Metafor

ULiege - Aerospace & Mechanical Engineering

User Tools

Site Tools


doc:user:elements:contact:laws

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision
Previous revision
Next revisionBoth sides next revision
doc:user:elements:contact:laws [2013/07/10 18:01] jorisdoc:user:elements:contact:laws [2014/11/05 18:34] – [TrescaContactMaterial] wautelet
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 calculated 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 calculated 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''              -           |
 +| Frictional shear factor |  ''TRESCA_M''          ''TM''        |
 +| Initial shear yield stress  |  ''TRESCA_K''          ''TM''        |
 +| Nominal thermal resistance            ''CTM_H_NOMINAL''            -           |
 +| Exponent                              ''CTM_EXPONENT_E''  |          -           |
 +| Material hardness                    |   ''CTM_HARDNESS''            -           |
 +| Type of contact                      |    ''TYPE_CONT''              -           |
 +
 +The threshold is usually calculated 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 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki