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strctures - Contenido educativo

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Subido el 27 de diciembre de 2022 por Isabel L.

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In this case we are going to talk about structures. 00:00:01
Well, each object also always have at least a structure and is the shape. 00:00:06
And the shape, you can get the shape joining different elements, different structural elements. 00:00:20
So we can define a structure as a set of elements arranged in an optimal way to support a body or an object. 00:00:30
It gives the object its shape, although it can be under different loads, different forces. 00:00:40
So we can have different types of structures. 00:00:51
we can have carcasses that just only protect part of the machines but they are never under any load 00:00:54
but in other case we have mass structures without any hole, truss structures composed by bars 00:01:06
which can form triangles, frame structures which are formed for columns and beams that 00:01:16
support different elements such as buildings for example, or suspended structures that are 00:01:28
holding by different types of cables. Indeed, you have three main important things. One is 00:01:35
is the materials in which you build the different parts of the structures. 00:01:47
Structures are usually composed by a set of elements, so each element is built in a specific material 00:01:55
that in conclusion is supporting the forces. 00:02:06
And forces, what are forces? Well, it's complicated to, it's not easy to define force, but we can define force taking into consideration its effects. 00:02:14
What I'm trying to say is a force can change the movement state of the object or if the objects are unable to move, they change its form. 00:02:30
So, this is a force and forces are something that we are going to explain better later. 00:02:48
Forces are under the dynamic law. 00:03:02
We have three dynamic laws. First, tell us that what I have already said, that forces can change the movement state or they can change the shape of the element. 00:03:06
The other two is in this slide. 00:03:25
Force can be mass and acceleration, and the forces usually works in pairs. 00:03:29
If you have an action, you can also have a reaction force that usually is more or less the same, equal, and in different sense. 00:03:42
Apart from this, in a structure is also important how the different elements join, what we usually call ligatures. 00:03:53
We can have some ligatures that can move, but in other times we need some ligatures such as guides 00:04:09
guides, such as others, that can rotate, for example, joints can rotate or have different types of movement. 00:04:23
So, from the material's point of view, if one material is under loads, is under forces, they can have different behaviors. 00:04:37
In this sledge the better or the best, for example is for materials, you always have a zone in which if you stop applying the force, the material can recover its shape, its length. 00:04:53
If you apply a force, obviously, it tends to change its length, which is usually called deformation. 00:05:23
Some materials, if you continue increasing the force, you can change the shape of the materials in a permanent way. 00:05:36
but without breaking, but others break if you try to change its shape. 00:05:51
So, when you are building different structures, you always have to build in the elastic zone, 00:06:04
in the zone in which the materials can recover its length so not only so is important 00:06:17
the quantity of the of the stress but it's also important how you do this stress you you can have 00:06:30
five elements five elements stresses that are compression if you tend to 00:06:39
to do the elements shortened, tension if you increase its length, shear if you try to cut 00:06:46
in something, bending when you flexure or bend, or torsion if you torsion something. 00:06:59
you have more than one type of this, an addition of more than one, well and so 00:07:12
you have a different forces, stresses and moments. One thing important is moments and 00:07:24
stresses, moments and loads are vectors. What does this mean? Well, in vectors you 00:07:38
need to give more information than just only its value. You need to study 00:07:48
them as vectors with a point of application, direction, sense and also 00:07:58
So, if you want to do the sum of two vectors, it's not just only to sum its values. 00:08:06
You can do this if the vectors have the same direction, but if the direction is different, 00:08:23
You must do the polygon to know the value of the force or the value of the addition. 00:08:30
So sometimes it can be important and if you want to have a structure in a static equilibrium 00:08:42
is obviously important that all the forces and all the movements can be compensated 00:08:52
that is means that the sum is O but this sum are vectorial sum you must do the sum 00:09:01
in a vectorial way apart from this you have some typical elements of a structure such as arches 00:09:10
pillars, straps, beams, that are always, for example, arches are always under bending, 00:09:21
pillars are always under compression, straps under tension, beams under bending also. So if 00:09:32
you can know the different elements in a structure, you can also know the type of 00:09:42
stress that they are a to to have a better structure without so many ways 00:09:48
without increasing it ways you can use a what we usually call triangle triangular 00:10:02
triangular structures in this case if you do the triangle is the 00:10:12
polygon will have just only three bars in this case or three sticks so they 00:10:29
can change its shape and this can make the structure more standard, more 00:10:43
stringy. If you have to study different structures you must 00:10:55
take into consideration the equilibrium of forces and also the 00:11:07
of movements and in each part of this structure you can know its value using the polygonal addition 00:11:13
and scale. If you do a scale the polygonal addition you can know the value of the forces 00:11:26
in each bar, and obviously the type of stress that they are supporting. 00:11:37
You also have another type of method to resolve or solve different types of structures, as 00:11:51
you can see here, if the structure, for example, is asymmetric, you can use Cremona method 00:11:59
return that is more or less what I have already explained but in this case for more complicated 00:12:08
structure. To do a good analyze of the structure we usually use some types of diagrams. 00:12:17
For example, here we know the diagram of the shear force, and to understand this, you can know it is traction, compression, cutting, and types of movements. 00:12:29
And here you have, for example, for forces, you can use the stress and surface, and for movement you can use this other thing in which you have other parameters. 00:12:49
In each part is also important the shape of the bar, because the distance to neutral free bar is also different. 00:13:05
So it can be different the dimensions in a bar depending on the profiles. 00:13:20
And finally, the structure as a whole must be studied because it must be obviously stable. 00:13:31
And to study the stability of a structure, we need to know the point, the action of gravity, 00:13:43
we need to know the point of application of the weight of the structure. 00:13:58
to do this we use this point and must must have to if I want a very stable 00:14:06
structure this point must be in the low zone and between the legs or the super 00:14:16
versus supports. This is all about the structures. I hope you can understand it better. 00:14:30
Idioma/s:
en
Autor/es:
isabel Lafuente
Subido por:
Isabel L.
Licencia:
Reconocimiento - No comercial
Visualizaciones:
35
Fecha:
27 de diciembre de 2022 - 16:54
Visibilidad:
Público
Centro:
IES EL BURGO - IGNACIO ECHEVERRÍA
Duración:
14′ 39″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
1440x1080 píxeles
Tamaño:
118.70 MBytes

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