MEXX - Numerical Software for the Integration of Constrained Mechanical Systems.
| SC 92-12 | Ch. Lubich, Ulrich Nowak, Uwe Pöhle, Ch. Engstler
MEXX - Numerical Software for the Integration of Constrained Mechanical Systems. | |
Abstract: MEXX (short for MEXanical systems
eXtrapolation integrator) is a Fortran code for time
integration of constrained mechanical systems. MEXX is
suited for direct integration of the equations of motion in
descriptor form. It is based on extrapolation of a time
stepping method that is explicit in the differential
equations and linearly implicit in the nonlinear
constraints. It only requires the solution of
well-structured systems of linear equations which can be
solved with a computational work growing linearly with the
number of bodies, in the case of multibody systems with few
closed kinematic loops. Position and velocity constraints
are enforced throughout the integration interval, whereas
acceleration constraints need not be formulated. MEXX has
options for time-continuous solution representation (useful
for graphics) and for the location of events such as
impacts. The present article describes MEXX and its
underlying concepts.