Elastic rod
= Elastic rod
An <elastic rod> is a slender elastic body represented by a centreline and an attached orthonormal director frame. Its <elastic energy> penalizes stretching, bending and twisting relative to a preferred configuration. The <director kinematics of a rod> describe changes of the frame along the centreline. An unshearable <elastic rod> has its third director parallel to the centreline <tangent vector>.