#  Step 2: Create and assign materials 

 



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#### Create and assign materials

Next we will create the two materials used in this model: Elastosil (for the elastomeric tube) and Kevlar (for the fibers).

To create the first material, double click on **Materials** in the model tree. Name the material ‘Elastosil’. This is a nonlinearly elastic material, so we assign it the property **Mechanical->Elasticity->Hyperelastic**. We will model it using a neo-Hookean strain energy potential. Choose ‘Coefficients’ as the input source, with C10=0.12MPa and D1=0.0. Click **OK**.

Sort   ![26_material1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/26_material1.png?itok=UHHa2Whi) 

 



   ![27_material2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/27_material2.png?itok=ovfetR7f) 

 







*For a bending actuator, instead of defining the Elastosil material, define the materials Smooth-Sil 950 and Dragon Skin 10, as follows:  
Double click on **Materials** in the model tree. Name the material ‘DS10’. This is a nonlinearly elastic material, so we assign it the property **Mechanical->Elasticity->Hyperelastic**. We will model it using a neo-Hookean strain energy potential. Choose ‘Coefficients’ as the input source, with C10=0.0425MPa and D1=0.0. Click **OK**.  
Make a second material and name it 'SS950'. Again, we will model it using a neo-Hookean strain energy potential. This time set C10=0.34MPa and D1=0.0.*  
  
To make the material for the fibers, we double click on **Materials** again. Name this material ‘Kevlar’. We model it as a linearly elastic material, with properties **Mechanical->Elasticity->Elastic**. Enter 31067 MPa for the Young’s modulus and 0.36 for the Poisson’s ratio. Click **OK**.

Sort   ![28_material3.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/28_material3.png?itok=-JAMiJDk) 

 



   ![29_material4.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/29_material4.png?itok=Ty0aiCQa) 

 







Sort   ![30_material5.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/30_material5.png?itok=cvar2dLb) 

 



  
Double click on **Sections** in the model tree.

Name the section elastosilSection. Click **Continue**, choose Elastosil as the material, and click **OK**.

*For a bending actuator, instead of defining the section elastosilSection, use the materials DS10 and SS950 to define DS-section and SS-section.*







Sort   ![31_section1.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/31_section1.png?itok=Cke__qS6) 

 



   ![32_section2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/32_section2.png?itok=QoctxdtF) 

 







Sort   ![33_section3.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/33_section3.png?itok=3_h05YAP) 

 



  
Double click on **Sections** again and name this section kevlarSection. Select **Beam** as the Category and as the Type, and click **Continue**.







Sort   ![34_section4.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/34_section4.png?itok=LoP84C1g) 

 



  
In the ‘Edit Beam Section’ dialog box that appears, click on **Create Beam Profile**.







Sort   ![35_section5.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/35_section5.png?itok=EX-mIraR) 

 



Name the profile fiberProfile, and select ‘Circular’ as the shape.







Sort   ![36_section6.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/36_section6.png?itok=rYl5COsh) 

 



Click **Continue**, enter 0.0889 as the radius ‘r’ and click **OK**. This models the fiber as a beam structure with a circular cross section.





Sort   ![37_section7.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/37_section7.png?itok=D-LwxROW) 

 



  
In the ‘Edit Beam Section’ dialog box, select ‘Kevlar’ as the Material name and enter 0.36 as the Section Poisson’s ratio. Click **OK**.







  
Now we need to assign a material to each of the parts. Expand **Merged\_Actuator** under **Parts** and double click **Section Assignments.** Select the actuator and click **Done**.

 ![38_section8.png](/sites/g/files/omnuum4601/files/sorotoolkit/files/38_section8.png)

 

Sort   ![39_section9.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/39_section9.png?itok=50sU0P0V) 

 



Click **OK** in the ‘Edit Section Assignment’ box.





*For a bending actuator, assign SS-section to the caps and the bottom half of the actuator. Assign DS-section to the top half of the actuator.*

Expand **fibers** under **Parts** and double click **Section Assignments**. Select the fiber and click **Done**.

Sort   ![41_section11.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/sorotoolkit/files/41_section11.png?itok=R_i9USAA) 

 



Click **OK** in the ‘Edit Section Assignment’ box.





Sort   ![42_section12.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/42_section12.png?itok=ykw7Nm6J) 

 



In the main toolbar, click **Assign->Beam Section Orientation**. Select the fiber and click **Done**.

  
Accept the default n1 direction of (0,0,-1) by hitting enter. Click **OK**.