#  Step 5: Add tie constraint 

 



 ##  

  expand\_more  

 
  

 

#### Add tie constraint

  
 The fibers and the elastomeric tube need to be connected to each other in some way, and this connection is modeled as a ‘tie constraint’, which ties the fibers to the surface of the actuator. To apply this constraint, double click on **Constraints** in the model tree. Accept the default type of ‘tie’ and click **Continue**.

   ![63_constraint1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/63_constraint1.png?itok=Pb8WVQcl) 

 

- Choose ‘Surface’ as the master type.
- Click on **Surfaces** in the bottom right corner, select ‘Merged\_Actuator-1.OuterSurf’, and click **Continue**.
- Choose ‘Node region’ as the slave type. Select ‘fibers-1.FiberSet’ and click **Continue**.
- Click **OK** in the ‘Edit Constraint’ dialog box to impose the constraint.

 ![64_constraint3.png](/sites/g/files/omnuum4601/files/sorotoolkit/files/64_constraint3.png)