Skin-Graft-Expansion-Ratio

Skin Graft Area Expansion Ratio Measurement

Prerequisites:

Ensure you have the following software installed:

• Abaqus
• Matlab
• Microsoft Excel

Instructions:

1. Download and extract the simulation folder: After downloading the simulation folder, extract its contents to a directory of your choice.

2. Open Windows command prompt: Open the Windows command prompt by either opening the Start menu and searching for "cmd" or pressing the Windows key + R, typing "cmd" or "cmd.exe" in the Run command box, and pressing Enter.

3. Navigate to the simulation folder: Use the command prompt to navigate to the drive and the path where you extracted the simulation folder. For example:

C: cd path\to\the\simulation\folder

4. Run Abaqus simulation: Execute the "squaredis.inp" file using Abaqus from the command prompt (the simulation results are already provided in the folder as "squaredis.odb" file):

abaqus job=squaredis

5. Verify simulation completion: Check the last line in the "squaredis.log" file to ensure the Abaqus job "squaredis" is completed.

6. Open simulation results in Abaqus: Open the "squaredis.odb" file generated by the simulation.

7. Adjust visualization settings: Set the visualization settings as follows:

• Navigate to Options > Common > Basic.
• Set Visible Edges to Free edges.
• Ensure the deformation scale factor is uniform and set to 1.

8. View deformed shape: Visualize the skin graft shape after stretching by selecting Plot > Deformed Shape. Since the geometry and loading is symmetric, just a quarter of the skin graft is modeled. Hence, area expansion measurements are for a quarter of the skin graft. You can visualize the whole skin by checking the Mirror planes of XZ and YZ in the Mirror/Pattern tab from View > ODB Display Options.

9. Create display groups: From Tools > Display Group > Create, pick Nodes and Node sets for Item and Method, respectively. Create display groups for each side of the skin graft by picking each node set (e.g. PART-3-1.BNC), clicking on Add and Save Selection As, and putting a name (e.g. bnc).

10. Pick the increment in which you want to measure the expansion ratio from Result > Step/Frame.

11. Query node coordinates: Use Tools > Query, and click on Node and Probe values. Pick Select a display group, choose Nodes, and select the intended Display group (e.g. bnc). Uncheck unnecessary data such as Attached elements and Mises stress by right-clicking on columns and selecting Edit Visible Columns. Check all the nodes and click on Write to File. Put a name for the report file (e.g. bnc) and uncheck Append to file. Click on OK to write the report file containing the coordinates of nodes on each side (the report files for each side are already provided in the simulation folder as .rpt files). The first column shows the node labels, while columns 2 to 7 show the x-y-z coordinates of the nodes before and after stretching (at the intended increment).

12. Prepare data in Excel: Import the generated report files (.rpt) into spreadsheet software like Microsoft Excel to separate the columns to be manipulated within Matlab. In Excel, go to the Data tab and select From Text. Locate and open the .rpt file. Select Delimited and click on Next. Check all Delimiters and click on Next and then on Finish (these steps might vary based on the version of Microsoft Excel).

13. Process data in Matlab: Open "SkinGraftMeshingRatioArea.m" file in Matlab. This code sorts the coordinates of node sets representing each side of the skin graft and performs operations on them to calculate the enclosed area before and after stretching using the "integration_discrete_data" function. This function integrates over the given discrete data points to compute the area. Copy the x-y coordinates of the nodes before and after stretching for each side and paste them into the appropriate variables in the Matlab script.

14. Run Matlab Script: Execute the "SkinGraftMeshingRatioArea.m" script in Matlab by clicking on Run in the EDITOR tab. The code plots the skin graft before and after stretching in Figure 1 and Figure 2, respectively. It also prints the area of skin graft before (total_area) and after (Total_Area) stretching along with the expansion ratio (Actual_Ratio) in the Command Window.

Files Included:

• squaredis.inp: Abaqus input file.
• squaredis.odb: Abaqus output database file.
• .rpt files: Report files containing node coordinates before and after stretching.
• SkinGraftMeshingRatioArea.m: Matlab script for calculating area expansion ratio.
• integration_discrete_data.m: Matlab function to be called within the main script.

Note:

The simulation results and all the required data are provided for reference in the simulation folder.