9. Recovery, archiving and initial state management#

If you want to continue a calculation that has already been executed, the RESULTAT keyword indicates which object is enriched.

9.1. Definition of an initial state#

The ETAT_INIT keyword allows you to define an initial reference state. In the event that the user specified that the concept result is reentrant (by the word RESULTAT), the ETAT_INIT keyword is mandatory. By convention, the initial state of a blank calculation (without rework) is stored at number of order 0.

By default (if nothing is specified) all fields are identically null. The initial state may be defined either by specifying each field of the initial state, or by extraction from a pre-existing evol_noli concept.

If we give a data structure of the type EVOL_NOLI =evol coming from another calculation by the keyword EVOL_NOLI, fields from this data structure are automatically extracted for the initial state.

The extraction of the initial mechanical state in the evol_noli data structure is done from the archiving number NUME_ORDRE or archiving time INST.

If NUME_ORDRE or INST are not filled in, the last existing archived number is taken. These extracted fields will be archived at the first moment of the defined time list. under the keyword INCREMENT. If you enter INST, the keywords PRECISION and CRITERE (see [U4.71.00] for detailed syntax) are used to find the correct order number. Indeed, the moments are identified by a serial number (an integer). If the user wants use an instant (a real one) and not a serial number for INST, the PRECISION operand allows you to select this order number.

A - Simple example (by default behavior)

listInst = DEFI_LIST_REEL (DEBUT =0. ,
                          INTERVALLE =_F (JUSQU_A = 10. , NOMBRE =10))),
evolNoli = MECA_NON_LINE (INCREMENT =_F (LIST_INST =listinst,
                         INST_FIN =4. )),
evolNoli = MECA_NON_LINE (reuse=evolnoli,
                         INCREMENT =_F (LIST_INST =listinst),
                         ETAT_INIT =_F (EVOL_NOLI =EvolNoli))

The first MECA_NON_LINE performs the calculation for the times 1, 2, 3 and 4.

The second MECA_NON_LINE: perform the calculation for the times from 5 to 10, the initial state corresponding to time 4.

B - Example to show the value of two different lists of instants

listInst1 = DEFI_LIST_REEL (DEBUT =0. ,
                           INTERVALLE =_F (JUSQU_A = 10., NOMBRE =10)),

evolNoli = MECA_NON_LINE (INCREMENT =_F (LIST_INST =listinst1))

listInst2 = DEFI_LIST_REEL (DEBUT =20. ,
                           INTERVALLE =_F (JUSQU_A = 30., NOMBRE =10))

evolNoli = MECA_NON_LINE (reuse=evolnoli,
                         RESULTAT = Evolnoli,
                         INCREMENT =_F (LIST_INST =listinst2, INST_INIT =20. ),
                         ETAT_INIT =_F (EVOL_NOLI =EvolNoli,))

The first MECA_NON_LINE does the calculation for the times from 1 to 10. The state initial, with order number 0, is empty (all fields are zero).

The second MECA_NON_LINE calculates the times 21 to 30. The initial state corresponds to instant 10 of the first MECA_NON_LINE (last moment calculated in first MECA_NON_LINE). For this second MECA_NON_LINE, this initial state corresponds to The moment 20 (INST_INIT =20.).

The use of a non-zero initial state will change the calculation of thermal deformation. If there is a non-zero initial state, then the thermal deformation calculation is pure incremental.

If an initial state whose model is different from the calculation model specified in To the operator, the transition between the two models is automatically carried out:

  • If the calculation model is included in the given model in the initial state, the data from the initial state are simply copied mesh by mesh for all fields

  • If the model given in the initial state is included in the calculation model, we start by copying the values of the initial state for the common cells and then complete with the zero value. You have to be careful about the meaning that a null internal variable can have. Initial in the calculation

The keywords DEPL, SIGM and VARI make it possible (respectively) to give a field of movement, of constraints and initial internal variables. If one of these fields is not specified, it is taken to be null by default. For example, they can be from the CREA_CHAMP [U4.72.04] command, or have been read in a file with the LIRE_RESU [U7.02.01] command.

The field of constraints and internal variables at Gauss points and the field of displacements is a field with nodes. If the fields are not set to the correct ones supports the conversions can be done automatically. There are no conditions imposed on the fields given by the user. They can very well represent a mechanical state that is not balanced and/or does not respect the law of behavior. If the calculation is difficult to converge in this case, the easiest way is to create artificially. a state of zero initial constraints to force the selection of the incremental mode, or to use a purely elastic matrix, which allows a certain convergence at the price a large number of iterations.

In large deformations, the user wishing to use the GDEF_LOG formalism with a initial constraint field (ETAT_INIT) will refer to test case SSNP159b. In fact, for impose an initial constraint field, the user must give as input the tensor of constraint defined in logarithmic space \(T\) (not Cauchy) \(\sigma\)). The components of the latter being stored as variables internal, you must use the VARI keyword.

If the material characteristics are highly dependent on control variables, it is appropriate to be careful when selecting the initial state, at the risk of not converging. In fact, elastic behaviors exist in two versions (see [U4.51.11]). The « pure » elastic version is chosen automatically by the code when there is no initial state, otherwise, we select the incremental version. However, only the latter is effective if there are strong variations in material characteristics. (elastic in this case) in relation to the control variables.

If you simultaneously use a report from a complete result (keyword EVOL_NOLI) and the individual definition of a field (for example constraints), the overload rule applies and the fields given individually replace those present in the data structure given as the initial state.

9.2. Archiving the results#

The keyword factor ARCHIVAGE (only one occurrence) allows you to archive some or all results at all or certain moments of the calculation.

In the absence of this keyword all time steps are archived, including the moments of newly created calculations by automatically redividing the time step. Archiving makes it possible to significantly reduce the size of the databases by selecting the saved moments.

The designation of the moments to be stored is carried out either by a list of moments. (keywords LIST_INST or INST) or by an archiving frequency PAS_ARCH =npas (all npas of time).

notes

  • the last calculation step is always stored to be able to perform a recovery

  • if we use access by list of moments, then the moments of calculation newly created by automatic redistribution of the time steps will not be archived

  • the initial state is systematically archived under the order number 0 when one is not Not in recomputation

The CHAM_EXCLU keyword allows you to specify the fields that will not be archived, except for last step of time.