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 # RAMaterialsInteraction

 Last update: 17.07.2025 

<a id="generated.RAMaterialsInteraction"></a>

### *class* RAMaterialsInteraction

Rocky PrePost Scripting wrapper for the interaction between two materials.

Retrieve a [`RAMaterialsInteraction`](#generated.RAMaterialsInteraction) from a [`RAMaterialsInteractionCollection`](RAMaterialsInteractionCollection.md#generated.RAMaterialsInteractionCollection) and two [`RASolidMaterial`](RASolidMaterial.md#generated.RASolidMaterial):

```python
material_1 = study.GetElement('Default Particles')
material_2 = study.GetElement('Default Boundaries')
interaction_collection = RAMaterialCollection.GetMaterialsInteractionCollection()
interaction = interaction_collection.GetMaterialsInteraction(material_1, material_2)

```

Note that the materials to which a [`RAMaterialsInteraction`](#generated.RAMaterialsInteraction) refers are fixed - while they can be retrieved with [`GetFirstMaterial()`](#generated.RAMaterialsInteraction.GetFirstMaterial) and [`GetSecondMaterial()`](#generated.RAMaterialsInteraction.GetSecondMaterial), they can’t be set.

**Methods:**

NameDescription[`GetAdhesiveDistance`](#generated.RAMaterialsInteraction.GetAdhesiveDistance)(\[unit\])Get the value of "Adhesive Distance".[`GetAdhesiveFraction`](#generated.RAMaterialsInteraction.GetAdhesiveFraction)(\[unit\])Get the value of "Adhesive Fraction".[`GetContactStiffnessMultiplier`](#generated.RAMaterialsInteraction.GetContactStiffnessMultiplier)(\[unit\])Get the value of "Contact Stiffness Multiplier".[`GetDynamicFriction`](#generated.RAMaterialsInteraction.GetDynamicFriction)(\[unit\])Get the value of "Dynamic Friction".[`GetFirstMaterial`](#generated.RAMaterialsInteraction.GetFirstMaterial)()Get this interaction's first material.[`GetModuleProperties`](#generated.RAMaterialsInteraction.GetModuleProperties)()Get the names of the module properties.[`GetModuleProperty`](#generated.RAMaterialsInteraction.GetModuleProperty)(property\_name\[, unit\])Get the value of a module property.[`GetRestitutionCoefficient`](#generated.RAMaterialsInteraction.GetRestitutionCoefficient)(\[unit\])Get the value of "Restitution Coefficient".[`GetSecondMaterial`](#generated.RAMaterialsInteraction.GetSecondMaterial)()Get this interaction's second material.[`GetStaticFriction`](#generated.RAMaterialsInteraction.GetStaticFriction)(\[unit\])Get the value of "Static Friction".[`GetSurfaceEnergy`](#generated.RAMaterialsInteraction.GetSurfaceEnergy)(\[unit\])Get the value of "Surface Energy".[`GetTangentialStiffnessRatio`](#generated.RAMaterialsInteraction.GetTangentialStiffnessRatio)(\[unit\])Get the value of "Tangential Stiffness Ratio".[`GetValidOptionsForModuleProperty`](#generated.RAMaterialsInteraction.GetValidOptionsForModuleProperty)(property\_name)Get all valid options only for properties that have a list of possible options.[`GetVelocityExponent`](#generated.RAMaterialsInteraction.GetVelocityExponent)(\[unit\])Get the value of "Velocity Exponent".[`GetVelocityLimit`](#generated.RAMaterialsInteraction.GetVelocityLimit)(\[unit\])Get the value of "Velocity Limit".[`SetAdhesiveDistance`](#generated.RAMaterialsInteraction.SetAdhesiveDistance)(value\[, unit\])Set the value of "Adhesive Distance".[`SetAdhesiveFraction`](#generated.RAMaterialsInteraction.SetAdhesiveFraction)(value\[, unit\])Set the value of "Adhesive Fraction".[`SetContactStiffnessMultiplier`](#generated.RAMaterialsInteraction.SetContactStiffnessMultiplier)(value\[, unit\])Set the value of "Contact Stiffness Multiplier".[`SetDynamicFriction`](#generated.RAMaterialsInteraction.SetDynamicFriction)(value\[, unit\])Set the value of "Dynamic Friction".[`SetModuleProperty`](#generated.RAMaterialsInteraction.SetModuleProperty)(property\_name, value\[, unit\])Set the value of a module property.[`SetRestitutionCoefficient`](#generated.RAMaterialsInteraction.SetRestitutionCoefficient)(value\[, unit\])Set the value of "Restitution Coefficient".[`SetStaticFriction`](#generated.RAMaterialsInteraction.SetStaticFriction)(value\[, unit\])Set the value of "Static Friction".[`SetSurfaceEnergy`](#generated.RAMaterialsInteraction.SetSurfaceEnergy)(value\[, unit\])Set the value of "Surface Energy".[`SetTangentialStiffnessRatio`](#generated.RAMaterialsInteraction.SetTangentialStiffnessRatio)(value\[, unit\])Set the value of "Tangential Stiffness Ratio".[`SetVelocityExponent`](#generated.RAMaterialsInteraction.SetVelocityExponent)(value\[, unit\])Set the value of "Velocity Exponent".[`SetVelocityLimit`](#generated.RAMaterialsInteraction.SetVelocityLimit)(value\[, unit\])Set the value of "Velocity Limit".<a id="generated.RAMaterialsInteraction.GetAdhesiveDistance"></a>

#### GetAdhesiveDistance(unit: Optional\[str\] = None)

Get the value of “Adhesive Distance”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “m”.

<a id="generated.RAMaterialsInteraction.GetAdhesiveFraction"></a>

#### GetAdhesiveFraction(unit: Optional\[str\] = None)

Get the value of “Adhesive Fraction”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetContactStiffnessMultiplier"></a>

#### GetContactStiffnessMultiplier(unit: Optional\[str\] = None)

Get the value of “Contact Stiffness Multiplier”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetDynamicFriction"></a>

#### GetDynamicFriction(unit: Optional\[str\] = None)

Get the value of “Dynamic Friction”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetFirstMaterial"></a>

#### GetFirstMaterial()

Get this interaction’s first material.

<a id="generated.RAMaterialsInteraction.GetModuleProperties"></a>

#### GetModuleProperties()

Get the names of the module properties.

- **Return type:**tuple(ModulePropertyIdentifier)

<a id="generated.RAMaterialsInteraction.GetModuleProperty"></a>

#### GetModuleProperty(property\_name: str | rocky30.plugins.api.ra\_addins.ModulePropertyIdentifier, unit: str | None = None)

Get the value of a module property.

- **Parameters:**
    - **property\_name** (*Union* \*\[\**str* *,* *ModulePropertyIdentifier* *\]*) – The name of the module property to get.
    - **unit** (*str*) – The unit for value, just for scalar properties. If no unit is provided, the returned value will be in the unit that was set before (via SetModuleProperty()).
- **Return type:**float, bool, str or [`RAModulePropertyList`](RAModulePropertyList.md#generated.RAModulePropertyList)
- **Returns:**
    - For basic module properties like numbers and booleans, the returned value is a basic Python type (float, bool, or string)
    - For input files, the returned value is the string of the full path to the file
    - For properties that are lists of other properties, the returned value is a : [`RAModulePropertyList`](RAModulePropertyList.md#generated.RAModulePropertyList).

<a id="generated.RAMaterialsInteraction.GetRestitutionCoefficient"></a>

#### GetRestitutionCoefficient(unit: Optional\[str\] = None)

Get the value of “Restitution Coefficient”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetSecondMaterial"></a>

#### GetSecondMaterial()

Get this interaction’s second material.

<a id="generated.RAMaterialsInteraction.GetStaticFriction"></a>

#### GetStaticFriction(unit: Optional\[str\] = None)

Get the value of “Static Friction”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetSurfaceEnergy"></a>

#### GetSurfaceEnergy(unit: Optional\[str\] = None)

Get the value of “Surface Energy”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “J/m2”.

<a id="generated.RAMaterialsInteraction.GetTangentialStiffnessRatio"></a>

#### GetTangentialStiffnessRatio(unit: Optional\[str\] = None)

Get the value of “Tangential Stiffness Ratio”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetValidOptionsForModuleProperty"></a>

#### GetValidOptionsForModuleProperty(property\_name)

Get all valid options only for properties that have a list of possible options.

- **Parameters:****property\_name** (*str*) – The name of the module property.
- **Return type:**List\[str\]

<a id="generated.RAMaterialsInteraction.GetVelocityExponent"></a>

#### GetVelocityExponent(unit: Optional\[str\] = None)

Get the value of “Velocity Exponent”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “-“.

<a id="generated.RAMaterialsInteraction.GetVelocityLimit"></a>

#### GetVelocityLimit(unit: Optional\[str\] = None)

Get the value of “Velocity Limit”.

- **Parameters:****unit** – The unit for the returned value. If no unit is provided, the returned value will be in “m/s”.

<a id="generated.RAMaterialsInteraction.SetAdhesiveDistance"></a>

#### SetAdhesiveDistance(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Adhesive Distance”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “m”.

<a id="generated.RAMaterialsInteraction.SetAdhesiveFraction"></a>

#### SetAdhesiveFraction(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Adhesive Fraction”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetContactStiffnessMultiplier"></a>

#### SetContactStiffnessMultiplier(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Contact Stiffness Multiplier”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetDynamicFriction"></a>

#### SetDynamicFriction(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Dynamic Friction”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetModuleProperty"></a>

#### SetModuleProperty(property\_name: str | rocky30.plugins.api.ra\_addins.ModulePropertyIdentifier, value: float | bool | str, unit: Optional\[str\] = None)

Set the value of a module property.

- **Parameters:**
    - **property\_name** (*Union* \*\[\**str* *,* *ModulePropertyIdentifier* *\]*) – The name of the module property to set.
    - **value** (*float* *,* *bool* *or* *str*) – The value to set. If the property\_name references to an enum property then value must be an str value.
    - **unit** (*str*) – The unit for value, just for scalar properties. If no unit is provided, value is assumed to be the unit was set before.

<a id="generated.RAMaterialsInteraction.SetRestitutionCoefficient"></a>

#### SetRestitutionCoefficient(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Restitution Coefficient”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetStaticFriction"></a>

#### SetStaticFriction(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Static Friction”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetSurfaceEnergy"></a>

#### SetSurfaceEnergy(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Surface Energy”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “J/m2”.

<a id="generated.RAMaterialsInteraction.SetTangentialStiffnessRatio"></a>

#### SetTangentialStiffnessRatio(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Tangential Stiffness Ratio”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetVelocityExponent"></a>

#### SetVelocityExponent(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Velocity Exponent”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “-“.

<a id="generated.RAMaterialsInteraction.SetVelocityLimit"></a>

#### SetVelocityLimit(value: Union\[str, float\], unit: Optional\[str\] = None)

Set the value of “Velocity Limit”.

- **Parameters:**
    - **value** – The value to set. This value can be an expression with input variables or float type.
    - **unit** – The unit for value. If no unit is provided, value is assumed to be in “m/s”.