## Domain

In order to perform an analysis a given geometrical *domain* you have to discretize your model by creating a mesh out of it. Details of CAD handling and Meshing are described in the *Pre-processing* section.

After you assigned a mesh to the simulation you can add some optional domain-related settings and have a look on the mesh details. Please note that if you have an assembly of multiple bodies that are not fused together, you have to add *Contacts* if you want to build connections between those independent parts.

## Model

In the *model* section everything that defines the physics of the simulation is specified e.g. material properties, boundary conditions etc. On the top level you can adapt some generic settings. For a **Thermomechanical** you can add a gravitational load for the whole domain.

### Materials

In order to define the material properties of the whole domain, you have to assign exactly one material to every part. You can choose the material behavior describing the constitutive law that is used for the stress-strain relation and the density of the material. Please note that the density is used for volumetric loads e.g. gravitation. Inertia effects are only considered in dynamic simulations (*Dynamic*). Please see the *Materials* section for more details.

### Initial Conditions

For a time dependent behaviour of a solid structure it is important to define the *Initial Conditions* carefully, since these values determine the solution of the analysis. In a **Dynamic** analysis the displacement, velocity and acceleration are the time dependent variables. They define the initial state of the domain before the loads and constraints are applied. Per default the displacements, velocities and accelerations are initialized as zero length vector. Thus if you use the default values there will be no displacement and velocity in the initial state. Additionally an initial stress state can be defined as it is a nonlinear analysis type. If not changed by the user the stresses are also taken as zero initially. Furthermore if you choose to run a transient analysis the temperature depends on time. As default it is set to room temperature (293.15 K).

### Boundary conditions

For a **Thermomechanical** analysis you may apply both structural as well as thermal boundary conditions:

#### Constraints and Loads (Boundary conditions)

You can define Constraints (Displacement boundary conditions) and Loads (Force boundary conditions). If you want to determine the position of a part of the domain, add at least one displacement constraint in every coordinate direction. Otherwise it is allowed to move freely in space. This is intended for e.g. drop tests.

In case of missing force boundary conditions (including gravitation), the geometry becomes load-free and apart from the prescribed displacement boundary conditions (constraints) no deformation will evolve. However, this might be intended to determine the strain distribution e.g. in pre-clamped structural components.

Constraint types (Displacement boundary conditions)

Load types (Force boundary conditions)

#### Temperature and Heat flux boundary conditions

You can define temperature and thermal load boundary conditions. If you provide a temperature boundary condition on an entity, the temperature value of all contained nodes is set to the given prescribed value. Thermal load boundary conditions define the heatflux into or out of the domain via different mechanisms. Note that a negative heat flux indicates a heat loss to the environment. As a temperature boundary condition prescribes the temperature value on a given part of the domain it is not possible to simultaneously add a thermal load on that part as it would be overconstrained in that case.

Temperature boundary condition types (Thermal Constraints)

Heat flux boundary condition types (Thermal Loads)

## Numerics

Under numerics you can set the equation solver of your simulation. The choice highly influences the computational time and the required memory size of the simulation.

## Simulation Control

The Simulation Control settings define the overall process of the calculation as for example the timestepping interval and the maximum time you want your simulation to run before it is automatically cancelled.

The description of the analysis type **Thermomechanical** refers to the use of the standard thermomechanical analysis type via the **physics perspective** or the **solver perspective** choosing the **Code_Aster** solver. You may as well choose the **Thermomechanical**analysis of the finite element package CalCuliX (CCX), which is only available via the **solver perspective** (*Thermomechanical analysis CCX*). See our *Third-party software section* for further information.