Lab Description:

Tensile "dog$-$bone" specimens were $3$D printed using PLA material. The lab consists of measuring the gauge length,

width, and thickness of each specimen and then using tension testing machine to pull until break$/$failure$.$ Follow the

lab requirements below to graph specimen data and calculate material properties. Answer all questions below and

hand in one document per student.

Lab Measurements:

Obtain a copy of the data for the specimens $($displacement$,$ load, $\%$ Strain$)$

Use MS Excel to plot Stress vs$.$ Strain $($until failure$)$ for each specimen

a$.$ Calculate a new Strain column using position $($change in length$)$ divided by gauge length

b$.$ Calculate a new Stress column using load divided by area of gauge region

c$.$ Graph entire Stress vs Strain data set until failure of specimen $($include axis labels$/$units$)$

d$.$ Use MS Excel or any graphical method to estimate the average yield strength using the

$0\mathrm{.}2\%$ offset method for each specimen.

e$.$ Use MS Excel or Equation of a Line $($between two points$)$ to calculate the Elastic

Modulus $($slope of linear elastic region$)$ for each specimen.

f$.$ Evaluate the Ultimate Tensile Strength of each specimen.

g$.$ Calculate the $\%$ Elongation for each specimen

Answer the following questions:

a$.$ Calculate the average values of Yield Strength, Ultimate Strength, and Elastic Modulus

b$.$ How does the yield strength from the $0\mathrm{.}2\%$ offset method match with the elastic limit

point $($where graph visibly stops being linear$)$ on the stress strain curves? Which do you

think is more accurate?

c$.$ Read textbook Chapter $10,$ and then define the following terms:

i$.$ Stiffness

ii$.$ Elasticity

iii. Ductility

iv$.$ Toughness

v$.$ Re$$ilience