Browsing by Author "McAndrew, Anthony R."

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    Interpass rolling of Ti-6Al-4V wire + arc additively manufactured features for microstructural refinement
    (Elsevier, 2018-03-05) McAndrew, Anthony R.; Alvarez Rosales, Marta; Colegrove, Paul A.; Hönnige, Jan R.; Ho, Alistair; Fayolle, Romain; Eyitayo, Kamal; Stan, Ioan; Sukrongpang, Punyawee; Crochemore, Antoine; Pinter, Zsolt
    In-process deformation methods such as rolling can be used to refine the large columnar grains that form when wire + arc additively manufacturing (WAAM) titanium alloys. Due to the laterally restrained geometry, application to thick walls and intersecting features required the development of a new ‘inverted profile’ roller. A larger radii roller increased the extent of the recrystallised area, providing a more uniform grain size, and higher loads increased the amount of refinement. Electron backscatter diffraction showed that the majority of the strain is generated toward the edges of the rolled groove, up to 3 mm below the rolled surface. These results will help facilitate future optimisation of the rolling process and industrialisation of WAAM for large-scale titanium components.
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    Prediction of residual stress within linear friction welds using a computationally efficient modelling approach
    (Elsevier, 2017-11-08) Buhr, Clement; Ahmad, Bilal; Colegrove, Paul A.; McAndrew, Anthony R.; Guo, Hua; Zhang, Xiang
    Modelling the mechanical mixing occurring at the interface of a linear friction weld (LFW) is complex, making it difficult to study the development of residual stresses within real engineering workpieces. To address this, a sequentially-coupled numerical model of a Ti-6Al-4V LFW was developed, bypassing the modelling of the oscillations by applying the heat at the weld interface and sequentially removing rows of elements to account for the burn-off. Increasing the rubbing velocity was found to numerically increase the peak of residual stress while narrowing the distribution. Only small changes arose from increasing the applied pressure or changing the oscillation direction. Predictions suggested a strong correlation between the phase 3 temperature profile and the residual stress field subsequently created. Validation against neutron diffraction and contour method are also presented. This approach provides a computationally efficient technique to study the residual stress development within large 3D structures.