Energy harvesting by a origami mechanism doctoral thesis major mechanical

In the context of using origami in real world engineering application, we extensively explore on the scale in medium to large scale system.. 1.1 Applications of origami structures in eng

ACKNOWLEDGEMENTS

First and foremost, I would like to send my deeply gratitude to National Chung Hsing University, Taiwan for providing me this valuable scholarship for Ph.D degree and Ho Chi Minh University of Technology and Education, Vietnam for supporting me

in the researches

I would like to thank my advisor Prof Dung-An Wang for his guidance, support and encouragement He has mentored, taught and inspired me in my academic as well as personal life I express my gratitude for the education that I have received from him

I would like to acknowledge the help of my fellow Vietnamese and Taiwanese labmates for their feedback, cooperation and of course friendship In addition, I would like to express my gratitude to the staff of Graduate Institute of Precision Engineering for the last minute favor

Finally, I would like to thank my friends for accepting nothing less than excellent from me Last but not the least; I am very grateful to my parents, my sister, my brother and my wife for their love, for supporting me spiritually throughout writing this thesis and encouragement of my academic pursuits, and for always expressing confidence in

my abilities

Graduate Institute of Precision Engineering, National Chung Hsing University

Keywords: Origami, Bistable, Energy harvesting

TABLE OF CONTENTS

ACKNOWLEDGEMENTS i

ABSTRACT ii

TABLE OF CONTENTS iii

LIST OF FIGURES vi

LIST OF TABLES ix

LIST OF ABBREVIATION AND SYMBOLS x

CHAPTER 1 LITERATURE REVIEW 1

1.1 Applications of origami structures in engineering 1

1.1.1 Application of small scale 1

1.1.2 Application of middle scale 2

1.1.3 Application of large scale 4

1.2 Materials for origami inspired structures 6

1.2.1 Panel and hinge systems 6

1.2.2 Composite systems 2

1.2.3 Homogeneous material systems 4

1.3 Methods for fabrication and deployment 9

CHAPTER 2 INTRODUCTION 12

2.1 Motivation 12

2.2 Contribution 13

2.3 Organization 13

CHAPTER 3 DESIGN CONCEPT 15

3.1 Conceptual design 15

3.2 Operation principles 16

CHAPTER 4 DEVICE FABRICATION 22

4.1 Manufacturing processes 22

4.2 Origami assemblage 23

4.3 Components for static experiment 23

4.4 Components for dynamic experiment 23

CHAPTER 5 FORCE-DISPLACEMNT EXPERIMENT 33

5.1 Experiment 33

5.2 Results 34

CHAPTER 6 DYNAMIC EXPERIMENTS 41

6.1 Control constant acceleration amplitude 41

6.2 Frequency response 41

6.2.1 Experimental setup 41

6.2.2 Results 43

6.3 Voltage 43

6.3.1 Experimental setup 43

6.3.2 Results 44

6.4 Power 44

6.4.1 Experimental setup 44

6.4.2 Results 45

CHAPTER 7 CONCLUSIONS AND FUTURE WORKS 59

7.1 Conclusions 59

7.2 Future works 59

References 61

Publications during Ph.D studies 68

LIST OF FIGURES

Fig 3.1 A schematic of background idea (a) Original configuration (b) Folded

configuration 17

Fig 3.2 Examples of origami structure 17

Fig 3.3 Waterbomb type origami structure (a) An origami at the first equilibrium position (b) An origami at the second equilibrium position 18

Fig 3.4 Origami fold pattern 18

Fig 3.5 Examples of pattern of OM 19

Fig 3.6 An OM can be viewed as a spherical 8 bar change-point mechanism 19

Fig 3.7 A schematic of origami mechanism for energy harvesting (a) The first stable position and (b) The second stable position 20

Fig 3.8 An explanation of bistability using the ball on a hill analogy 20

Fig 3.9 A typical f-d curve of an OM 21

Fig 3.10 Dimension of OM including PVDF film 21

Fig 4.1 A laser cutting process of OM (a) Experimental setup (b) The origami prototype 26

Fig 4.2 A laser cutting process of PVDF panels (a) Experimental setup (b) The fabricated PVDF film 26

Fig 4.3 A process of origami assembly for static and dynamic testing 27

Fig 4.4 An exploded view of fabricated fixture for static testing 28

Fig 4.5 A photo of components for static testing 28

Fig 4.6 Dimension of the substrate for static testing 29

Fig 4.7 Dimension of the base support for static testing 29

Fig 4.8 An exploded view of fabricated fixtures for dynamic testing 30

Fig 4.9 A photo of fabricated components for dynamic testing 30

Fig 4.10 Dimension of the block support 31

Fig 4.11 Dimension of the bearing holder 31

Fig 4.12 Dimension of the base 32

Fig 4.13 Dimension of the connector 32

Fig 4.14 Dimension of the rod 32

Fig 5.1 Experimental setup for f-d characterization of the OM 35

Fig 5.2 An exploded view of f-d experimental setup 36

Fig 5.3 Switch configurations 37

Fig 5.4 The process of “Zero” adjustment 37

Fig 5.5 A process of “Span” adjustment 38

Fig 5.6 A console of controlling f-d experiment after calibration 38

Fig 5.7 A setup of linear guideways for f-d testing 39

Fig 5.8 A block diagram of f-d experiment 39

Fig 5.9 The f-d curve results of five times testing 40

Fig 5.10 The average result of f-d experiment with error bar 40

Fig 6.1 An experimental setup of controlling constant acceleration amplitude 47

Fig 6.2 An “ArbConnection” software for controlling function generator 47

Fig 6.3 A block diagram of experiment of controlling constant acceleration amplitude 48

Fig 6.4 A flowchart of experiment of controlling constant acceleration amplitude 48

Fig 6.5 An experimental setup of frequency response testing of the device 49

Fig 6.6 A block diagram of the position sensing of the device and feedback loop for frequency sweep experiment 49

Fig 6.7 The software of calibrating analog output scaling 50

Fig 6.8 A console of frequency response experiment in “Auto” mode 50

Fig 6.9 A flowchart of frequency sweep experiment in “Auto” mode 51

Fig 6.10 Frequency response of the OM with different excitation (a) 0.1g, (b) 0.4g and (c) 0.6g 52

Fig 6.11 An experimental setup of voltage output testing 53

Fig 6.12 A block diagram of voltage output experiment 53

Fig 6.13 A console of obtaining voltage output in “Auto” mode 54

Fig 6.14 Experimental harvested voltage with different excitation (a) 0.1g, (b) 0.4g and (c) 0.6g 55

Fig 6.15 An experimental setup of harvested power with impedance matching strategy 56

Fig 6.16 A block diagram of harvested power experiment 56

Fig 6.17 A console of obtaining harvested power 57

Fig 6.18 Experimental harvested power with impedance matching strategies for

different acceleration amplitude (a) 0.1g, (b) 0.4g and (c) 0.6g 58

LIST OF TABLES

Table 4.1 Parameters of laser cutter for PEEK1000 25 Table 4.1 Parameters of laser cutter for PVDF 25 Table 6.1 Parameters of laser cutter for PVDF 46

LIST OF ABBREVIATION AND SYMBOLS

OM Origami mechanism

Chapter 1 LITERATURE REVIEW

Origami, the ancient Japanese art of folding paper that can be established in a variety of ways from bending, twisting, crumping a piece of paper to create facets and hinges system that can have a more defined fashion In our research, we

overwhelmingly concentrate on energy harvester by exploring dynamic experiments on origami The scale of the system materially affects the use of materials as well as

manufacturing methods The application can have measuring range-size rarity with the largest possible in mega-structures to medium in the macro range or even molecular scale In the context of using origami in real world engineering application, we

extensively explore on the scale in medium to large scale system

The transformable origami structure can be envisioned in one of the followings categories:

a) Initially flat systems will be folded to adapt to new area constraints or to work

an alternative function;

b) Formation of initially folded assemblages such that the new structure would meet some set or fill some predefined space requirements;

c) A structure is designed to be folded and unfolded numerous occasions

throughout its design life cycle to meet a single or multiple of tasks;

d) Cases where (a) and (b) are coupled

1.1 Applications of origami structures in engineering

1.1.1 Application of small scale

The scale of small origami in a centimeter or less can achieve the folding of the structure by taking advantage of material and local flexibility Micro and nano origami structures do not require the rigidity folded motion and can adjust bends in the panel segments These structures do not require a large dimension in thickness panels, they would be constructed either from composite type systems or from a homogeneous

system Small-scale applications will somewhat not be entirely concentrated in this study thus only a brief literature summary is provided here

In micro and nano applications, we believe that origami can be used potentially

in the following topics:

 Biomedical devices

 Micro and nanorobotics and devices

 Electronics manufacturing and assembly

 Synthetic material design

 Molecular and DNA folding for improvements in biochemistry

Kuribayashi et al [40] presented an interesting biomedical application of using origami titanium/nickel stent-grafts to open up blocked arteries By folding a thin silicon sheet into cells, Guo et al [41] introduced a method to significantly improved photovoltaic properties Aten et al [42] introduced microscopic nanoinjector adopting origami techniques They can be used for injecting mouse zygotes Using transformable origami for manufacturing micro and nanoscale structures that can be employed for electronic and optical functionality published by [43] and others, recently

Metamaterials have also become a backbone topic in the origami category because cellular arrays of patterned origami can react in unconventional ways Fuchi et

al [44], Wei et al [45], Lv et al [46], Silverberg et al [18] and Waitukaitis et al [21] discussed some devices of the structured metamaterials developed by inspired origami

Andersen et al [47], Schmidt et al [48], Han et al [49] and Yoo et al [50] applied the mechanics of origami that have been used in the molecular scale and tailor the characteristics of molecules and DNA Jiang et al [51] discussed the idea of folding DNA structure so that it can be used to deliver drugs to cancer cells by using folded origami techniques

1.1.2 Application of middle scale

The medium-scale is that origami structures can range from a few centimeters to perhaps a meter or so in length We believe that medium-sized systems will be ably constructed using any of the three systems discussed in section 1.2 with drastic

improvements in manufacturing technology and materials Potential applications of medium-sized origami structures include:

 Robotic arms, legs, and other components

 Deployable actuator and cantilevers

 Collapsible furniture

 Devices and systems, allowing thermal expansion or movement of a large structure (thermal joint in a freeway bridge)

 Toys for amusement and entertainment

 Devices used for education in origami, mathematics, and engineering

In robotics research, origami has made breakthroughs, allowing for easy production and kinetically functional, multi-DOF systems that can be efficiently operated Ma et al [52, 53] developed a working flying robot assembled by folding and bending thin materials that are cut from a laser-cut plate at specific locations, then snap into a three-dimensional configuration Hawkes et al [54] presented a method of folding

a reprogrammable material, in which a flat sheet is reconfigured into a 3D object that is several centimeters long using heat By heating the creases, which are created by cutting

a layered sheet, a three-dimensional walking robot is presented by Felton et al [55]

The implementation of larger-origami applications is still a challenge but there is

an enormous amount of potential for future application and deployment For example, Filipov et al [56] presents the coupled folding tubes have the possibility to be used as deployable cantilevers In humanoid size robots, they could be utilized to construct transfigured legs and deployable arms Origami is more commonly used in traditional forms of mechanical engineering, besides the robotics industry The origami technique

by itself has been successfully used to create tubes that act as actuators or deployable booms Because of the pre-configured small stowing configuration, origami has especially suitable for related applications

Martinez et al [57], Schenk et al [58, 59] and Fernadez et al [60] study and test for these systems One end of these structures accepts gases and liquids get in then can lead to the structure to deploy These types of deployable boom structures could also be scrutinized as "large" and can reach the order of several meters However, in contrast to most other applications, these structures do not require the use of thick materials or rigid

origami kinematics and can be constructed by flexible materials There are exists a kind

of structure like scissor trusses, deployable tensegrity structures and many more that has deployable structures completeness For brevity, we do not discuss these structures here, but we note that rigidity origami has similar the kinetic considerations for truss structures and is often applied to in conjunction with other deployable mechanisms In everyday objects, equipment, and devices, we use numerous origami structures For example, tables and chairs are capable of changing the height, taking advantage of the flexibility of origami structures in creating lifting mechanisms, and side covers or perhaps countertops can increase in area by having folding origami expansion In industry, Bellows and similar origami systems are already implemented typically In the construction of bellows, the rigidly foldable polyhedral cannot be applied and cannot follow the rigidity folded motion

Connelly et al [61] used bellows required some form of elastic or plastic deformation, beyond that defined by the kinematics of the system Inspired by traditional folding chairs and tables available on the market, the use of folding and origami in furniture is becoming increasingly popular Folding is a key determinant in these designs, to distribute multi-purpose product can be stowed away compactly when not in use

1.1.3 Application of large scale

For a large scale system, due to its scale, these systems are required to have thick

in length In the architecture of building structures field, the fashioned origami patterns have been used for inspiration and conceptualizing In most cases, these designs are static and their configurations are fixed with multitude geometries so that they can acclimate and alter to variety purposes By flexibly adjusting building structure shells and present a method to improve the acoustic properties, Del Grosso and Basso [62] obtained some significant advantages For civil engineering, the inspired origami engineering can be applied in the following methods:

 Deployable disaster response (DR) shelter for use following ecological catastrophe and other emergencies

 Built bridges that can responsive reconfigure to carry land vehicles and allow passage of water traffic as well

 Deployable systems for large structures

 Prefabricated systems that can be tucked firmly for transportation

 Expand retaining walls, culverts, pipelines, protective barrier or other structures

 For large scale architectural applications, we can conceive the considerable advantages that can be gained by applying inspired origami structures in design:

 Façade, walls, decorations and other artistic structures can be achieved a high level of complementary aesthetics

 Enhance the sound properties for the wall and ceiling panels of a concert hall or multifunctional meeting room

 Depending on the essential usage, partition walls that can reconfigure

 Improve pertinent ventilation function by automatically opening or closing windows and panels

 The shadow system has flexible components to reduce the heat gain of the building during sunny days or shelter from the rain

Not only inspiring the civil engineering community, but large-scale origami structures can also be applied in aerospace and heavy industry Multi-function machines often require to have transformable components, for example, entertainment facilities that need to be designed to allow expanding the capacity for occupants

In the space industry, origami has made prominence distribution since a small structure is launched into space and can then be expanded into a large functional system to implement some tasks required Researchers have explored, studied, and tested an assortment of spatial array structure systems that could be implemented [63,64,65,66] Some types of origami patterns have the ability to transform a much large surface area, which helps to absorb solar energy more effectively Because there is no gravity and air in space, a thin membrane would not be experienced by common forces on earth and it can be used for origami array structures Large-scale mechanical, aerospace and multidisciplinary applications may include:

 The generic car body can be developed to achieve aerodynamics-optimization

 Covers for trucks and trains

 Crane structure needs to be changed in shape and size in a flexible and rapid way to fulfill its working function

 Construction equipment, cranes and other heavy machines that need to have adjustable moving parts

 Solar panel arrays that can be expanded in space

 Space station compartment for astronauts

1.2 Materials for origami inspired structures

The scale, purpose of the structure, the number of expected folding-unfolding cycles, allowed kinematics, cost, deployment mechanism, and other factors greatly affect choosing materials and type of assembly system In this chapter, we introduce several generally origami assembled systems and materials that are assumed to be feasible for each one

 a separate hinge system and control panel;

 a combination of clamping layers;

 a uniform material system

The hinge and facet systems will be more suitable for large application systems; small applications are achievable with a sandwich and homogeneous systems; and medium-sized applications can be established with any of the three methods discussed methods above

1.2.1 Panel and hinge systems

The thickened panels which have rigid foldable structures will often not undergo bending during moving or operational deployment The strong metallic hinges can be used to act in the same way as the folds due in a simple origami model to interconnect thickened plates This technique introduces several advantages such as:

 Without changing in characteristics, the hinges can accommodate a large number of folding unfolding cycles

 Structural and architectural elements are considered the role of thickened panels (e.g insulation);

The hinges can allow for conveying mass among panels and the transformable of the structure There are several issues with thickened facets that they could not adhere to the rigid body kinematics of zero-thickness origami structures Tachi [66] and Zirbel et

al [65] present the possible realizations of the panels that have a finite thickness Placing hinges on the ends of the panels is often used in these methods, then inserting thin panels to activate kinematics of the thickened material and design the fashioned global array of panels and folds to allow continuous rigid motion of the system The placement of hinge connections is sometimes discussed in these methods since they considerably influence the kinematics of the system The panel-hinge systems can often

be constructed with cost-effective materials that are commonly available We consider that the articulated system requires high stiffness to be able to carry the large forces To allow easy deployment, bearings are always integrated into hinges so that reduced hinge friction forces We can use plastics, wood, metal, concrete, and a variety of engineered composite materials to construct the panels In architecture and product design, there are several practical applications employ metal, wood, and plastic prototypes and there is tremendous potential for innovating the panel materiality

1.2.2 Composite systems

In large-scale applications, composite materials have great potential than medium-scale and small-scale ones in manufacturing origami prototypes The structure mainly used is a sandwiched structure Flexible materials will be attached to stiff materials so that they can bend allowing fold rotation at the fold lines and the stiff material is removed A basic example of this system is to apply the rigid panel attached

to the cloth, permitting the rotation of two panels However, there are several constrains that do not allow the panels to move apart Depending on the construction methods, there are many different types of materials used to create panels Kinematic characteristics need to be constantly updated similar to the control panel and hinge systems There are a variety of traditional and newly developed materials may be used for both flexible and rigid materials At the crease, fabrics, polymers, and alloys can be implemented due to their versatility, while the panels can use metals, engineered plastics, and corrugated material assemblies Peraza-Hernandez et al [87] have been built active systems by evaluating composite material systems Garolite (a type of fiberglass-epoxy laminate) panels used to attach on a thin Kapton film that is used as

backing to connect the thin panels [65] There is a multitude of methods for these composite systems [54, 68, 8]

1.2.3 Homogeneous material systems

These systems consist of a single material that is used throughout the structure

By deforming the same base material, the bending will be created The rigid folding motions do not be necessarily used in the types of systems By decreasing the cross-section along the fold line or alter the mechanical characteristics at that segment, the bending hinge along the crease can be facilitated Decreasing the cross-section area of the structure can be performed in several methods In typical corrugated cardboard box manufacturing, commonly, to reduce the cross-section, they compress the structure at the fold line or pre-crease or score the material In manufacturing and product packaging, this method applied for folding thin homogeneous materials has been existing for around for decades This type of fold creation has been researched to study about the constitutive relations and behaviors [69, 70, 71] Flexible polymers can be used to made living hinges and thus concentrate on numerous cycles of bending and deformation Reducing the cross-section will increase fatigue and fracture of the base material, unexpectedly These are usually cases when the material reaches the state of plastic deformations (e.g crease lines in most types of paper cannot be removed) The creases could help to reduce the stiffness of the material and the fold will become more flexible over time (after some cycles, the fold will experience a full fracture and failure) Another way to create prescribing the fold is by creating a localized stress concentration bending the material instead of removing material It can be interpreted as bending a piece of paper without scoring or etching it initially This method will meet some difficult situations since its location is more dependent on the global structure geometry and the external forces Thus more difficult to prescribe accurately By applying heat, light, electric fields or chemicals to attain local stresses and bending, this type of behavior can also be achieved In order to create the patterning thin sheets, they applied stress concentration in specific locations to obtain the folding of thin continuous membranes [72, 73, 74] It does not require to have etched or perforating prior to manufacture, and just basically concentrate sufficient stresses on a fold line to cause the fold to bend

1.3 Methods for fabrication and deployment

Depending on the type of structures and the governed scale of the structure, the fabrication method, and the implementation could be deployed in many different ways

As we discuss in section 1.2, a multitude of origami structures, the type of system, the specific material used as well may influence the materials and systems They are also a byproduct of the type of deployment scheme deployed to the system Thus, not all different methods are feasible for all scales It is possible to visualize a perfectly flat structure then proceed to deploy the folds or we can start with some parts of the whole structure and then add on hinges and panels sequentially With layered sandwich-type systems that have a specific prescribed fold line, it is possible to machine and removes layers to layers In this way, the manufacturing method used for homogenous material can also be used in these sandwiched structures Nowadays, users can effectively and easy way construct a rigid (or flexible) 3-dimensional object, complex shapes, possibly multi-material with additive manufacturing (commonly known as 3D printing) which uses raw material and computational input, initially This process can create an arbitrary object without any molds, specific fixtures It has been used successfully in designing engineered structures to print out device For designing origami structures, the 3D printing technology has been done in a variety of applications The 3D printing has become a key role in the manufacturing and assembly of origami structures Multi-material manufacturing can be implemented in constructing the composite type systems

in its early phases Additive manufacturing can be used to manufacture homogeneous material systems or components of the other systems The accuracy of 3D printing is a major challenge that needs to be developed to create complex and distinct shapes The large structures usually receive large force and thus mostly mechanical sources of energy will be mandatory to gain deployment For example, external cranes or actuators inside of the structure would be used to expand a global system By integrating panels with hinged elements, these systems will be pre-assembled Recent advances in robotics, computer science, and automation have possibly allowed using computer-operated robots to fold simple paper origami pattern [75] Shape memory alloys (SMAs) will be widely anticipated to become potential and interest research in large-scale structures Peraza-Hernandez et al [76] perform a way to form along specific fold lines by using heat and how can they obtain the consequence of relatively large rotations from an

initially flat sheet In the pre-manufacturing origami patterned process, Tolley et al [77] introduce a SMAs which can be simply uniformly heated up, then transform from a flat state configuration to a fully deployed state Hawkes et al [54] present the connection

of folding reprogrammable sheets substantially enhanced by SMAs Then bending along the creases patterned and global deployment of the structure could be obtained by applying energy in nonlinear mechanical properties for medium to small-scale research

A light which have an appropriate wavelength can produce heat Liu et al [78] and Ryu

et al [68] used this method for multi-layered pre-strained polymers at specific prescribed fold lines to obtain strain on one face of the structure and thus achieve bending (folding) of the entire structure Using light, heat, electrical current and application of chemical stimulation, the transformable thin structures can be attained by deploying biochemically responsive materials A detail literature review of the method for actuating origami systems has taken into account by paper review [67] There are enormous methods to gain bending and deployment of the structure in the size of the micro-scale In order to create the folded structures, Birnbaum and Pique [43] reported a method that folds micro-scale nanofilms out of plane using external propulsion induced

by laser Arora et al [74] apply the ion implementation method to active stresses on one side of the cantilever made of by Si3N4 (silicon nitride) results in folding at an identified location For deployment of the origami structure, we contribute the incomplete list of methods following this summary:

 External force or actuation used to transform structures

 The force can be generated by a system of actuators located inside of the structure

 Deployment can be achieved by using fictitious forces of the structure (e.g gravity, centrifugal, or electromagnetic forces)

 Changing internal volume (e.g using origami as a deployable boom/cylinder or using vaccumatics)

 Release internally stored forces (e.g pre-stressed fold and panel elements)

 Fold rotation and structural deployment obtains by applying heat, light or even chemical reaction

We note that some origami designs can active their full functions such as

deployment or stowing when providing minimum initial energy for the structure to

obtain a deployed or stowed state This could be particularly beneficial because just use

a necessary influenced factor may be needed for the structural deployment Since there

is no energy change between the states, these types of systems are called zero-stiffness structures

Chapter 2 INTRODUCTION

be a dynamic process and origami structures could possess rich dynamic characteristics under excitations For instance, the hinges of origami can fold and unfold rapidly and

reciprocally Sound or wave propagation in terms of the fluid category can be the inspiration for designing origami-based metamaterials Thus, the topic of dynamic origami cannot be excluded from studying origami engineering systems and its applications Yasuda et al [25] have used origami-based metamaterials inspired by Tachi-Miura polyhedron (TMP) origami cells to explore the nonlinear rarefaction waves dynamics in the multi-DOF origami structure They found that transition from linear to non-linear behavior happens due to the flexible transform of geometric configuration Hence, the TMP cells where the Tachi-Miura polyhedron is exploited can be developed

to efficiently handle alleviating vibration and impact structures These examples above give us an interest in that dynamic characteristic of origami is considerable research in relation to a multitude of potential applications On the other hand, beside [25] There are not many works which list origami dynamic in the literature Moreover, there is a lack of punctilious tools and framework to comprehensively deploy the dynamic of origami The deployment of the folding line is a distinctive feature of the origami structure However, previous origami dynamic studies have not taken full advantage crease line characteristic instead they used the equivalent linkage systems with multi-bars, spring or shafts [25] These approaches could help to simply or decrease the problem complexity yet will eliminate crucial crease-related characterizations that are extraordinary to origami Thus, we need to discover new mechanical properties from origami folding, such as bistable and multistable characteristics [16, 20, 21, 22] that can produce attractive and beneficial system dynamic behaviors The coexistence of bending stiffness at the fold lines and the deployment of the crease pattern can generate non-linear relationship among creases result in inducing the bistability characteristic, that means it can be able to jump in two different stable configurations regardless of any external force [20] The bistable behavior itself shows a powerful nonlinear characteristic with such a rich dynamics system In some cases, it could be utilized to enhance the performance in a variety of applications for instance energy harvesting [26–29], motion amplification [30,31], damping [32], sensing [33, 34] and vibration cancelation [35], and isolation [36] In spite of its potential, the study of bistable or even multi-sable dynamics in origami structure needs to adequately and comprehensively pursue

2.2 Contribution

The main contributions of this dissertation are, listed in order of appearance: The design of OM with different patterns

The origami assembly for static dynamic testing

The fabrication of the prototype and setup of the experiments to evaluate the performance of OM

The dynamic experiments are carried out to investigate the energy harvesting of

an OM prototype

A concise overview of OM in engineering

2.3 Organization

Chapter 2 describes the design concept of OM

Chapter 3 illustrates the fabrication process of the device and fixtures

Chapter 4 shows the force-displacement experiment and results

Chapter 5 interprets the dynamic experiments and results

Chapter 6 summarizes this dissertation and gives possible directions for future works

Chapter 3 DESIGN CONCEPT

3.1 Conceptual design

One technique that has been used for an origami-inspired solar array is called a Miura fold This well-known origami fold was invented by Japanese astrophysicist Koryo Miura The original stage (flat configuration) of the solar panel is shown in Fig 3.1 (a) When the structure is opened, it appears to be divided evenly into a checkerboard of parallelograms, see Fig 3.1 (b) Based on the vast area of the origami structure, it is possible to generate a large deformation, thus resulting in a highly efficient energy harvest when placing a piezoelectric film on the origami structure Before proceeding with the design for a specific origami structure, we present some of the existing origami mechanism described in Fig 3.2 as reference designs for this work

A waterbomb shaped design was selected for energy harvestings, as shown Fig 3.3 The solid lines represent to mountain folds that the two adjacent panels intersect at the fold point upward On the other hand, the dash lines indicate the valley folds that the two panels meet at the point downward It is obvious that all the folding lines do not have the same length because the OM is created by a rectangular thin material The four-mountain fold has the same length but longer than the rest of the fold lines An interesting behavior of the OM is that the mountain folds and valley folds still can hold their characteristics in both equilibrium positions under applying load A typical crease pattern of OM is described in Fig 3.4 The outside edges of the material are illustrated

by the solid lines and the straight lines are folding lines with all neighboring pairs separated by 45o Initially, we introduce a number of patterns depicted in Fig 3.5 that can be potential used for the purpose of harvesting energy due to folding at the creases

In the Fig 3.5 (a), the pattern has largest bending stiffness compared to the other, thus the structure becomes extremely hard to deploy and twist or bend Fig 3.5 (b), (c) and (d) show the pattern with approximately 95%, 80% and 30% of the material removed along each crease, further reducing the stiffness By using trial and error method, we recognized that the case of 95% shows the folding lines were completely destroyed under high excitation of acceleration, whereas, the case with 30% showed high rigidity