Joseph Al Ahmar

Fracture mechanics analysis of cracks in multilayer ceramic capacitors

Finite element modelling of multilayer ceramic capacitors (MLCCs) is presented. The stress distribution due to thermo-mechanical loads is estimated. Thermal cool down after soldering process is considered and afterwards a three point bending test has been done. Once the critical stress regions on ceramic are estimated, a fracture mechanics analysis has been performed. Cracks are initiated and fracture parameters were estimated using a direct approach, based on the crack opening displacement and also an energy approach by calculating the J-integral parameter. Finally the fracture mechanics parameters are used for investigating the crack bifurcation.

A low-frequency stable finite-element formulation for modal waveguide analysis

This paper presents a low-frequency stable finite element formulation in terms of the electric fiel and the magnetic flu density for the modal analysis of waveguides. In contrast to competing methods, the eigenvalues of the proposed formulation represent propagation coefficient rather than their squares, which allows to resolve solutions close to zero more accurately.

An E-B mixed finite element method for axially uniform electromagnetic waveguides

A numerically stable mixed finite element method for axially uniform electromagnetic waveguides is presented. The mathematical formulation is valid from DC up to optical frequencies. The proposed methodology uses the electric field intensity E and magnetic flux density B as state variables and employs face, edge, and node Whitney elements for the spatial discretization. Low-frequency stability is obtained by enforcing the Maxwell divergence laws explicitly, by means of a discrete Helmholtz decomposition. Numerical examples demonstrate the stability and low error of the suggested approach.