# Question about double shear pin connections

• Bill Nye Tho
In summary, the shear force at pin A is the resultant of the axial and vertical components of the reaction at pin A. The pin can't distinguish a separate horizontal force and vertical force; component forces are mathematical conveniences used to solve problems. To calculate the shear force at pin A, use the 40 kN link force which is directed 30 degrees below the horizontal.
Bill Nye Tho

## Homework Statement

Double Shear Pin Connection

## Homework Equations

∑Fx = -2V + P = 0

## The Attempt at a Solution

When calculating the shear force along the planes of the pin, where I have a reaction at Ax and Ay, why do I have to use the magnitude of the reaction force as opposed to the axial force that is acting colinear to the shear plane?

For example, if I have a horizontal reaction of 34.64 kN and a vertical reaction of 20 kN, why am I wrong for using 34.64 kN, instead of √34.642 + 202, to determine my shear forces?

Wouldn't the magnitude of the force have to be projected along the same shear plane thus returning me to my original horizontal reaction?

I'm having a hard time visualizing what you are asking. Can you provide a sketch?

SteamKing said:
I'm having a hard time visualizing what you are asking. Can you provide a sketch?

Sure.

Pin A is the one I'm talking about.

For some reason the solutions manual uses the magnitude of the vertical and horizontal reaction but I can't see why since that would not be along the surface of the shear plane that I'm looking at.

#### Attachments

• 2kcOsRx.jpg
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The shear experienced by the pin is the resultant of the axial and vertical components of the reaction at pin A. The pin can't distinguish a separate horizontal force and vertical force; component forces are mathematical conveniences used to solve problems.

Just like forces can be decomposed into different components, stresses can as well, by using techniques like the Mohr's circle:

http://en.wikipedia.org/wiki/Mohr's_circle

Once you have the basic stress components, you can use Mohr's circle to find the normal stress and the shear stress components for an arbitrary stress plane.

Bill Nye Tho said:
Sure.

Pin A is the one I'm talking about.

For some reason the solutions manual uses the magnitude of the vertical and horizontal reaction but I can't see why since that would not be along the surface of the shear plane that I'm looking at.
Well Bill, you seem to have no problem at all in correctly calculating the shear force and stress at the pin at C, using the 40 kN link force which is directed 30 degrees below the horizontal. Did you know that the 40 kN force can be resolved into its vector components as 40 sin 30 = 20 kN in the y direction and 40 cos 30 = 34.6 kN in the x direction? Which is precisely the same as the x and y force components at A. That is, the resultant of the force components at A is sq rt (34.64^2 + 20^2) = 40 kN directed 30 degrees above the horizontal. Same magnitude as at C. That is why you must use the 40 kN force when calculating shear forces on the pin at A. As SteamKing has pointed out, the pin doesn't much care about component shear forces, only resultant shear force.

## 1) What is a double shear pin connection?

A double shear pin connection is a type of mechanical connection used to join two pieces of material together. It is commonly used in heavy machinery and construction equipment to transfer loads and prevent slippage between the two connected components.

## 2) How does a double shear pin connection work?

A double shear pin connection works by inserting two pins through aligned holes in the two connected components. The pins are then secured with bolts or other mechanical fasteners. This creates a stronger and more secure connection compared to a single shear pin connection.

## 3) What are the advantages of using a double shear pin connection?

The main advantage of a double shear pin connection is its ability to withstand higher loads and resist shearing forces. It also provides better alignment and stability between the connected components, reducing the risk of slippage or misalignment.

## 4) What materials are commonly used for double shear pins?

Double shear pins are typically made from high-strength materials such as steel, stainless steel, or titanium. The specific material used will depend on the application and the required strength and durability of the connection.

## 5) Are there any limitations or considerations when using a double shear pin connection?

One limitation of a double shear pin connection is that it may be more expensive and time-consuming to install compared to other types of connections. It also requires careful alignment and proper torqueing of the bolts to ensure optimal performance. Additionally, it is important to regularly inspect and replace worn or damaged double shear pins to maintain the integrity of the connection.

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