Welding Force: Get a Closer Look

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SUMMARY

The discussion centers on calculating the welding force applied through a valve controlled by airflow pressure. The key factors include the total area of contact with airflow and the material properties of the flapper, which significantly influence the force exerted. The conversation highlights the importance of Young's modulus in determining the maximum force at the weld, particularly when considering different materials, such as tissue paper versus hardened steel. The conclusion emphasizes the need for a complete understanding of material properties to accurately solve the problem.

PREREQUISITES
  • Understanding of fluid dynamics and pressure principles
  • Knowledge of material properties, specifically Young's modulus
  • Familiarity with welding processes and force calculations
  • Basic grasp of valve mechanics and airflow control
NEXT STEPS
  • Research the application of Young's modulus in force calculations
  • Study the relationship between airflow pressure and force in valve systems
  • Explore different material properties and their impact on welding force
  • Learn about transient versus steady-state analysis in mechanical systems
USEFUL FOR

Engineers, material scientists, and professionals involved in welding and valve design who seek to understand the dynamics of force application in real-world scenarios.

GZunich
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Homework Statement
There is a flapper valve that is a 4.5mm disc welded to a body with a 3.5mm opening. They are attached with a spot weld approximately 0.5x0.5mm. There is a maximum flow through the opening of 0.20684N/mm2. What is the maximum force seen on the spot weld?
Relevant Equations
M=wl^2/2
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Perhaps you could attempt a solution first? What do you think the best approach is for this problem?
 
I’m having trouble trying to figure out how to start. The pressure applied to the weld comes from the air flowing through the valve. It’s controlled by air flow, but does that come from the pressure?

I know this for will apply a force to the valve but the force applied to the weld will be controlled by the properties of the material. I don’t know what equation will take the material properties into account.
 
If the flapper is less than 100% open pushing against the stops, you know how much lifting force there is. Can you start from that?
 
I’ve gotten here: total area of contact with the airflow times the pressure gives you the total force applied to the valve. But from there is where I get confused because of how flexible the material is.
 
Yes, as I read the problem it is incomplete without the description of the flapper material. I assume the problem is asking about the steady state where the flapper is held open at some position. For example there would be nearly zero force on a flapper made of tissue paper, it would just open completely. Hardened steel 2cm thick would hardly move at all and would take the full force from the pressure given. I suppose my answer would be somewhere between 0 and 2N.
If they want the transient solution, where the valve is closed and by some miracle the pressure is instantly applied, then it will see the full force as it starts to accelerate to open.
 
If the young’s modulus E was known, would there be an equation to fit the maximum force seen at the weld?
 
Can anyone help? I’m still stuck on this real world problem
 

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