Choosing the Right Diameter for an Aluminum Rod | Stress Analysis Homework Help

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Discussion Overview

The discussion revolves around determining an appropriate diameter for an aluminum rod based on stress analysis, specifically addressing a homework problem involving allowable stress and load conditions. The context includes considerations of material properties and practical availability of rod diameters.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant states that the allowable stress for aluminum is σall = 100 MPa and calculates the required diameter to be 25.2 mm based on the applied load of 50 kN.
  • Another participant questions the reasoning behind selecting a diameter of 26 mm or more, seeking clarification on why this choice is made.
  • Several participants clarify that using a diameter less than 25.2 mm would exceed the allowable stress, thus necessitating a rounding up to the next available diameter, which is suggested to be 26 mm.
  • There is uncertainty expressed regarding the availability of metric diameters for aluminum rods, with a suggestion that if 26 mm is not available, a larger diameter such as 30 mm may need to be considered.

Areas of Agreement / Disagreement

Participants generally agree on the calculation leading to a required diameter of 25.2 mm, but there is disagreement and confusion regarding the rationale for rounding up to 26 mm or more, as well as the implications of using a lesser diameter.

Contextual Notes

There is a lack of clarity on the specific metric diameters available for aluminum rods, which may affect the choice of diameter. Additionally, the discussion does not resolve why a diameter greater than 25.2 mm is deemed necessary beyond the calculation itself.

Who May Find This Useful

This discussion may be useful for students or individuals engaged in mechanical engineering or materials science, particularly those dealing with stress analysis and material selection in practical applications.

Amr719
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Homework Statement


For reasons based on cost,weight,availability , etc., the choice is made to construct the rod from aluminum of
σall = 100 MPA. What is an appropriate choice for the rod diameter ? Givens: (P=50 KN)

Homework Equations

The Attempt at a Solution


σall=P/A , then he get the Area and from area he then gets the Diameter=25.2mm[/B]
Then he said an aluminum rod 26m or more in diameter is adequate
My question is : why an aluminum rod of 26m or more in diameter is adequate ?!
 
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Amr719 said:

Homework Statement


For reasons based on cost,weight,availability , etc., the choice is made to construct the rod from aluminum of
σall = 100 MPA. What is an appropriate choice for the rod diameter ? Givens: (P=50 KN)

Homework Equations




The Attempt at a Solution


σall=P/A , then he get the Area and from area he then gets the Diameter=25.2mm[/B]
Then he said an aluminum rod 26m or more in diameter is adequate
My question is : why an aluminum rod of 26m or more in diameter is adequate ?!
25.2 mm diameter required, use 26 mm, not 26 m
 
PhanthomJay said:
25.2 mm diameter required, use 26 mm, not 26 m
I meant 26mm , I don't know why 26mm or more . Why not less and why more ?
 
Amr719 said:
I meant 26mm , I don't know why 26mm or more . Why not less and why more ?
If 25.2 mm diameter is required, then if you use a lesser diameter, you will exceed the allowable stress. So you have to round up to the next available greater diameter. I am not familiar with metric diameters available for aluminum rod, if 26 mm dia not available, you'll have to go to say 30 mm diameter, or whatever is in stock that is in that range.
 
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Great .Thank you very much !
 

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