6. Post-treatment#
In the case where TYPE_RESU is different from “FICHIER”, the Miss3D result files are post-processed by CALC_MISS in order to provide the harmonic or temporal response of the structure, or changes in the characteristic quantities (displacement, speed, acceleration, acceleration, oscillator spectrum) at certain post-processing points.
6.1. Common settings#
6.1.1. Operands ACCE_X, ACCE_Y, ACCE_Z, and PAS_INST/INST_FIN#
The operands ACCE_X, ACCE_Yet ACCE_Zpermettent to provide accelerographs. These can be on a time basis or on a frequency basis.
When time-based accelerograms are provided, the keywords PAS_INST and INST_FIN are mandatory and the accelerograms are then systematically interpolated over the interval [0., INST_FIN] with the step PAS_INST.
When frequency-based accelerograms are provided, this has the effect of passing the interpolation and FFT steps. The keywords PAS_INST and INST_FINne need to be entered as a step.
6.2. Calculation of the harmonic or temporal response of the structure#
We are in the case TYPE_RESU =” HARM_GENE “(harmonic response) or” TRAN_GENE “(temporal response).
The harmonic response of the structure to the load provided is then calculated (accelerograms or EXCIT_HARMO).
In the case “TRAN_GENE”, the time rendering is performed using the REST_SPEC_TEMP operator (option PROL_ZERO).
The frequencies used for harmonic calculation depend on the load and are described in paragraph 6.2.2.
6.2.1. Operand MODELE#
This is the structure model (passed to DYNA_LINE_HARM).
6.2.2. Operands ACCE_X, ACCE_Y, ACCE_Z, DEPL_X,, DEPL_Y,, DEPL_Z, EXCIT_HARMO#
We provide either EXCIT_HARMO, or an accelerogram in one or more directions (ACCE_X, ACCE_Y, ACCE_Z), or movements imposed in one or more directions (DEPL_X, DEPL_Y, DEPL_Z).
In the presence of EXCIT_HARMO, the frequency range used for the harmonic calculation is the same as that used for the Miss3D calculation: [FREQ_MIN, FREQ_MAX] in steps of FREQ_PAS \(\mathit{Hz}\) or LIST_FREQ.
The accelerograms or movements imposed can be given either on a frequency basis or on a time basis. In the latter case, these functions are interpolated using PAS_INST, noted \(\mathit{dt}\) and INST_FIN, noted \({t}_{\mathit{max}}\), then an \(\mathit{FFT}\) is applied to them. The frequency range used is that of the \(\mathit{FFT}\) of the accelerogram, i.e.:
\(\left[\mathrm{0,}\frac{1}{2\mathit{dt}}\right]\) with a step of \(\mathit{df}\mathrm{=}\frac{1}{\mathit{npas}\mathrm{\times }\mathit{dt}}\) or \(\mathit{npas}\mathrm{=}{2}^{n},\text{tq}\mathit{npas}\mathrm{\ge }\frac{{t}_{\mathit{max}}}{\mathit{dt}}\).
On a frequency basis, you should not enter the keywords PAS_INST and INST_FIN, in a time base they must be entered.
6.3. Calculation of changes in certain points#
This is how we are in the case TYPE_RESU =” TABLE “.
In this case, the harmonic response of the structure to a unit acceleration (in the direction or directions requested) is calculated. Then, for each load, the unit frequency contributions are recombined at each post-processing location \(M\):
\({u}_{M}(f)={u}_{x}\mathrm{.}\mathit{FFT}({\mathit{acce}}_{x})+{u}_{y}\mathrm{.}\mathit{FFT}({\mathit{acce}}_{y})+{u}_{z}\mathrm{.}\mathit{FFT}({\mathit{acce}}_{z})\)
We also calculate the \(\mathit{FFT}\) of this response and the oscillator spectrum provided by CALC_FONCTION/SPEC_OSCI.
We do the same for \({\dot{u}}_{M}\) and \({\ddot{u}}_{M}\).
All these functions are stored in the produced table:
GROUP_NO NOM_CHAM NOM_PARA FONC_X FONC_Y FONC_Z
ACCE INST ACCE1 ACCE2 ACCE3
ACCE FREQ _9003066 _9003068 _9003070
SOMMET DEPL INST _9003129 _9003129 _9003135 _9003141
SOMMET DEPL FREQ _9003128 _9003128 _9003134 _9003140
SOMMET DEPL SPEC_OSCI _9003130 _9003130 _9003136 _9003142
SOMMET VITE INST _9003147 _9003147 _9003153 _9003159
SOMMET VITE FREQ _9003146 _9003146 _9003152 _9003158
SOMMET VITE SPEC_OSCI _9003148 _9003148 _9003154 _9003160
SOMMET ACCE INST _9003165 _9003171 _9003177
SOMMET ACCE FREQ _9003164 _9003170 _9003176
SOMMET ACCE SPEC_OSCI _9003166 _9003172 _9003178
For each load case (for the first one NUME_CAS = 0), we thus find:
On the first line, the « loading functions », that is to say the accelerograms of the excitation (temporal, NOM_PARA =” INST “) in the 3 directions: FONC_X, FONC_Y, FONC_Z.
On the second line, the \(\mathit{FFT}\) of these signals (NOM_PARA =” FREQ “).
Then for each point (here SOMMET), the evolution of movement, speed and acceleration. With for each, the signal, its \(\mathit{FFT}\) and the oscillator spectrum.
6.3.1. Operand MODELE#
This is the structure model (passed to DYNA_LINE_HARM).
6.3.2. Operands ACCE_X, ACCE_Y, ACCE_Z, INST_FIN, PAS_INST#
An accelerogram is provided in one or more directions (ACCE_X, ACCE_Y, ACCE_Z), a final instant (INST_FIN) and a time step (PAS_INST).
The frequency range of the harmonic calculation is determined from the accelerograms as in paragraph 6.2.2. All accelerograms must have the same time step and this one must be constant.
6.3.3. Operand NORME, AMOR_SPEC_OSCI, LIST_FREQ_SPEC_OSCI#
These parameters are passed to CALC_FONCTION for option SPEC_OSCI (cf. [U4.32.04]) where AMOR_REDUIT has been renamed to AMOR_SPEC_OSCI to not be confused with the list of depreciations used for the harmonic calculation. Likewise LIST_FREQ has also been renamed here to LIST_FREQ_SPEC_OSCI to avoid confusion with the keyword LIST_FREQ which is used to specify the frequency list for harmonic calculation and for MISS3D (cf. paragraph 5.1.2).
6.4. Post-processing of the results at the checkpoints#
This is how we are in the case TYPE_RESU =” TABLE_CONTROL “.
Note
In the Miss3D run with this option, what counts, for the reproduction of signals at the control points, * is in the discretization time parameters given by the operands INST_FINet PAS_INST. On the other hand, we are no longer required to define by the operands FREQ_MIN, * FREQ_MAXet FREQ_PASdu keyword PARAMETREune frequency discretization corresponding to the FFT of these signals and we can therefore use a much less refined discretization necessary for the calculation of frequency impedances.
6.4.1. Operand GROUP_MA_CONTROL#
This is the group of point cells that locate the control points (transmitted to IMPR_MACR_ELEM). During post-processing, response functions are created for each of the points that are taken in the order in which this group of elements is defined.
Thus, in the table, the point designated PC1 does not generally correspond to a node or group of nodes named PC1. This is the first point stitch in GROUP_MA_CONTROL.
6.4.2. Operand TOUT_CHAM#
If this operand is absent, only the accelerations at the control points are post-processed in time. If it is present with the value TOUT_CHAM =” OUI “, we will also post-process the speed and displacement fields in time.
Operands ACCE_X, ACCE_Y, ACCE_Z, INST_FIN,, PAS_INST,, NORME, AMOR_SPEC_OSCI, LIST_FREQ_SPEC_OSCI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~
6.4.3. Table produced#
The load applied in the Miss3D calculation is a unit harmonic acceleration.
The first two lines correspond to the accelerations ACCE_X /Y/Z provided by the user, interpolated with the time step provided, and its \(\mathit{FFT}\).
At each control point, the transfer function is recovered in the three directions at this stress. These are the lines with TRANSFERT/FREQ.
Then, we have the combination:
\({a}_{\mathit{Mx}}(f)={\mathit{ft}}_{x}(f)\mathrm{.}\mathit{FFT}({\mathit{acce}}_{x})\) and the same thing in y and z depending on the load applied.
We also calculate the \(\mathit{FFT}\) of this response and the oscillator spectrum provided by CALC_FONCTION/SPEC_OSCI.
All these functions are stored in the produced table (example with a request only ACCE_Z):
GROUP_NO. NOM_CHAM.. NOM_PARA.. FONC_X… FONC_Y.. FONC_Z
…….. ACCE…. INST…… -…………….. ._9000034
…….. ACCE…. FREQ…… -……………. ._9000035
PC1….. TRANSFERT. FREQ….. _9000036… ._9000037.. _9000038.. _9000038..
PC1….. ACCE….. INST…… -…………….. ._9000040
PC1….. ACCE….. FREQ…… -……………. ._9000039
PC1….. ACCE….. SPEC_OSCI…………….. ._9000041
PC2….. TRANSFERT. FREQ….. _9000042… ._9000043.. _9000044.. _9000044
PC2….. ACCE….. INST…… -…………… ._9000046
PC2….. ACCE….. FREQ…… -……………. ._9000045
PC2….. ACCE….. SPEC_OSCI…………….. ._9000047
PC3….. TRANSFERT. FREQ….. _9000048… ._9000049.. _9000050.. _9000050
PC3….. ACCE…. INST…… -……………. ._9000052
PC3…. ACCE…. FREQ…… -………………………… -……….
PC3…. ACCE…. SPEC_OSCI…………….. ._9000053
The parameter in the table designating the control point is named GROUP_NO to be consistent with case TABLE. As we saw above, it is simply a point number in the control point group of elements.