WXYZ Chair
___Cardboard Chair Project
ARC104 Name: Nan.Yang ID number: 10116493
Material Research Brief Corrugated cardboard is a stiff, strong, and light-weight material made up of some layers of brown kraft paper. Corrugated fiberboard is a paper-based material consisting of a fluted corrugated sheet and one or two flat linerboards. It is typically used in the manufacture of corrugated boxes and shipping containers. The corrugated medium and linerboard are made of containerboard, a paper-like material usually over ten mils (0.010 inch, or 0.25 mm) thick. Paperboard and corrugated fiberboard are sometimes called cardboard; although cardboard might be any heavy paper-pulp based board. Structural Properties Types: Single wall cardboard is the most common form and is one piece of fluted paper sandwiched between two cardboard pieces. Double wall cardboard has two layers of fluting between three layers of cardboard and triple wall cardboard has three layers of fluting between four layers of cardboard.
A finished piece of cardboard consists of a single corrugated layer sandwiched between two liner layers.
Grain in one direction. clearly in wood and in the wavy layer of cardboard.
Durability: The wood fibers that make up cardboard are strong and resilient. Cardboard is puncture resistant and does not tear easily. The arched design of the interior fluting lends durability to the cardboard as well. The fluting is lined up vertically, so the interior paper forms columns that are able to support a great deal of weight. Insulating: When force is applied to an arch, it transfers along the curve of the arch to the base. Therefore, the arched flutes allow the cardboard to stand more external force. The flutes also trap air between the two layers of cardboard, extending the amount of time needed to transfer heat energy from the exterior of the box to the interior. Orthotropic Material The cardboard we will use is an orthotropic material. This means it is stronger, both in compression and tension, in one direction than in the other. Cardboard structure as support, the small air pockets inside the sheets of cardboard act as tiny columns to support weight when that weight is applied along the side of the corrugation Since material is strongest in compression and tension along its orthotropic lines, it will be essential for us to cut cardboard with this in mind.
First Design: Search for Stable and Simple
Friction Between Layers At the beginning, I want to use soft cardboard to roll it to a big column as support and cut part of it for seat. Even it is possible, but it’s difficult to cut. When soft material gather together, it is flexible and stable in a shape. The same situation, the friction between many layers or material itself is strong. Crossing Structure Then we discus about crossing structure which can take Force easily from top to bottom. It is stable for tolerate compression and tension. The shortage is that crossing is not stable for bending and horizontal lateral Force. Tube Structure When vertical loads act, the perimeter frames aligned in the direction of loads act as the webs of the tube cantilever and columns. Even though framed tube is a structurally efficient form, horizontal frames tend to suffer from shear force.
First Design: Search for Stable Design Introduction The main structure is composed of a tube structure. There is no glue or any other type of fastener; the structure is held together from strategic slotting of the components and the friction between them. It is capable of holding upwards 70 kg. Feedback and problems 1.Static and Dynamic Loads As long as a person sits still on the stool the load is said to be static (or not moving.) If the user does not sit down gently or moves around while sitting the load is dynamic (or moving.) We have seen this when we observed the little girl, it is easier to break something with a quick shot than with a gradual and steady force. Dynamic loads require bigger scale structure strength or a higher factor of safety.
2.Loads at unexpected locations Not everyone will sit on chair where we planned. For example, girl may sit on the front edge rather than center of the seat. This would put a greater load on the fringe so we need other load bearing members. Therefore it is useful to plan your structure for the person who may not follow your instructions about where to sit. The strength of the material available and the amount of it may not allow us to make our chair strong enough to increase its factor of safety. Thus, we will have to work to get the most from the least. 3.Making Joints Tight Keeping in mind that your chair will fail at its weakest link, we should make slots that will not allow any motion or "play" of the members as they sit in the joints. We should try to cut all slots carefully so they are straight, parallel and the exact width of the material that will fit into them. Many chairs fail from unwanted swaying. 4.Playful and popular for more people
Second Design: Construction and Process Introduction The bench is composed of series of cardboard sections.. It is capable of holding upwards of 5 persons’ weight, and is actually very free to sit or lie. Slot Joint Each piece of the cardboard section is formed from identically cut and component becomes a support, connector. There is no glue or any other type of fastener; the structure is held together from strategic slotting of the components and the friction between them
Construction Analysis In the construction, a method was presented for the simplified analysis of frame-tube structures under bending actions. By replacing the discrete structure by an equivalent orthotropic tube, and by making simplifying assumptions regarding the stress distributions in the structure, design curves or polygon were derived for rapid approximate analysis of the dominant behavior. Problems during construction The slots location in each piece of cardboard, they need to be accurate unless they cannot fit together. The management of pieces of finished cardboard and installation. Slot joints in different locations have some errors so we need to make slot bigger during installation. When we cut the cardboard, it’s difficult to keep the grain original for stability.
Second Design: Entertained and Multifunctional Structure and Shape From the first design, we found that tube structure is efficient with any glued or connection joints. Therefore we decided to reuse it as the main support structure for new design. In the first design, we mainly focus on the stable structure to hold the weight of people. Thus, we ignore the entertainment and other functions for a chair. This time we were going to make a chair playful and can be used in different ways. Shapes like curve or other geometry was designed. Maybe create a slide for children but it’s too big for a chair.
Sit and use in two dimensions Our version was to design a chair which can used for more than 3 children at the same time in one dimension use. (like the left pictures show) For another, the chair can also be used for one person comfortably sit.
Fail results and problems As the pictures show left, at last, we just use it in one dimension because of structure problems of the chair. The tube structure can only hold the vertical force on it. The shape we like a bridge but tube cannot connect each side. If people lie down on it, it will cause bending and break in the middle. The solution is to create truss structure inside the each tube or stable structure to connect the frame of rectangle possibly like triangle frame.
Final Design: Children Scale and Behaviors Research Brief The design of chairs and seats has been hampered by a lack of detailed anthropometric data directly relevant to the design problem. Traditional lengths, widths, and circumferences are not very useful for constructing three-dimensional surfaces intended to provide comfortable support for a wide range of the design population. Posture Changes The male and female body models described above characterize body shape in the scanned posture, but often the design posture is different from the scanned posture. Using a skeletal linkage fit to the inside of the body scans, a statistical model that includes the effects of posture change was created. The images to the left and below show the effects of modifying both body mass index and seated posture over a wide range typical of automotive applications. The model illustrated here is used to conduct virtual seat fit assessments and has applications to the development of finite-element models for assessing the performance of occupant restraint systems.
Children Sitting Posture changes This is the first picture to gather three-dimensional data on child posture in automotive seated postures. The primary near-term application of the data will be to improve the design of crash dummies and computational models of child occupants. But the data will also have broad application for the design of child restraints, protective equipment, clothing, and other products and environments that interact physically with children in this age range.
Behaviors for Design scheme There are a few different types of children's chairs. Some are built like a small chair for just one child; these are appropriate for a reading book or a play corner. Another type of chair is one that folds into a bed. Sofa chair can be made narrow, for an individual child, or made to look more like a sofa upon which two children can sit when it’s folded up, or sleep on when it is opened up as a mattress.
Final Design: Comfortable and Enjoyable Design introduction Our lounge chair turns into a designer chair after we took ergonomic into consideration. Simply, assembled from many durable pieces of material, combined with a modern, minimalist look. The chair is comfortable in function, offering children the opportunity to interact with them in different ways. Development from previous design The integrated bench is inadequate in a number of ways: specifically, it has limited accessibility and provide no upper body, lower body, or extremity support. Naturally, a larger child will require a stronger device, and a stronger device will require stronger and, most likely, using bulkier and heavier material. Unfortunately, bulky, heavy material is in direct conflict with mobility and storage like cardboard. Characters Safety: the seat area is 50x70cm which is enough for two kids Accessibility: Small incline ramp ensures ability to push upwards Enjoyable and comfortable design based on physical body
Final Design: Comfortable and Enjoyable Layers Vertical layers are made of 10 cardboard layers, but each 2 layers get together as a main support structure, the dimension between is 15cm. The curve of layer is designed based on human body research. It is also rely on the force from human body through the structure in different locations. Horizontal layers are consisted of many pieces of cardboard whose length is 70cm to cover the whole curve surface, back and bottom. Horizontal layers
Vertical layers
Double layers joints The slot we design is just suitable for 2 layers difficulty fill in. During the installation, it need 4 people install it together. One needed for making the vertical layers stable, two persons need to insert one side of two layers into slot together, and another person need to confirm the 5 slot fit the layers at the same time.
The double layers joints have a tight connection because of the friction between material and the compression between vertical layers and horizontal layers.
Strength Against Bending and forces in different directions We are all familiar with the term bending. We see it, for example, when we overload a bookshelf as shown above. To understand why structural members bend we need to envision an imaginary line, known as the neutral axis, running through the length of the members. As a load is applied to the member, it bends. If the material is strong enough in compression to resist being pushed together (compressed) and strong enough in tension to resist being stretched (by a tensile force) it will not bend. The force analysis shows that in our chair’s tube structure, in different directions, forces are equal for the same layer. The more force, the more layers for tolerating.
Reflection: Tough but fruitful As projects go, this was definitely the most challenging I’ve ever participated in. I was frustrated that our project seemed to involve far more work and travel time, not to mention non-refundable personal spending on my part, than many of the projects that did not require such a big scale physical deliverable. I was also frustrated by the lack of advising. I feel that I stepped into my role of designer and team player quite well, and was happy to see the team through the project. I am no stranger to group or leadership positions, and value each one I undertake. I was pleased with WXYZ’s amazing encouragement and assistance. Any questions I had in the studio or out were instantly addressed. I felt that I learned a lot about alternative materials and how combining unconventional resources could produce a truly remarkable product. I’ve worked landscaping, construction, and as a handyman, and am very familiar with cardboard. Working with cardboard added a new dimension to the design and construction process, but in the end I was very pleased with the way the project turned out. I learned a very important lesson in communication and discussing alternative ideas with administration. The skills I’ve learned in this semester are all applicable to any project I’ll encounter in my education or eventual occupation. Advantages: High execution and self-study ability Productive and make use of information and materials Disadvantages: Difficult to be convinced and serious Lack of new, exciting and crazy ideas -Nan.Yang