/FRICTION

Block Format Keyword Specific contact friction between groups of parts or two parts. This friction definition overwrites the friction model defined in the contact interface for the defined set of interfaces.

This friction model is compatible with contact interfaces: TYPE7, TYPE11, TYPE19, TYPE24 and TYPE25.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/FRICTION/fric_ID/unit_ID
friction_title
Ifric Ifiltr Xfreq Iform
Default friction values, used for any parts are not specifically defined below.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
C1 C2 C3 C4 C5
C0 Fric VISF
Repeat these 3 lines to define different friction values for specific parts or groups of parts. For orthotropic friction Idir =1, repeat the next 5 lines where the first set of coefficients is for the first direction and the second set defines the second direction.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
grpart_ID1 grpart_ID2 part_ID1 part_ID2 Idir
C1 C2 C3 C4 C5
C6 Fric VISF
If Idir =1, enter 2 additional lines to define friction in the second direction of orthotropy. 7
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
C1 C2 C3 C4 C5
C6 Fric VISF

Definition

Field Contents SI Unit Example
fric_ID Friction identifier.

(Integer, maximum 10 digits)

unit_ID Unit Identifier.

(Integer, maximum 10 digits)

friction_title Friction model title.

(Character, maximum 100 characters)

Ifric Friction formulation flag. 1
= 0 (Default)
Static Coulomb friction law.
= 1
Generalized viscous friction law.
=2
(Modified) Darmstad friction law.
=3
Renard friction law.
= 4
Exponential decay friction law.

(Integer)

Ifiltr Friction filtering flag. 5
= 0 (Default)
No filter is used.
= 1
Simple numerical filter.
= 2
Standard -3dB filter with filtering period.
= 3
Standard -3dB filter with cutting frequency.

(Integer)

Xfreq Filtering coefficient.

This coefficient should have a value between 0 and 1.

Default = 1.0 (Real)

Iform Friction penalty formulation type. 6
=0
Set to 1.
=1 (Default)
Viscous (total) formulation.
= 2
Stiffness (incremental) formulation.

(Integer)

C1 Friction law coefficient.

(Real)

C2 Friction law coefficient.

(Real)

C3 Friction law coefficient.

(Real)

C4 Friction law coefficient.

(Real)

C5 Friction law coefficient.

(Real)

C6 Friction law coefficient.

(Real)

Fric Coulomb friction.

(Real)

VISF Critical damping coefficient on interface friction. 4

Default = 1.0 (Real)

grpart_ID1 Part group identifier. /GRPART for the first set.

(Integer)

grpart_ID2 Part group identifier /GRPART for the second set.

(Integer)

part_ID1 Part identifier 1.

Ignored if grpart_ID1 is defined.

(Integer)

part_ID2 Part identifier 2.

Ignored if grpart_ID2 is defined.

(Integer)

Idir Orthotropic friction flag for a couple of parts.
= 0
Isotropic friction.
= 1
Orthotropic friction.

(Integer)

Example

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FRICTION/999
test no 1
#    Ifric    Ifiltr               Xfreq     Iform
         0         0                   0         2
# default friction for rest parts which not specifically defined below
#                 C1                  C2                  C3                  C4                  C5
                   0                   0                   0                   0                   0
#                 C6                Fric                VisF
                   0                  .2                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#friction between part group ID 111 and ID 222
#GRpartID1 GRpartID2  PartID_1  PartID_2                Idir
       111       222         0         0	               0   
#                 C1                  C2                  C3                  C4                  C5
                   0                   0                   0                   0                   0
#                 C6                Fric                VisF
                   0                  .1                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#friction between part ID 1 and ID 3	
#GRpartID1 GRpartID2  PartID_1  PartID_2                Idir
         0         0         1         3	               0
#                 C1                  C2                  C3                  C4                  C5
                   0                   0                   0                   0                   0
#                 C6                Fric                VisF
                   0                  .2                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|	
#friction between part ID 1 and ID 4; orthotropic direction considered	
#GRpartID1 GRpartID2  PartID_1  PartID_2                Idir
         0         0         1         4                   1 
#                 C1                  C2                  C3                  C4                  C5
                   0                   0                   0                   0                   0
#                 C6                Fric                VisF
                   0                  .4                   0
#                 C1                  C2                  C3                  C4                  C5
                   0                   0                   0                   0                   0
#                 C6                Fric                VisF
                   0                  .2                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#friction between part ID 1 and ID 5	
#GRpartID1 GRpartID2  PartID_1  PartID_2                Idir
         0         0         1         5	               0
#                 C1                  C2                  C3                  C4                  C5
                   0                   0                   0                   0                   0
#                 C6                Fric                VisF
                   0                  .3                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/INTER/TYPE7/2
New INTER 2
#  Slav_id   Mast_id      Istf      Ithe      Igap                Ibag      Idel     Icurv      Iadm
         9        10         0         0         2                   0         1         0         0
#          Fscalegap             Gap_max             Fpenmax
                   0                   0                 0.8
#              Stmin               Stmax          %mesh_size               dtmin  Irem_gap   Irem_i2
                   1                   0                   0                   0         0         0
#              Stfac                Fric              Gapmin              Tstart               Tstop
                   0                 .35                 2.1                   0                   0
#      IBC                        Inacti                VisS                VisF              Bumult
       000                             6                   0                   0                   0
#    Ifric    Ifiltr               Xfreq     Iform   sens_ID   fct_IDf             AscaleF   fric_ID
         0         0                   0         2         0         0                   0         0
/GRNOD/PART/9
INTER_group_9_of_SURF
         4         5
/SURF/PART/10
INTER_group_10_of_PART
         1         
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/SH_ORTH/11
PROPERTY FOR PART ID 1
#   Ishell    Ismstr     Ish3n    Idrill
        24         0         0         1
#                 hm                  hf                  hr                  dm                  dn
                   0                   0                   0                  .1                  .1
#        N                         Thick              Ashear              Ithick     Iplas
         5                           1.0                   0                   1         1
#                 Vx                  Vy                  Vz                 Phi
                   1                   0                   1                  45
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
Table 1. Friction used by model based on input example
Parts Idir Friction Coefficient
All parts not listed - 0.2
/GRPART/111 - /GRPART/222 0: Isotropic 0.1
part_ID1 - part_ID3 0: Isotropic 0.2
part_ID1 - part_ID4 1: Orthotropic Dir1 = 0.4 Dir2 = 0.2
part_ID1 - part_ID5 0: Isotropic 0.3

In this example, the orthotropic direction for friction between parts 1 and 4 is defined by the part 1 property /PROP/SH_ORTH/11 because part 1 is the main contact surface.

Comments

  1. The friction defined in /FRICTION overrides any friction defined in the contact interface.
  2. Default values listed in the first section are used for any parts whose friction is not specifically defined in the repeating section using grpart_ID1, grpart_ID2, part_ID1, and part_ID2.
  3. If friction between parts is defined more than one time in the model, the friction defined in the last position are used.
  4. The friction value μ is defined.
    • Ifric = 0 (Coulomb friction):
      μ = Fric
    • Ifric = 1 (Generalized Viscous Friction law):

      μ = Fric + C 1 . p + C 2 V + C 3 . p V + C 4 p 2 + C 5 V 2

      Where,
      p MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiCaaaa@36EB@
      Pressure of the normal force on the main segment
      V MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOvaaaa@36D1@
      Tangential velocity of the secondary node
    • Ifric = 2 (Modified Darmstad law):
      μ = Fric + C 1 . e ( C 2 V ) . p 2 + C 3 . e ( C 4 V ) . p + C 5 . e ( C 6 V )
      Where,
      p MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiCaaaa@36EB@
      Pressure of the normal force on the main segment
      V MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOvaaaa@36D1@
      Tangential velocity of the secondary node
    • Ifric = 3 (Renard law):
      μ = C 1 + ( C 3 C 1 ) V C 5 ( 2 V C 5 ) if V [ 0 , C 5 ]
      μ = C 3 ( ( C 3 C 4 ) ( V C 5 C 6 C 5 ) 2 ( 3 2 V C 5 C 6 C 5 ) ) if V [ C 5 C 6 ]
      μ = C 2 1 1 C 2 C 4 + ( V C 6 ) 2 if V C 6
      Where,
      C 1 = μ s
      C 2 = μ d
      C 3 = μ max
      C 4 = μ min
      C 5 = V cr 1
      C 6 = V c r 2
      • First critical velocity V c r 1 = C 5 must be different to 0 ( C 5 0 ).
      • First critical velocity V c r 1 = C 5 must be less than the second critical velocity V c r 2 = C 6 ( C 5 < C 6 ) .
      • The static friction coefficient C 1 and the dynamic friction coefficient C 2 , must be less than the maximum friction C 3 ( C 1 C 3 and C 2 C 3 ).
      • The minimum friction coefficient C 4 must be less than the static friction coefficient C 1 and the dynamic friction coefficient C 2 ( C 4 C 1 and C 4 C 2 ).
    • Ifric = 4 (Exponential decay friction law)

      The frictional coefficient is assumed to be dependent on the relative velocity V MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOvaaaa@36D1@ of the surfaces in contact according to:

      μ = C 1 + F r i c C 1 e C 2 V MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH8oqBcq GH9aqpcaWGdbWaaSbaaSqaaiaaigdaaeqaaOGaey4kaSYaaeWaaeaa caWGgbGaamOCaiaadMgacaWGJbGaeyOeI0Iaam4qamaaBaaaleaaca aIXaaabeaaaOGaayjkaiaawMcaaiabgwSixlaadwgadaahaaWcbeqa amaabmaabaGaeyOeI0Iaam4qamaaBaaameaacaaIYaaabeaalmaaem aabaGaamOvaaGaay5bSlaawIa7aaGaayjkaiaawMcaaaaaaaa@4F0A@

    Table 2. Units of Friction Formulation
    Ifric Fric C1 C2 C3 C4 C5 C6
    1 [ 1 Pa ] MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaaGymaaqaaiaabcfacaqGHbaaaaGaay5waiaaw2faaaaa @3AD3@ [ s m ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4Caaqaaiaab2gaaaaacaGLBbGaayzxaaaaaa@3A46@ [ s Pa m ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4CaaqaaiaabcfacaqGHbGaeyyXICTaaeyBaaaaaiaa wUfacaGLDbaaaaa@3E47@ [ 1 Pa 2 ] MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaaGymaaqaaiaabcfacaqGHbWaaWbaaSqabeaacaaIYaaa aaaaaOGaay5waiaaw2faaaaa@3BC6@ [ s 2 m 2 ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4CamaaCaaaleqabaGaaGOmaaaaaOqaaiaab2gadaah aaWcbeqaaiaaikdaaaaaaaGccaGLBbGaayzxaaaaaa@3C2C@
    2 [ s m ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4Caaqaaiaab2gaaaaacaGLBbGaayzxaaaaaa@3A46@ [ s m ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4Caaqaaiaab2gaaaaacaGLBbGaayzxaaaaaa@3A46@ [ s m ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4Caaqaaiaab2gaaaaacaGLBbGaayzxaaaaaa@3A46@
    3 [ m s ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada Wcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@ [ m s ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada Wcaaqaaiaab2gaaeaacaqGZbaaaaGaay5waiaaw2faaaaa@39DE@
    4 [ s m ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaam aalaaabaGaae4Caaqaaiaab2gaaaaacaGLBbGaayzxaaaaaa@3A46@
  5. Friction filtering

    If Ifiltr ≠ 0, the tangential forces are smoothed using a filter:

    F t = α F t + ( 1 α ) F t 1

    Where, α MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegaaa@3792@ coefficient is calculated from:
    • If Ifiltr = 1: α = X f r e q MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHXoqycq GH9aqpcaWGybWaaSbaaSqaaiaadAgacaWGYbGaamyzaiaadghaaeqa aaaa@3DCF@ , simple numerical filter
    • If Ifiltr = 2: α = 2 π X f r e q , standard -3dB filter, with X f r e q = d t T , and T = filtering period
    • If Ifiltr = 3: α = 2 π X freq d t , standard -3dB filter, with Xfreq = cutting frequency

    The filtering coefficient Xfreq should have a value between 0 and 1.

  6. Friction penalty formulation Iform:
    • If Iform = 1 (default) viscous formulation, the friction forces are:
      F t = min ( μ F n , F adh )

      While an adhesion force is computed as:

      F adh = C V t with C = VIS F 2 Km

    • If Iform = 2, stiffness formulation, the friction forces are:
      F t new = min ( μ F n , F adh )

      While an adhesion is computed as:

      F adh = F t old + Δ F t with Δ F t = K V t δ t

      Where, V t is the contact tangential velocity.

      Iform = 2 is recommended for implicit and low speed impact explicit analysis.

  7. Orthotropic friction for shell elements, if Idir = 1.
    • Two sets of friction coefficients must be defined after the line that contains Idir
    • The orthotropic directions are defined only on the main contact surface
    • The 2 ways to define the orthotropic friction direction
      • Use the orthotropic direction from the shell element as defined in /PROP/TYPE9, /PROP/TYPE10, /PROP/TYPE11, /PROP/TYPE17, /PROP/TYPE51, or /PROP/PCOMPP.

        Direction 1 from element.

        Direction 2 is orthogonal to Direction 1 in the segment plane.

      • Use Direction 1 defined from the vector V MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaCOvaaaa@36D5@ and angle ϕ defined in /FRIC_ORIENT.
    • Not supported for solid element, beam, truss or spring elements or edge to edge contact.