# Calculating Welded Area and Rivet Diameter for Shear Stress - Homework Solution

• Femme_physics
In summary: The equation for vertical shear in the weld is simple enough, but you are not applying it correctly. You should first calculate the end reactions before determining weld stresses. There will be a shear load, a bending moment, and a torsional moment. For the vertical shear , your value of the vertical reaction is correct, but you are incorrectly summing your l's. The l's are not related to the overhang length. They relate to the overall weld length at B.What do you mean by end reaction? Technical mechanics? Sum of all forces = 0? Your value of the vertical reaction is correct, but you are incorrectly summing your l's. The l's are not related to the over
Femme_physics
Gold Member

## Homework Statement

The depicted construct is made of a rod with a square cross-section and two plates. The plates are jointed together through 4 similar rivets. The square rod is welded to the wall at "B" and to the plates at the other end through peripheral corner welds.

On the board acts an external force F = 6000 [N]

A) Calculate the needed width of the welded area at B
B) The rivets' diameter.

Given:

Allowable stress at welded area = 80 MPa
Allowable shearing stress at the rivet = 60 MPa
Allowable local compression at the rivets = 100 MPahttp://img202.imageshack.us/img202/5481/lookad.jpg

## Homework Equations

http://img39.imageshack.us/img39/6965/equationssss.jpg

## The Attempt at a Solution

Can it be ths simple??

http://img845.imageshack.us/img845/6205/solsssss.jpg

Last edited by a moderator:
The equation for vertical shear in the weld is simple enough, but you are not applying it correctly. You should first calculate the end reactions before determining weld stresses. There will be a shear load, a bending moment, and a torsional moment. For the vertical shear , your value of the vertical reaction is correct, but you are incorrectly summing your l's. The l's are not related to the overhang length. They relate to the overall weld length at B.

What do you mean by end reaction? Technical mechanics? Sum of all forces = 0?

your value of the vertical reaction is correct, but you are incorrectly summing your l's. The l's are not related to the overhang length. They relate to the overall weld length at B.

Hmm, I think I see what you're saying

My "l" should be 800 + 80 + 80 + 80 + 80

Since it's square shaped

Femme_physics said:
What do you mean by end reaction? Technical mechanics? Sum of all forces = 0?
At B, use sum of all forces acting vertical on the beam = 0 , to solve for the vertical end reaction at B. Use sum of all moments about an axis running thru B out of the plane of the paper to solve for the bending moment at B. Use sum of moments about an axis passing thru B along the length of the beam to solve for the torsional moment at B.
Hmm, I think I see what you're saying

My "l" should be 800 + 80 + 80 + 80 + 80

Since it's square shaped
why the extra 800?

Thank you, noticed my mistake. Solved it for shearing :)

## What is shear stress in welding?

Shear stress in welding is a type of stress that occurs when two pieces of metal are joined together through welding. It is caused by the forces applied to the welded joint and can result in the deformation, cracking, or failure of the joint.

## How does shear stress affect the strength of a welded joint?

Shear stress can significantly impact the strength of a welded joint. If the shear stress is too high, it can cause the joint to fail, resulting in a weak or broken weld. Proper welding techniques and materials can help minimize shear stress and increase the strength of the joint.

## What factors can contribute to shear stress in welding?

Several factors can contribute to shear stress in welding, including the type of welding process used, the welding parameters (such as heat input and travel speed), the design of the joint, and the properties of the materials being welded. It is essential to consider all of these factors to minimize shear stress and ensure a strong weld.

## How can shear stress be measured in welding?

Shear stress can be measured using various techniques, such as strain gauges, load cells, and ultrasonic testing. These methods can provide information about the stress levels in the welded joint and help identify potential weaknesses or areas of concern.

## How can shear stress in welding be reduced?

To reduce shear stress in welding, proper welding techniques and parameters must be used, such as controlling heat input and travel speed. The design of the joint and the selection of appropriate welding materials can also play a significant role in minimizing shear stress. Regular inspections and testing can also help identify and address any potential issues with shear stress in a welded joint.

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