[static equilibrium] pin and link support type

In summary: Thus, a pin or link support at an angle is always a 2-force member. In summary, there are two types of support - pin and link. A pin support provides two reaction forces, fx and fy, which prevent the object from translating vertically and horizontally. A link support is similar to a pin support, but can only support axial loads. At point G, which is a pin support, there is only one force component because the member connected to it, GB, can only support axial loads. This is due to equilibrium considerations for 2-force members. The same reasoning applies for link supports, which can also be at an angle and still only support axial loads.
  • #1
kougou
82
0
Hello every one

I am confused between two support type:
the pin, and the link

On the textbook, it says, the pin prevents the object from translating vertically and horzontally, therefore, it provides fx and fy reaction forces.

but another type of support is much identical to the pin, which is the link support, the photo is here: http://imageshack.us/f/105/pinconnectiontw4.jpg/

at point A, the beam AB is subjected to the pin support, so it has two components of reaction forces, namely fx and fy

but what about at point G, how come it only provides one force components, namely fx, but not fy as well? is the point G also classified as pin support?
i am very confused; instructor said that whenever u see a pin support, there's two force components; how come this is not a case here?
 
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  • #2


is the link support the beam which connects from GB, and pin support the node at G and A?
 
  • #3


G is a pinned support as well as A. The reason there is reaction in x only at G is because member GB can support axial loads only.
 
  • #4
kougou said:
Hello every one

I am confused between two support type:
the pin, and the link

On the textbook, it says, the pin prevents the object from translating vertically and horzontally, therefore, it provides fx and fy reaction forces.

but another type of support is much identical to the pin, which is the link support, the photo is here: http://imageshack.us/f/105/pinconnectiontw4.jpg/

at point A, the beam AB is subjected to the pin support, so it has two components of reaction forces, namely fx and fy

but what about at point G, how come it only provides one force components, namely fx, but not fy as well? is the point G also classified as pin support?
i am very confused; instructor said that whenever u see a pin support, there's two force components; how come this is not a case here?
Yes, point G is a pin support. In general, there are 2 force components at a pin, in the x and y direction, but in some cases, such as joint G, there is only one. This is due to equilibrium considerations for so called '2-force' members. A 2-force member is a member subjected to a force (applied or a reaction force) at each end with no forces applied in between. All members of a truss are 2 force members when loads are applied at the joints only. Member BG is a 2-force member. As such, it can only take axial loading in tension or compression along its longitudinal axis. Thus , the reaction at G must be entirely horizontal; otherwise, the resultant reaction force could not be directed along the BG axis.

EDIT: I notice you are posting the same question in the ME sub-forum. You should stick to that forum and communicate further with the responder if you have additional questions.
 
Last edited:
  • #5
PhanthomJay said:
Yes, point G is a pin support. In general, there are 2 force components at a pin, in the x and y direction, but in some cases, such as joint G, there is only one. This is due to equilibrium considerations for so called '2-force' members. A 2-force member is a member subjected to a force (applied or a reaction force) at each end with no forces applied in between. All members of a truss are 2 force members when loads are applied at the joints only. Member BG is a 2-force member. As such, it can only take axial loading in tension or compression along its longitudinal axis. Thus , the reaction at G must be entirely horizontal; otherwise, the resultant reaction force could not be directed along the BG axis.

EDIT: I notice you are posting the same question in the ME sub-forum. You should stick to that forum and communicate further with the responder if you have additional questions.

apologize, this is my first time to use this forum... . I will never do that again.

and what about this http://www.ecourses.ou.edu/cgi-bin/view_anime.cgi?file=512LIN.swf&course=st&chap_sec=05.1, the link support, which is very similar to the pin support? Same reasoning as well?
 
  • #6
kougou said:
apologize, this is my first time to use this forum... . I will never do that again.

and what about this http://www.ecourses.ou.edu/cgi-bin/view_anime.cgi?file=512LIN.swf&course=st&chap_sec=05.1, the link support, which is very similar to the pin support? Same reasoning as well?
Welcome to Physics forums, kougou! Yes, same reasoning for a link support; the support reactions are always directed along the longitudinal axis of the member, creating only tension or compression axial forces in the member, regardless of the angle of the link, provided that there are no forces applied in between the 2 ends. NOTE that when the link is at an angle, there are still x and y components of the link reaction forces, but their resultant sum is a single force directed axially along the link, no bending or shear stresses.
 

1. What is a pin and link support type in static equilibrium?

A pin and link support type in static equilibrium refers to a type of structural support that uses pins and links to connect different parts of a system. This type of support allows for rotation and translation of the connected parts while maintaining stability and balance.

2. How does a pin and link support type achieve static equilibrium?

A pin and link support type achieves static equilibrium by distributing the forces acting on the system evenly throughout the connected parts. The pins and links allow for rotation and translation, which helps to balance out any external forces acting on the system.

3. What are the advantages of using a pin and link support type in static equilibrium?

There are several advantages of using a pin and link support type in static equilibrium. It allows for greater flexibility and movement in the system, making it more adaptable to different load conditions. It also distributes forces evenly, reducing stress on individual parts and improving the overall stability of the system.

4. Are there any limitations to using a pin and link support type in static equilibrium?

While pin and link support types are effective in many situations, they do have some limitations. They may not be suitable for supporting heavy loads or for systems that require high levels of precision. Additionally, they may require more maintenance and upkeep compared to other types of supports.

5. How is a pin and link support type different from other types of supports in static equilibrium?

A pin and link support type differs from other types of supports in static equilibrium, such as fixed supports or roller supports, in that it allows for both rotation and translation of the connected parts. This makes it more versatile and adaptable to different load conditions. It also tends to have a simpler design, making it easier to construct and maintain.

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