A Basic Idea of Identifying the Stiffness of an Elastic Rod along its Backbone

In this paper, we present a basic idea for identifying the stiffness along an elastic rod which is considered as being useful for capturing the stiffness of any long and slender structure such as an animal trunk or a biological micro/nano wire. After formulating the rod stiffness identification problem based on the rod theory, we consider the problem to identifying a spring constant of one degree-of-freedom (DOF) spring, and show a reasonable solution in an optimal manner based on the force balance equation as the simplest example of stiffness identification. Then, we show that this simple idea can be extended to the case of an elastic rod analogously where we have to identify three stiffness parameters with respect to bending in two different directions and twisting at each point on the backbone curve of an elastic rod.