# Metafor

ULiege - Aerospace & Mechanical Engineering

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 doc:user:elements:contact:laws [2015/01/26 12:13]joris doc:user:elements:contact:laws [2016/03/30 15:23] 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 :!: