Rationale
1. Research
Based on the research, for normal lifebuoy in china, the outside diameter is more than 725mm and inner diameter is more than 440 mm as well as the thicknesses are more than 107mm. However, the weight of the lifebuoy will not large than 2.5kg and buoyancy is not less than 14.5kg in fresh water up to 24 hours. Also, shell High density polyethylene buoyancy material Polyurethane foam mini order 500 pcs (in one container).
Actually, there are several materials can be mainly used in China. Most of the Life Buoys are manufactured in durable high visibility orange synthetic material and requires no maintenance, but this kind of material is not the eco material. Same as the orange synthetic material, PVC is another popular material for lifebuoy because of the cost, manufacture and durability reasons. However, the cork wood is different from others. It can satisfy all requires about durability, manufacture, and cost especially environmental friendly requirement.
Cork wood is used to describe wood from conifers. It may also be used to describe these trees, which tend to be evergreen, notable exceptions being bald cypress and the larches. The woods of longleaf pine, douglas fir, and yew are much harder in the mechanical sense than several hardwoods.Cork wood due to many air-filled cells, good insulating material, lightweight, floats. Cork cambium develops within the secondary phloem.
The brief description of the production process:
1. Cork harvest
2. Seasoning
3. Cutting the wedges
4. Boiling
5. Corkwood sorting
6. Slicing
7. Punching
8. Drastic reduction
9. Mechanical finishing
In the world wide, cork wood come out 350,000 tons per year. The main producing country is Portugal which produces 50 percent of the output of the world volume of production. China as the large producing country output 50,000 tons per year.
3. Buoyancy
The calculation of the largest weight for cork wood life buoy can be carry.
G= ρ*g*V
=0.03m3* 0.24* 103kg/m3* 9.8N/kg
=70.56N
F1=ρ*g*V
=1* 103kg/m3* 9.8N/kg* 0.03m3
=294N
F= F1- G
=294N- 70.57N = 223.44N
G=mg (g= 9.8N/kg)
∴223.44N* 9.8N/kg≈2189Kg
Based on the calculation the cork wood lifebuoy has enough buoyancy to carry a person.
The average height and weight of Chinese people:
Male: height: 1.697m weight: 67.7Kg
Female: height: 1.586m weight: 59.6Kg
4. Ergonomic
For a handle which is to be held in a power grip, the handle length should be sufficiently long to provide space for the whole palm (generally 100mm, but 110 to 120mm may be preferable). Diagonal hand width is a good approximation to define the minimum length, but the handle should not be so long as to contact the wrist. Handle of circular cross-section (and appropriate diameter 30 to 50mm) will be most comfortable to grip since there will be no possibility of high spots- but they may not provide adequate purchase for exertion of high force. Rectangular or polyhedral sections will give greater purchase but will be less comfortable. When a handle is used in a gripping action, its shape should reflect the curves of the hand- a concave surface described by the fingers opposed to a convex surface formed by the heel of the palm and base of the thumb- but with a gentle curve which does not risk exerting excessive pressure in the palms of users with small hands. The handle should be able to be used equally comfortably and efficiently by left- and right- handed users.
Reflection
The project is designing for disasters and our group force on 1998 Yangtze River Flood in China. In research part, we tried to find as much information as we can so that we through information to design the most necessary product for victims of a natural calamity. We did research on disaster events, response efforts, reconstruction efforts, socio-cultural issues, personal interview and trade literature. Based on research information, we found during the flood we can do nothing because everything was destroyed by the flood. However, it is necessary and useful to design a kind of products use to preventive and post-disaster rehabilitation for flood.
1. Concept
From the basic information, I realize that concepts most sample and useful so that people do not need to decode the usage when the critical incident appended. So, I come out three concepts which are lifebuoy, rubber bracelet and flashlight. The material of the lifebuoy is rubber and it had container build-in, because it used for emergency so I choose orange. The rubber bracelet use to generate personal information and health conditions. The flashlight I want design it becomes a tool box. At last, I choose to develop the lifebuoy and to make it become the ergonomic and convenient design.
The firstly, I have not consider that material need to be eco material. In deeply research I found that cork wood can be used for lifebuoy. Cork wood use to be the popular material because cork wood due to many air-filled cells, well insulating material, lightweight, floats. Cork cambium develops within the secondary phloem. Also cork wood is strong, light, high buoyancy and anti- corrosion material. However, the old design of cork wood life buoy does not follow the ergonomic method that if people want to grip the life buoy the only part they can use is the rope around the life buoy. So, I decide to change the original shape of the life buoy that people can easier grip and the rescue can throw it relaxed. Based on the research, the handle length should be sufficiently long to provide space for the whole palm, generally 100mm, but 110 to 120mm may be preferable. Also, Handle of circular cross-section and appropriate diameter 30 to 50mm. At last, for the convenient reason, I decide to make my life buoy as a package bench which was located at bus station, bridge, and some high terrain place so that when disaster happening it can produce the best possible results.
3. Improvement
As the industrial designer, I realize that during the concept stage I need to consider the eco material must be the first choice for me to use. To use eco material is not only the behavior to sustain environmental friendly but also it is the way to improve the value of product. As well as, for the mature design I need to consider as much using situation as I can. It is responsible behavior for all users that can develop ability of the design and the project.
