“DESIGN, DEVELOPMENT AND TESTING OF MODEL WIND MILL … · Project title “DESIGN, DEVELOPMENT AND TESTING OF MODEL WIND MILL BLADE USING ADDITIVE MANUFACTURING PROCESS” Submitted

Project title

“DESIGN, DEVELOPMENT AND TESTING OF MODEL WINDMILL BLADE USING ADDITIVE MANUFACTURING

PROCESS”Submitted in the partial fulfillment for the

RequirementIn

“BACHELOR OF ENGINEERING”

Prescribed by

VISVESVARAYA TECHNOLOGICAL UNIVERSITYBELAGAVI

Submitted by

Aalam Mh Shamsher Shamshad 2SA13ME001

Jameer Pash A. Havergi 2SA13ME028

Taha Khan 2SA13ME087

Sibatulla N S Khan 2SA13ME084

Under The Guidance OfAsst. Prof.: Shashidhar A.L.

Asst.Prof. B.A.Badiger

2016-2017

Department of Mechanical EngineeringSECAB INSTITUTE OF ENGINEERING & TECHNOLOGY

Project title



RequirementIn


Prescribed by


Submitted by







2016-2017


Project title



RequirementIn


Prescribed by


Submitted by







2016-2017


ACKNOWLEDGEMENT

The satisfaction that implies the successful completion of our project work would be

incomplete without the mention of people who made possible.

We wish to place our gratitude to our respected principal, Dr. A Pasupathy, Head of

Department, Dr. Syed Abbas Ali, and all the staff members of Mechanical Engineering

Department, SECAB Institute of Engineering & Technology, Vijayapur, for their inspiration and

support during the project work.

We are indebted to our guides Asst. Professor Shashidhar A.L and Asst.Prof.

B.A.Badiger, Mechanical Engineering Department motivated us and guided us throughout the

project work. They made the entire task simple with their valuable suggestions.

We would like to acknowledge with the deep sense of thanks to the Karnataka State

Council for Science and Technology (KSCST), Indian Institute of Science Campus, Bangaluru-

560012, Government of Karnataka for rendering financial support for this work under 40th Series

of Student Project Program through Project Proposal Reference Number 40S_BE_1247. In

addition to this, we also thank KSCST meet term evaluation committee for their valuable

suggestions.

Our special thanks to our friends for their timely help and kind co-operation.

Finally, no words would be sufficient to express our acknowledgement to our parents.

We thank them for their moral support. Without their encouragement this project would never

have been completed.

Aalam MH Shamsher Shamshad 2SA13ME001



Sibgatulla N S Khan 2SA13ME084

ABSTRACT

The increase in global demand for energy and environmental concerns has made a shift to

renewable energy sources. Wind turbines produce electricity by using the power of wind to drive

an electric generator whose blades are usually made up of composite material. While designing a

wind turbine blade, the aim is to attain the highest possible power output. The latest trend of

designing and manufacturing of blade are through designing software and Additive

Manufacturing Technique. Design softwares have given the opportunities to enhance the design

capabilities and development of more efficient blades that can also reduce cost and time

considerably. Blade is the key component to capture wind energy. It plays a vital role in the

whole wind turbine.

Airfoil design has been the paramount step in designing the wind turbine blades. For

designing of a blade two factors are to be considered namely structural properties and aerodynamics

performances. After extensive review of literature, two airfoils are choosen i.e., FX84-W175 for

the root section and NACA4412 for rest of the blade part. The optimum chord length and angle

of twist along the span of the blade are calculated using Wind Blade Calculator software. Using

QBLADE open source software two blades of length 200mm are designed. The first blade is

designed as per its standard t/c ratio of 17.5% and second blade has a t/c ratio of 20%. The

designed blades are saved in .STL format to for 3D printing process. FDM 3D printing

technology is employed for manufacturing of wind turbine blades using high strength ABS

plastic as raw material. The structural test is carried out on the blade in UTM with root end fixed

and an incremental load applied at the tip treating it as a cantilever beam. The load versus

deflection graph is generated in computer. The failure loads for both the specimens are noted

down. The same failure loads are used for simulations in QFEM module of QBLADE software

to determine the maximum bending stress induced.

The structural tests on UTM indicated a failure load of 6KN for the t/c 17.5% specimen

and 6.5KN for the t/c 20% specimen. Using the same failure loads in the simulation, the

maximum bending stress induced are 64.95MPa and 70.42MPa for t/c 17.5% and t/c 20%

respectively. Therefore, wind mill blades (length 0.85m-1m) can withstand significant higher

loads than model blades. The feasibility of using 3D printed blades in roof-top power generation

units seems to be reality in near future.

CONTENTS

SL.No TILTE Page No.

1. CHAPTER 1INTRODUCTION1.1 Introduction to Renewable Energy Sources 11.2 Evolution of Wind Mill Blades 11.3 Literature Review 21.4 Objectives 51.5 Project Report Organization 6

2. CHAPTER 2THEORIES AND CONCEPTS2.1 Terminology 72.2 Betz Limit 82.3 Blade Element Momentum (BEM) Theory 92.4 Airfoil Families 92.5 Material Used For Blades 102.6 3D-printing 11

3. CHAPTER 3RESEARCH AND METHODOLOGY3.1 Selection of Airfoil 153.2 Selection of Material 163.3 Selection of Manufacturing Process in 3D printing 193.4 Methodology 20

4. CHAPTER 4DESIGN AND MANUFACTURING4.1 Design and Modeling 214.2 Manufacturing of blades 24

5. CHAPTER 5TESTING AND SIMULATION5.1 Testing 265.2 Simulation 30

6. CHAPTER 6RESULT, CONCLUSION AND SCOPE FOR FUTURE

6.1 Result 326.2 Conclusion and Scope for Future work 32

References

LIST OF FIGURES

Fig. 2.1 Cross section of airfoil 8

Fig. 2.2 Explanation of Blade Element Momentum 9

Fig. 2.3 Stereo lithography Process 12

Fig. 2.4 Fused deposition modelling (FDM) Process 13

Fig. 2.5 Selective laser sintering (SLS) Process 14

Fig. 2.6 Multi-jet modelling (MJM) Process 14

Fig. 3.1 FX84-W-175 Airfoil 15

Fig. 3.2 NACA4412 Airfoil 16

Fig. 3.3 ABS Plastic 3D Printing Filaments 17

Fig. 3.4 Schematic Diagram of Fused Deposition Modeling (FDM) Process 19

Fig. 4.1 Airfoils for t/c 17.5% 22

Fig. 4.2 Airfoils for t/c 20% 22

Fig. 4.3 3D model of blade with t/c 17.5 23

Fig. 4.4 3D model of blade with t/c 20% 23

Fig 4.5 3D printing machine is preparing for printing 24

Fig. 4.6 Manufactured blades by 3D printing process 25

Fig. 5.1 Testing setup 26

Fig. 5.2 Computer control UTM machine 27

Fig. 5.3 Deflected blade under incremental loading 27

Fig. 5.4 Failed Blades 28

Fig. 5.4 Load vs deflection graph for t/c 17.5% 29

Fig. 5.5 Load vs deflection graph for t/c 20% 29

Fig. 5.6 Stress distribution in blade t/c 17.5% 30

Fig. 5.6 Stress distribution in blade t/c 20% 31

DESIGN, DEVELOPMENT AND TESTING OF MODEL WIND MILL BLADE USING ADDITIVEMANUFACTURING PROCESS

Department of Mechanical Engineering, SIET, Vijayapur Page 1

CHAPTER 1

INTRODUCTION

1.1 Introduction to Renewable Energy Sources

Renewable energy is the term used to cover those energy flows that occur naturally

and repeatedly in the environment and can be harnessed for human benefit human benefit.

The time of cheap oil and gas is over. Mankind can survive without globalization, financial

crises and flights to the moon or Mars but not without adequate and affordable energy

availability. Renewable energy offers our planet a chance to reduce carbon emissions, clean

the air, and put our civilization on a more sustainable footing. Renewable sources of energy

are an essential part of an overall strategy of sustainable development. Renewable energies

will provide a more diversified, balanced, and stable pool of energy sources. Renewable

energy sources derive their energy from existing flows of energy from ongoing natural

processes, such as sunshine, wind, flowing water, biological processes, and geothermal heat

flows. The most promising alternative energy sources include wind power, solar power, and

hydroelectric power.

The need for power generation from renewable energy sources has been increasing

over the years with faster rate of depletion in fossil fuel and crude oils. Solar energy, wind

energy and hydro energy has been the area under current focus in research. Current trend is

dominated by wind energy as a result there is an increase in the number of turbines

installation and as well as the increasing diameter of turbine rotors with the corresponding

energy output per turbine.

1.2 Evolution of Wind Mill Blades

Wind energy has been used since hundreds years ago. The first wind turbine for

electric power generation was built by the company S. Morgan-Smith at Grandpa’s Knob in

Vermont, USA, in 1941. The turbine (53.3 m rotor, 2 blades, power rating 1.25 MW) was

equipped with massive steel blades. One of the blades failed after only a few hundred hours

of intermittent operation. Thus, the importance of the proper choice of materials and inherent

limitations of metals as a wind blade material was demonstrated just at the beginning of the

history of wind energy development. The next, quite successful example of wind turbine for

energy generation is so called Gedser wind turbine, built by Johannes Juul for the electricity



company SEAS at Gedser coast in 1956-57. The turbine was produced already with

composite blades, built from steel spars, with aluminum shells supported by wooden ribs. The

turbine (three blades, 24 m rotor, 200 kW) war the first success story of wind energy: it has

run for 11 years without maintenance.

The performance of the model turbines fabricated using the AM technique has been

noticeably better than that of models produced by hand, the previous method. Introducing the

AM method has also given an extra educational dimension to this design-build-test project.

Working in pairs, the students are able to make design decisions on the blade geometry and

the number of blades on the turbine. Utilizing fused-deposition modeling (FDM) additive-

manufacturing (AM) technology, students are able to produce their turbine blades by additive

manufacture, which has provided an opportunity to greatly improve the accuracy and finish

of the model airfoils that students can produce, as well as ensuring geometric repeatability of

blades on the same hub. It also allows students the capability to produce concave surfaces on

the underside of their blades, which was almost impossible when producing the blades by

hand methods. In this project, students learn about airfoils and simple aerodynamics and

mechanics. The project introduces them to testing and measurement methods, as well as to

the advantages and limitations of the particular AM technology used.

1.3 Literature Review

Martin Widden,et. al[1],worked on design, development and testing of a scale-

model wind turbine. Authors used fused-deposition modelling (FDM) additive manufacturing

(AM) technology to produce turbine blades. AM technique gave freedom to design blades

according to their desired parameters which was difficult to achieve by hand method. AM

technique turned out to be an effective technique to manufacture turbine blades over the other

traditional methods. The work exposes testing and measurement methods, advantages and

limitations of AM technology. The model was tested at different torque magnitudes and

varying of air speeds. Dimensionless performances curves of power coefficient against blade-

tip-speed ratio were plotted. The performance of a full-size rotor with similar geometry could

be predicted with the above curves.

A Munõz, et.al [2], investigated and demonstrated innovative designs for offshore

wind turbines. From the structural point of view, the root is the region in charge of

transmitting all the loads of the blade to the hub. Therefore it is very important to include

airfoils with adequate structural properties in this region. At the root, airfoils used were of



high-thickness and blunt trailing edge to improve the structural characteristics of the blade.

The airfoil profiles which can be used as the root the Göttingen (GOE), Wortmann (FX),

Delft University (DU) and ¨ NREL-SANDIA (FB) airfoils. Out of these the Delft University

and the Wortmann airfoils were chosen due to their fitness to the objectives and to the

technical specification. DU airfoils are relatively thick but they keep the trailing edge gap

below 2% and the FX family exhibits quite large trailing edge. From the DU series of airfoils

DU 95-W-180 and from the FX series FX84-W-175 were chosen for comparing. The

experimental results described how high-thickness blunt-trailing-edge airfoils have a higher

slope of the α−CL curve and a higher level of drag co-efficient. The aerodynamic motor of

the CENER airfoil design tool is XFOIL. The panel-method theory which was not suitable

for calculation of high-thickness and blunt trailing edges airfoils. XFOIL made used of

empirical correlations to account for blunt trailing edge effect. The main characteristics of the

new airfoils were that they had high lift and low sensitivity. At the same time, they provided

good structural behaviour increasing the enclosed area and the moment of inertia with respect

to both axis. The performance of the airfoils within the “INNWIND.EU” blade has to be

evaluated using the BEM theory. The results showed that the contribution of airfoils to the

torque generated by the wind turbine was very small. The new blade geometry was not

optimized but a small increase in energy production was observed. The new geometries

design showed that there was a big margin for structural properties improvement without

penalizing the aerodynamic behaviour.

Richard E. Stamper and Don L. Dekker [3], discussed the use of rapid prototyping.

Four leading rapid prototyping fabrication technologies are sterolithography (SLA),

laminated object manufacturing (LOM), selective laser sintering (SLS), and fused deposition

modeling (FDM). Rapid prototyping equipment was used as part of research effort for the

purpose of training. The FDM process uses a layer-wise building process to create the part.

The FDM rapid prototyping process was used for design methodology concept of parametric

design. An airfoil with a Clark Y cross section was constructed from the ABS. A wing from

ABS (Acylonitrile Butadiene Styrene) material in order to compare it with an aluminium one

of the same cross-section. The rough wing didn't correspond very well to the aluminum wing

but after the ABS wing was smoothed, the lift and drag curves approached the curves

obtained from the aluminum wing. Further tensile and torsion test were performed on the

modeled specimens.



Peter J. Schubel and Richard J. Crossley [4], reviewed wind turbine blade design,

theoretical maximum efficiency, propulsion, practical efficiency and blade loads. A complete

picture of wind turbine blade design and the modern horizontal axis rotors was demonstrated.

The aerodynamic design principles blade plan shape, aerofoil selection and optimum angle of

attack were included in the review. The study also described aerodynamic, gravitational,

centrifugal, gyroscopic and operational conditions. Both Horizontal Axis Wind turbine

(HAWT) and Vertical Axis Wind Turbine (VAWT) were tested for above given parameters.

It was concluded that HAWT dominated design configuration and manufacture in large scale.

Study also compared performance of slender aerofoils with thicker aerofoils.

N.Manikandan, B.Stalin,[5],worked with the objective to increase reliability of wind

turbine blades through airfoil structure and to reduce the noise level of the wind turbine

during its running period. Pro/E, Hypermesh software was used to design blades. NACA 63-

215 airfoil profile was considered for the analysis. The wind turbine blade was modeled and

several sections were created from root to tip for improving the efficiency. The efficiency was

to be increased and reduce the noise produced from the blades in working condition by

introducing winglet at the tip of the blade. The conventional blades and modified blades with

winglet were compared for results. The aerodynamic performance was made using

computational techniques and the computations were predicted using clean and soiled

surface. Generic model was developed for different shapes and sizes with associated

parameters and was used in the pre-design stage of winglets, where spending more time in the

design process was minimized. All the winglets developed were designed according to the

design criteria provided by the respective research papers and so there were no need for

designing a specific type of winglet from the base, when this model was used.

F.W Perkins and D.E Cromack[6], worked on blade stress analysis, design,

aerodynamic, natural frequency and cost. The main problems encountered were aerodynamic

performance, structural integrity and cost. The problems of the aerodynamic and structural

integrity were studied by NASTRAN programming. The characteristics were computed using

programs, the overall cost of the design was reduced as repetitive codes were used. The

Rayleigh Ritz method was used for the solution of the natural frequencies. The mode shapes

were a11 normalized to the magnitude of the tip displacement vector. The object of the study

was the development of computer programs useful to the wind turbine designer. Codes were

developed which allowed the resolution of bending stress and natural frequencies of wind



turbine blades. The codes were inexpensive to operate when compared with finite element

codes of comparable sophistication. Good agreement between the predicted and observed

flexural deflections was showed along with natural frequencies. The strong evidence for the

application of Rayleigh's method to the problem of free beam vibration, allowing coupling

between deflections in two directions, was valid. All other parts of the programming codes

were also verified.

Lance Manuel, Paul S. Veers, Steven R. Winterstein [7], worked on the parametric

models for estimating wind turbine fatigue loads for design. Statistical models of loads for

fatigue application were described and demonstrated using flap and edge blade-bending data

from a commercial turbine in complex terrain. Distributions of rain flow-counted for three

statistical moments mean, coefficient of variation, and skewness. The moments were mapped

to the wind conditions with a two-dimensional regression for long-term loads derived by

integration over wind speed distribution alone, using standard-specified turbulence levels.

Next was the integration over both wind speed and turbulence distribution in the proposed

site. Results were compared between standard-driven and site-driven load. Finally, graphs

were plotted over the input conditions and the uncertainty (due to the limited data set) in the

long-term load distribution was represented by 95% confidence bounds on predicted loads.

The unbiased turbulence with higher load factor – may result in 14 more uniform reliability

across a range of cases. In contrast, current standards could have lead to potential.

1.4 Objectives

The primary objective of the project is to design (QBLADE) and develop a low cost,

wind mill blade using additive manufacturing process (3D printing) for small scale power

production units which could be installed on roof-top of homes. The secondary objective of

the project is to carry out structural test (Two-point bending) in universal testing machine for

incremental loading at the tip and simulate the same failure load to determine the maximum

flexural stress induced.



1.5 Project Report Organization

CHAPTER 1 – INTRODUCTION presents current global scenario of energy crisis and

availability and literature review on basic design parameters of blade design, loading on wind

mill blades, different 3D printing technologies and objectives.

CHAPTER 2 - THEORIES AND CONCEPTS presents basic terminologies, theories

involved, general information about airfoil families, materials for blade manufacturing and

3D printing

CHAPTER 3- RESEARCH AND METHODOLOGY presents detailed study on section of

airfoils, materials and manufacturing process and steps to be followed.

CHAPTER 4- DESIGN AND MANUFACTURING gives details about designing

procedures, modeling and manufacturing of blades.

CHAPTER 5- TESTING AND SIMULATION presents testing of manufactured blades in

UTM and simulation of modeled blades for bending stress.

CHAPTER 6- RESULT, CONCLUSION AND SCOPE FOR FUTURE presents results from

both flexural test and simulations.



CHAPTER 2

THEORIES AND CONCEPTS

2.1 Terminology

Airfoil: The cross sectional shape obtained by the intersection of the wing with by the

perpendicular plane is called an airfoil.

Mean camber line: It is the line which is the locus of points halfway between the

upper and lower surface.

Leading edge: It is the point at the front of the airfoil that has maximum curvature.

The most forward point of the mean camber line.

Trailing edge: It is the point of minimum curvature at the rear of the airfoil. The

Most rearward point of the mean camber line.

Chord line: The straight line connecting the leading and trailing edges is chord line.

Chord: It is the shortest distance between leading and trailing edge.

Chamber: The camber is the maximum distance between the mean camber line and

the chord line measured perpendicular to the chord line.

Angle of attack: The angle between the relative wind and the chord line is the angle

of attack.

Drag: Drag is defined as the component of the aerodynamic force parallel to the

relative wind.

lift: Lift is defined as the component of the aerodynamic force perpendicular to the

relative wind

Quarter-chord point: The moment about a point on the chords at a distance c/4 from

the leading edge is known as quarter-chord point.

Aerodynamic moment: The moment at the leading edge is known as aerodynamic

moment.

Aerodynamic center: A certain point on the airfoil about which moment do not vary

with angle of attack is known as aerodynamic center.



Fig. 2.1 Cross section of airfoil

2.2 Betz Limit

Assumptions

1. The rotor does not possess a hub and is ideal, with an infinite number of blades which

have no drag. Any resulting drag would only lower this idealized value.

2. The flow into and out of the rotor is axial. This is a control volume analysis, and to

construct a solution the control volume must contain all flow going in and out, failure to

account for that flow would violate the conservation equations.

3. The flow is incompressible. Density remains constant, and there is no heat transfer.

4. Uniform thrust over the disc or rotor

Betz's law indicates the maximum power that can be extracted from the wind, independent of

the design of a wind turbine in open flow. The law is derived from the principles of

conservation of mass and momentum of the air stream flowing through an idealized "actuator

disk" that extracts energy from the wind stream. According to Betz's law, no turbine can

capture more than16/27(59.3%) of the kinetic energy in wind. The factor 16/27 (0.593) is

known as Betz's coefficient. Practical utility-scale wind turbines achieve at peak 75% to 80%




2.2 Betz Limit

Assumptions

















2.2 Betz Limit

Assumptions
















of the Betz limit. The Betz Limit shows the maximum possible energy that may be derived

by means of an infinitely thin rotor from a fluid flowing at a certain speed. In order to

calculate the maximum theoretical efficiency of a thin rotor one imagines it to be replaced by

a disc that withdraws energy from the fluid passing through it. At a certain distance behind

this disc the fluid that has passed through flows with a reduced velocity.

2.3 Blade Element Momentum (BEM) Theory:

Blade element momentum theory combines both blade element theory and momentum

theory. It is used to calculate the local forces on a wind-turbine blade. Blade element theory is

combined with momentum theory to alleviate some of the difficulties in calculating the

induced velocities at the rotor. The blade is divided into several sections. As rotor rotates

each section sweeps an annular area with no interaction between each other the forces and

power are calculated and integrated based on sectional airfoil lift and drag co-efficient.

Fig. 2.2 Explanation of Blade Element Momentum

































2.3Airfoil Families

NACA Aerofoil: The NACA airfoils are airfoil shapes for aircraft wings developed by

the National Advisory Committee for Aeronautics (NACA). The shape of the NACA airfoils

is described using a series of digits following the word "NACA". The parameters in the

numerical code can be entered into equations to precisely generate the cross-section of the

airfoil and calculate its properties. There are various types of NACA airfoils which vary with

no of Digit such as 4-Digit, 5-digit and 6-Digit.

NREL Aerofoil: NREL's (National Renewable Energy Laboratories) airfoils come in thin

and thick families. Thick series are used for the roots and thin airfoil series are used for the

tip of the blades. Basically s series of NREL airfoils are used for designing wind mill blades.

S835, S823, S811, S818 these are the commonly used thick airfoils for the root and for the

rest of the blade S834, S833,S805, S806 which are the thin the profile.

DU Aerofoil: This airfoil family is from the delft university of technology(DUT),

Netherlands. The airfoils ranging from 15%-40% relative thickness have been developed by

DU. The general designation of DU airfoils in DUyy-W-XXX where W stands for wind

energy and DU as delft university.

FX Aerofoil: This airfoil family is called wortmann’s series airfoils after Dr Franz Xaver

wortmann. For example Fx84-W-175. It was invented in the year 1984. W indicates the

application – wind turbines and 175 numbers indicates 10 times the maximum thickness i.e.

17.5%.

2.5Material Used For Blades

Wind energy is captured by the rotation of the wind turbine's rotor blades. Rotor

blades have historically been made of wood. Wood is a composite of cellulose and lignin, but

their low stiffness makes it difficult to limit the (elastic) deflections for very large rotor

blades and weather away over the period of time which is a limitation. Then steel blades were

introduced, it is an alloy of iron and carbon. Older style wind turbines were designed with

heavier steel blades or nickel alloy steels which have higher inertia, and rotated at speeds

governed by the AC frequency of the power lines. The introduction of nickel alloy reduced

distortion in quenching and lowers the critical temperatures of steel and widens the range of

successful heat treatment. The self weight of the blades creates self starting problems of

blades. Idea of using aluminum was widely accepted because of its light weight, ductility and



good heat conductor. The main drawback of aluminum is lower fatigue level than steel. With

the advancement of new technologies composites are used as the blade material which has

improved properties. The fibers and the matrix materials like polyesters, vinyl esters, epoxies

etc., are combined into the composites. These composites have good properties like

mechanical, thermal and chemical properties. In recent years carbon fibers have become of

increasing interest because of the requirements presented by the ever-larger rotor blades and

the decreasing price of carbon fibers. Now a day’s 3D printing has been the forefront

technology in producing engineering components.3D printed parts with ABS plastic have

replaced many metallic components. Acrylonitrile Butadiene Styrene (ABS) plastic which

has higher strength seems to be feasible option for wind turbine blades.

2.6 3D-printing

3D printing is a kind of additive manufacturing (AM), refers to processes used to

create a three-dimensional object in which layers of material are formed under computer

control to create an object. Objects can be of almost any shape or geometry and are produced

using digital model data from a 3D model or another electronic data source such as

an Additive Manufacturing File (AMF) file. 3D-printing is no longer the stuff of science

fiction, it is a new reality. The face of the manufacturing industry has changed as new

participant, new products and new materials emerge, and mainstream processes like

distribution may no longer be needed. A single printer can produce a vast range of products,

sometimes already assembled. It’s a factory without a factory floor and it has created a

platform for innovation, enabling manufacturing to flourish in uncommon areas and

spawning a new generation of do-it-yourself (DIY) manufacturers. The Economist calls 3D

printing the third Industrial Revolution, following mechanization in the 19th century and

assembly-line in mass production in the 20th century.

Types of 3D-printing Process:

Stereo lithography - Stereo lithographic 3D printers position a perforated platform just

below the surface of a vat of liquid photo curable polymer. A UV laser beam then traces the

first slice of an object on the surface of this liquid, causing a very thin layer of photopolymer

to harden. The perforated platform is then lowered very slightly and another slice is traced

out and hardened by the laser. Another slice is then created, and then another, until a

complete object has been printed and can be removed from the vat of photopolymer, drained

of excess liquid.



Fused deposition modelling (FDM) - A hot thermoplastic is extruded from a temperature-

controlled printing head to produce fairly robust objects to a high degree of accuracy.

Developed by Scott Crump of Stratasys, FDM is one of the most widely used manufacturing

technologies for rapid prototyping today. As the print head traces the design of each defined

cross-sectional layer horizontally, the semimolten materials are extruded out of the nozzle

and solidified in the desired areas. The stage then lowers and another layer is deposited in the

same way. These steps are repeated to fabricate a 3D structure in a layer-by-layer manner.

The outline of the part is usually printed first, with the internal structures (2D plane) printed

layer by layer. Other than PC, polystyrene (PS), and ABS, FDM can also print 3D models out

of glass reinforced polymers, metal, ceramics, and bioresorbable materials. A binder is mixed

with ceramic or metal powders, enabling the material to be used in a filament form.

Selective laser sintering (SLS) - This builds objects by using a laser to selectively fuse

together successive layers of a cocktail of powdered wax, ceramic, metal, nylon or one of a

range of other materials. Developed by Carl Deckard and Joseph Beaman in the Mechanical

Engineering Department at the University of Texas-Austin in the mid1980s. SLS uses a high

power laser, e.g, CO2 and Nd:YAG,47 to sinter polymer powders to generate a 3D model,

rather than using liquid binding materials to glue powder particles together. In the SLS

process, a first layer of powder is distributed evenly onto a stage by a roller and is then heated

to a temperature just below the powder’s melting point. Following the cross-sectional profiles

designated in the .STL file, a laser beam is selectively scanned over the powder to raise the

local temperature to the powder’s melting point to fuse powder particles together. After the

first layer is completed, a second layer of powder is added, leveled, and sintered in the

desired areas. These steps are repeated to create a 3D model. The powders that are not

sintered by the laser serve as support material during the process and are removed after

fabrication.

Multi-jet modelling (MJM) - This again builds up objects from successive layers of powder,

with an inkjet-like print head used to spray on a binder solution that glues only the required

granules together. It has one large printhead, which covers the full width of the building

platform. Users of this technology are virtually independent of the build-speed, because no

matter whether just one part or 10 to be produced, the build-time is almost identical.

MJM uses an acrylic photopolymer, which offers a very high surface quality, accuracy,

and precision. The material is heated and “trickled” out of Nano-Jets on the build



platform. There it is hardened immediately and cured with UV light. Support structures will

be generated automatically with this technology. The support material is a wax which has a

lower melting temperature than the component material and thus easily could melt out.

Fig 2.3 Stereo lithography Process

Fig 2.4 Fused deposition modelling (FDM) Process



Fig 2.5 Selective laser sintering (SLS) Process

Fig. 2.6 Multi-jet modelling (MJM) Process



CHAPTER 3

RESEARCH AND METHODOLOGY

3.1 Selection of Airfoil



performances. After extensive study of papers from different publications the blade design was

drafted and finalized. National Renewable Energy centre of Spain (CENER) compared four airfoil

families, Göttingen (GÖE), Wortmann (FX), Delft (DU) and NREL-SANDIA (FB) airfoils.

They customized two airfoils Fx84-W-175 and DU95-W-180 specifically for the root sections of

wind turbine blades to enhance structural properties. The cross sectional area and second moment of

area are the parameters to be focused in enhancing the structural properties [3]. As Fx-84-W-175

coordinates were available in open source this profile was selected for the root region for better

structural performance. National Advisory Committee for Aeronautics (NACA) is an American

Research Organization for designing of airfoils had invented NACA airfoil family. From the

aerodynamic point of view NACA airfoil family exhibits the best structural design. NREL suggested

that NACA44XX series airfoils have good aerodynamic performance [7] . The NACA4412 is selected

for rest of the blade because it shows better aerodynamic properties than rest of NACA44XX series.

Fig: 3.1 FX84-W-175 Airfoil



CHAPTER 3




















CHAPTER 3




















Fig: 3.2 NACA4412 Airfoil

3.2 Selection of Material

Numbers of materials are readily available which can used as row materials for 3D

printing and it is often tough to decide the right one. 3D printing material achievements have

skyrocketed over the past five to ten years. The ability of a material’s mechanical

composition to react positively to a certain directed energy merges that material to a

technology which can deliver the desired change. In 3D printing, material defined in terms of

state changes, final mechanical properties and design capabilities. The materials in 3D

printing are chosen based on function, application, post-processing and geometry. Basic

materials used in 3D printing are Nylon (Polyamide), Acrylonitrile Butadiene Styrene (ABS)

plastic, metals, such as stainless, bronze, steel, gold, nickel steel, aluminum, and titanium,

PLA (poly lactic acid). Among these ABS plastic is most preferable for 3D printing because

of it structural and thermal properties. ABS is a terpolymer made by

polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions can

vary from 15 to 35% acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. ABS plastic is

made out of oil-based resources, it is part of the thermoplastic polymer family, chemical

formula (C8H8)x·(C4H6)y· (C3H3N)z and it has a much higher melting point about 200oC. ABS

has good flexural strength properties and exhibit high tensile and impact properties. It is

popular in large part because it is lightweight having density 1.04gm/cm3 and is affordable.

Because of these particular features, ABS is widely used in injection molding and the design















































complexities of 3D printing, FDM materials have found wide acceptance in aerospace,

medical, packaging and other low volume, customized production applications.

Fig: 3.3 ABS Plastic 3D Printing Filaments



Table: 3.4 Material Data sheet



3.3 Selection of Manufacturing Process in 3D printing

There are mainly four 3D printing processes namely Stereo lithography, fused

deposition modelling (FDM), Selective laser sintering (SLS) and Multi-jet modelling (MJM).

Among above mention processes FDM is the most popular and reliable process of 3D

printing. Fused deposition modelling (FDM) is a fast growing rapid prototyping (RP)

technology due to its ability to build functional parts having complex geometrical shapes in

reasonable build time. The process gives high dimensional accuracy, minimum surface

roughness and high mechanical strength [8]. The main advantage of the process is it can be

handled easily and not much of skill is needed. FDM fabricates a 3D model by extruding

thermoplastic materials and depositing the semimolten materials onto a support bed layer by

layer. Thermoplastic filament, the material used to build 3D models, are moved by two rollers

down to the nozzle tip of the extruder of a print head, where they are heated by temperature

control units to a semimolten state. As the print head traces the design of each defined cross-

sectional layer horizontally, the semimolten materials are extruded out of the nozzle and

solidified in the desired areas. The Extruder is maintained at 200oC and the support bed is

maintained at around 55oC for proper binding of each layers extruded materials. The stage

then lowers and another layer is deposited in the same way. These steps are repeated to

fabricate a 3D structure in a layer-by-layer manner. The outline of the part is usually printed

first, with the internal structures (2D plane) printed layer by layer. Surface defects from this

particular process include staircase and chordal effects result.

Fig: 3.4 Schematic Diagram of Fused Deposition Modeling (FDM) Process

















































3.4 Methodology

Design model wind mill blade using QBLADE open

source software

Save the model in .STL format (Required for

manufacturing the blade using rapid prototyping)

Blades are manufactured by Fused Deposition

Modeling (FDM) 3D printing process

Structural testing of the blade on

UTM for maximum tip deflection

and maximum bending stress

induced

Analysis of the blade using

numerical simulation software

To determine the maximum tip deflection and

maximum bending stress induced



CHAPTER 4

DESIGN AND MANUFACTURING

4.1 Design and Modeling

Two blades were designed the designs were made with the help of two open source

softwares Wind Blade Calculator and Qblade. These softwares are specially designed for

wind mill blade design. The Wind blade calculator software calculates chord length and twist

angles for the inputs, angle of attack, lift co-efficient and (TSR).

Table 4.1 Tabulation of position(mm), chord(mm),twist angle(degrees) and airfoil used.



CHAPTER 4










CHAPTER 4










The standard airfoils coordinates were imported into Qblade software from an open

source website “www.Airfoiltool.com” and 2D model of airfoils were created. In the First

blade no design alteration were made and designed as per its standard t/c 17.5%. But in the

second blade t/c was changed to 20%. Two different airfoils FX84-W-175 and NACA4412

were blended together to design the blades. The FX84W175 is used at the root section and

NACA4412 is used for the rest of the blade. The 3D models of blades were designed for the

length of 200mm. The maximum Chord of the blade is 32.58mm and minimum chord is

13.7mm at the tip. The maximum twist angle at root is 14.50 and at the tip it is 1.80. The

trailing edge gap was provided 1% of chord length to both blades for smooth manufacturing

of models.

Fig 4.1: Airfoils for t/c 17.5%

Fig4.2: Airfoils for t/c 20%



Fig 4.3: 3D model of blade with t/c 17.5%

Fig 4.4: 3D model of blade with t/c 20%











4.2 Manufacturing of blades

The blades were manufactured by Fused deposition Modeling (FDM) technology, a

3D printing process. It is a layer by layer deposition technique. It is known for its high

dimensional accuracy, minimum surface roughness and high mechanical strength. First .STL

file is imported into 3D printing software Simplified 3D from Qblade software. There the

design is sliced and the each slice is 0.1778mm in height. Then tool path is generated for

manufacturing of the structure. The minimum layer that 3Dprinter can print is 1mm

thickness. The model is supported by the soluble support which dissolved in detergent or

water and product is ready for use. The each slice was 0.1778mm in height. High definition

3D printing by FDM process is selected for manufacturing of blades. In FDM process parts

are build layer-by-layer by heating thermoplastic material to a semiliquid state and extrude it

according to computer-controlled paths. The extruders in FDM simultaneously extrude

Modeling material, which constitutes the finished piece, and support material, which acts as

elevated platform. Material filaments are fed from the 3D printer’s material bays to the print

head, which moves in X and Y coordinates, depositing material to complete each layer before

the base moves down the Z axis and the next layer begins. The material used for

manufacturing of blade of blades was ABS plastic. The material density is 1.04gm/cm3. It

took about 3hrs 16mins to manufacture each blade.

Fig 4.5: 3D printing machine is preparing for printing



Fig 4.6: Manufactured blades by 3D printing process

t/c 17.5%

t/c 20%



CHAPTER 5

TESTING AND SIMULATION

5.1 Testing

Flexural test was carried on both the blades under 2-point bending in UTM. A special

arrangement was made for test in UTM because the blades were considered to be cantilever

beams, the root ends of the blades were fixed and load was applied 20mm from the tip. A

gradual incremental load was applied until the specimens developed crack or fail. The blade

with t/c 17.5% failed for the loading of 6KN and maximum deflection was 13.6 mm. The

modified blade having t/c 20% failed for the loading of 6.5KN and maximum deflection was

12.4 mm. Finally the graphs were plotted loads vs. deflection.

Fig 5.1: Testing setup



Fig 5.2: Computer control UTM machine

Fig 5.3: Deflected blade under incremental loading



Fig 5.4: Failed Blades

t/c 17.5%

t/c 20%



Fig 5.5: load vs deflection graph for t/c 17.5%

Fig 5.6: load vs deflection graph for t/c 20%

-1

0

1

2

3

4

5

6

7

-2 0 2 4 6 8 10 12 14 16

Loa

d K

N

Deflection mm

-1

0

1

2

3

4

5

6

7

-2 0 2 4 6 8 10 12 14

Loa

d K

N

Deflection mm



5.2 Simulation

Numerical Simulation was performed in QFEM an integral part of the Qblade

software. This tool is used for structural analysis of blade under the normal and tangential

loadings. It shows the stress distributions in the specimens. For simulation the inputs were

load, material properties and boundary condition. 6 KN load was applied at distance of 20mm

from the tip normal to the blade for determining the bending stress. It was found to be

64.95MPa for t/c 17% of the blade. The same was simulated for t/c 20% of the blade for the

load of 6.5KN and bending stress was 70.42MPa.

Fig 5.6 Stress distribution in blade t/c 17.5%



Fig 5.6 Stress distribution in blade t/c 20%



CHAPTER 6

RESULT, CONCLUSION AND SCOPE FOR FUTURE

6.1 Result

Result for flexural test in UTM the blade with t/c 17.5% failed for the loading of 6KN

and maximum deflection was 13.6 mm. The modified blade having t/c 20% failed for the

loading of 6.5KN and maximum deflection was 12.4 mm. Simulation test in QFEM result, 6

KN load was applied at distance of 20mm from the tip normal to the blade for determining

the bending stress. It was found to be 64.95MPa for t/c 17% of the blade. The same was

simulated for t/c 20% of the blade for the load of 6.5KN and bending stress was 70.42MPa.

SL. No Thickness/chord ratio

Airfoilsection at

root

Airfoil sectionfor remaining

length

Maximum load inUTM test

KN

Numericalsimulation

using QFEMFlexural stress

MPa

Specimen 1 17.5% FX84-W-175

NACA4412 6 64.95

Specimen 2 20% FX84-W-175

NACA4412 6.5 70.42

Table 6.1 Tabulation results

6.2 Conclusion and Scope for Future work

The wind turbine blade specimens manufactured from ABS plastic using 3D printing

show promising resistance to the loads of winds in roof-top applications.

The airfoils FX84-W-175 when inculcated in root sections of the blade shows impressive

stress withstanding capability.

The alternative materials in 3D printing technology can be examined for higher strength

in wind turbine applications.

A full scale blade upto a meter can be designed and manufactured for testing as well as

roof-top power generation unit.



References

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[10] “FDM reduces tooling costs by 99% and prototyping costs by 73%,” Stratasys case

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