Date of Graduation

2017

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Ever J Barbero

Committee Co-Chair

Ever J Barbero

Committee Member

Fritz A Campo

Committee Member

Yun Chen

Committee Member

Xueyan Song

Committee Member

Eduardo M Sosa

Abstract

Magnetoelectric (ME) composites can be produced by placing magnetostrictive particles in a piezoelectric-matrix. Ferrite magnetostrictive (H) particles, if allowed to percolate, can short the potential difference generated in the piezoelectric (E) phase. This work focuses on modeling an ME composite as bi-disperse hard shells with the magnetostrictive H particles scaled to 100nm where particle dynamics is used to explore relationships among relative particle size, particle affinity, and electrical percolation with the goal of maximizing the percolation threshold. It was found that the two factors that increase the H to H intra-phase percolation threshold are: (1) the size of H particles relative to the E particles, and (2) the affinity between the H and E particles. Other factors that were also found to decrease the same percolation threshold are: the (1) deformation of the H particles from spherical geometry, and (2) a tipping point in the relative RH/RE size ratio where if the size of the E particles goes below a value of approximately (3.5) --1 H particle size, then the percolation threshold decreases.

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