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4D printing report final

Engineering Mathematics (K S School of Engineering and Management)

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“4D PRINTING TECHNOLOGY”

A Seminar Report submitted to

VISVESVARAYA TECHNOLOGICAL UNIVERSITY

in partial fulfilment of the requirements
for the award of degree of

BACHELOR OF ENGINEERING
in
MECHANICAL ENGINEERING
Submitted by

BHARATH KUMAR P
1KG21ME400

Under the guidance of Under the co-guidance of

Mr HARSHA J Ms NISHCHITHA AH
Asst Professor Asst Professor
Dept of Mechanical Engineering Dept of Mechanical Engineering

Department of Mechanical Engineering

K.S. School of Engineering and Management
No. 15, Mallasandra, off Kanakapura Road, Bengaluru-560109
2023-24

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K.S. SCHOOL OF ENGINEERING AND MANAGEMENT

DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that the seminar “4D PRINTING TECHNOLOGY” is a technical report
presented by Bharath Kumar P (1KG21ME400) in partial fulfilment for the award of Bachelor
of Engineering in Mechanical Engineering of Visvesvaraya Technological University,
Belagavi, during the year 2023-24. It is certified that all the suggestions indicated during
internal assessment have been incorporated in the report and this report satisfies the academic
requirement with respect to Seminar 18MES84 prescribed for the degree.

Internal Guide
Internal Co-Guide

Mr Harsha J
Ms Nishchitha AH
Asst Professor
Asst Professor
Dept. of Mechanical Engg.
Dept. of Mechanical Engg.
KSSEM, Bengaluru - 109
KSSEM, Bengaluru - 109

Head of the Department

Principal

Dr. B. Balaji
Dr. K. Ramanarasimha
Professor & Head
Dept. of Mechanical Engg. Principle/Director
KSSEM, Bengaluru - 109 KSSEM, Bengaluru - 109

Examiners

Name and Signature of Examiner-1 Name and Signature of Examiner-2

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K.S. SCHOOL OF ENGINEERING AND MANAGEMENT

DEPARTMENT OF MECHANICAL ENGINEERING

DECLARATION

I Bharath Kumar P (1KG21ME400) the student of BE Mechanical Engineering VIII

Semester declare that the seminar report titled “4D PRINTING TECHNOLOGY” is
prepared by me as partial fulfilment of academic requirement of degree under Visvesvaraya
Technological University. The content in the report is original and are free from plagiarism
and other academic dishonesty and are not submitted to any other University either partially or
wholly for the award of any other degree.

Bharath Kumar P
1KG21ME400
Date: 20th Mar
2024 Place:
Bengaluru

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ACKNOWLEDGEMENT
The successful completion of this seminar report was made possible with the help of guidance
received from my faculty members. I would like to avail this opportunity to express my sincere
thanks and gratitude to all of them.

I am grateful to my management for providing the necessary infrastructure and an ambience

environment to work. I express my profound gratitude to Dr. K. Ramanarasimha,
Principal/Director, KSSEM, Bengaluru for providing the necessary infrastructure and an
ambience environment to work.

I am grateful to my guide Dr. B. Balaji, Professor and Head, Department of Mechanical

Engineering, KSSEM, Bengaluru for his valuable suggestions and advice throughout the
preparation of seminar presentation and report.

I would also like to thank all the staff members of Department of Mechanical Engineering for
their support and encouragement. Finally, I would like to thank all of my friends without whose
help and encouragement this technical seminar would have been impossible.

Definitely most, I want to thank my family. Words cannot express my gratitude to my family
members for all their love and encouragement.

BHARATH KUMAR P
1KG21ME400

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ABSTRACT

4D printing is an emerging technology poised to revolutionize various industries by

introducing dynamic functionality to 3D-printed objects. Unlike traditional 3D printing, which
creates static objects, 4D printing adds the dimension of time, enabling materials to change
shape, properties, or functionality in response to external stimuli such as temperature, moisture,
light, or pressure. This transformative capability is achieved through the use of smart materials,
including shape-memory polymers, hydrogels, and stimuli-responsive composites.

we provide a concise overview and applications of 4D printing technology. We discuss the

design process, which involves programming desired shape transformations into the material
itself or through the printing process. Furthermore, we explore key application areas such as
biomedical implants, aerospace components, soft robotics, and architecture, where 4D printing
offers unique advantages like self-assembly, adaptability, and enhanced performance.

The potential societal impact of 4D printing is significant, ranging from more efficient and
personalized medical treatments to sustainable manufacturing processes. However, challenges
such as material optimization, scalability, and regulatory considerations remain to be addressed
for widespread adoption. Overall, 4D printing represents a promising frontier in additive
manufacturing, opening doors to a new era of dynamic, responsive, and intelligent materials.

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TABLE OF CONTENTS
Acknowledgement i
Abstract ii
Table of Contents iii
List of Figures iv

CHAPTER 1 PG NO
1 INTRODUCTION 1
1.1 4D PRINTING 2
CHAPTER 2
2 PROCESSING OF 4D PRINTING 3
2.1 GENERIC ADDITIVE MANUFACTURING 3
2.2 PROCESS INVOLVED IN 4D PRINTING 5
2.3 PROGRAMMING STEPS IN PRINTING 6
2.4 CURRENT STAGE OF TECHNOLOGY 8
CHAPTER 3
3 SMART MATERIALS AND POLYMERS 9
3.1 LIST OF SMART MATERIALS 9
3.2 PIEZO ELECTRIC MATERIALS 9
3.3 SHAPE MEMORY POLYMERS 10
3.4 MAGNETO STRICTIVE MATERIALS 10
3.5 COMPOSITES IN 4D PRINTING 10
3.6 FUNDAMENTS OF 4D PRINTING 11
CHAPTER 4
4 TECHNIQUES USED IN 4D PRINTING 12
4.1 FUSED DEPOSITED MDOELLING 12
4.2 STERIOLITHOGRAPHY 13
4.3 DIRECT INK-WRITING 13
4.4 SELECTIVE LASER SINTERING 14
CHAPTER 5
5 APPLICATIONS 15
5.1 POTENTIAL APLLICATIONS OF 4D PRINTING 15
CHAPTER 6
6 BENEFITS AND DRAWBACKS 19
6.1 BENEFITS OF 4D PRINTING 19
6.2 DRAWBACKS OF 4D PRINTING 20
CONCLUSIONS 21
REFERENCES 22

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LIST OF FIGURES

FIG NO TOPIC PG NO
1.1 SCHEMATIC OF 4D CONCEPT 2
2.1 GENERIC PROCESS OF CAD 4
2.2 PROCESS INVOLVED IN 4D PRINTING 5
2.3 STEPS OF PROGRAMMING 7
4.1 FUSED DEPOSITED MODELLING 12
4.2 STERIOLITHOGRAPHY 13
4.3 DIRECT INK-WRITING 13
4.4 SELECTIVE LASER-SINTERING 14
5.1 SELF ASSEMBLY FURNITURE 16
5.2 SOFT ROBOTS 17
5.3 PROGRAMMED STENT 17
5.4 4D PRINTED SHOE 18

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CHAPTER 1
1. INTRODUCTION
4-dimensional printing (4D printing; also known as 4D bioprinting, active origami, or
shape-morphing systems) uses the same techniques of 3D printing through
computerprogrammed deposition of material in successive layers to create a three-dimensional
object. However, 4D printing adds the dimension of transformation over time. It is therefore a
type of programmable matter, wherein after the fabrication process, the printed product reacts
with parameters within the environment (humidity, temperature, etc.,) and changes its form
accordingly. The ability to do so arises from the near infinite configurations at a micrometre
resolution, creating solids with engineered molecular spatial distributions and thus allowing
unprecedented multifunctional performance.
The term 4D printing was first coined by TED professor Skylar Tibbits in his February,
2013 speech at the MIT Conference.
Tibbits, Skylar J. E stated that the increasing complexity of the physical structures
surrounding our everyday environment buildings, machines, computers and almost every other
physical object that humans interact with the processes of assembling these complex structures
are inevitably caught in a battle of time, complexity and human/machine processing power. If
we are to keep up with this exponential growth in construction complexity, we need to develop
automated assembly logic embedded within our material parts to aid in construction. In this
thesis I introduce Logic Matter as a system of passive mechanical digital logic modules for self-
guided-assembly of large-scale structures. As opposed to current systems in self-reconfigurable
robotics, Logic Matter introduces scalability, robustness, redundancy and local heuristics to
achieve passive assembly. I propose a mechanical module that implements digital NAND logic
as an effective tool for encoding local and global assembly sequences. I then show a physical
prototype that successfully demonstrates the described mechanics, encoded information and
passive self-guided-assembly. Finally, I show exciting potentials of Logic Matter as a new
system of computing with applications in space/volume filling, surface construction, and 3D
circuit assembly.
A definition of 4D printing could be:
The use of a 3D printer in the creation of objects which change/alter their shape when
they are removed from the 3D printer. The objective is that objects made self-assemble when
being exposed to air, heat or water, this is caused by a chemical reaction due to the materials
utilised in the manufacturing process.

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Technology has always been amazing us with its beautiful inventions in the nature by
making the life of human simpler to a greater extent. Additive manufacturing, more popularly
known as 3-Dimensional (3D) printing technology, has been developed for more than 30
years. Recently, 3D printing has been recognized as a disruptive technology for future
advanced manufacturing systems. With a great potential to change everything from our daily
lives to the global economy, significant advances in 3D printing technology have been made
with respect to materials, printers, and processes. Now an innovative concept of printing
technology known as 4D printing technology has been developed. Although similar to 3D
printing, 4D printing technology involves the fourth dimension of time in addition to the 3D
space coordinates. Therefore, one can regard 4D printing as giving the printed structure the
ability to change its form or function with time (t) under stimuli such as pressure, temperature,
wind, water, or light.

1.1 4-D Printing

4-dimensional printing (also known as 4D bioprinting, active origami, or shape-
morphing systems) uses the same techniques of 3D printing through computer- programmed
deposition of material in successive layers to create a three-dimensional object. However, 4D
printing adds the dimension of transformation over time. It is therefore a type of programmable
matter, wherein after the fabrication process, the printed product reacts with parameters within
the environment (humidity, temperature, etc.,) and changes its form accordingly. light. Figure
1 depicts a schematic of the 1- 2- 3- and 4D concepts. The concepts of 1-, 2-, & 3D represent
line, plane, and 3D space structures, respectively. For 4D, the concept of changes in the
3Dstructure (x, y, z) with respect to time (t) is added, as indicated by curved arrows,

Fig. 1.1 Schematic of 1-, 2-, 3-, and 4D concepts. A 4D structure is a structure (x, y, z)
made by 3D changes over time (t). Arrows indicate the direction of change with respect
to time.

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CHAPTER 2
2. PROCESSING OF 4D PRINTING
4d printing similar to current additive manufacturing process (3D printing). The main
difference is the programmable materials or smart materials which are used for making the
product.
The 4D printing relies predominantly on four factors.
✓ The basic additive manufacturing process,
✓ Types of stimulus-responsive material,
✓ Interaction mechanisms.
✓ Smart design.

2.1 GENERIC ADDITIVE MANUFACTURING PROCESS

AM involves a number of steps that move from the virtual CAD description to the physical
resultant part. Different products will involve AM in different ways and to different degrees.
Small, relatively simple products may only make use of AM for visualization models, while
larger, more complex products with greater engineering content may involve AM during
numerous stages and iterations throughout the development process. Furthermore, early stages
of the product development process may only require rough parts, with AM being used because
of the speed at which they can be fabricated. At later stages of the process, parts may require
careful cleaning and post processing (including sanding, surface preparation and painting)
before they are used, with AM being useful here because of the complexity of form that can be
created without having to consider tooling. The use of AM processes enables freeform objects
to be produced directly from digital information without the need for intermediate shaping tools.
Most AM processes can support 4D printing as long as the selected stimulus-responsive
material is supported by or compatible with the printer. Steps involved in process.
• CAD
• STL convert
• File transfer to machine
• Machine setup
• Build
• Remove
• Post Process

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Fig. 2.1 Generic process of CAD to part, showing all 7 stages

Step 1: CAD
All AM parts must start from a software model that fully describes the external geometry.
This can involve the use of almost any professional CAD solid modelling software, but the
output must be a 3D solid or surface representation. Reverse engineering equipment (e.g., laser
scanning) can also be used to create this representation.
Step 2: Conversion to STL
Nearly every AM machine accepts the STL file format, which has become a defect standard,
and nearly every CAD system can output such a file format. This file describes the external
closed surfaces of the original CAD model and forms the basis for calculation of the slices.
Step 3: Transfer to AM Machine and STL File Manipulation
The STL file describing the part must be transferred to the AM machine. Here, there may
be some general manipulation of the file so that it is the correct size, position, and orientation
for building.
Step 4: Machine Setup
The AM machine must be properly set up prior to the build process. Such settings would
relate to the build parameters like the material constraints, energy source, layer thickness,
timings, etc.

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Step 5: Build
Building the part is mainly an automated process and the machines can largely carryon
without supervision. Only superficial monitoring of the machine needs to take place at this time
to ensure no errors have taken place like running out of material, power or software glitches, etc.
Step 6: Removal
Once the AM machine has completed the build, the parts must be removed. This may
require interaction with the machine, which may have safety interlocks ensure for example that
the operating temperatures are sufficiently low or that there are no actively moving parts.
Step 7: Post processing
Once removed from the machine, parts may require an amount of additional cleaning up
before they are ready for use. Parts may be weak at this stage or they may have supporting
features that must be removed. This therefore often requires time and careful, experienced
manual manipulation.

2.2 PROCESS INVOLVED IN 4D PRINTING

Fig. 2.2 Process involved in 4d printing

2.3 Design and Modeling:
The process begins with the creation of a digital 3D model using computer-aided design (CAD)
software. This model defines the initial geometry of the object to be printed and specifies the
desired shape changes or transformations over time.
Design considerations include selecting appropriate smart materials and programming the
activation mechanisms for triggering the desired responses.

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2. Material Selection:
Smart materials, also known as stimuli-responsive materials, are carefully chosen based on
their ability to undergo reversible or irreversible changes in response to specific stimuli such
as temperature, moisture, light, pH, or magnetic fields.
Common smart materials used in 4D printing include shape-memory polymers, hydrogels,
shape-memory alloys, and responsive composites.
3. Printing Process:
The digital model is sliced into thin horizontal layers using slicing software, similar to 3D
printing. Each layer corresponds to a cross-section of the object and serves as a blueprint for the
printer.
The sliced layers are then sent to the 4D printer, which deposits the smart material layer by
layer according to the design specifications.
Depending on the 4D printing technology and materials used, various printing techniques such
as fused deposition Modeling (FDM), stereolithography (SLA), or selective laser sintering (SLS)
may be employed.
4. Activation and Transformation:
Once the object is printed, it remains in a dormant state until exposed to the specified stimulus.
Activation mechanisms may include heating, exposure to water, application of light, or other
triggers, depending on the properties of the smart material.
Upon activation, the printed object undergoes a programmed transformation, changing its
shape, structure, or properties in a controlled manner.
The transformation may involve expansion, contraction, bending, folding, twisting, or other
shape changes, depending on the design parameters and the behaviour of the smart material used.
5. Post-Processing and Integration:
After the transformation is complete, the 4D-printed object may undergo post-processing steps
such as removal of support structures, surface finishing, or additional treatments to enhance its
properties or functionality.
The transformed object can then be integrated into larger systems or assemblies, depending on
its intended application.

2.3 PROGRAMMING STEPS IN PRINTING

CAD modelling in 4D printing involves creating digital models of objects that can undergo
shape transformations over time in response to external stimuli. Here are the key steps involved
in CAD modelling for 4D printing:

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Fig 2.3 steps of programming

1. Initial Design: Begin by designing the initial shape of the object using CAD software. This
initial shape serves as the starting point for the 4D-printed object before any shape
transformation occurs.
2. Define Transformation: Determine the desired transformation(s) that the object will undergo
over time. This transformation could involve changes in shape, stiffness, color, or other
properties in response to external stimuli such as temperature, moisture, light, or mechanical
stress.
3. Incorporate Responsive Features: Modify the CAD model to incorporate features that
enable the desired transformation. This may involve designing the geometry to accommodate
shape-memory materials, structures that respond to moisture absorption or release, or other
responsive elements.
4. Simulation and Analysis: Use simulation tools within the CAD software to analyze how the
object will deform or change over time in response to the specified stimuli. This step helps
validate the design and optimize parameters to achieve the desired transformation.
5. Iterative Design: Iterate on the CAD model based on simulation results and feedback. Make
adjustments to the geometry, material properties, or stimulus parameters as needed to improve
the performance and functionality of the 4D-printed object.

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6. Validation: Validate the CAD model through physical prototyping or experimental testing to
ensure that the predicted transformations match the actual behaviour of the printed object. Make
any necessary adjustments to the CAD model based on validation results.
7. Documentation: Document the CAD model, including design specifications, material
properties, and transformation characteristics. This documentation is essential for manufacturing
the 4D-printed object and for future reference.

2.4 CURRENT STATE OF TECHNOLOGY

4D printing is a novel advancement to 3D printing technology.
4D printing is focused on developing materials and newer printing techniques that could reduce
the time taken for assembly of parts, in turn improving the overall efficiency of the
manufacturing processes.
• Parts manufactured using this novel technology would employ different types of SMART
materials.

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CHAPTER 3
3. SMART MATERIALS AND POLYMERS

3.1 List of Smart Materials

3.2 PIEZOELECTRIC MATERIALS

Those materials capable of generating electric charge in response to applied mechanical
stress are piezoelectric materials. Not all the smart materials do exhibit a shape change but they
do carry significant properties such as electro and magneto theological fluids. Those fluids can
change viscosity upon application of external magnetic or electric field. Naturally occurring
crystals like quartz and sucrose, human bone, ceramics, Polyvinylidene fluoride (PVDF) are
known to have piezoelectric characteristics. Followed by the automotive industry and medical
instruments, global demands for these materials have huge application in industrial and
manufacturing sector. Researchers from University of Warwick in UK have developed new
micro stereolithography (MSL) 3D printing technology that can be used to create piezoceramic
object. Piezoceramics are special type of ceramic materials that can create electrical response
and responds to external electrical stimulation by changing shape. These are very useful
materials and applicable all around, sensor in airbag systems, fuel injectors in engines, electric
cigarette lighter and electronic equipment.

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3.3 SHAPE MEMORY POLYMERS

Shape memory alloy or polymers are emerging smart materials that have dual shape
capability. Shape memory alloys go transformation under predefined shape from one to another
when exposed to appropriate stimulus. Initially founded on thermal induced dual shape research,
this concept has been extended to other activating process such as direct thermal actuation or
indirect actuation. The applications can be found in various areas of 41 our everyday life. Heat
shrinkable tubes, intelligent medical parts, self-deployable part in spacecraft are few used areas
with potential in broad other applications. The process in shape memory polymer is not intrinsic,
it requires combination of a polymer and programmed afterwards. The structure of polymer is
deformed and put it into temporary shape. Whenever required, the polymer gains its final shape
when external energy is applied. Most of the shape memory polymers required heat as activating
agent. The material used in tube is poly demethylate polymer. Initially the shape was
programmed to form flat helix, using heat energy ranging from 10 degree to 50-degree
centigrade, flat helix transformed into tube shape structure.

3.4 MAGNETO STRICTIVE MATERIALS

Similar to piezoelectric and electro strictive materials magneto strictive materials uses
magnetic energy. They convert magnetic energy into mechanical energy or other way. Iron,
terbium, Naval Ordnance Laboratory (NOL) and dysprosium (D) are most common magneto
strictive materials. Those materials can be used as transducers and actuators where magnetic
energy is used to cause shape change. The application includes telephone 42 receivers,
oscillators, sonar scanning, hearing head, damping systems, and positioning equipment. The
development of magneto strictive material alloys with better features will certainly help the 4D
printing technology.

3.5 COMPOSITES IN 4D PRINTING

Ge et al used a multi-material 3D printer to print an active composite material. The printed
active composite (PAC) consisted of a glassy polymer fibre embedded in an elastomeric resin.
The glass fibres exhibited a shape memory effect with a shape fixity ratio of approximately 80%
whereas the elastomeric resin was not capable of shape shifting and had a shape fixing ratio of
0. This bilayer laminate comprising a pure elastomer lamina and a PAC lamina with a prescribed
fibre structure which includes the shape, size and orientation was printed, heated, stretched,

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cooled and realized. Upon release of the deformation stress, the laminate turned into a complex
temporary shape due to the mismatch in the shape fixity ratio between the elastomer lamina and
the shape memorizing PAC lamina. Depending on the fibre properties complex 3D
configurations can be produced including bent, coiled, twisted, and folded shapes. This PAC
laminate can be integrated with other structures or functional components to create active
devices. For an example the PAC laminate could be used to enable active origami as a means to
creating 3D structures.

3.6 FUNDAMENTALS OF 4D PRINTING

3D printing technology has been used to make static structures from digital data in 3D
coordinates, 4 D printing adds the concept of change in the printed configuration over time,
dependent on environmental stimuli. The key difference between 3D and 4D printing are the
smart design and smart materials as 4D printed structures may transform in shape or function.
This implies that the 4D printed structures should be fully programmed in detail by accounting
for any anticipated time-dependent deformation of the object. 4D printing was firstly introduced
by a research group of Massachusetts Institute of Technology (MIT) and defined as the
fabrication of 3D printed structures with adaptable and programmable shapes, properties or
functionality as a function of time. Intelligent materials are able to sense stimulus from the
external environment and create a useful response. Thus, intelligent materials can be seen as
those which provide a means of achieving an active intelligent response in a product that would
otherwise be lacking and have the potential to yield a multitude of enhanced capabilities and
functionalities. Three key aspects must be fulfilled for 4D printing to take place. The first is the
use of stimuli responsive composite materials that are blended or incorporate multi-materials
with varying properties being sandwiched layer upon layer. The second is the stimuli that will
act on the object causing it to animate. Examples of these stimuli include heating, cooling,
gravity, ultraviolet (UV) light, magnetic energy, wind, water or even humidity. The last aspect
is time for the simulation to occur, and the final result is the change of state of the object.

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CHAPTER 4
4. TECHNIQUES USED IN 4D PRINTING

4D printing as we know is the advancement of already existing 3D printing. The techniques used
in 4D printing are the AM printing techniques. In this section, we will briefly discuss about the
different printing techniques used in 4D printing

4.1 FUSED DEPOSITION MODELLING (FDM)

Fig 4.1 Fused deposited modelling

FDM is the printing technique in which the material to be printed is extruded out through a nozzle
and gets hardened on a substrate. The nozzle is supported by a motor which allows it to move in
X and Y axis. When a 2D layer is printed on a substrate, the nozzle is moved upwards in Z axis
and another layer is printed over the already printed layer. In this a way, a layer-by-layer addition
is done till a final 3D or 4D printed structure is obtained. FDM is used widely for both 3D and
4D printing-as it is cost-effective when it comes to maintenance and consumables used. FDM
technique has been modified regularly to make it compatible for printing new materials. For
example, a new FDM technique for 3D printing of composites like continuous fibre-reinforced
thermoplastic composites (CFRTC). This new technique made use of two inputs for material (as
the material to be printed is a composite), one nozzle for extrusion, and this method proved useful
while printing a structure requiring high mechanical properties. They performed simulations and
also printed structure capable of SME using FDM printing. FDM is used widely is 4D printing
and also research is being carried out to make it more effective and compatible with new
materials.

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4.2 STEREO LITHOGRAPHY (SLA)

Fig 4.2 Stereolithography

SLA (Stereo lithography) is another printing technique that is used in 4D printing

technology. In this technique, a light sensitive material (photopolymer) is used that gets
solidified when exposed to light. Various radiations such as UV light, visible light, X rays,
electron beam, etc. can be used to solidify the material. But on a commercial scale only UV and
visible lights are used. The mechanism is simple i.e.; the light falls on the material and creates
a curing reaction due to which the molecules of resin bind together forming a solid structure.
Upon curing, the viscosity of photopolymer increases and are converted into gel which
eventually converts into a solid cross-linked polymer. SLA has been successfully employed to
fabricate complex and difficult structures efficiently. Also, materials have been developed that
are compatible with SLA printing technique.

4.3 DIRECT INK-WRITING (DIW)

Fig 4.3 Direct ink-writing

The DIW technique refers to a printing method based on extrusion through a nozzle under
pressure, utilizing a computer-controlled robot to move the dispenser filled with printed ink to

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construct geometries layer-by-layer. The use of micronozzles in DIW enables to achieve high
printing resolution, which is favourable when considering radio frequency and autonomously
powered microdevices. Compared to other printing methods, the DIW technique shows the
superiority due to free choices of materials, small number of raw materials, open source and
feasibility for multi material printing. It is a laboratory-friendly technique especially when
printing nanocomposites with different content of nanofillers or nanoparticles, regardless of
whether they are transparent or not. The expense of printing process is cheap and the choice of
barrel volume and nozzle size is quite flexible according to the demands of customers. It is easy
to build such a printing platform by labs themselves as the working principle is easy, consisting
of a three-axis platform, computer, and dispenser So far, DIW has successfully printed various
types of materials, such as metal particles, polymers, ceramics and Multi Material. In the DIW
technique, the viscosity of ink needs to be carefully regulated because it is required to possess
specific rheological performance.

4.4 SELECTIVE LASER SINTERING (SLS)

Fig 4.4 Selective laser sintering

Selective Laser Sintering (SLS) is an additive manufacturing process where a high-powered laser
selectively fuses powdered material, typically nylon or other polymers, layer by layer, based on
a 3D digital model. The laser scans the surface of a powder bed, solidifying the material
according to the cross-section of the model. Once a layer is complete, the build platform lowers,
and a new layer of powder is spread. This process repeats until the entire object is formed. SLS
offers high accuracy, complex geometries, and the ability to produce functional parts without
the need for support structures, making it widely used in prototyping and production.

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CHAPTER 5
5. APPLICATIONS
3D printing has been used to create car parts, smartphone cases, fashion accessories,
medical equipment and artificial organs. Manufacturing corporations and aerospace organizations
have saved billions of dollars by using 3D printing for building parts. 3D printing has also helped
save lives. One of the best ways to learn about what 3D printing can do is by researching reallife
applications on the technology. Other applications include:

 Rapid prototyping
 3D Printed Organs
 Personal printing
 In the Automotive Industry
 In the Aerospace Industry

5.1 POTENTIAL APPLICATIONS OF 4D PRINTING

Though, even if these examples are not characterized by great complexity, we can foresee
great potential in this technology.

Self-repair piping system

One potential application of 4D Printing in the real world be pipes of a plumbing system
that dynamically change their diameter in response to the flow rate and water demand. Pipes that
could possibly heal themselves automatically if they crack or break, due to their ability to change
in response to the environment’s change. The error corrects and self-repairing capability of 4D
manufactured products show tremendous advantages with regard to reusability and recycling.
Self-healing pipes and self-healing hydrogels are some of the potential applications of 4D
printing. Self-healing of polymers can be achieved by a few categories of reactions, which include
covalent bonding, supramolecular chemistry, H-bonding, ionic interactions, and π-π stacking.
Self-healing materials have also been shown to have great potential for producing soft actuators
with enhanced durability, due to their ability to self-repair damage ranging from bulk cracks to
surface scratches. The use of self-healing hydrogels as inks for additive manufacturing has been
successfully demonstrated.

Self-assembly furniture
Since 3D printing furniture is limited by the size of the printer, 4D printing could allow to just
print a flat board that will curl up into a chair by just adding water or light to it. A future
application can be on a large scale and in a harsh environment. Individual parts can be printed

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with small 3D printers and then self-assembled into larger structures, such as space antennae and
satellites. This capability can be exploited for the creation of transportation systems for complex
parts to the international space station.

Fig 5.1 self-assembly furniture

Further applications include self-assembling buildings, this is especially useful in war zones or in
outer space where the elements can come together to give a fully formed building with minimum
work force. Revive et al argue that construction must be made smarter and solve problems of
wasting large amounts of energy, materials, money and time for building. These issues can be
solved using design programs and software to embed information into the materials that makes
the material and construction more accurate. Self-assembly may not be efficient for every
purpose, which implies different sectors and applications must be identified that benefit most
from self-assembly

Self-adaptability
4D printing allows the integration of sensing and actuation directly into a material rendering
external electromechanically systems unnecessary. This decreases the number of parts in a
structure, assembly time, material and energy costs as well as the number of failure prone devices,
which is associated with electromechanics al systems. This technology is finding use in self-
adaptive 4D printed tissues and 4D printed personalized medical devices such as tracheal stems.

4D printing in extreme conditions

4D Printing: Surface to Sine Wave from Self-Assembly Lab, MIT. 4D Printing would be
even more useful in big scale projects. For example, in extreme environments, such as space, it
can have very promising applications. In space, currently, the 3D printing process of the building
causes some issues related to cost, efficiency, and energy consumption. So, instead of using 3D
printed materials, 4D printed materials could be used to take advantage of their transformable
shape. They could provide the solution to build bridges, shelters or any kind of installations, as
they would build up themselves or repair themselves in case of weather damage.

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Soft robots

Fig 5.2 soft robots

Soft robots are biomimetic creations that trade in harsh hardware for compliant materials
that better resemble living organisms. Their hydrogel makeup provides a flexible structure that
changes in size and shape, making them more applicable to use cases requiring a softer touch,
according to a study published in the scientific journal Polymer. The gentleness and versatility
offered by these 4D prototypes provides value to areas such as medical and bionic fields. Two
researchers at Rice University say that they’re not far off from 4D-printing shapeshifting,
biomedical implants. With assistance from a liquid crystal polymer ink, their approach decouples
the printing process from the object’s autonomous transformation in order to optimize shaping
control and print more complex structures, as reported by healthcare tech publication Tectales.

Military weapons
MIT’s Self-Assembly Labs have developed a morphing jet engine air inlet prototype out of
programmable carbon fibre. Unlike its mechanical counterparts, this model is lightweight,
minimizes accident-prone mechanisms and operates independent of electronics, sensors or
actuators, according to Air University researchers. Self-assembling micro-drones are thought to
be the next evolution of full-fledged, customizable 3D- printed quadcopters current in use. Other
applications include self (in the event that cracks form) and self-adjusting shelters.

Medical industry
On the other hand, imagine 4D printing being
applied to a very small scale, in sectors such as the
medicinal one. 4D printed proteins could be a great
application, as the self-reconfiguring protein
example illustrated in the following video.
Another special material researcher is Fig 5.3 Programmed stent

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working on is self-folding protein. 4D Printing: Self-Folding Protein from Self Assembly

Lab, MIT. Another application of 4D printing in the medical field could be designing sent.
Programmed stents would travel through the human body, and when they reach their destination,
they would open up.

Fashion
4D printing could also change the face of fashion.
Self-Assembly Printing Lab from MIT is studying
potential applications of 4D technologies. One of the
ideas is that clothing could change accordingly to the
weather or the activity. For instance, shoes could
change their shape when you start running to provide
you with better comfort and amortization. Fig 5.4 4d printed shoe

Manufacturing

A 2015 feasibility study out of the Georgia Institute of Technology demonstrated this using
thermally-responsive, shape-memory polymers. The technique enables a manufacturing
procedure with “promises to advance immediate engineering applications for low-cost, rapid,
and mass production,” according to the study. Potential uses for this technology include milk
cartons, shopping bags and car airbags.

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CHAPTER 6
6. BENEFITS AND DRAWBACKS
6.1 BENEFITS OF 4D PRINTING
4D printing can provide benefits, such as:
• Enhancing the capabilities of printed products
• Designing new applications of adaptive materials
• More efficient manufacturing
• Reduced manufacturing costs and carbon footprints.

All these could be realized because the technology is characterized by:

Self-repair: 4D-printed plumbing pipes, for instance, can change their diameter depending on
how much water flows through them. As such, they can potentially repair themselves if they
crack or break because they can respond to environmental changes.

Self-assembly: 4D-printed building materials, which can change their shape, will take doit-
yourself (DIY) construction to the next level. Imagine being able to print custom shapes to
instantly build a bridge. You won’t need to spend more on labour costs so long as the structures
are deemed structurally sound by engineers.

Self-adjustment: 4D-printed clothes can be made of materials that adjust to the current weather
or climate. Imagine how much money people would be able to save buying only a single set of
clothes for all seasons

Greater customization: allows for the creation of objects with unique properties that are tailored
to specific applications

Increased efficiency: objects that can change shape or functionality on their own can lead to
more efficient systems, such as self-assembling structures
Reduced material waste: objects can potentially repair themselves or adapt to changing
conditions, reducing the need for replacement parts and lowering material waste
Sustainability: 4D printing materials, such as renewable soybean oil, are eco-friendly and
contribute to a more sustainable manufacturing process

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6.2 DRAWBACKS OF 4D PRINTING

Complexity: Designing and manufacturing 4D printed objects can be more complex than
traditional 3D printing.

Cost: he use of smart materials and specialized printing processes can make 4D printing more
expensive than traditional 3D printing.

Limited material options: The range of smart materials suitable for 4D printing is currently
limited, restricting the Scope of potential applications at the moment.

Production Speed: Current 4D printing processes can be relatively slow compared to traditional
manufacturing methods, limiting scalability for mass production.

Technical Challenges: Controlling and predicting the behavior of 4D-printed objects accurately
under various stimuli poses technical challenges, requiring further research and development.

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CONCLUSION
4D printing is a field that is still expanding and finding many uses in other fields. The
possibilities are massive with connections to many other domains allowing for a huge amount
of research opportunities. The field is simply too fresh and wide that all areas of research
regarding 4D printing are largely viable. Although this is the case, some specific fields require
more attention to keep up with this rapidly- changing field. Since the backbone of 4D printing
falls in the smart materials used, the testing and documentation of SMP composites with
specifically controllable characteristics that can be used for printing are still in need of
improvements.

The steps of fabrication along with the degree of control on the SME of these composites
are still in heavy requirements. Non-manual programming of SME needs more research, as it
can provide many advantages over manual programming. Biomedical applications are the
frontrunners in benefiting from 4D printing, but more research into actuation mechanisms is
needed for these applications to be safe enough, and controllable with high reliability for real-
life applications.

The materials that are required in biomedical applications must be of a relatively low
activation temperature, allowing the safe activation when in life-form contact. Suitable materials
or composites for 4D printing should be a priority in research, for anyone furthering biomedical
4D printing. From the literature, it can be observed that application-based prints are starting to
expand in recent years. Thus, 4D printing is still in its prime, where applicable 4D-printed
devices are not in the position to be applied yet. 4D printing, as a concept, has endless
possibilities in terms of applications that need to be realised, and the impact that it will have on
the world is of no small feat

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