! ----------------------------------------------------------------------
! M11 - English course download: 11_challenge.mac
! Follow the matching English lesson for explanations and task details.
! Commands, parameter names, file names, CSV keys, and result tokens are preserved.
! ----------------------------------------------------------------------

/CLEAR,START                        ! Add friction or change gap/displacement with a prediction.
/FILNAME,m11_challenge,1
/UNITS,SI

! Base case (deliverable): frictionless contact, initial_gap=0.0005 m,
! disp_close=-0.0012 m.
!
! Challenge A (friction): KEYOPT,2,12,1 activates Coulomb on CONTA174; MP,MU,1,0.15 defines mu.
! Challenge B (gap): initial_gap=0.001 m with disp_close=-0.0015 m.
!
! TODO 1: copy 11_contact_pair.mac to a clean directory.
! TODO 2: choose Challenge A or B; write a prediction for RFY or contact_closed.
! TODO 3: run from a clean session and record an extra row in the CSV or a note.
! TODO 4: confirm n_converged>=10 and equilibrium consistent with your prediction.
! TODO 5: repeat in a second clean directory and verify reproducibility.
!
! Base references (frictionless):
! n_nodes=150, n_conta=16, rfy_close~5.65E6 N, study_passes=1
!
! Inherited tolerances:
! contact_closed=1 in the closure case
! force_error_close < 0.55: version-dependent diagnostic between non-equivalent resultants.
! Do not interpret it as an equilibrium tolerance or professional acceptance criterion.

FINISH