Helio-nastic Shading Device
Duy Vo, Pushkala R, Flore Marion,Vaama Joshi, Rich May Bio_Logic Lab School of Architecture, Carnegie Mellon University Professor Dale Clifford
aBstRact The Mimosa Pudica, of the Fabaccae family is nicknamed the sensitive plant or â€œtouch-me-notâ€? for its response to external stimulus by drooping down and shutting its leaves. This attribute inspires a thought process that aims at applying this movement to an architectural application. The project undertaken outlines an idea that could be used in real time. Our research aims to emulate this phenomenon, to recreate it in a way that it can be incorporated as a functional element in the building, interweaving the principles of energy efficiency and aesthetics with the existing design scope. The design of a moving petal system inspired by the nastic movements of the mimosa pudica is created with shading and solar energy harvesting as its major functions. The mechanism of the device functions on the principles of contraction of Nitinol which is triggered as a function of light intensity, with more light causing the wings to unfold. This phenomenon is used to shade the surface above which the device is fixed. By generating arrays of the same prototype, we hypothesize that it shall be possible to harness the incident solar energy by mounting solar panels on the wing surface and generate interesting shading patterns.
MetHodologY The study was carried in 4 steps: 1. Understanding the organism: The Mimosa Pudica was studied with special attention given to the movements exhibited by the plant.The study involved understanding the reactions causing the nastic movements and the processes happening simultaneously at the leaf level. 2. Recreating the action of the leaves: This part of the study incorporated simple experiments to generate the collapsing movements similar to the leaflets. Simple planes and mechanical means of movement were used to recreate this motion. Techniques like origami, introduction of magnetic fields and chemical reactions were studied to identify the most suitable method for further development of the idea. 3. Actuation methods and material study: this step involved two major aspects of the design. Multiple prototypes were designed to model the movement and enable the flapping motion of the petals using shape-memory alloy(SMA), arduino, bi-metallic strips etc.This phase involved creation of the working model that could be applied to an architectural function. Material study was another important aspect which involved studying the material for creating
the various parts of the system, methods to create a more proactive prototype like lamination, stress-holes, material combinations etc. This study also involved shadow study using various modules created with different materials, which highlighted the functionality of the petal surface. 4. Realizing an Application: The prototype was designed to replicate the motion of the leaves.With time, the architectural application of this idea was worked on and various uses were tested. It was decided that the device would function as a shading device and in an array could also be used to collect solar energy by mounting PV cells on the planar surface.
PRoJect conclUsion A working prototype was successfully created to culminate our entire study on the Mimosa pudica and its response to external stimulus. The motion was recreated using simple mechanics and technology to create a device that functioned as a shading device on one hand and a solar energy harnessing device on the other. This unique feature enabled its use on facades facing any direction, be it shading on north-south direction or trapping incident solar energy on the east-west orientation. The use of NiTinol to generate the simple open-close motion of the petals induced a sense of fluidity to the entire setup thus creating a visually appealing array which can be applied to any building. The incorporation of colorful PV film made it all the more aesthetically appealing, making this device fully functional. The prototype dealt with the basic principles of motion and addressed the very effects of daylight that matter the most i.e. shading and solar power. This is an idea which has a larger scope when the aspects of scale and functionality are researched further. It has a potential to function as a simple yet elegant design element which, if worked on more, can yield very positive results and has the
Mimosa Pudica & Nastic Movement Specie Overview Mimosa Pudica (mimos; meaning mimic and Pudica; bashful or shrinking to contact), Common name-“touch me not”. This behaviour is believed to have evolved to protect leaves against harmful insects, during intense wind or rain storms and as a means of conserving water. The Mimosa Pudica has been a curiosity to humanity since antiquity for its remarkable ability to react to touch. Early on, Ancient Greeks observed that the plant moved in response to something moving against it. Its scientific named was coined by Linnaeus, founding father of biology, in 1753, Mimosa, from the Greek mimos, meaning mimic, and Pudica, from Latin meaning bashful or shrinking to contact.This specie is naturally found in the tropical regions of South America. Mimosa Pudica, of the Fabaccae family, is also nicknamed the sensitive plant or “touch me not” for its ability to rapidly droop its leaves when touched or in the presence of heat.This behavior is believed to have evolved to protect leaves against harmful insects, during intense wind or rain storms and as a means of conserving water.
Image 1. Mimosa Pudica Flower
The plant’s movement is directed by motor cells and tissue mainly in the pulvinus, which is a joint like member at the base of the leaf.These motor cells are driven by phenomena called turgor pressure. The influx of ions causes the osmotic flow of water from an area of low solute concentration to an area of high solute concentration. In the motor cells the water flows from the outside the cell, to inside the cell’s vacuole.The vacuole then grows, pushing the plasma membrane against the cell wall, and in turn making the cell and pulvinus rigid. When the Mimosa is perturbed, a signal is sent to the motor cells, activating a sudden and sharp increase in membrane permeability. The water in the cells’ vacuoles then floods the intercellular spaces, leaving the cells nonrigid and malleable. The rapid loss of turgor pressure is observed by the eye as the down folding of its leaves. Recovery of the pressure requires active ions in the cell to start osmosis and refill the cells vacuole. Recovery takes roughly fifteen minutes but can only occur during the day. Individual agitation sensors are located on each individual pulvinus but can spread to other pulvini through what is believed to be an electric pulse.
Image 2. Mimosa Pudica Leaf
Image 3. Mimosa Leaf closing
Image 4. Mimosa Leaf fully closed
Image 5. Mimosa Leaf half closed
Nastic Movement The reaction of the Mimosa pudica has been studied over the years due to its spontaneous reaction to an external stimulus. The nastic movements observed in the Mimosa are made possible due to variation of the turgor pressure in the motor cells. Whenever the leaflet is subjected to touch or heat or harsh wind, the cell vacuole loses water molecules through its membrane as certain ions including potassium ions are generated. This response of the cell vacuole causes dehydration and the inner cell wall collapses to accommodate the difference in pressure. This turgor pressure is passed on to adjacent cells and th water is finally collected at the pulvinus at the base of the leaflet. This weighs the pulvinus down, causing the leaflet to collapse. Adjacent leaves collapse in an orderly progression till the entire leaf collapses and it finally droops downward, seeming lifeless.
Diagram 1. Mimosa Pudica leaf mechanism
Image 6. Mimosa Leaves
Image 7. Mimosa Leaves Close-Up
Image 8. Drooped Mimosa Leaves
Image 9. Mimosa Leaflet Close-Up
Diagram 2. Microscopic scale: Turgor Pressure
System Variation After identifying the underlying mechanism of the mimosa pudica plant, we then further simplified it down to a system of an actuation sensor node and two moving arms, as shown in diagram 4. We then decide to approach this simplest mechanism in 2 different ways: • Continuous System • Discontinous System - composed of a node and 2 functional arms
Diagram 3. Mechanism variation Based on these two variations, we went on to further explore how we can best replicate this mechanism using different technologies.We’ve settled on 3 different areas of study: • Origami - Japanese Art of paper folding. We felt that this would relate to the continous system • Chemical reactions - The release of CO2 from the chemical reaction of vinegar and baking soda causing the expansion of a membrane, follows the discontinuous system. • Magnetism: The principle of magnetism causing movement of oppositely charged surfaces towards each other
Diagram 4. Mechanism break-down
Recreating The Motion Origami Samples As stated, Origami, the Japanese Art of Paper Folding, is explored. Diagram 6, diagram 7 and diagram 8 display 3 common ways one can replicate the â€œclosingâ€? motion of mimosa pudica leaf. Origami has provided some insights into how we can potentially make the continuous system become reality through the use malleable materials and pressure exertion.
Diagram 6. Action Origami - Flapping bat
Diagram 5. Action Origami - Simplified flapping butterfly
Diagram 7. Action Origami - Flapping bird
Magnet The use of magnetic strips was considered to create the collapsing mechanism of the leaflets. The apparatus was envisioned to have 4 plates - the outer ones having magnetic strips and the inner plates had metal strips on them that were connected to an electric source. This allowed for creation of a magnetic field when required, allowing the use of properties associated with electromagnets. Under normal conditions the 4 plates lay apart as there is no attractive force working between them. When an electric current is introduced, the metal plates get charged creating a magnetic field, thereby exerting magnetic forces on the other plates. This creates an attractive field resulting in the collapse of the plates.
Chemical reaction driven The use of chemical reaction between baking powder and vinegar was to imitate the turgor pressure taken inside the cells of the mimosa pudicaâ€™s pulvinus. The baking powder (basic substance) reacts with vinegar (acidic substance) releasing the carbon dioxide as followed NaHCO3 + CH3CO2H -> CH3CO2Na + H20 + CO2 This exploration not only helps us understand the turgor pressure but also provides some creative insights into how we can mimick the mechanism. Diagram 9. Vinegar + Baking powder
Diagram 8. Action Origami - Simplified flapping butterfly
Origami Prototype: Response: The prototype responds to variations in Pressure similar to the cells in Mimosa pudica
Materials: What is the prototype made of? The first model was made of plain paper that was folded creating a ridge in between. The final setup was made of paper and an elastic band.
What properties? Paper: Paper is highly flexible Easy to make perforations in the paper surface Easy to modify Very light Rubberband: Very high elasticity Thin
Why these properties were used: • The flexibility of the paper helped reconstruct the planar surface of a leaf blade and this helped replicate the action of the Mimosa pudica when subjected to external stimuli. • Paper also functions as a membrane which allowed creating perforations on the surface. • Paper is easy to fold and bend. This allowed for creating the central ridge which fixed the line of action of pressure causing it to clap when pressure was applied. • The elasticity of the rubberband allows for instantaneous shape regain once the pressure is removed. This allowed simulating the response mechanism to pressure differences that is concentrated. • The thickness of the band allowed for each connection to be made in simple knots and creating a tight network of strings attached to each other.
Did these properties help generate the idea? The mechanism of the Mimosa, which is highlighted by the nastic movements of the leaves when subject to external stimuli changing the turgor pressure, helped develop the design idea to recreate this movement using pressure differences by using the simple mechanism of push and pull and exerting force as required.
Diagram 10. The working of Origami prototype
Turgor Pressure Prototype(s) Response: The prototype responds to variations in Pressure similar to the cells in Mimosa pudica
Materials: Balloons, syringes, papers
What is the prototype made of? - 2a: The first prototype was made by using a single syringe and balloons. A Y-shaped connector was attached to the end of a syringe. Two balloons were fixed to each ends and paper strips were attached to either balloon. - 2b: It uses two syringes and balloons at the end of either syringe. Folded paper was inserted between the two balloons
What properties? Paper: - Paper is highly flexible - Easy to make perforations in the paper surface - Easy to modify Very light Balloons: elasticity - inflation properties Syringes and Y-shaped connector: - Concentrated and controlled air propulsion. - Y-shaped connector helps divert air uniformly
Why these properties were used: - Paper is very light making it easy to lift by inflating the balloon. This property was used in 2a. - Paper, being highly easy to fold was used to create the fold in 2b, which functioned as the hinge along which the plane folded. - The inflation of the balloon helped replicate the expansion of the pulvinus causing the paper to move inward and simulate the motion of collapsing. Did these properties help generate the idea? - The flexibility of paper inspired the idea to replicate movement of the leaf blades using simple planes made out of paper.
Did these properties help generate the idea? â€˘
The flexibility of paper inspired the idea to replicate movement of the leaf blades using simple
Diagram 11. Hydraulics Prototype
Shape or geometry study:
Why we chose Origami: 1. Use of lesser material to obtain higher levels of clarity in the motion. 2. The other systems were non-homogenous and were highly mechanical 3. The actuation is highly uncontrolled which is a major criterion in this study. Origami allows for a user controlled experimental setup. Considering the study is focused on the movement of the Mimosa and not the internal reactions There are three areas identified to proceed further in the design for prototypes: Material study Shape Motion/Movement The study of actuation is to be carried out in the later stages once the first phase of passive modeling is finished.
The shape of the plane included two aspects: 1. Study of the planar surface 2. Study of the stress diamond at the fulcrum Study of the Planar surface: •
The plane performs the major action of opening and closing when pressure is applied along the ridge at its center. The process started by studying the plane keeping the shape of the leaf but as this did not provide the results expected, a different approach was adopted. The technique of origami was studied and the basic shape of a flapping butterfly was made and more models were made using this shape. Once the motion was acquired, various shapes are analyzed to understand how the shape varies the motion. Iteration should help produce the best design solutions. Another aspect of geometry that was studied was symmetry. The question asked here was – Do the wings have to be symmetrical along all axes or would it do if it was symmetrical only along the vertical axis i.e. shorter axis. Perforations were another factor. They would result in reducing the overall weight of the plane along with creating interesting patterns. Study of Stress Diamond:
• Image 10. Origami Crane
Image 11. Origami Swan
The stress diamond at the center of the plane plays a major role in diverting the pressure along the path intended and reduces the cracking or splitting of the material. The corners of the diamond are made circular for this purpose.
Material study: •
• • •
The study of material is important to understand how the prototype would function when subjected to real time scenarios. A list of materials was identified that would function similar to paper and would be able to replicate the movement and not break when pressure is applied. Materials tested: paper, Plastics sheet, Mylar, chip board same design modules were made for different materials and tested for the movement. It was observed that the change in material does not change the nature of the movement, but changes the fluidity and speed of motion. Mylar was observed to be the best material for motion studies.
Study of Motion/Movement: • Image 12. Origami Polyhedra
The simple action of opening and folding seen in the Mimosa was replicated by making a sheet of paper fold when pressure was applied at the corners.
Petal Variation Elongation
Petal Variation Perforation
Petal Variation Transformation
Material Composite: Lamination Variation This study of the wing is comprised of understanding how different materials and connecting methods influence the action and characteristics of the wing. While doing this study, the main focus was to create more options and combinations merging different materials with contradictory properties. This study didnot focus on the functionality of the wing surface which resulted in some samples not depicting the desired motion. Thicker plastic and acrylic were tried which proved impossible to recreate the movement. Three different experiments were carried out with these two materials. One withchipboard, which can represent any materials, was explored as a ways of combining two materials, another with a wooden framed petal attached to a strictly folding center, and the last was a silicone casting in which holes were place in the center materials for a more cohesive bond. We also tried casting the wooden frame petal into silicone as well. All the studies produced qualities that we may like to explore in the futureas well. A significant observation was that rigidity was a property that could be desired in the wing and not the central position, for which acrylic would be a suitable material.
Material Composite: Lamination
Different lamination methods were tested out as to provide feedback on the following: • The impact that material thickness has on the shape’s functionality • The impact that material weight has on the flappability of the wings. • The necessary strengthening of material in order for the shape to work properly • Possible combinations of various different materials used in the making of the shape.
Material Composite: Lamination
Motion Study Shape 1 This shape is selected because it best displays the symmetrical motion of the two wings, while produces interesting interesting soft interaction at the midpoint between the two wing tips.
Specifications: • •
Laser-cut mylar shape Elongated shape with fork-like wing tips
Observation: • • •
Observation Motion Patterning
The movement is generally smooth At the midpoint, the two wing tips interact softly, smoothly and appear almost intertwine. This pattern achieves symmetrical motion for the two wings.
Motion Study Shape 2:
Specifications: • •
Laser-cut mylar shape Elongated skinny diamond
Observation: • •
Observation Motion Patterning
The movement for this particular shape is a lot more fluid than other shapes. It is harder to achieve the symmetrical motion patterning, as the two wings tend to flap sideway once met at the “midpoint”
Motion Study Shape 3:
Specifications: • •
Laser-cut mylar shape Fork-like wing tips
Observation Motion Patterning
Observation: • •
The movement is generally smooth At the midpoint, the two wing tips interact softly, smoothly and appear almost intertwine.
Motion Study Shape 4:
Laser-cut plastic shape
Observation Motion Patterning
Observation: • •
It requires a lot of pressure exerted on the two sides of the flap to get it in motion “Flopping” does not occur during the movement, as plastic holds its shape quite well.
Material Study Nickel Titanium - Nitinol
Image 13. Nitinol sample 1
Image 14. Nitinol tubing
Image 15. Nitinol stent
Image 16. Nitinol stent 2
Image 17. Nitinol spring
Image 18. Nitinol forms
What is this material? Nickle titanium, aka nitinol, is a material that displays 2 unique properties: • Shape memory • Super-elasticity + The material undergoes phase transformation between two compound solid states – austenite(simple cubic crystal structure) and martensite (complex monoclinic crystal structure) The transformation is instantaneous and completely reversible. It occurs at specific temperatures and the material can undergo 6-8% strain. + This strain causes an elongation which remains as long as the temperature is maintained. As the temperature is reduced, the material reverts back to its previous austenitic state and regains its previous length and shape. What are the applications of this particular material? There are 4 major applications of Nitinol that we have identified. They are as follow: • Free recovery - The material is heated which triggers the deformation to take place. Once the temperature diminishes, the wire returns to its initial shape. • Constrained recovery - Heated and deformation takes place, the wire allowed to regain its shape but is constrained which generates stress in the wire. • Work Production - the alloy regains its shape as it is forced to perform some action. This application is currently explored in the our current working prototype) • Super elasticity - the material can potentially act as a super spring What forms are available for this material? • Wire – Round or Rectangular • Tube • Strip/Ribbon • Sheet • Bar
Prototype Testing Material Mylar (Stretched Polyester Film)
Image 19. BoPET mylar sheet
Image 20. BoPET plastic sheet
Why was mylar selected as testing material? The prototype is inspired from the origami folding methods. Various materials such as mylar, origami paper, acrylic sheet, chip board, plastic sheets were explored to make the prototype work. Out of all these materials Mylar was found to be most appropriate to imitate the movement of Mimosa pudica plant. What is this material? • Mylar, biaxially-oriented polyethelene terephthalate (BoPET), is a material created from stretching the Polyethelene Terephthalate. • This mateiral is widely used in many industries as it has many practical applications such as packaging, electrical and thermal insulating, solar, marine and aviation applications, electronic and acoustic applications, and graphic arts...etc What are the most notable properties? • Transparency • High Tensile Strength • Chemical and dimensional stability • Reflectivity • Gas and Aroma Barrier properties • Electrical insulation What forms are available for this material? • Sheet form (Source: http://www.flexfilm.com) What is the next step? In our search for the material which can sustain outdoor weather impacts and has mylar-like properties we came across following materials. The criteria used for material selection are as follow: • Thickness of around 0.05” to 0.1” • High durability • Chemical-heat resistance. • Flexibility • Light weight
Material Exploration Shape Retaining Plastic
Image 21. Shape Retaining Plastic
Image 22. Shape Retaining Plastic Rolled
What is this material? • This is a 100% polyethelene plastic that can hold its position when bent and does not bounce back. Its malleability is due to its manufacturing process. The plastic is produced by first extruding and then stretching. The stretching orients all the molecules along the same axis. The manufacturer initially intended to add strength to the polyethelene. Stretching does in fact successfully add strength to material and shape retention is an unintended side-effect. • This material can only deform latitudinally. It will crack once bent longitudinally. • This material will lose 20% of its original stiffness after 30 bends. However, the material is quite durable as it does not break after 10,000 bends. • This material has a return angle of 4 degrees meaning after it is bent into the desired shape, it tends to kick back about 4 degrees. • This material is used as replacement for metal as it also posesses shape retention ability. There are fewer concerns in regards to safety, allergies. Shape retaining plastic is lighter, not conductive and not detectable by x-ray. What are the most notable properties? • Shape retention • Foldability • Light weight What forms are available for this material? • Strip form • Sheet form • Bar stick Notes: These forms can be supplied with adhesive backing (Source: Inventables - https://www.inventables.com/)
Multi-Directional Shape Retaining Plastic
Image 23. Multi-Directional Shape Retaining Plastic
What is this material? • This version of the Shape Retaining Plastic comes in a 4-ply vertically and horizontally laminated, flexible HDPE (high density polyethelene) sheet that can be bent and hold its position in any direction. • This material can withstand the maximum temperature of 180 degree Farenheit (or 80 degree Celsius) What are the most notable properties? • Shape retention • Multi-directional Foldability • Light weight What forms are available for this material? • Sheet Notes: These forms can be supplied with adhesive backing (Source: Inventables - https://www.inventables.com/)
Image 24. Carbon Fiber Sheet
What is this material? • Carbon fiber is a material consisting of fibers about 5-10 microns in diameter and composed mostly of bundled carbon atoms. These fibers are then impregnated with resin or epoxy and hardener to produce a high strength-to-weight-ratio sheet of carbon fiber sheet. • With all the pre-impregnated epoxy composite materials, carbon fiber sheet is very tough. It can withstand temperatures over 100 degree Celsius. Additionally it is highly resistant to corrosion, thus having great longevity. What are the most notable properties? • High tensile strength • Durability • Corrosion-resistance • Low thermal expansion • Light weight What forms are available for this material? • Sheet (Source: www.carbonology.com)
Carbon Fiber Sheet
Thin Film Photovoltaics Solar Panel
Image 25. Thin Film Solar Panel
What is this material? • This material is created by the depostion of one or more thin films of photovoltaic material (a-Si, TF-Si, CdTe, CIS, CIGS, DSC) on a substrate (a semiconductor material). The thickness of these layers varies a few nanometers to tens of micrometers. • This material has lower enegry conversion efficiency than the conventional photovolatics solar cells (approximately 9%-12%). However it is a lot cheaper to produce. Additionally, because of its superior flexibility, it can be applied to variety of special places. What are the most notable properties? • Energy Generation • Flexibility • Light weight What forms are available for this material? • Sheet (Source: http://www.brijfootcare.in/solar-technologies)
UHMW Polyethelene Film
Image 26. UHMW Polyethelene Film
What is this material? • Ultra high molecular weight Polyethelene (UHMW) possesses high abrasion (wear & tear) resistance. In certain forms, this material has even higher abrasion resistance than carbon steel. This material is as slippery as Teflon, aka PTFE (polytetrafluoroethylene) • This material is odorless, tasteless and non-toxic, thus appropriate for food-related applications. • This material is currently used for Inner-outer surfaces of chemical, water, fuel storage facilities. What are the most notable properties? • High abrasion resistance • Low moisture absorption • Self-lubrication • High impact strength What forms are available for this material? • Sheet • Slit roll • Custom and standard die-cut shapes (Source: http://catalog.cshyde.com/viewitems/films/uhmw-pe-film)
Nylon 6-6 Film What is this material? • This material possesses high viscosity level. It is a polyamide thermoplastic resin suitable for molding and extrusiin applications such as film and tubing. Nylon 6-6 can maintain its physical properties over a large temperature range. • Nylon 6-6’s melting point is at 265 degree Celcius, which is on the high end for synthetic fiber • Nylon 6-6 has a dense structure with evenly-spaced pores. This makes it difficult to dye the material, however it is colorfast and impervious to fading due to sunlight and yellowing due to nitrous oxide once dyed. What are the most notable properties? • Heat and friction resistance • High Resilience What forms are available for this material? • Sheet (Source: http://catalog.cshyde.com/viewitems/films/) Image 27. Nylon 6-6 Film
Image 28. PES Ultrason Film
Image 29. PES membrane cartridge filter
PES Ultrason Film What is this material? • Polyethersulfone Resin (PES) Ultrason is used in electrical, aerospace, automotive, and mass transit industries • This material is good for continuous use in temperatures up to 356 degree Farenheit with exceptional tensile and flexural strength. What are the most notable properties? • High resistance to heat and combustibility • Low smoke emission • Transparency • Light weight • High tear initiation • Propagation strength • Dimensional stability • Chemical resistance • Thermoformability What forms are available for this material? • Sheet (Source: http://catalog.cshyde.com/viewitems/films/)
MKIIIQ Solar Panel What is this material? • Light weight solar cells with 20% efficiency panel based on about 1/10 of solar cells used in similar size. • energy produced- 200 watts/ 1m2 panel • cost: $ 0.94/ watt What are the most notable properties? • -no tracking needed • -uses diffused light • -has a flat panel • - Low maintenance • -can be transformed into different shapes • -uses non-toxic materials What forms are available for this material? • Tailored to projects (Source: http://www.greensun.biz/Products/)
Material & Shadow Studies The material study is one of the most importance aspects of this study to understand functions the wing could perform with combination of different materials and its properties. Materials chosen for this study are the once which met with the material selection criteria for this. Properties such as flexibility, transparency, sturdiness are given preferences. Since, not all materials can be acquired easily, 3D modelling softwares were used to model these modules to ease visualization and understand shadow patterns. Balsa wood, thick plastic sheets are used as a material for skeleton and its primary function is to hold wings in place and allow for the desired wing movement. Transparent tinted and clear plastic sheets, opaque plastic sheets are used as the wing material. Lightweight and transparency are the properties which were considered important for â€˜wingsâ€™ as they reduce load on stress diamond and percolate light. This module has potential to be used as a facade-shading device and thus, the above mentioned properties of wing-materials are mandatory. The materials were applied on the shapes studied earlier and slight modifications were made to accommodate skeleton. After applying materials to specific element of module observations were made to understand combined effect of material and shapes ( form, perforations) on the shadow patterns. In order to be more precise, these shadow studies were conducted for â€˜ summer and winter solstice days. Since we studied shadows for extreme sun angles, we were able to define the movement shadow patterns were forming. It also enabled us to compare different prototypes and their form-shadows. After studying these aspects for one material combination, we interchanged these materials within the same module and made same studies. For instance, if mylar is used for the wings and polypropylene is used for skeleton and stress diamond in one combination, the other combination interchanged the materials using mylar for skeleton and stress diamond and polypropylene for wings. In some cases initially intended perforations were covered with opaque or transparent material to form interesting shadow effects. This process was used for all modules and materials.
Another aspect that we undertook n this shape and material study was the incorporation of perforations and the kind of materials that would affect the functionality of the wing surface. A study was carried out to create longitudinal slits across the length of the wing surface that would enable action similar to that of a pergola device. This prototype was studied through #D modelling and it yielded results conducive to efficient use in the building industry. The slits were then converted to resemble louvers which can be controlled to regulate the amount of light being let through the surface. This action of the louvers can be incorporated into the design of the surface to function as a selective shading device that is inspired from blinds. The material of these louvers is reflective metal that diverts light according to the angle at which the louver is maintained. The frame to support these reflective louvers are designed of opaque plastic which is simulated to support PV film that could further increase the surface area exposed to the sun to harness more energy and convert it to more usable forms through the PV cells. The movement of these fins facilitates more collection of solar power and this aspect is studied in the material study to address the application of this design in the construction industry. The results obtained from this study gave us possible range of material combinations and shapes and triggered our further research in material studies.
Material Lamination Petal Combinations Various combinations of different materials were tested using the lamination method. Depending on their physical properties such as transparency, flexibility, stiffness, shape memory, etc., materials were used accordingly to provide potentially interesting results once used in real-life application.
Shadow Studies | Model 1 Summer Solstice Study Wood Grey Tinted Petal
Module 01: OP4- Summer solistics study
Shadow Studies - Model 1 Winter Solstice Study Polypropylene & Acrylic Petal 10.30 am
Module 01: OP3- Winter solistics study
Shadow Studies - Model 2 Summer Solstice Study Blue Tinted Opaque Petal 7.30 am
Module 01: OP1- Summer solistics study
Shadow Studies - Model 2 Summer Solstice Study Polypropylene Petal 7.30 am
Module 01: OP2- Summer solistics study
Shadow Studies - Model 2 Summer Solstice Study Polarizing Material for Petal & Perforated Layer 10.30 am
Shadow Studies - Model 3 Summer Solstice Study Wood for Petal â€œSkeletonâ€?
Module 03: OP3- Summer solistics study
Shadow Studies - Model 3 Winter Solstice Study Transparent Clear Acrylic Petal “Skeleton” 10.30 am
Shadow Studies - Model 4 Summer Solstice Study Reflective Louvers 8.00 am
Module 04: OP1- Summer solistics study
Shadow Studies - Model 4 Winter Solstice Study Reflective Louvers 9.00 am
Module 04: OP1- Winter solistics study
Shadow Studies - Model 4 Summer Solstice Study Reflective Louvers 8.00 am
Module 04: OP2- Summer solistics study
Shadow Studies - Model 4 Winter Solstice Study Reflective Louvers 9.00 am
Module 04: OP2- Winter solistics study
Actuation Prototype - Protype v.1 Prototype description: This prototype is derived from our effort to slowly remove the pressure applied directly onto the petal by our own fingers. Prototype v.1.1 has a base with two sticks that come through the two holes located by the two pressing tips of the petal. We did not need to apply pressure directly onto the petal in order to get the flapping to occur. Instead, we would only apply pressure to the tips of the two sticks. As the sticks are pressed together, the resulting bowing of the sticks causes the petal to close itself. After having done this, we realized that we needed something that can replace the pressure that causes the bowing. Consequently, prototype v.1.2 was derived. Prototype v.1.2 shows the true departure from the pressure-based actuation. We have decided to use nitinol, a material that contracts in response to heat, as the replacing actuation means. As the material pulls on itself, it pulls the two sides of the petal forcing them to close. Materials: • Mylar • Wooden sticks • Nitinol • Cardboard • Rubber band • Tape
Actuation Prototype - Protype v.2 Prototype description: This prototype aims to take advantage of shrinkage of nitinol due to the introduction of electrical current. It comprises of 2 semi-circular frames that rotate around a central pivot. This prototype aimed to study merely the actuation method using nitinol; hence we did not include the petal component. As we conducted experiments with this particular prototype, 2 issues occurred: • There is a lot of friction occuring inside the holes through which the semi-circular jigs are placed.This consequently caused the movement of the jigs to be a lot less fluid than what we had anticipated. • The two semi-circular jigs are disconnected at the base. Once the movement is induced, it appeared difficult to have the 2 jigs to move in unison. Possible improvement strategies: • Decrease the amount of friction inside the holes • Connect the 2 jigs at the base Materials: • Wooden sticks • Nitinol • 1.5 ply chipboard • Glue
Actuation Prototype - Protype v.3 Prototype description: On the same lines of actuation as the previous prototype, Nitinol is used to create the desired movement. However, some modifications have been made. It comprises of 2 semi-circular frames that rotate around a central pivot point.The petal components are made of mylar sheet and attached to the two jigs, which means that once movement is induced, the two petals close. In addition, the two jigs are connected at the base. As we conducted experiments with this particular prototype, 2 issues occurred: • There is a lot of friction occuring inside the holes through which the semi-circular jigs are placed.This consequently caused the movement of the jigs to be a lot less fluid than what we had anticipated. • We’ve set up a rig which the nitinol is strung tight on one side of the prototype and then connected to the power source. As the nitinol shrunk, instead of causing the two jigs to move uni-directionally towards each other, it caused them to move towards the power source resulting in the buckling of the prototype itself. Possible improvement strategies: • Decrease the amount of friction inside the holes • Refine the set-up to avoid buckling Materials: • Mylar • Wooden sticks • 1.5 ply chipboard • Glue
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Actuation Prototype - Protype v.4
Prototype description: This prototype departed from the semi-circular jigs, as we decided to try a different way movement can be induced via the use of nitinol. The “flapping” movement that we had anticipated was translated simply into a system that has 2 separate arms that move along their own rotational axis. The nitinol is strung through the 2 arms, causing them to close after it shrinks.We have developed 2 other variations of this prototype, to explore issues such as range of motion and repeatability of the actuation system. As we conducted the experiements, we have discovered several issues: • After the nitinol shrank to cause the “flapping” movement that we expected, it left a lot of slacks which eventually caused the arms unable to return to its initial position. • The “flapping” movement occured, however it was not as formally dynamic as that of the origami technique. Possible improvement strategies: • Possible addition of a spring in order to encourage the “return” movement. • Explore ways to increase the formal dynamics of the petals Materials: • Mylar • Wooden sticks • 1.5 ply chipboard • Glue
Prototype 4 - Variation 2
Prototype 4 - Variation 3
Actuation Prototype - Protype v.5 Prototype description: This prototype explored the gear mechanism that is triggered by the shrinkage of the nitinol. The “flapping” movement that we had anticipated was translated simply into a gear-based system. The nitinol is strung through the 2 saw-toothed bars causing them to move inward after it shrinks. This ultimately triggers the gears to rotate, hence producing the “flapping movement”. As we conducted the experiements, we have discovered several issues: • After the nitinol shrank to cause the “flapping” movement that we expected, it left a lot of slacks which eventually caused the bars unable to return to its initial position. • The two petals are separately attached onto the two top gears.. The “flapping” movement occured, however it was not as formally dynamic as that of the origami technique, where the two petals are part of a continous piece. Possible improvement strategies: • Possible addition of a spring in order to encourage the “return” movement. • Explore ways to increase the formal dynamics of the petals Materials: • Mylar • Wooden sticks • 1.5 ply chipboard • Glue
Actuation Prototype - Protype v.6 Prototype description: We decided to try a different way movement can be induced via the use of nitinol. The “flapping” movement that we had anticipated was translated simply into a system that has 2 separate arms that move along 1 shared rotational axis. The nitinol is strung through the 2 arms, causing them to close after it shrinks. We have developed 2 other variations of this prototype, as to explore issues such as range of motion and repeatability of the actuation system. As we conducted the experiements, we have discovered several issues: • Due to the lack of attachment base, the system has to be held while being operated. • Because the petals are made of the same materials as the system itsef, there was a lack of a gradient in material mallability. This ultimately caused the “flapping” movement to not be as formally dynamic as that of the origami technique. Possible improvement strategies: • Possible addition of an attachment base to stabilize the system in its operation • Explore ways to integrate petals that are made of different materials into the system Materials: • Bass wood • Wood dowels
Prototype 6 - Variation 2
Prototype 6 - Variation 3
Actuation Prototype - Protype v.7 Prototype description: This prototype is made of two main elements: the closing arms and a shape retentive base that keeps the flap from losing its curvature, letting the wing to regain its shape which is an inherent property of the material used. The two arms forming the petals/ wings replicate the dynamic movements established in the initial stages of the study, only that this time the action of nitinol is used to obtain this movement. As we conductedAs we conducted the experiements, we have discovered several issues: • The shape retention base distorted the shape and did not perform as well as what we had anticipated in terms of shape retention. • After the nitinol shrank to cause the closing action of the 2 arms that we expected, it left a lot of slack which eventually caused the bars to remain where they were and not return to the previous position. Possible improvement strategies: • Reengineering the base to reduce shape distortion. • Explore ways to ensure the “return” of nitinol to its initial position after the operation is carried out Materials: • Mylar • Wooden sticks • 1.5 ply chipboard • Glue
Actuation Prototype - Protype v.8 Prototype description: This prototype, comprised of 2 racks and 2 gears, causes the “close” movement using the shrinkage of nitinol. As the nitinol is introduced to electrical current, it shrinks and pulls inward the 2 racks through which it is strung. The 2 racks moving causes the gears to rotate, resulting in the “close” movement. As we conducted various experiments with this particular prototype, we have discovered several issues: • The racks did not move as smoothly as anticipated due to the set up for the prototype on the base. Instead of moving inward, they were pulled outward towards where the nitinol is connected to the power source. • Non-unison movement of the racks causes the petals to not have the same range of motion • Friction prevents the gear & ratio interaction from being smooth Possible improvement strategies: • Explore use new materials that do not create so much friction. • Re-engineering the base so that the nitinol can effectively and efficiently induce the inward movement of the racks. Materials: • Mylar • Wooden sticks • 1.5 ply chipboard • Glue
Actuation Prototype - Protype v.9 Prototype description: Similarly to prototype 8, this particular prototype employs a system of rack and gears to create the “close” movement of the petals.The rack is alligned and pulled vertically by the nitinol due to its shrinkage. As it moves, it causes the 2 gears to move, creating the “close” movement we anticipated. We’ve figured out that in order for the petals to achieve the expected range of motion, the rack would need to move 0.5 inch. In order to cause the rack to move downward at that distance, we would need to have the nitnol to be 10 inches or longer. Due to this calculation, the prototype turned out to be vertical to compensate for the required length of the nitinol. Due to various experiments with this prototype, we’ve observed several issues: Friction, once again, becomes an issue with the movement of the rack The system, though achieving the anticipated “close” movement, is not capable of returning to its initial position. Possible improvement strategies: • Possible addition of a spring in order to encourage the “return” movement. • Explore different materials for less friction Materials: • Mylar • Wooden sticks • 1.5 in davy board • Glue
Actuation Prototype - Protype v.10 Prototype description: This prototype is the refined version of prototype 9, and is also our selected prototype to proceed with the architectural application. We made some modifications based on our observations from previous experiments with prototype 9. They are as follow: • The gear has a smaller number of teeth.The teeth are only present on the portion of the gear that comes into interaction with the rack, as it moves. • The extending arms clip into the petal, which is comprised of two different materials. • The rack is reduced in size in order to make the overall body of the prototype more compact. • A spring is added to the head of the prototype in order to aid with the “return” movement of the petal. Materials: • Mylar • White Flexible Plastic • Wooden sticks • 1.5 in davy board • Glue • Black Acrylic
Architectural Application After arriving to a final prototype that meets our expectation, we’ve made an attempt to explore possible application of our newly-developed system. Shading device seems to be the most appropriate application for our system. The system is capable of not only shading the building’s facade, but also permit sunlight to enter interior spaces as it closes.
Shading device in operation: “Flap” open shading unwanted sun
Shading device in operation: Close up to let in sunlight
References Volkov A. & Foster J. & Baker K. & Markin V. (2010) â€œMechanical and Electrical anisotropy in Mimosa pudica pulviniâ€? - Plant Signaling & Behavior 5:10, 1211 - 1221 http://www.landesbioscience.com/journals/psb/VolkovPSB5-10.pdf?nocache=1323024341 http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.1979.tb00870.x/pdf Physiological and anatomical investigations on mimosa pudica or touch-me-not plant http://lifeofplant.blogspot.com/2011/03/nastic-movements.html A study of excitability in plant with the touch-me-not plant being the main model http://www.mls.sophia.ac.jp/~kanzawa/research-e.html On adaptive strategies developed in Mimosa pudica http://biology.stackexchange.com/questions/1114/why-did-the-sensitive-plant-mimosapudica-evolve-its-leaf-closing-mechanism Evolutionary Explanation for Mimosa Image 1. Mimosa Pudica Flower http://pcdn.500px.net/5548967/072d496c656d61b615c8606211514f2eb93d3f1c/4.jpg Image 2. Mimosa Pudica Leaf http://www.flickr.com/photos/idizc/3642074918/sizes/l/in/photostream/ Image 3. Mimosa Leaf closing http://www.esacademic.com/pictures/eswiki/77/Mimosa_pudica_Feuille2.jpg Image 4. Mimosa Leaf Half-closed http://www.flickr.com/photos/thtungdl/2736017960/sizes/l/in/photostream/ Image 5. Mimosa Leaf fully closed http://www.flickr.com/photos/blueridgekitties/4041732414/sizes/l/in/photostream/ Image 6. Mimosa Leaves http://www.flickr.com/photos/k_v_/3595593161/sizes/o/ Image 7. Mimosa Leaves Close-Up http://www.flickr.com/photos/95159322@N00/866008174/sizes/l/ Image 8. Mimosa Leaflet Close-Up http://www.flickr.com/photos/13389908@N03/1782935196/sizes/l/ Image 9. Mimosa Leaves Close-Up http://www.flickr.com/photos/nuriamp/3839464365/sizes/l/ Image 10 . Origami Swan http://eliinbar.files.wordpress.com/2011/02/origami-crane1lg1.jpg Image 11. Origami Pelican http://www.origami-fun.com/images/Pelican_l.gif Image 12. Origami Polyhedra http://www.flickr.com/photos/goorigami/6524984307/
Image 13. Nitinol Sample http://www.osypka.de/media/Nitinol-flechten_web_252_0765.jpg Image 14. Nitinol tubing http://cdn.content.compendiumblog.com/uploads/user/ Image 15. Nitinol Stent 1 http://www.biomaterials.org/images/biomat_of_month/Dummy_Stent.jpg Image 16. Nitinol Stent 2 http://info.admet.com/Portals/70514/images/stent.jpg Image 17. Nitinol. spring http://file.seekpart.com/productsimage/2012/6/20/20126201618575317.jpg Image 18. Nitinol forms http://www.keytometals.com/images/Articles/ktn/Fig212_2.jpg Image 19. BoPET mylar sheet http://media5.rsdelivers.cataloguesolutions.com/LargeProductImages/R53639701.jpg Image 20. BoPET plastic sheet http://www.b2bir.com/uploadedimages/57637111.jpg Image 21. Shape Retaining Plastic Strip https://dzevsq2emy08i.cloudfront.net/paperclip/technology_image_uploaded_ images/3540/default/865_big_web.jpg?1335199292 Image 22. Shape Retaining Plastic Strip rolled http://openmaterials.org/wp-content/uploads/2011/06/1314_big_web.jpg Image 23. Multi-Directional Shape Retaining Plastic Strip https://dzevsq2emy08i.cloudfront.net/paperclip/technology_image_uploaded_ images/10932/default/300x400.jpg?1335201474 Image 24. Carbon Fiber sheet http://images.thetruthaboutcars.com/2012/04/carbon-fiber-frame-lg.jpg Image 25. Thin Film Solar Panel http://www.brijfootcare.in/wp-content/uploads/2012/05/flexible-solar-panel.jpg Image 26. UHMW Polyethelene Film http://catalog.cshyde.com/image?cid=1472&plpver=1002&categid=1002&prod id=3001039 Image 27. Nylon 6-6 Film http://catalog.cshyde.com/image?cid=1472&plpver=1002&categid=1002&prod id=3001248
Image 28. PES Ultrason Film http://catalog.cshyde.com/image?cid=1472&plpver=1002&categid=1002&prodid=3001042 Image 29. PES membrane cartridge filter http://www.filtersource.com/mc_images/category/152/ztec-b.jpg