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doc:user:elements:contact:laws [2013/07/10 18:01]
joris [StickingVariablePenaltyContactMaterial]
doc:user:elements:contact:laws [2015/01/26 12:13]
joris
Line 1: Line 1:
 +====== Contact materials ======
 +
 +===== Description =====
 +
 +For all contact materials, a penalty along the normal direction and a depth at which contact is detected are required. Contact can be:
 +  * positively unilateral  (''UNILATERAL_POSITIF''), contact for $\mbox{gap} \geq 0$ (by default)
 +  * negatively unilateral (''UNILATERAL_NEGATIF''), contact for $\mbox{gap} \leq 0$
 +  * bilateral (''BILATERAL''), contact for both $\mbox{gap} \geq 0$ and $\mbox{gap}\leq 0$
 +
 +
 +__Choice of depth at which contact is detected:__ If the contact matrix is made of circles, the depth must be smaller than the smallest radius. If it is planar, the depth is arbitrary, but a large depth leads to a slow contact detection, when if the depth is too small some contacts can be missed.
 +
 +===== FrictionlessContactMaterial =====
 +
 +=== Description ===
 +
 +Contact without friction.
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^  Default  ^
 +| Penalty along normal direction         ''PEN_NORMALE''    |        ''TM''        |            |
 +| Depth at which contact is detected      ''PROF_CONT''              -                       |
 +| Type of contact                      |    ''TYPE_CONT''              -            ''UNILATERAL_POSITIF''  |
 +
 +===== FrictionlessVariablePenaltyContactMaterial =====
 +
 +=== Description ===
 +
 +Contact without friction where penalty can depend on the gap.
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Penalty along normal direction                       ''PEN_NORMALE''    |        ''GD''        |
 +:!: No ''TM'' dependency here!
 +
 +An evolution function must be associated to ''PEN_NORMALE'' (depending on generalized displacements GD).
 +===== StickingContactMaterial =====
 +
 +=== Description ===
 +
 +Sticking contact. A penalty along the tangential direction is added.
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Penalty along normal direction                       ''PEN_NORMALE''    |        ''TM''        |
 +| Penalty along tangential direction                    |   ''PEN_TANGENT''    |        ''TM''        |
 +| Depth at which contact is detected      ''PROF_CONT''              -           |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +===== StickingVariablePenaltyContactMaterial =====
 +
 +=== Description ===
 +
 +Sticking contact where penalty can depend on the gap.
 +
 +=== Parameters ===
 +^   Name                                   Metafor Code      Dependency ^
 +| Penalty along normal direction                       ''PEN_NORMALE''    |        ''GD''        |
 +| Penalty along tangential direction                    |   ''PEN_TANGENT''    |        ''GD''        |
 +:!: No ''TM'' dependency here!
 +
 +An evolution function must be associated to ''PEN_NORMALE'' and/or ''PEN_TANGENT'' (depending on generalized displacements GD). These function can be different.
 +
 +===== CoulombContactMaterial =====
 +
 +=== Description ===
 +
 +Coulomb's friction law. A tangential penalty, a coefficient of static friction (setting the maximal tangential force before sliding) and a coefficient of dynamic friction (setting the value of the sliding force) are required.
 +
 +=== Parameters ===
 +^   Name                              ^     Metafor Code      Dependency ^
 +| Penalty along normal direction         ''PEN_NORMALE''    |        ''TM''        |
 +| Penalty along tangential direction     ''PEN_TANGENT''    |        ''TM''        |
 +| Depth at which contact is detected      ''PROF_CONT''              -           |
 +| Coefficient of static friction        ''COEF_FROT_STA''          ''TM''        |
 +| Coefficient of dynamic friction      |  ''COEF_FROT_DYN''          ''TM''        |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +===== TrescaContactMaterial =====
 +
 +=== Description ===
 +
 +Tresca's friction law. Friction do not depend on pressure. It is computed using penalty method with sticking contact, and starts sliding once the tangential stress reaches a threshold entered by the user.
 +
 +:!: This law requires the use of ''AREAINCONTACT'' = ''AIC_ONCEPERSTEP''
 + 
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Penalty along normal direction                       ''PEN_NORMALE''    |        ''TM''        |
 +| Penalty along tangential direction                   ''PEN_TANGENT''    |        ''TM''        |
 +| Depth at which contact is detected                    ''PROF_CONT''              -           |
 +| Static frictional shear factor |  ''TRESCA_STA_M''          ''TM''        |
 +| Dynamic frictional shear factor |  ''TRESCA_DYN_M''          ''TM''        |
 +| Initial shear yield stress  |  ''TRESCA_K''          -        |
 +| Type of contact                                    |    ''TYPE_CONT''              -           |
 +
 +The threshold is usually computed using $m\,\sigma_0\,/\sqrt{3}$ where //m// is Tresca's coefficient of friction  and $\sigma_0$ is the tensile yield stress of the material.
 +
 +===== TmFrictionlessContactMaterial =====
 +
 +Thermomechanical contact without friction.
 +
 +The heat flux $q_{N}$ normal to the contact interaction (going out of the slave surface) is given by
 +
 +$$q_{N} = h_c \left(p_{N} \right) \left(T^{S} - T^{M}\left(\bf{\xi}^{S}\right)\right), $$
 +
 +where
 +  * $p_{N}$ is the contact pressure,
 +  * $T^{S}$ is the temperature of the slave node,
 +  * $T^{M}\left(\bf{\xi}^{S}\right)$ is the temperature of a point on the master surface corresponding to the closest projection of the slave node on the master surface,
 +  * $h_c$ is the thermal resistance under conduction.
 + 
 +This thermal resistance under conduction $h_c$ is modeled as 
 +
 +$$h_c \left(p_{N} \right) = h_{c0} \left(\frac{p_{N}}{H_v}\right)^{w}, $$      
 +
 +where 
 +     * $H_v$ Vickers's material hardness ,
 +     * $w$ is an exponent, 
 +     * $h_{c0}$ is the nominal thermal resistance under conduction.
 +
 +=== Parameters ===
 +^   Name                                   Metafor Code      Dependency          ^
 +| Penalty along normal direction         ''PEN_NORMALE''    |        ''TM''        |
 +| Depth at which contact is detected      ''PROF_CONT''              -           |
 +| Nominal thermal resistance            ''CTM_H_NOMINAL''            -           |
 +| Exponent                              ''CTM_EXPONENT_E''  |          -           |
 +| Material hardness                    |   ''CTM_HARDNESS''            -           |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +:!: Not tested in 3D :!:
 +
 +===== TmStickingContactMaterial =====
 +
 +Sticking thermomechanical contact
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Penalty along normal direction                       ''PEN_NORMALE''    |        ''TM''        |
 +| Penalty along tangential direction                    |   ''PEN_TANGENT''    |        ''TM''        |
 +| Depth at which contact is detected      ''PROF_CONT''              -           |
 +| Nominal thermal resistance            ''CTM_H_NOMINAL''            -           |
 +| Exponent                              ''CTM_EXPONENT_E''  |          -           |
 +| Material hardness                    |   ''CTM_HARDNESS''            -           |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +:!: Not tested in 3D :!:
 +
 +===== TmCoulombContactMaterial =====
 +
 +=== Description ===
 +
 +Thermomechanical contact using Coulomb's friction law
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Penalty along normal direction                       ''PEN_NORMALE''    |        ''TM''        |
 +| Penalty along tangential direction                    |   ''PEN_TANGENT''    |        ''TM''        |
 +| Depth at which contact is detected      ''PROF_CONT''              -           |
 +| Coefficient of static friction        ''COEF_FROT_STA''          ''TM''        |
 +| Coefficient of dynamic friction      |  ''COEF_FROT_DYN''          ''TM''        |
 +| Nominal thermal resistance            ''CTM_H_NOMINAL''            -           |
 +| Exponent                              ''CTM_EXPONENT_E''  |          -           |
 +| Material hardness                    |   ''CTM_HARDNESS''            -           |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +:!: Not tested in 3D :!:
 +
 +===== TmTrescaContactMaterial =====
 +
 +=== Description ===
 +
 +Thermomechanical contact using Tresca's friction law
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Penalty along normal direction         ''PEN_NORMALE''    |        ''TM''        |
 +| Penalty along tangential direction     ''PEN_TANGENT''    |        ''TM''        |
 +| Depth at which contact is detected      ''PROF_CONT''              -           |
 +| Static frictional shear factor |  ''TRESCA_STA_M''          ''TM''        |
 +| Dynamic frictional shear factor |  ''TRESCA_DYN_M''          ''TM''        |
 +| Initial shear yield stress  |  ''TRESCA_K''          -        |
 +| Nominal thermal resistance            ''CTM_H_NOMINAL''            -           |
 +| Exponent                              ''CTM_EXPONENT_E''  |          -           |
 +| Material hardness                    |   ''CTM_HARDNESS''            -           |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +The threshold is usually computed using $m\,\sigma_0\,/\sqrt{3}$ where //m// is Tresca's coefficient of friction  and $\sigma_0$ is the tensile yield stress of the material.
 +
 +:!: Not tested in 3D :!:
  
doc/user/elements/contact/laws.txt · Last modified: 2016/03/30 15:23 (external edit)