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This paper explores the use of both macroscale and microscale modelling for the analysis of extrusion of an AA2009+25%SiC p metal matrix composite (MMC). The performance of a micromechanical model, where the heterogeneous microstructure of the MMC is explicitly modelled, in predicting the tensile stress-strain behaviour of an AA2009+25%SiC p MMC is examined. A macroscale modelling approach is used to simulate extrusion of the MMC through two different die designs, where the MMC is modelled as a homogeneous continuum. Firstly, the extrusion results are used to compare the two die designs, to determine which is the more favourable. Secondly, the predicted macroscale plastic strain distributions and pressures are used with the micromechanical model to assess microscale stress states in the material during extrusion with a view to gaining insights into the risk of damage in the material. In this context, pressure is shown to be hugely important in controlling tensile stress magnitude and in reducing microscale damage risk, and essentially ensuring that extrusion can be achieved in practice. However, the results reveal that damage risk is not totally eliminated and that there may still be locations where the material may rupture.second objective, linked to the first, is to use micromechanical FE simulations of deformation in the nuigalway.ie JSA232

Percussion drilling of blind holes and vias in Kapton ® film was investigated using Q-switched solid state lasers operating at UV (355nm) and VUV (266nm) wavelengths. Holes were analyzed using different methods such as scanning electron microscopy (SEM) and surface profilometry. Ablation rates for the two wavelengths are compared. No abrupt thresholds were found and there was no evidence of an incubation effect within the first few pulses. Introducing pauses during the drilling increased the number of shots required for perforation of the film. The effects of fluence on diameter, depth and taper of the holes are presented. Smaller and neater holes are achieved more accurately with a lower fluence. An observed skin effect brought about by long exposure to low fluence VUV laser light is also discussed.

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