Nonlinear dynamic strand model with coupled tension and torsion

We simulate the nonlinear dynamic responses in Kirchhoff rod by including the important effects due to inertia and kinematic coupling of tension and torsion. We begin by reviewing a dynamic rod model of a strand (length of cable or DNA) in the form of a 12th order partial differential equation system. Numerical solutions reveal the effects of dynamics on clamped strands due to slow movements of their ends. We note that inertia plays a critical role in this process, particularly under loading conditions that pass through an instability. For example, we simulated a dynamic trasition path between two possible equilibria of a clamped rod subject to very slow compression.