A coupled diffusion-deformation, multiphase field model for elastoplastic materials is presented. The equations governing the evolution of the phase fields and the molar concentration field are derived in a thermodynamically consistent way using microforce balance laws. As an example of its capabilities, the model is used to study the growth of the intermetallic compound (IMC) Cu 6 Sn 5 during room-temperature aging. This IMC is of great importance in, e.g., soldering of electronic components. The model accounts for grain boundary diffusion between IMC grains and plastic deformation of the microstructure. A plasticity model with hardening, based on an evolving dislocation density, is used for the Cu and Sn phases. Results from the numerical simulations suggest that the thickness of the IMC layer increases linearly with time and that the morphology of the IMC gradually changes from scallop-like to planar, consistent with previous experimental findings. The model predicts that plastic deformation occurs in both the Cu and the Sn layers. Furthermore, the mean value of the biaxial stress in the Sn layer is found to saturate at a level of −8 MPa to −10 MPa during aging. This is in good agreement with experimental data.

This paper investigates the use of seismic anisotropy and amplitude variation with offset and azimuth (AVOA) for fracture characterisation. Specifically the aim of this work is to provide links between rock and fracture properties, elastic modelling and the interpretation of seismic signatures to reduce the potential ambiguity when interpreting AVOA data. Analytical expressions and numerical modelling are used to highlight the sensitivity of AVOA to fracture properties. Furthermore, little prior attention has been paid to wave propagation in media with multiple fracture alignments or fractured media with a permeable matrix therefore an investigation of AVOA for these cases is included. P-wave AVOA is of obvious interest since there are more of these data. However converted wave and shear-wave AVOA are also investigated as these may provide additional insight into fracture characteristics. It is shown that P-P and P-S AVOA hold significant information about fracturing but potential ambiguity in the interpretation of these data is observed that could lead to incorrect determination of fracture orientation. This highlights the need for forward modelling with rock properties data to constrain the interpretation. Additionally, shear-wave (S-S) AVOA is shown to exhibit significant azimuthal variations which provide strong indications of fracture orientation but only at near offsets and little insight can be gained into other fracture properties.

The construction of molecular models of crosslinked polymers is an area of some difficulty and considerable interest. We report here a new method of constructing these models and validate the method by modelling three epoxy systems based on the epoxy monomers bisphenol F diglycidyl ether (BFDGE) and triglycidyl-p-amino phenol (TGAP) with the curing agent diamino diphenyl sulphone (DDS). The main emphasis of the work concerns the improvement of the techniques for the molecular simulation of these epoxies and specific attention is paid towards model construction techniques, including automated model building and prediction of glass transition temperatures (Tg). Typical models comprise some 4200–4600 atoms (ca. 120–130 monomers). In a parallel empirical study, these systems have been cast, cured and analysed by dynamic mechanical thermal analysis (DMTA) to measure Tg. Results for the three epoxy systems yield good agreement with experimental Tg ranges of 200–220°C, 270–285°C and 285–290°C with corresponding simulated ranges of 210–230°C, 250–300°C, and 250–300°C respectively.

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