Epoxy polymers are widely used for structural applications. One challenge is the brittle nature of the material and there are many approaches to enhancing the toughness. Two such approaches are the addition of graphene nanoplatelets (GnP) and the addition of carboxyl-terminated butadiene-acrylonitrile (CTBN) rubber. However, both of these approaches have been documented to have impacts on other mechanical properties as well.

The following data (extension and load) were generated in a series of tensile experiments. All samples failed during testing. The following sample dimensions were used in the test:

Calculate the stress / strain data for all three samples. Plot all three stress-strain curves on the same plot, making sure the different curves can be distinguished from each other. Include axis labels with units, a legend and grid lines.

Choose an appropriate range of data and calculate the Youngs modulus of each sample. Report these values in a table with appropriate headers.

Calculate the toughness of the three materials from the provided data. Report these values in a table with appropriate headers. What do you conclude about the toughness of the different materials relative to one another?

13mm Sample Width Sample Thickness Gauge Length 2mm 50mm 20 DGEBA+ 3wt% GnP M25 Extension Load [N] [mm] 0 0 5 273 10 507 15 683 897 25 1090 37.5 1697 50 2145 62.5 2638 3086 87.5 3476 100 3785 112.5 4084 125 4313 137.5 4485 150 4657 75 Neat DGEBA Extension Load [N] [mm] 0 0 5 109 10 203 15 273 20 359 25 436 38 679 50 858 63 1055 75 1234 88 1390 100 1514 113 1634 125 1725 138 1794 150 1863 175 1959 200 2010 225 2037 250 2037 275 2037 300 2019 325 1986.8 337.5 1950 350 1918.8 375 1840.8 400 1778.4 75 DGEBA+ 6% CTBN Extension Load [N] [mm] 0 0 5 70 10 130 15 175 20 230 25 279 38 435 50 549 63 675 790 88 890 100 969 113 1046 125 1104 138 1148 150 1192 175 1254 200 1286 225 1304 250 1304 275 1304 300 1292 325 1272 338 1248 350 1228 375 1178 400 1138 13mm Sample Width Sample Thickness Gauge Length 2mm 50mm 20 DGEBA+ 3wt% GnP M25 Extension Load [N] [mm] 0 0 5 273 10 507 15 683 897 25 1090 37.5 1697 50 2145 62.5 2638 3086 87.5 3476 100 3785 112.5 4084 125 4313 137.5 4485 150 4657 75 Neat DGEBA Extension Load [N] [mm] 0 0 5 109 10 203 15 273 20 359 25 436 38 679 50 858 63 1055 75 1234 88 1390 100 1514 113 1634 125 1725 138 1794 150 1863 175 1959 200 2010 225 2037 250 2037 275 2037 300 2019 325 1986.8 337.5 1950 350 1918.8 375 1840.8 400 1778.4 75 DGEBA+ 6% CTBN Extension Load [N] [mm] 0 0 5 70 10 130 15 175 20 230 25 279 38 435 50 549 63 675 790 88 890 100 969 113 1046 125 1104 138 1148 150 1192 175 1254 200 1286 225 1304 250 1304 275 1304 300 1292 325 1272 338 1248 350 1228 375 1178 400 1138