Dynamical systems in finite elements yield systems of second-order differential
equations. Incorporating inelastic material properties, thermomechanical
coupling and particular Dirichlet boundary conditions essentially changes
the underlying mathematical problem. In this respect, we investigate the
behavior of a number of subproblems such as reaction force computation,
high-order time-integration, time-adaptivity, etc., which yield (depending on the
underlying problem) systems of differential-algebraic equations or a mixture
of systems of second-order and first-order ordinary differential equations
(especially if the constitutive equations are of evolutionary-type, as in the case of
viscoelasticity and viscoplasticity). The main goals are to provide higher-order time
integration schemes using diagonally implicit Runge–Kutta methods and the
generalized-
method so that they may be applied to the constitutive equations, and to apply
time-adaptivity via embedded schemes so that step-sizes are chosen automatically.
The constitutive equations are given by a thermoviscoplasticity model of
Perzyna/Chaboche-type with nonlinear kinematic hardening.