/SHSUB

Engine Keyword Enables you to activate new sub-cycling option, for which Isubcycle =2 in the /ANALY Radioss Starter option should be specified.

Format

/SHSUB/NSH print/NSH ctrl

Definitions

Data Description SI Unit Example
NSH print Defines the output frequency (in the output file or .out file in new extension) for the shell elements, over sub-cycles (that is to say over the only cycles for which internal forces of shell elements are computed).  
NSH ctrl In some cases where the sub-cycling time step falls down, shells may need to be computed each cycle and this process may require to be more CPU time-consuming than deactivating sub-cycling.

Default = 1000

 

Comments

  1. It is possible to make a run with sub-cycling and to switch after restart to a non sub-cycling (standard) computation, and reciprocally.
  2. NSH print defines the output frequency (in the output file .out in new extension) for the shell elements, over subcycles (that is to say over the only cycles for which internal forces of shell elements are computed).

    With a negative value, the printing is also done to the standard output.

    This additional output to the .out file for Radioss Engine will be written with frequency NSH_print over subcycles:

    in case of /DT/SHNOD (nodal time step for SHELL and SH3N elements sub-cycling):
    NC T DTSUB NODE SUBCYCLE
    Where,
    NC
    Current cycle number
    T
    Current time
    DTSUB
    Time step for sub-cycling
    NODE
    SUBCYCLE
    node_ID
    Sub-cycle number

    At this time, the node_ID gives the time step for sub-cycling.

    else:
    NC T DTSUB SHELL or SH3N SUBCYCLE
    Where,
    NC
    Current cycle number
    T
    Current time
    DTSUB
    Time step for sub-cycling
    SHELL or SH3N
    shell_ID or sh3n_ID
    SUBCYCLE
    Sub-cycle number

    At this time, the shell_ID or sh3n_ID gives the time step for sub-cycling.

  3. NSH ctrl has been introduced with the /SHSUB keyword, since in case of the sub-cycling time step falls down, shells may need to be computed each cycle and this process may become some more CPU time consuming than deactivating sub-cycling.

    Indeed, shells and 3-nodes shell elements are computed each D t MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraiaads haaaa@37B8@ time step, corresponding to the D t MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraiaads haaaa@37B8@ stability time step for shells: sub-cycling time step is a stability time step related to shells.

    NSH ctrl: if NSH ctrl cycles are computed without sub-cycling, that is to say if shell elements are computed each cycle during NSH ctrl consecutive cycles, the sub-cycling method will be deactivated by Radioss Engine.

  4. Shells and 3-nodes shell elements are computed each D t MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraiaads haaaa@37B8@ time step, corresponding to the D t MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraiaads haaaa@37B8@ stability time step for shells: sub-cycling time step is a stability time step related to shells.
  5. In case of element time step (/DT/NODA is not specified in the Radioss Engine Input deck):

    D t = Δ T s c a min o v e r _ s h e l l s _ a n d _ 3 n o d e s _ s h e l l s ( l c / c ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraiaads hacqGH9aqpcaqGuoGaamivamaaBaaaleaacaWGZbGaam4yaiaadgga aeqaaOGaaGjcVlaaysW7cqGHflY1ciGGTbGaaiyAaiaac6gadaWgaa WcbaGaam4BaiaadAhacaWGLbGaamOCaiaaygW7caGGFbGaaGzaVlaa dohacaWGObGaamyzaiaadYgacaWGSbGaam4CaiaaygW7caGGFbGaaG zaVlaadggacaWGUbGaamizaiaac+facaaIZaGaeyOeI0IaamOBaiaa d+gacaWGKbGaamyzaiaadohacaaMb8Uaai4xaiaaygW7caWGZbGaam iAaiaadwgacaWGSbGaamiBaiaadohaaeqaaOWaaeWaaeaacaWGSbGa am4yaiaac+cacaWGJbaacaGLOaGaayzkaaaaaa@7022@

    Where,
    l c MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiBamaaBa aaleaacaWGJbaabeaaaaa@37FB@
    Characteristic length
    c
    Sound speed of the related material

    Parameters of /DT/SHELL will be considered, especially for the value of Δ T s c a (default value is 0.9). Parameters of the sub-options /DT/SHELL will be normally considered.

  6. In case of nodal time step (/DT/NODA is specified in the Radioss Engine Input deck).

    D t = Δ T s c a min o v e r _ n o d e s _ c o n n e c t e d _ t o _ s h e l l s s q r t ( 2 m / K s h ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraiaads hacqGH9aqpcaqGuoGaamivamaaBaaaleaacaWGZbGaam4yaiaadgga aeqaaOGaaGjcVlaaysW7cqGHflY1ciGGTbGaaiyAaiaac6gadaWgaa WcbaGaam4BaiaadAhacaWGLbGaamOCaiaaygW7caGGFbGaaGzaVlaa d6gacaWGVbGaamizaiaadwgacaWGZbGaaGzaVlaac+facaaMb8Uaam 4yaiaad+gacaWGUbGaamOBaiaadwgacaWGJbGaamiDaiaadwgacaWG KbGaaGzaVlaac+facaWG0bGaam4BaiaaygW7caGGFbGaaGzaVlaado hacaWGObGaamyzaiaadYgacaWGSbGaam4CaaqabaGccaWGZbGaamyC aiaadkhacaWG0bWaaeWaaeaacaaIYaGaeyyXICTaamyBaiaac+caca WGlbGaam4CaiaadIgaaiaawIcacaGLPaaaaaa@79AE@

    Where,
    m
    Nodal mass
    Ksh
    Stiffness corresponding to the connected shells
    Δ T s c a
    The value given in /DT/NODA; but may be changed by using /DT/SHNOD