Finding Young's Modulus for Normalized Steel: Experimental Results & Analysis

In summary, the student was tasked with experimentally finding the Young's modulus for normalized steel. However, their calculated value was around 33 GPa, which is significantly lower than the expected value of 200 GPa. They are unsure if they made a mistake or if the measured data is incorrect, but they have provided the data and graphs used in their calculation. The correct equation for Young's modulus was used, but it is possible that they did not accurately read the values from the graph. The advice given was to make sure to take points from the straight line section of the curves and to calculate strain with respect to the original length.
  • #1
Clancy
3
0

Homework Statement


I was given the problem to try experimentally find youngs modulus for normalized steel but when i did the equation the value i got was about 33 GPa. It is supposed to be around 200 isn't it? I cannot figure out what is wrong, am i missing something or is the measured data probably wrong? these values were all measured experimentally and in a bit of a hurry so it could be that, that is causing the problem, but i can't see howthe result could be thrown so off...

heres the data anyway

Test piece original length: 25mm
Diameter: 3.52mm -- cross sec area:9.73mm^2

and the graphs attached , looking at the one for normalized steel, but also tried it with tempered steel with similiarbad results

Homework Equations



Youngs modulus -> dStress/dStrain

The Attempt at a Solution



i took 2 points at x=1.28mm, y = 9600 N and x=1mm, y = 6000 N

[ (9600/9.73*10^-6) - (6000/9.73*10^-6) ] / [ (1.28/25) - (1/25) ] = 33.035 GPa

I know i probably didnt read the values off the graph very accurately but I didnt expect the answer to be so far off because of that.
 

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  • #2
Clancy, welcome to PF! You have the right equation. The graph appears to be a plot of force vs. deformation. Did you interpret it correctly? Please show your work so someone can check your math.
 
  • #3
Be sure to take points in the straightline section of the curves. This is where the definition Youngs modulus = dStress/dStrain is defined. I cannot see you have taken the correct points. Be sure to claculate strain with respect to its original length.
 

1. What is Young's Modulus for Steel?

Young's Modulus for Steel, also known as the elastic modulus, is a measure of the stiffness of a material. It represents the ratio of stress to strain in a material when subjected to tensile (stretching) or compressive (squeezing) forces.

2. How is Young's Modulus for Steel determined?

To determine Young's Modulus for Steel, an experiment is conducted where a sample of the steel is subjected to a range of known stresses and strains. The resulting data is then plotted on a stress-strain curve, and Young's Modulus is calculated as the slope of the linear portion of the curve.

3. What is the unit of measurement for Young's Modulus for Steel?

The unit of measurement for Young's Modulus for Steel is the same as that of stress and pressure, which is Pascal (Pa) or Newton per square meter (N/m²).

4. Does Young's Modulus for Steel vary with temperature?

Yes, Young's Modulus for Steel is affected by temperature. As the temperature increases, the atoms in the steel vibrate more, causing the material to expand and become less stiff. This results in a decrease in Young's Modulus.

5. How is Young's Modulus for Steel used in engineering?

Young's Modulus for Steel is a crucial factor in material selection and design in engineering. It helps engineers determine the amount of stress a material can withstand before it reaches its elastic limit, and if it is suitable for the intended application. It is also used in structural analysis and design to ensure the safety and stability of structures.

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