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Structures - Coggle Diagram
Structures
Types of structures
Frame structures. The frame structure is the most common type of structure.
These structures have long elements (bars, tubes...) joined to each other at the ends.
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The elements in the bicycle’s frame are the aluminium tubes; the unions are the aluminium
welding, the nuts and bolts...
Advantages: they are relatively easy to design and build, inexpensive to manufacture, lightweight and do not require much material
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Shell structures. Shell structures are made of a thin outer layer of material around a volume. That volume can be empty space or contain something with no structural relevance.
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The shell can be thin because the forces are spread throughout
the whole structure, dissipating the load all over the shell.
There are many examples of natural shell structures: eggs,
shellfish...
There are also many examples of artificial shell structures:
cardboard boxes, bottles, balloons, cars, aeroplanes...
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Mix and Match. Very often, we combine different types of structures into a more complex structure.
For example, houses have brick walls (mass structures), columns
and beams (elements of a frame structure), etc. 
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Suspension structures. A suspension structure holds an element (often a beam) by cables that are held from the top of a tall column.
The space (distance) between one column and the next is called the “span”. This type of structure has the longest span of all structures.
Because of this, suspension structures are often best for bridges that cover big rivers or even small parts of the sea
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Forces on structural elementsA successful structure supports all the forces that act on it. Each of the elements in the structure supports a type of force, which is a result of the load that the structure supports.
Tension This is the force that stretches an element. Tensional forces normally pull an element from its ends.
Compression This is the force which squeezes or buckles an element. When we “squeeze” an element, it becomes shorter and thicker.
When an element “bends” in the middle due to the compression forces, it “buckles”. In the case of buckling, an element loses its strength and, if the force doesn’t disappear quickly, the buckling continues until the element breaks.
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Torsion. If we apply a turning force (called “torque”) at one end of an element and, if the element is fixed to a support at the other end, the element twists. If the element isn’t fixed at the other end it turns without changing shape.
Bending. Bending forces act at an angle to the element (at 90º in the drawing), making it bend.
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Analysis of structural behaviour, using
different models.
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Types of unions. The structural elements must be united to each other.
The structure is often united to the floor/ground.
Permanent unions These are for structures that we don’t need to disassemble. Examples: welding, rivets, glue...
Non-permanent unions With non-permanent unions we can assemble and disassemble the elements of the structure. Examples: nuts and bolts, clamps, friction ...
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Applications. The design of the structure of an object (a beam for a house, the shell of a car, etc) helps reduce the amount of material used. This reduces the price and the weight and improves safety.
For example, we design the shell of a car so that
the shell is as thin as possible to reduce weight.