A Study of Meteoroid Impact Phenomena

Process of crater formation resulting from impact of hypervelocity projectile - meteoroid impac

Thermo-metallo-mechanical modelling of heat treatment induced residual stress in Ti–6Al–4V alloy

Residual stress fields dynamically fluctuate throughout the manufacturing process of metallic components and are caused by local misfit of a thermal, mechanical or metallurgical nature. Recent advances have been made in the area of microstructure and residual stress prediction; yet few have considered dual-phase titanium alloys. The aim of the work presented was to carry out a review of the existing state-of-the-art in residual stress modelling with an intended application to industrial heat treatment of Ti–6Al–4V alloy. Four areas were evaluated: thermal, mechanical and metallurgical sub-models, and model validation via residual stress measurement. Recommendations for future research include further investigation of transformation induced plasticity and stress relaxation behaviour in Ti–6Al–4V

On the transonic aerodynamics of a compressor blade row

Linearized analyses have been carried out for the induced velocity and pressure fields within a compressor blade row operating in an infinite annulus at transonic Mach numbers of the flow relative to the blades. In addition, the relationship between the induced velocity and the shape of the mean blade surface has been determined. A computational scheme has been developed for evaluating the blade mean surface ordinates and surface pressure distributions. The separation of the effects of a specified blade thickness distribution from the effects of a specified distribution of the blade lift has been established. In this way, blade mean surface shapes that are necessary for the blades to be locally nonlifting have been computed and are presented for two examples of blades with biconvex parabolic arc sections of radially tapering thickness. Blade shapes that are required to achieve a zero thickness, uniform chordwise loading, constant work spanwise loading are also presented for two examples. In addition, corresponding surface pressure distributions are given. The flow relative to the blade tips has a high subsonic Mach number in the examples that have been computed. The results suggest that at near-sonic relative tip speeds the effective blade shape is dominated by the thickness distribution, with the lift distribution playing only a minor role