A, SEM images of tensile fracture morphologies of A. yamamai silk and B. mori silk. B, Stress-strain curve of original and notched A. yamamai silk fiber. C and D, The microphotograph of notched A. yamamai silk fiber before (C, optical microscopy image) and after (D, SEM image) the tensile fracture. E, Stress-strain curve of original and notched Nylon 66 fiber. F and G, The microphotograph of notched Nylon 66 fiber before (F, optical microscopy image) and after (G, SEM image) the tensile fracture. The red arrows in C and F indicates the notch of the fibers. These images confirmed the notched width was smaller than the half width of the fiber using in testing. The red arrows in D and G displays the crack propagation direction after tensile failure.