Abstract
It is well known that the tensile strength of knotted strings is weaker than the material strength of the strings. However, the strength of the knotted strings has not fully understood from the scientific viewpoint. In the present study, digital image correlation method is applied to examine the strength and characteristics of knots, especially overhand knot and figure-of-eight knot. The result shows that the shearing strain at the shoulder part of the overhand knot is larger than that of the figure-of-eight knot. This result is in good agreement with the result of tensile tests, which shows that the fracture stress of the overhand knot is lower than that of the figure-of-eight knot.
