This article presents a formulation for one-dimensional structures. It uses the
structure of Lie groups and the associated differential calculus to describe
deformations and the dynamic equation of the structure. Three levels of equation
setting are explored: level one is the most abstract where a single equation is
obtained using the Lie algebra of the displacement group, level two refers to the
semidirect product decomposition of the displacement group into a rotation and a
translation group, and the third level is obtained by selecting a suitable basis within
the Lie algebra, which leads to scalar equations. Equations at each level
are derived, and a comparison with the literature is made for the static
equilibrium.
The article also addresses perturbations of the linear dynamic around an
equilibrium position. The symmetry of the deformation operator is examined, which
has implications for the study of instability.
Keywords
beam theory, large transformation, Lie group, differential
geometry