Machine elements stress concentration

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SUMMARY

The discussion centers on calculating the load capacity of a flat part under tension, specifically comparing two configurations with different dimensions. The original configuration has a height of 50 mm and a radius of 4.0 mm, while the modified configuration has a height of 100 mm and a radius of 10 mm. The stress concentration factor (Kc) is calculated as 2.5 for the original configuration. The key conclusion is that the problem requires a relative comparison of load capacities rather than absolute stress calculations, assuming both pieces are made from the same material.

PREREQUISITES
  • Understanding of tensile stress and load calculations (σ = P/A)
  • Familiarity with stress concentration factors (Kc)
  • Knowledge of material properties and their impact on load capacity
  • Basic principles of mechanics of materials
NEXT STEPS
  • Research the effects of geometry on stress concentration in mechanical components
  • Study material selection criteria for tensile applications
  • Learn about finite element analysis (FEA) for stress distribution evaluation
  • Explore advanced topics in mechanics of materials, including failure theories
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Mechanical engineers, materials scientists, and students studying mechanics of materials who are interested in understanding stress concentration and load capacity in structural components.

Triathlete
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Homework Statement



A flat part with constant thickness b is loaded in tension as shown. The height changes from 50 to 87 mm with a radius r = 4.0 mm. Find how much lower a load can be transmitted through the bar if the height increases from 50 to 100 mm and the radius increases from 4.0 to 10 mm.

media%2F9c6%2F9c638aea-a63a-46d9-8257-a6802214c9e8%2Fphp907Bhf.png


Homework Equations



σ = P/A = P/bh

Kc = σmax/σave

The Attempt at a Solution



For the fist case, r/h = 4/50 = 0.08, H/h = 87/50 = 1.74, Kc = 2.5

But I'm stuck because I don't know the material or the stress so I don't know how to determine the load. Do I even need the Kc value?
 
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Triathlete said:

Homework Statement



A flat part with constant thickness b is loaded in tension as shown. The height changes from 50 to 87 mm with a radius r = 4.0 mm. Find how much lower a load can be transmitted through the bar if the height increases from 50 to 100 mm and the radius increases from 4.0 to 10 mm.

media%2F9c6%2F9c638aea-a63a-46d9-8257-a6802214c9e8%2Fphp907Bhf.png


Homework Equations



σ = P/A = P/bh

Kc = σmax/σave

The Attempt at a Solution



For the fist case, r/h = 4/50 = 0.08, H/h = 87/50 = 1.74, Kc = 2.5

But I'm stuck because I don't know the material or the stress so I don't know how to determine the load. Do I even need the Kc value?
The problem isn't asking you to calculate the actual stress or the actual load. You are not even given the thickness of the part.

You should assume that both pieces are made from the same material, which will have the same strength. All you are asked to find is the load the modified piece can carry in relation to the original piece as shown.
 

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