Compressive deformation behaviour of a closed-cell aluminum

The mechanical properties of a closed-cell aluminium foam were investigated by compressive tests, and the deformation behaviours of the aluminium foams were studied using Xray microtomography. The results indicate that the deformation of the aluminium foams under compressive loading was localized in narrow continuous deformation bands having widths of order of a cell diameter. The cells in the deformation bands collapsed by a mixed deformation mechanism, which includes mainly bending and minor buckling and yielding. Different fractions of the three deformation modes led to variations in the peak stress and energy absorption for different foam samples with the same density. It was also found that the cell morphology affects the deformation mechanism significantly, whilst the cell size shows little influence.

Geometrical effects on residual stresses in 7050-T7451 aluminum alloy rods subject to laser shock peening

Laser shock peening (LSP) is an emerging surface treatment technology for metallic materials, which appears to produce more significant compressive residual stresses than those from the conventional shot peening (SP) for fatigue, corrosion and wear resistance, etc. The finite element method has been applied to simulate the laser shock peening treatment to provide the overall numerical assessment of the characteristic physical processes and transformations. However, the previous researchers mostly focused on metallic specimens with simple geometry, e.g. flat surface. The current work investigates geometrical effects of metallic specimens with curved surface on the residual stress fields produced by LSP process using three-dimensional finite element (3-D FEM) analysis and aluminium alloy rods with a middle scalloped section subject to two-sided laser shock peening. Specimens were numerically studied to determine dynamic and residual stress fields with varying laser parameters and geometrical parameters, e.g. laser power intensity and radius of the middle scalloped section. The results showed that the geometrical effects of the curved target surface greatly influenced residual stress fields.

Hollow avowals of human rights protection-time for an Australian federal bill of rights?

Unlike the constitutions of many nations, such as the United States of America and the Republic of South Africa, the constitutions of the Australian States and Territories and the Commonwealth Constitution Act 1901 (UK) contain no bill of rights. Australia is the only western democracy without a federal bill of rights. The debate regarding the need for a bill of rights necessitates an understanding of what human rights the people of Australia already enjoy. If sufficient protection can be found in existing sources, does Australia really need a federal bill of rights? Opponents of a bill of rights state that we have sufficient protection from arbitrary government intervention in our personal affairs and thus a bill of rights is unnecessary. There are a number of potential sources of human rights in Australia that might provide the suggested existing protection, including the common law, specific domestic legislation, international law and constitutional law. Each of these sources of human rights has, however, important limitations. The focus of this article is on the inadequacy of the Australian constitutions as a source of purported protection. This in turn suggests that an alternative source of rights is needed - a federal bill of rights? In the course of this analysis the author makes suggestions for reform; specifically how a federal bill of rights may address the paucity of constitutional protection.

Geometrical effects on residual stresses in 7050-T7451 aluminum alloy rods subject to laser shock peening

Laser shock peening (LSP) is an emerging surface treatment technology for metallic materials, which appears to produce more significant compressive residual stresses than those from the conventional shot peening (SP) for fatigue, corrosion and wear resistance, etc. The finite element method has been applied to simulate the laser shock peening treatment to provide the overall numerical assessment of the characteristic physical processes and transformations. However, the previous researchers mostly focused on metallic specimens with simple geometry, e.g. flat surface. The current work investigates geometrical effects of metallic specimens with curved surface on the residual stress fields produced by LSP process using three-dimensional finite element (3-D FEM) analysis and aluminium alloy rods with a middle scalloped section subject to two-sided laser shock peening. Specimens were numerically studied to determine dynamic and residual stress fields with varying laser parameters and geometrical parameters, e.g. laser power intensity and radius of the middle scalloped section. The results showed that the geometrical effects of the curved target surface greatly influenced residual stress fields.

Audiences and public : when cultural engagement matters for the public sphere

Audiences and Publics: When Cultural Engagement Matters for the Public Sphere, edited by Sonia Livingstone, is reviewed.

Improvement in mechanical properties of aluminum polypropylene composite fiber

Aluminum particles (Al) were added to polypropylene (PP) in the presence of poly ethylene glycol (PEG) and polypropylene-graft-maleic anhydride to produce composites. The composites were then melt-spun into a mono filament and tested for tensile properties, diameter evenness and morphology. Melt rheological properties of Al/PP composites were studied in linear viscoelastic response regions. It was observed that level of dispersion of aluminum particles within a polypropylene composite fiber could be improved by incorporating polyethylene glycol. The improvement of dispersion led to an improvement in the fibers mechanical properties through a reduction of the coefficient of variation of fiber diameter.

Reinvigorating the public sphere : the role of voluntary associations

This thesis examines the key question: can voluntary associations enhance democracy? It tests critical claims made by Habermas and others that voluntary associations have the potential to reinvigorate a public sphere in a state of atrophy. The thesis outlines the major theoretical arguments pertaining to these areas and then presents the results of empirical work within voluntary organisations. Specifically the thesis: Critically examines the concept of the public sphere, being a sphere between the state and civil society and investigates why theorists have advocated voluntary associations, claimed to be the core institutions of civil society, as sites where democratic ideals can be secured; Goes on to examine the concept of civil society and reviews the recent literature that has attempted to define and analyse the role of voluntary associations in contemporary society; Tests empirically the normative ideals that have been advocated on behalf of voluntary associations through the presentation of data obtained using qualitative methodology. The analysis of the data collected during interviews with key employees and members of six voluntary associations in Melbourne, Australia allows for a more informed knowledge regarding the key concepts and themes of the thesis. The thesis ends by directly addressing the following points: whether or not the public sphere is in a state of atrophy; the particular nature of voluntary associations contemporary engagement in the public sphere; and whether voluntary associations can indeed, be sites where democracy can be enhanced and democratic ideals be secured. It is concluded that voluntary associations operate within Habermasian public spheres, counterspheres, and postmodern public spheres and that unitary notions of the public sphere, such as those Habermas proposes, do not adequately explain voluntary associations engagement in the public sphere. Accordingly, it is concluded that voluntary associations have the potential to invigorate public spheres, though not in ways that many theorists writing on the subject suggest.