ELASTIC PROPERTIES WITH IMAGE ANALYSIS
AND TENSILE TESTING
Name: Fei Jia
Class: BE 210
The purpose of this lab will be to examine the difference in failure forces for Confor Polyurethane Foam sutured with the Pulley Stitch, and for chicken skin sutured with the same technique; force-displacement and stress-strain graphs could be made after applying forces with the Instron 4444. Through these graphs, maximum failure force could be determined by the ultimate strength points on the force-displacement graph. The Young’s Modulus could be confirmed for the two materials by taking the area under the stress-strain graph through Matlab. The chicken skin and Confor foam could be expected to break before the suturing thread breaks since with the Pulley Stitch, a single stitch is comprised of 6 threads that reinforce the material, and must be broken for the stitching to break (Figure 1), which would require a force greater than that to break chicken skin and Confor Foam. A force of 88.2 N would be required to break the Tex 26 thread used for suturing in a Pulley Stitch, whereas 24.1 ± 1.85 N and 13.6 ± 0.675 N would break chicken skin and Confor foam respectively (Table 1). The two different materials will also be deformed using a uniaxial loading of 3- kg hanging weight. Pictures will be taken before and after this load is applied, so that the distance of deformation could be observed. Since chicken skin has a significantly higher Young’s Moduli than Confor foam, under tensile loading, skin sutured using the Pulley Stitch should withstand a higher failure load and exhibit less deformation than the Confor foam sutured with the same technique. By testing the difference in mechanical properties of the two materials, we will be able to determine how foam would perform in real-life situation as a chicken skin substitute.