Finite Element Driven Design Domain Identification of a Beating Left Ventricular Simulator

Figures

• 

  Figure 1. (a) Dumbbell test sample. The surface of the sample was smooth and there were no discontinuities on the surface; (b) Test sample was clamped at both ends and subjected to a controlled tension until rupture.

• 

  Figure 2. (a) Revolved solid body of the left ventricular (LV) cavity. The total height of the cavity is 97 mm. Apex diameter is 38.10 mm and the height of the apex is 10 mm. The diameter of the bottom surface is 44.66 mm; (b) Thicken feature in Autodesk Inventor was used to generate desired thickness; (c) Diameter of the McKibben actuators is 6.35 mm. The 90 degrees orientation model is given as an example. The crossectional view shows the continuous contact region between the simulator and the actuator; (d) 0.5 mm slots were added on the mold body. The 90 degrees orientation mold is given as an example; (e) 3D printed 90 degrees orientation mold.

• 

  Figure 3. The 90 degrees orientation model is given as an example; (a) Meshed geometry with tetrahedral elements; (b) Fixed supports were defined on the LV simulator and the McKibben actuators. Remote displacements were added to the bottom surfaces of the actuators with rigid behavior; (c) Continuous contact region was defined on the surface of the slot of LV simulator and the surface of the actuators.

• 

  Figure 4. McKibben actuators were placed on the slots. Two rubber bands were added on the bottom and the top to keep actuators in place. Rubber bands were removed after the actuators were fixed on the latex rubber.

• 

  Figure 5. Setup of the validation experiment. All the actuators were loaded simultaneously.

• 

  Figure 6. Stress-strain curve of the latex rubber. The blue line indicates the average of three tests and the error bars represent the standard error. The shaded area is magnified to show 400 mm/mm to 600 mm/mm strain range clearly.

• 

  Figure 7. (a) Contour bands of the directional deformation along the y-axis. The positive y-axis is located on the upward direction; (b) Deformed FE model; (c) Deformed LV simulator prototype; (d) Before and after loading states of the model and the experiment from the apical view. Similar deformation mechanics were observed on the model and the experiment.

• 

  Figure 8. Time change of directional deformation and rotation of the apex over one beating. Actuators were loaded from 0 to 0.5 s and unloaded from 0.5 s to 1 s. (a) Directional deformation of the apex; (b) Rotation of the apex.

• 

  Figure 9. Design domain of the LV simulator. Subdomains were identified with respect to the orientation angle and legend represents the wall thickness of the LV simulator.

• 

  Figure 10. Effect of the number of actuators on different wall thickness in the design domain. Actuator orientation is changing from 15 degrees to 90 degrees, from left to right in the figures.

• 

  Figure 11. (a) 90 degrees subdomain; (b) 75 degrees subdomain; (c) 60 degrees subdomain; (d) 45 degrees subdomain; (e) 30 degrees subdomain; (f) 15 degrees subdomain.

• 

  Figure 12. Configurations with the highest directional deformation and the highest rotation in the subdomains.