A tensile testing machine is used to determine the behavior of materials as they are deformed. In the typical test a specimen is stretched at a steady rate. The force (load) required to deform the material is measured, as is the resulting deformation. The Excel spreadsheet 'loads.xlsx' has data in sheet1 for one such test. Sheet2 contains a list of several different materials and their yield strength.
Formulas needed:
F is the applied force in lbf
l is the sample length
A is the sample cross sectional area in in2
lo is the original sample length
a) Read the data from the provided spreadsheet and calculate the stress and the corresponding strain for each data pair for each test. The tested sample was a rod of diameter 0.505 in., so you'll need to find the cross sectional area to use in your calculation
b) Create an x - y plot with strain on the x-axis and stress on the y-axis. Connect the data points with a line with your choice of color and style (don't use the defaults), and mark each data point with a symbol of your choice.
c) Add a title, appropriate axis labels, and a legend.
d) The point where the graph changes from a straight line with a steep slope to a flattened curve is called the yield stress or yield point. This corresponds to significant change in the material behavior. Before the yield point the material is elastic, returning to its original shape if the load is removed. Once the material has been deformed past the yield point, the change in shape becomes permanent and is called plastic deformation. Use a text box to mark the yield point on your graph.
e) Read the data on sheet2 and graph it using an appropriate style graph. Both graphs (the x-y plot and this graph) should appear on the same figure.