PASCO AP-8214A Stress_Strain Apparatus - Manual (Page 9)

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M o d e l N o . A P - 8 2 1 4 A 0 1 2 - 1 3 2 8 2 A D a t a A n a l y s i s
9
• Turn the crank clockwise. Starting just before the lever arm comes into contact
with the Force sensor, turn the crank very slowly.*
• When you have finished collecting data, click Stop. (If you reach the maximum
force, DataStudio will stop automatically.) If the coupon breaks, it should break in
the middle. If the coupon breaks near the end, it was probably twisted slightly
when you mounted it, resulting in a point of higher stress where it broke.
4. Rename the data run to identify the coupon. Use the same method you used to rename the calibration
data.
Data Analysis
On the Stress versus Strain graph, you can identify features such as the elastic region, the plastic region, the yield
point, and the break point.
To calculate Young's modulus, drag the mouse to select a data region covering the linear, lower left-hand part of the
graph. (You may find that the very first part of the plot is not linear. This nonlinearity is likely due to the straightening
of bends and twists in the coupon as force is first applied. Do not include this region in your selection.) Click the Fit
button to apply a linear curve fit to the selected data. The slope of the line is Young's modulus in units of MPa (or
MN/m
2
or N/mm
2
).
Sample Data
* When you observe on
the Stress versus Strain
plot that the material has
been stretched beyond
the elastic region, you
can begin to turn the
crank faster.
Sample 1: Force vs. displacement - brass 0.003 and
brass 0.005
Sample 2: Stress vs. strain - aluminum 0.003
Units of slope are MPa
Sample 3: Force vs. displacement -
plastic coupons
Sample 4: Stress vs. strain - black nylon 6
Units of slope are MPa