# MECH

This step is actually common to a certain number of different applications. The instruction mentioned in this page are completely defining all these applications, even though some limitations may occur in some of them, consisting in a reduced number of possible choices availability.

## MECHANICAL MODELS

The first section someone has to define in a static mechanical simulation regards the mechanical model. This is a system of hypothesis that link calculated displacement with stress and shear. The models available are:

• Mechanical model: dropdown menu with all the choices
• Isotropic linear elastic: isotropic material with linear relation between stress and shear: $\sigma = E \cdot \varepsilon$.
• Isotropic linear elastic (large displacement): isotropic material with linear relation between stress and shear: $\sigma = E \cdot \varepsilon$ and the hypotesys of large displacements.

For each of the choices made in the mechanical model, it is then necessary the definition of the material properties such as:

• $\rho$ density
• $\nu$ Poisson ration
• $E$ Young modulus

## BODY FORCE

In this section it is possible to insert a body force, a force acting on the whole volume we are simulating. Among the possible choices you have:

• None: no body force is applied
• Centrifugal force: the whole body is considered in rotation.
• Rotating point represents the centre of the rotation
• Rotating axis is the axis along which the body is rotating
• Rotating speed is the rotational speed

## BOUNDARY CONDITIONS

Similarly to what happens in CFD simulations, it is now necessary to insert a mixed of boundary conditions in order to define the external loads and constraints. To do so, CONSELF web applications gives you the opportunity to use the following boundaries:

• CONSTRAINT - Free: simple boundary condition where neither constraints nor loads are applied.
• CONSTRAINT - Fixed: possibility to define a constraint boundary condition. The constraint can be applied through a combinations of constraints along the X, Y and Z axis. It is user resposibility the definition of a fully constraint system to avoid liabilities.
• LOAD - Force: load application as a distributed force in N/mm². The force direction is specified by the user by the definition of the three components along the X, Y and Z axis.
• LOAD - Pressure: load application of a pressure in Pa. The pressure generates a force which is always orthogonal to the surface.

## SIMULATION SETTINGS

In simulation settings the user interface requires a set of numerical parameters. In particular:

• Iterations number: definition of the number of iterations required to complete the simulation
• Output frequency: the frequency we are using to save an output visualization file
• Cores number: the number of cores required to run the simulation and the RAM available

## RUNTIME RESIDUALS AND CONVERGENCE

Since MECH analysis can be non-linear (i.e. large displacement analysis), the FEA assumes an iterative process to calculate the results. As usual, it is possible to monitor real-time the residuals calculated after each iteration by clicking on the appropriate button of the progress bar.