= Material frame of a rod
{title2=$\{\mathbf d_1,\mathbf d_2,\mathbf d_3\}$}
A right-handed <orthonormal frame> attached to the cross-sections of an <elastic rod>. For an unshearable <elastic rod>, $\mathbf d_3$ is the unit <tangent vector> to its centreline, while $\mathbf d_1$ and $\mathbf d_2$ follow the orientation of its material cross-section. Unlike a frame constructed only from the centreline <curvature>, the material frame records the twist of the material about the tangent.
Back to article page
