Investigation of crack propagation in ceramic/conductive epoxy/glass systems

The primary objective of this combined experimental and analytical study was to investigate the mechanical behavior of glass/conductive adhesive/Al/sub 2/O/sub 3/ systems with a surface notch, measure the properties of the system at various temperatures, implement these temperature dependent properties into a nonlinear finite element framework, and predict the initiation and growth of cracking. The three major tasks of this work include: (a) testing of fracture strength of the systems at three different temperatures, including the determination of thermal crack initiation and growth, (b) determination of basic thermal-mechanical properties of adhesive, glass, and Al/sub 2/O/sub 3/, respectively, and (c) identification of appropriate quantities to predict damage modes, including initiation and growth, at different temperatures and comparing the data with experiments. The major conclusions are as follows: (a) realistic nonlinear material properties are essential input for correct nonlinear finite element modeling, (b) J-integral can be applied to predict the crack initiation and growth for the material system considered, (c) either bulk glass material or the adhesive/glass interface may fail depending on the applied temperature and notch length, and (d) curved crack growth path inside the glass can be predicted by fracture mechanics.<
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