#  Step 3: Create surfaces and loads 

 



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  expand\_more  

 
  

 

#### Create surface for applying pressure

  
 We will want to apply a pressure load to the internal surface of the actuator, so we first need to create this surface. Expand **Merged\_Actuator** under **Parts**, and double click on **Surfaces**. Name the surface ‘InnerSurf’.

   ![43_surface1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/43_surface1.png?itok=uxsPYyX_) 

 

In order to access the inner surfaces, we need to deselect the **Select Entity Closest to Screen** icon.

Now hold the shift key and select the inner surfaces of the actuator (the curved surfaces and the two flat surfaces) and click **Done**. To check that the new surface has been defined correctly, you can go to **Surfaces** and click once on ‘InnerSurf’, and check that the correct surfaces are highlighted.

   ![44_surface2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/44_surface2.png?itok=ubJ_j28L) 

 

   ![45_surface3.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/45_surface3.png?itok=kAVktZOt) 

 

Later, we will also need to refer to the outer surface of the actuator, so under **Parts->Merged\_Actuator**, double click on **Surfaces** again. Reselect **Select Entity Closest to Screen**. Name the surface ‘OuterSurf’. Select the outer curved surface of the actuator and click **Done**.

#### Create Step

In the model tree, double click on **Steps**, to create the step in which we will apply the pressure load. Accept the default options of a static general step.

   ![46_step1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/46_step1.png?itok=dJru7qab) 

 

  
In the ‘Edit Step’ dialog box, select Nlgeom ‘On’ under the **Basic** tab. Under the **Incrementation** tab, set 1000 as the Maximum number of increments, 0.01 as the Initial increment size, 1E-5 as the Minimum increment size, and 0.01 as the Maximum increment size. Click **OK**. Sort   ![47_step2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/47_step2.png?itok=opvV6bST) 

 



   ![48_step3.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/48_step3.png?itok=cqkFOj2E) 

 







#### Define Boundary Conditions

For our boundary condition, we will fix the actuator completely at one end. Double click on **BCs** in the model tree. Choose **Displacement/Rotation** as the type of boundary condition and click **Continue**.

Sort   ![50_rotate.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/50_rotate.png?itok=RVj8tQcG) 

 



  
Click on **Rotate View** to rotate the actuator so you can select the actuator face located at (0,0,0), and click **Done**.







   ![51_bc1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/51_bc1.png?itok=_FwHdwyz) 

 

Sort   ![52_bc2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/52_bc2.png?itok=gDbDVYe-) 

 



We want to impose zero displacement on this actuator face, so check the boxes next to U1, U2 and U3, and accept the default displacement values of 0.0.







To control the rate at which the pressure load is applied, we create an amplitude. Double click on **Amplitudes**, and select ‘Equally spaced’. In the ‘Edit Amplitude’ dialog box, enter \[0,1\] in the coumn under ‘Amplitude’. This will apply the load linearly as a function of time.

Sort   ![53_amp1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/53_amp1.png?itok=Dd0yZYqv) 

 



   ![54_amp2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/54_amp2.png?itok=t40olzgg) 

 







#### Apply load

Sort   ![55_load1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/55_load1.png?itok=dVdH6hxM) 

 



Now we define the pressure load, by double clicking on **Loads**. Select ‘Pressure’ as the load type, and click **Continue**.





  
 When prompted to select a surface for the load, click on the **Surfaces** button at the bottom right of the screen.

   ![55_load2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/55_load2.png?itok=P2HPWwyD) 

 

Sort   ![56_load3.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/56_load3.png?itok=pBuUSdFG) 

 



Select ‘Merged_Actuator-1.InnerSurf’.





Sort   ![57_load4.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/57_load4.png?itok=Fiw_urFF) 

 



Enter 0.06 as the magnitude in the ‘Edit Load’ dialog box, and select ‘Amp-1’ as the amplitude.