## ForceToStress Solver

**Solver Fortran File:** `ForceToStress.f90`

**Solver Name:** `ForceToStress`

**Required Output Variable(s):** `Stress`

(user defined)

**Required Input Variable(s):** `Force`

**Optional Output Variable(s):** None

**Optional Input Variable(s):** None

### General Description

For a given boundary, this solver computes the nodal stress equivalent to a given nodal force. Force here means the result of a variable, named stress, which is of the same units than the force but per unit-area in 3D or unit-length in 2D. This can be used also to infer the flux from the value of a debit or to infer a tangential stress from the value of a tangential force.

### SIF contents

In the SIF example below, the normal stress on a boundary is inferred from the 3rd component of the Stokes residual.

Solver 1
Equation = "Navier-Stokes"
Stabilization Method = String Stabilized
Flow Model = Stokes
...
Exported Variable 1 = Flow Solution Loads[Fx:1 Fy:1 Fz:1 CEQ Residual:1 ]
Calculate Loads = Logical True
End
Solver 2
Equation = "ForceToStress"
Procedure = File "ElmerIceSolvers" "ForceToStress"
Variable = String "Stress"
Variable DOFs = 1
Force Variable Name = String "Fz"
Linear System Solver = Direct
Linear System Direct Method = umfpack
End
! Solve this for body Id 2 (=boundary 3 here)
Equation 2
Active Solvers(1) = 2
End
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Boundary Condition 3
Target Boundaries = 5
Body Id = 2
...
End

### Examples

In the example found in `[ELMER_TRUNK]/elmerice/Tests/ForceToStress`

, a pressure applied on a boundary is first integrated to get nodal force using the GetHydrostaticLoad Solver, and then the pressure is recovered using the `ForceToStress`

Solver.