Link to the source code for this example:

The console output of the program:

***************************************************************
* Running Example fem_system_ex5:
*   ./example-opt deltat=0.25 n_timesteps=5 time_solver=newmark write_interval=1 solver_quiet=false relative_step_tolerance=1e-3 relative_residual_tolerance=1.e-3 -ksp_type cg -pc_type jacobi
***************************************************************


Reading IGA mesh.

 Mesh Information:
  elem_dimensions()={0, 2}
  spatial_dimension()=2
  n_nodes()=1413
    n_local_nodes()=1413
  n_elem()=580
    n_local_elem()=580
    n_active_elem()=580
  n_subdomains()=2
  n_partitions()=1
  n_processors()=1
  n_threads()=1
  processor_id()=0

 EquationSystems
  n_systems()=3
   System #2, "Acceleration"
    Type "Explicit"
    Variables={ "u_accel" "v_accel" }
    Finite Element Types="RATIONAL_BERNSTEIN"
    Approximation Orders="SECOND"
    n_dofs()=2826
    n_local_dofs()=2826
    n_constrained_dofs()=0
    n_local_constrained_dofs()=0
    n_vectors()=1
    n_matrices()=0
    DofMap Sparsity
      Average  On-Processor Bandwidth <= 0
      Average Off-Processor Bandwidth <= 0
      Maximum  On-Processor Bandwidth <= 0
      Maximum Off-Processor Bandwidth <= 0
    DofMap Constraints
      Number of DoF Constraints = 0
      Number of Node Constraints = 0
   System #0, "Linear Elasticity"
    Type "Implicit"
    Variables={ "Ux" "Uy" }
    Finite Element Types="RATIONAL_BERNSTEIN"
    Approximation Orders="SECOND"
    n_dofs()=2826
    n_local_dofs()=2826
    n_constrained_dofs()=66
    n_local_constrained_dofs()=66
    n_vectors()=4
    n_matrices()=1
    DofMap Sparsity
      Average  On-Processor Bandwidth <= 24.0127
      Average Off-Processor Bandwidth <= 0
      Maximum  On-Processor Bandwidth <= 50
      Maximum Off-Processor Bandwidth <= 0
    DofMap Constraints
      Number of DoF Constraints = 66
      Average DoF Constraint Length= 0
      Number of Node Constraints = 0
   System #1, "Velocity"
    Type "Explicit"
    Variables={ "u_vel" "v_vel" }
    Finite Element Types="RATIONAL_BERNSTEIN"
    Approximation Orders="SECOND"
    n_dofs()=2826
    n_local_dofs()=2826
    n_constrained_dofs()=0
    n_local_constrained_dofs()=0
    n_vectors()=1
    n_matrices()=0
    DofMap Sparsity
      Average  On-Processor Bandwidth <= 0
      Average Off-Processor Bandwidth <= 0
      Maximum  On-Processor Bandwidth <= 0
      Maximum Off-Processor Bandwidth <= 0
    DofMap Constraints
      Number of DoF Constraints = 0
      Number of Node Constraints = 0

Assembling the System
Nonlinear Residual: 17.3841
Linear solve starting, tolerance 0.001
Linear solve finished, step 23, residual 180.796
Trying full Newton step
  Current Residual: 0.0209492
  Nonlinear step: |du|/|u| = 1, |du| = 260597
Assembling the System
Nonlinear Residual: 0.0209492
Linear solve starting, tolerance 2.09492e-05
Linear solve finished, step 48, residual 0.00305561
Trying full Newton step
  Current Residual: 3.00015e-07
  Nonlinear solver converged, step 1, residual reduction 1.7258e-08 < 0.001
  Nonlinear solver relative step size 0.003918 > 0.001


Solving time step 0, time = 0
Assembling the System
Nonlinear Residual: 34.7683
Linear solve starting, tolerance 0.001
Linear solve finished, step 147, residual 0.000352181
Trying full Newton step
  Current Residual: 0.0446599
  Nonlinear solver relative residual 0.0012845 > 0.001
  Nonlinear solver converged, step 0, relative step size 0.000220539 < 0.001


Solving time step 1, time = 0.25
Assembling the System
Nonlinear Residual: 34.7817
Linear solve starting, tolerance 0.001
Linear solve finished, step 146, residual 0.000369086
Trying full Newton step
  Current Residual: 0.0494522
  Nonlinear solver relative residual 0.00142179 > 0.001
  Nonlinear solver converged, step 0, relative step size 1.25039e-05 < 0.001


Solving time step 2, time = 0.5
Assembling the System
Nonlinear Residual: 36.1779
Linear solve starting, tolerance 0.001
Linear solve finished, step 134, residual 0.000344099
Trying full Newton step
  Current Residual: 0.0444696
  Nonlinear solver relative residual 0.00122919 > 0.001
  Nonlinear solver converged, step 0, relative step size 0.000226171 < 0.001


Solving time step 3, time = 0.75
Assembling the System
Nonlinear Residual: 35.7777
Linear solve starting, tolerance 0.001
Linear solve finished, step 134, residual 0.000334166
Trying full Newton step
  Current Residual: 0.0439709
  Nonlinear solver relative residual 0.00121541 > 0.001
  Nonlinear solver converged, step 0, relative step size 0.000207538 < 0.001


Solving time step 4, time = 1
Assembling the System
Nonlinear Residual: 34.1024
Linear solve starting, tolerance 0.001
Linear solve finished, step 145, residual 0.000341582
Trying full Newton step
  Current Residual: 0.0430732
  Nonlinear solver relative residual 0.00119059 > 0.001
  Nonlinear solver converged, step 0, relative step size 2.97201e-05 < 0.001


***************************************************************
* Done Running Example fem_system_ex5:
*   ./example-opt deltat=0.25 n_timesteps=5 time_solver=newmark write_interval=1 solver_quiet=false relative_step_tolerance=1e-3 relative_residual_tolerance=1.e-3 -ksp_type cg -pc_type jacobi
***************************************************************