You can use stress-strain curve already available..
Or
if you willing to perform experiment, you can use a standard test specimen, load it on universal testing machine with graph plotting attachment. You will get Stress-Strain graph and from that you can find out Young's modulus..

Most accurate method of Young's module determination is recording of curve "sigma-epsilon" of specially prepared specimen during tension test. Inclination of curve in the elastic region gives E : "sigma = E * epsilon" or "E=sigma/epsilon".
Other methods use calibration based on mechanically determined values of E.

Unfortunately, there are significant differences in the elastic behavior of metals based on their cell structures and binding energies. While steels generally have a rather linear load/deflection or stress/strain up to their yield point, aluminum has an ever-decreasing one in a curved fashion. Therefore, for the latter the datum for "elastic modulus" is somewhat arbitrary. Ultrasonic measurements can be made to deduce an elastic modulus for such alloys, but how they would look actually plotted on a load/deflection or stress/strain plot and how they should be interpreted is another matter. I've never performed a comparison myself, but presumably they correlate fairly well with the standard proportional limit method.

One can also measure the Young's Modulus by non-destructive method. Excite a specially prepared test specimen by a sound impulse and measure the time-decay of the impulse signal. The modulus is related to the velocity of sound. By a set of calculations one can evaluate the modulus.

note: when acoustic method is used - speed of sound measurement - density of material is needed. Besides, need to be aware of the type of acoustic wave - usually longitudinal wave is taken, but its amplitude is often small compare to transverse wave.
As to stress-strain experiment - have to conduct it according to ASTM standards (experience from thousands of experiments conducted in dozens of laboratories) - since the obtained value of E depends on the methodology of measurements.

If you do it by stress-strain you need to approach it differently than you would a tensile test.
When I do it I take a few steps.
1. modify extensometer for longer gage length, usually 4" or 5" instead of 2"
2. carefully cycle sample loading. start by loading to 50% of yield, then unload to 20%, then relaod and take measurements. This helps take mechanical slack out of the system and assure cleaner data.
3. take multiple tests (5 is my favorite) and verify data.

As has already been noted some materials have poorly defined stress/strain curves. For these the stress level of interest is important. You may need to focus on a portion of the curve only.

Test methods for Young's modulus usually include four types:
1. static (tensile, torsion, bending test)
2. dynamic (resonant frequency method)
3. wave propagation methods (ultrasonic echo-pulse method)
4. nanoindentation

Each method has its own advantages and disadvantages. Also, the measured Young's modulus values are different, even for the same sample material.

I tested a 0.55% Carbon steel in UTM. The Yield strength is 409.8 MPa. THe machine gave me a load (N) vs Displacement (mm) curve. Gauge length is 50 mm. Displacement at Yield limit is 5 mm. Using elastic limit formula for Young's modulus , I calculated as (409.8/ 0.1) = 4098 MPa. Young's modulus is 4.098 GPa which is very less compared to 210 GPa we follow for any calculations. So help me to predict and calculate the Young's modulus correctly.

I believe that you confused with displacement and strain. During monotonic tensile test, we put a mechanical extensometer on the gauge length region. then, from computer output, we obtain some sets of data: grip displacement, force, strain, time. Then, true strain and true stress can be obtained. you mentioned, YS=409.8MPa (0.2% offset strain + slope E0). No problem with that. E=YS/(strain@YS-0.2%). The question is, how do you obtain 0.1 in the equation? that is a wrong number. You need check it again. Hope it helps.

Dec 5, 2014

Paul Bosomworth · Association pour l'étude des pics de production de pétrole et de gaz naturel

You can also use the impulse excitation technique (IET) to get the dynamic elastic properties nondestructively. The technique is described in several ASTM standards such as E1876 and C1259. Basically one excites a test piece mechanically by tapping it with a small hammer. The resulting natural vibrations are then used along with the size, shape and mass/density of the sample to obtain the Young's modulus, shear modulus and Poisson's ratio. My company has a commercial instrument also. Contact me if you are interested <paul@buzzmac.com>.

## All Answers (15)

Shantanu Deshpande· Auburn UniversityOr

if you willing to perform experiment, you can use a standard test specimen, load it on universal testing machine with graph plotting attachment. You will get Stress-Strain graph and from that you can find out Young's modulus..

Sairam .KAnurag Tilak· Aditya Birla GroupViktor Savitsky· E.O. Paton Electric Welding InstituteOther methods use calibration based on mechanically determined values of E.

Dave HimmelblauVmj Sharma· Vikram Sarabhai Space CentreSviatoslav Hirnyj· Lviv Institute of Physics and MechanicsAs to stress-strain experiment - have to conduct it according to ASTM standards (experience from thousands of experiments conducted in dozens of laboratories) - since the obtained value of E depends on the methodology of measurements.

Ed Blessman· Director of Technical DevelopmentWhen I do it I take a few steps.

1. modify extensometer for longer gage length, usually 4" or 5" instead of 2"

2. carefully cycle sample loading. start by loading to 50% of yield, then unload to 20%, then relaod and take measurements. This helps take mechanical slack out of the system and assure cleaner data.

3. take multiple tests (5 is my favorite) and verify data.

As has already been noted some materials have poorly defined stress/strain curves. For these the stress level of interest is important. You may need to focus on a portion of the curve only.

Praveennath Koppad· RAPSRI ENGINEERING PRODUCTS COMPANY LTDSairam .KZhong Chen· The Ohio State UniversityTest methods for Young's modulus usually include four types:

1. static (tensile, torsion, bending test)

2. dynamic (resonant frequency method)

3. wave propagation methods (ultrasonic echo-pulse method)

4. nanoindentation

Each method has its own advantages and disadvantages. Also, the measured Young's modulus values are different, even for the same sample material.

Hope it helps!

Best wishes,

Zhong

Pradeep Samiappan· VIT UniversityI tested a 0.55% Carbon steel in UTM. The Yield strength is 409.8 MPa. THe machine gave me a load (N) vs Displacement (mm) curve. Gauge length is 50 mm. Displacement at Yield limit is 5 mm. Using elastic limit formula for Young's modulus , I calculated as (409.8/ 0.1) = 4098 MPa. Young's modulus is 4.098 GPa which is very less compared to 210 GPa we follow for any calculations. So help me to predict and calculate the Young's modulus correctly.

Zhong Chen· The Ohio State UniversityDear Pradeep Samiappan,

I believe that you confused with displacement and strain. During monotonic tensile test, we put a mechanical extensometer on the gauge length region. then, from computer output, we obtain some sets of data: grip displacement, force, strain, time. Then, true strain and true stress can be obtained. you mentioned, YS=409.8MPa (0.2% offset strain + slope E0). No problem with that. E=YS/(strain@YS-0.2%). The question is, how do you obtain 0.1 in the equation? that is a wrong number. You need check it again. Hope it helps.

Paul Bosomworth· Association pour l'étude des pics de production de pétrole et de gaz naturelYou can also use the impulse excitation technique (IET) to get the dynamic elastic properties nondestructively. The technique is described in several ASTM standards such as E1876 and C1259. Basically one excites a test piece mechanically by tapping it with a small hammer. The resulting natural vibrations are then used along with the size, shape and mass/density of the sample to obtain the Young's modulus, shear modulus and Poisson's ratio. My company has a commercial instrument also. Contact me if you are interested <paul@buzzmac.com>.

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