This formulation solves the momentum balance equations as described in hyperelasticity. The dynamic example uses the PETSc Timestepper (TS) object to manage timestepping.

Specifically, Ratel uses the Generalized-Alpha method for second order systems (TSALPHA2) to solve the second order system of equations given by the momentum balance. More information on the PETSc TSALPHA2 time stepper can be found in the PETSc documentation.