Mechanical Behavior of Spider Silk
Authors:Yuriy Bazylev, Jessica Lopez
Mentor:Ravi Vilupanur, Dr., California State Polytechnic University Pomona
Spider silk is a natural material that has unique mechanical properties. These include high mechanical strength and toughness, and strength to weight ratios five times superior to that of steel. The structure of spider silk is also of particular interest both at a macroscopic level and at the molecular level, and is believed to affect the properties of the material, in particular mechanical behavior. Research at Cal Poly Pomona over the past few years has focused on evaluating the mechanical properties of fibers from different spider species with a view to elucidating structure-property interrelationships that would form the basis for new material designs. Our focus in the current project has been on the determination of the mechanical properties of spider silk produced by the Araneus gemma also known as the orb weaver. The Araneus gemma silk was tested in uniaxial tension test using a mechanical test frame - the Instron 3342. A 5 N load cell was used to obtain the load-extension data for the analysis. The properties of this silk were compared to the silk from the Lactrodectus geometricus (brown widow) and the Nephila clavipes, a member of the golden orb weaver family. The effect of strain rate on the ultimate tensile strength, extensibility, etc., of these silks will be discussed. The behavior of spider silk will be discussed as a viscoelastic polymer. Ideas for future research, e.g., tensile testing under varying humidity conditions, will be presented as well.