Leitz T, Leyendecker S (2018)
Publication Type: Journal article, Review article
Publication year: 2018
Book Volume: 338
Pages Range: 333-361
DOI: 10.1016/j.cma.2018.04.022
Lie-group variational integrators of arbitrary order are developed using
 the Galerkin method, based on unit quaternion interpolation. To our 
knowledge, quaternions have not been used before for this purpose, 
though they allow a very simple and efficient way to perform the 
interpolation. The resulting integrators are symplectic and structure 
preserving, in the sense that certain symmetries in the Lagrangian of 
the mechanical system are carried over to the discrete setting, which 
leads to the preservation of the corresponding momentum maps. The 
integrators furthermore exhibit a very good long time energy behavior, 
i.e. energy is neither dissipated nor gained artificially. At the same 
time, the Lie-group structure is preserved by carefully defining the 
variations, the interpolation method and by solving the non-linear 
system of equations directly on the manifold, rather than constraining 
it in a surrounding space using Lagrange multipliers. As a consequence, 
we are able to show that Lie-group variational integrators based on the 
special orthogonal group, are equivalent to the variational integrators 
for constrained systems using the discrete null-space method employed 
e.g. in DMOCC (discrete mechanics and optimal control of constrained 
systems). We show new numerical results on the convergence rates, which 
are substantially higher than the known theoretical bounds, and on the 
relation between accuracy and computational cost.
APA:
Leitz, T., & Leyendecker, S. (2018). Galerkin Lie-group variational integrators based on unit quaternion interpolation. Computer Methods in Applied Mechanics and Engineering, 338, 333-361. https://doi.org/10.1016/j.cma.2018.04.022
MLA:
Leitz, Thomas, and Sigrid Leyendecker. "Galerkin Lie-group variational integrators based on unit quaternion interpolation." Computer Methods in Applied Mechanics and Engineering 338 (2018): 333-361.
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