*WINNER* Investigation of mechanical boundary conditions on impedance based structural health monitoring in a biomedical environment


  • Nathan Ghattas
  • Robert Ponder


The purpose of this research is to test the feasibility of the electromechanical impedance (EMI) method, to detect damage under different boundary conditions found inside of a typical total knee replacement (TKR) system. This is achieved by creating a test setup that is able to replicate the basic properties of a typical TKR using materials similar to those in a true system, including simulated bone material, bone cement, and a metallic knee replacement component. In order to determine if the EMI method can be used in an environment that includes the loads present in a knee, two bearings are designed: one that transfers the axial knee load directly to the PZT, and one where the axial knee load bypasses the PZT and flows directly to the underlying sample. The impedance is analyzed at different axial knee loads. Damage is inflicted upon the test setup by removing a portion of the bone cement between the metallic component and synthetic bone, and the same tests are run under the damaged conditions. The impedance is then compared for undamaged and damaged conditions when the load is transferred to the PZT and when the load bypasses the PZT and is transferred to the sample in order to test the validity of the EMI method for damage detection under loaded conditions. Then the impedance is compared between the two load conditions first in the undamaged case than in the damaged case in order to validate static force sensing.