Materials

In DynamFluid, the different materials used in Engineering are modeled using the objectMaterial. Using this object it is possible to model the properties of the material found in the environment (mechanical properties, thermal properties or fluid properties).

The management of the list of materials found in the project is done by selecting the menu option Material of the Model menu that shows the diálogo List of materials dialog box showing the list of existing materials in the model.

This dialog box allows creating a new material (New button), modifying an existing material (Edit button) or delting an existing material (Deleting button).

Creating a new material

To define a new material you must define the object identifier (that must be a positive integer and different than the identifier of any existing object), and the material type (Elastic, Fluid, Plastic, Porous or Thermal). Additional, you must define the properties of each material.

Elastic Material

An elastic material is defined by the following properties:

·   Young module                   Young module of the material

·   Shear module         Shear module of the material.

·   Poisson coeff.                     Poisson coefficient of the material.

·   Density                               Mass per volume of the material.

·   Thermal Expansion coeff. Thermal expansion coefficient of the material.

·   Reference temperature      Reference temperature of the Thermal expansion coefficient.

·   Humidity coeff.              Humidity coefficient of the material.

·   Elastic limit                       Elastic limit of the material under traction, from which the material ends behaving linearly.

·       Shear stress limit                Elastic limit of the material under stress, from which the material ends behaving linearly.

·   Compresson limit               Elastic limit of the material under compression, from which the material ends behaving linearly.

Fluid-dynamic material

This type of object is intended to model the properties of fluid (a material simulating the behaviour of a fluid):

·   Viscosity                        Dynamic viscosity of the material.

·   Thermal conductivity         Thermal conductivity of the material.

·   Difusivity                       Thermal diffusion coefficient of the material.

·   Density Reference temp.   Reference temperature of the thermal diffusion coefficient. The introduced value in this edit box must be equal or greater than zero. If the introduced value is zero, the material is considered incompressible (it means the material density does not depend on the temperature).

·   Thermal expansion            Thermal expansion coefficient of the material. The introduced value in this edit box is only taken into account when the Density Reference temp / Viscous coefficient temp / Therm. Conduct. Ref. Temp is greater than zero. If the Density Reference temperature is greater than zero but the Thermal expansion coefficient is zero, the material is considered an ideal gas.

·   Viscous coefficient temp   Not used.

·   Viscosity Reference temp  Reference temperature of the viscosity. The introduced value in this edit box must be equal or greater than zero.

·   Therm. Conduct. Ref. Temp  Thermal conductivity reference temperature. This is the temperature at which the thermal conductivity is equal to the value introduced. As the temperature varies, the thermal conductivity varies. The introduced value in this edit box must be equal or greater than zero.

·   Compressibility.                 Compressibility module of the material.

·   Sound velocity                   Sound velocity in the fluid.

Plastic material

This type of object permits defining the non-linear properties of the material, which is used when simulating the material under isotropic plasticity.

·   Isotropic hardening            Coefficient for the material isotropic hardening

·   Kinematic hardening         Coefficient for the material kinematic hardening

·   Exhaustion criteria            Exhaustion criteria to use in the simulation (Von Misses, only currently supported).

Thermal material

This type of object permits defining the thermal properties of a material.

·   Thermal conductivity                Thermal conductivity coefficient of the material.

·   Thermal convection coefficient    Thermal convection coefficient of the material.

·   Reference entalpy                          Reference entalpy of the material

·   Temperature range                        Range of temperature for the thermal material properties.

·   Specific heat                                  Material specific heat capacity.

·   Generation heat capacity               Capacity of the material to generate heat.

·   Bottom temperature limit.             Lowest temperature the material properties are valid

·   Latent heat                                     Material latent heat.

Modifying an exiting material

Modifying an existing material can be done pushing the Edit button of the List of Material dialog box. The only non-modifying edit box is the identifier of the object (Identifier edit box). The rest of fields can be modified as when creating / defining a new material.