Euler-Bernoulli’s beam theory, [5].

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Table1. Properties of the materials

Name

Density

(Kg/

m3)

Young

Modulus

(GPa)

Poisso

n Ratio

Shear

Modulus

(GPa)

E-Glass

Fiber

2.565

72.4

0.2

30

Kevlar

Aramid

Fiber

1.437

112

0.36

7

Solvay

APC-

2/AS4

Carbon

Fiber

1.319

138

0.3

5,7

S-Glass

Fiber

2.482

86.3

0.22

35

S-2

Glass

Fiber

2.457

86.9

0.23

35

In the finite element mesh considered for the

blade (Figure 13), an element size of 20 cm was

chosen. The program created the best possible

mesh with different types of elements (triangular,

tetrahedral, etc.). They have been taken about 5,241

finite elements, approximately 90 times less than

that in the Fluent analysis.

Fig. 13: Blade finite element mesh

At first, the total displacements are calculated.

It is observed in Figure 14, that we have the shifts

that we expected in the blade. The maximum

displacements are created at the tip and when we

approach the root of the blade, there is a reduction

in displacements in all the examined cases. In Table

2, the maximum displacements according to the

different materials are given. It is observed that

Solvay APC-2/AS4 Carbon has the maximum

displacement.

Fig. 14: Overall displacement of E-Glass blade in

relation to its original position

Table 2. Maximum displacement

Material

Máximum displacement

(m)

Ε-Glass

0.698

Kevlar/ Aramid

0.488

Solvay APC-2/AS4

Carbon

0.414

S-Glass

0.589

S-2 Glass

0.600

Fig. 15: Stresses profiles on the front of the E-Glass

blade

Fig. 16: Stresses profiles in the back of the E-Glass

blade

Table 3. Maximum Von-Mises stresses

Material

MaximumVon-Mises

stresses (MPa)

Ε-Glass

30.66

Kevlar 49/ Aramid

32.585

Solvay APC-2/AS4

Carbon

34.084

S-Glass

31.776

S-2 Glass

31.655

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In Figure 15 and Figure 16, the Von-Mises

stresses are given in the case of the E-glass blade.

The area where the maximum stresses occur is the

most critical, both in terms of the appearance of

cracks and in terms of the manifestation of fatigue.

This suggests that the specific blade geometry

needs material reinforcement at those points. In

addition, the use of stronger material may be a

solution to a better confronting of the maximum

stresses.

In Table 3 the max Von-Mises stresses

according to the different materials are given. It is

observed that at Solvay APC-2/AS4 appeared the

maximum Von-Mises stress.

Fig. 17: Shear stresses profile on the back side of

the E-Glass blade

Fig. 18: Shear stresses profile on the front side of

the E-Glass blade

Regarding the shear stresses (Figure 17 and

Figure 18), we conclude that the maximum shear

stresses appear in the same order as that of Von-

Mises stresses. The display of the stress profile on

the blade is identical to the Von-Mises stresses; the

maximum stresses appear at the same points. The

values of the maximum shear stresses are

summarized in the following Table 4.

Table 4. Maximum Shear stresses

Material

Maximum shear stress

(MPa)

Ε-Glass

2.161

Kevlar 49 /Aramid

1.609

Solvay APC-2/AS4

Carbon

1.251

S-Glass

2.083

S-2 Glass

2.093

5 Analysis and Results in Extreme

Wind Conditions 60 m/s

Concerning our initial study for 15m/s wind, we

conclude that the wind speed profile does not

change much. The maximum values at the tip of the

blade are around 88m/s, slightly higher. On the

contrary, to the previous 15 m/s, the pressure

profile has changed significantly. Not so much in

terms of the distribution of pressures (Figure 20

and Figure 21) but in terms of their size. More

specifically, the maximum pressures are 5,972 Pa;

significantly, higher than the 1,834 Pa (Figure 8)

we had for wind speed at 15 m/s.The total

displacements for wind speed 60m/s have changed

significantly too (Figure 19), from 0.6983 m (Table

2) to 1.567 m (Table 5). Furthermore, the

maximum Von Mises stresses (Table 6) and the

maximum shear stresses (Table 7) have changed

significantly.

Fig. 19: Overall displacement of E-Glass blade for

wind speed 60 m/s

Table 5. Maximum displacements for wind speed

60 m/s

Material Maximum displacement

(m)

Ε-Glass 1.567

Kevlar 49 1.115

Solvay APC-2/AS4

Carbon

0.945

S-Glass 1.322

S-2 Glass 1.348

WSEAS TRANSACTIONS on APPLIED and THEORETICAL MECHANICS

DOI: 10.37394/232011.2023.18.6

Efstathios E. Theotokoglou, Georgios Xenakis

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Volume 18, 2023

Lastly, the shear stresses profiles on the back of the

E-Glass blade for wind speed 60 m/s are presented in

Figure 22.

Fig. 20: Stresses profiles on the front of the E-

Glass blade for wind speed 60 m/s

Fig. 21: Stresses profiles on the back of the E-Glass

blade for wind speed 60 m/s

Table 6. Maximum Von-Mises stresses for wind

speed 60 m/s

Name

Maximum stresses

Von-Mises (MPa)

Ε-Glass

63.22

Kevlar 49

65.47

Solvay APC-2/AS4

69.26

S-Glass

64.45

S-2 Glass

64.24

Fig. 22: Shear stresses profiles on the back of the

E-Glass blade for wind speed 60 m/s

Table 7. Maximum Shear stresses for wind speed

60 m/s

Material

Maximum shear

stresses (MPa)

Ε-Glass

4.5

Kevlar 49

3.82

Solvay APC-2/AS4

2.89

S-Glass

4.38

S-2 Glass

4.42

6 Conclusions

The present work concerned the analysis of a wind

turbine blade specifically the GE 1.5 XLE model,

through computational methods with various

composite materials that are the materials of the

future for wind turbines. The materials considered

are E-Glass, S-2 Glass, S-Glass, Kevlar 42, and

finally Solvay APC-2 / AS4 Carbon. For the study

of the proposed materials, a computational analysis

is carried out.

Initially, to simulate the model, the pressure

which will be exerted on the blade should be

calculated. To calculate the pressures, a fluent

analysis was performed with a wind simulation of

15m/s. The wind was blowing on the blade from all

directions. The form of pressure observed was as

expected. The air velocity and the pressure profiles

that they extracted were as expected.

Then a static analysis was performed on the

blade. The input was the pressure from the fluent

analysis. All five materials were analyzed. Von

Mises stresses exerted on the materials, shear

stresses, and displacements were calculated. The

same study for a wind speed of 60 m /s, considered

an extreme wind speed, took place, from which

much greater pressures have been calculated.

Finally, the results present that the failure rate of

the materials used is much lower than the stress

limit, so there is no risk of abrupt breakage.

The results also show that the E-Glass material

has the highest displacements in both winds. It is

followed by the S-2 Glass, the S-Glass, the Kevlar

49, and finally the Solvay APC-2 / AS4 Carbon.

This justifies the prices that the materials have in

the market, as the most expensive shows the

smallest shifts.

It is noted that even in extreme wind conditions

(60 m/s) there is no failure of any material.

However, the displacements are more than double

for each material separately in relation to wind

speed under normal conditions (15 m/s), while the

stresses are almost double.

In our study for the GE 1.5XLE wind turbine,

the stresses and displacements for different blade

materials, in normal and in extreme wind

conditions, are given. Due to the computer

constraints at the nodes and the data of the

computational study, the results are considered

approximate. Our study may be considered a first

step to analyzing a GE 1.5 XLE.

In addition, the proposed study performs one-

way-Fluent Solid Interaction (FSI), and the results

extracted from the liquid are entered into the solid.

An improved version has the ability for two-way-

FSI, presenting more accurate results, with a

WSEAS TRANSACTIONS on APPLIED and THEORETICAL MECHANICS

DOI: 10.37394/232011.2023.18.6

Efstathios E. Theotokoglou, Georgios Xenakis

E-ISSN: 2224-3429

65

Volume 18, 2023

detailed calculation of the Tangential Force by the

coefficients of buoyancy and traction (section 4.1).

Ideally, it would be an experimental study to verify

the results. The coefficients and variables will be

adjusted in such a way that there would be a

convergence between a theoretical and an

experimental model.

To accurately calculate fatigue, it would be

appropriate to use known and tested materials. The

simulation of the specimens in fatigue conditions

based on the theoretical model would lead to a

calculation of the lifespan of the model.

In addition, the stress of corrosion of the

materials was not considered. Extreme

temperatures or rain conditions can introduce into

the model.

Finally, the most important part for future

expansion concerns the techno-economic study of

the wind turbine. That is, to study the cost of

construction for each material in the blade. The

difference in performance (due to weight) during its

operation and the lifespan of the wind turbine for

each of the different materials should be

considered. This study will be the criterion for the

final selection of the materials that will be used.

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