On a modified-Lorentz-transformation based gravity model confirming basic GRT experiments

Implementing Poincar\'e's `geometric conventionalism' a scalar Lorentz-covariant gravity model is obtained based on gravitationally modified Lorentz transformations (or GMLT). The modification essentially consists of an appropriate space-time and momentum-energy scaling ("normalization") relative to a nondynamical flat background geometry according to an isotropic, nonsingular gravitational `affecting' function Phi(r). Elimination of the gravitationally `unaffected' S_0 perspective by local composition of space-time GMLT recovers the local Minkowskian metric and thus preserves the invariance of the locally observed velocity of light. The associated energy-momentum GMLT provides a covariant Hamiltonian description for test particles and photons which, in a static gravitational field configuration, endorses the four `basic' experiments for testing General Relativity Theory: gravitational i) deflection of light, ii) precession of perihelia, iii) delay of radar echo, iv) shift of spectral lines. The model recovers the Lagrangian of the Lorentz-Poincar\'e gravity model by Torgny Sj\"odin and integrates elements of the precursor gravitational theories, with spatially Variable Speed of Light (VSL) by Einstein and Abraham, and gravitationally variable mass by Nordstr\"om.Comment: v1: 14 pages, extended version of conf. paper PIRT VIII, London, 2002. v2: section added on effective tensorial rank, references added, appendix added, WEP issue deleted, abstract and other parts rewritten, same results (to appear in Found. Phys.

Application of traditional investment casting process to aluminium matrix composites

This paper is aimed at studying the application of traditional investment casting process to obtain components in discontinuously particle reinforced aluminium matrix composites. Using the double stir method, a mixed liquid slurry of aluminium alloy and 20% SiC or 7.5% B4C carbides was obtained. As a case study a component from the textile sector was produced in unreinforced alloy and in both composites. The wear resistance of the components in the three different materials was ranked. Moreover, analysis of particle distribution and optical and scanning electron microscope observations of reaction products were also performed. Results show that components in aluminium alloy with SiC as reinforcement have uniform distribution of ceramic particles, sound interface without fragile compounds and wear resistance higher than that of components reinforced with B4C particles

Design and fabrication of a helicopter unitized structure using resin transfer moulding

We present the numerical and experimental studies for the design of a novel unitized configuration for the manufacture of a three-dimensional aerodynamic beanie using resin transfer moulding (RTM). The beanie is a component with complex closed-shell geometry, which is traditionally manufactured using autoclave processes that require several bonding steps during production. In our work we use a multidisciplinary approach to fabricate the component not through a succession of steps but rather integrating design and manufacturing into the realization of a pre-industrial RTM prototype, with significant reduction of the production time. The new RTM-based design has several advantages in terms of reduced manufacturing cost and enhanced mechanical properties. A bird impact analysis was performed to investigate the structural behavior of the unitized solution. The peak contact pressure during the bird strike is reduced, as well as the maximum vertical displacement. At the same time, the total weight of the structure is reduced by approximately 26% and the production time of 47% with respect to prepreg manufacturing processes. Mechanical tests performed on the manufactured RTM-based prototype also show that the interlaminar shear strength is improved by 70% with respect to the prepreg-based ones.We present the numerical and experimental studies for the design of a novel unitized configuration for the manufacture of a three-dimensional aerodynamic beanie using resin transfer moulding (RTM). The beanie is a component with complex closed-shell geometry, which is traditionally manufactured using autoclave processes that require several bonding steps during production. In our work we use a multidisciplinary approach to fabricate the component not through a succession of steps but rather integrating design and manufacturing into the realization of a pre-industrial RTM prototype, with significant reduction of the production time. The new RTM-based design has several advantages in terms of reduced manufacturing cost and enhanced mechanical properties. A bird impact analysis was performed to investigate the structural behavior of the unitized solution. The peak contact pressure during the bird strike is reduced, as well as the maximum vertical displacement. At the same time, the tota