Novel design and geometry for mechanical gearing

This thesis presents quasi-static Finite Element Methods for the analysis of the stress state occurring in a pair of loaded spur gears and aims to further research the effect of tooth profile modifications on the mechanical performance of a mating gear pair. The investigation is then extended to epicyclic transmissions as they are considered the most viable solution when the transmission of high torque level within a compact volume is required. Since, for the current study, only low speed conditions are considered, dynamic loads do not play a crucial role. Vibrations and the resulting noise might be considered negligible and consequently the design process is dictated entirely by the stress state occurring on the mating components. Gear load carrying capacity is limited by maximum contact and bending stress and their correlated failure modes. Consequently, the occurring stress state is the main criteria to characterise the load carrying capacity of a gear system. Contact and bending stresses are evaluated for multiple positions over a mesh cycle of a contacting tooth pair in order to consider the stress fluctuation as consequence of the alternation of single and double pairs of teeth in contact. The influence of gear geometrical proportions on mechanical properties of gears in mesh is studied thoroughly by means of the definition of a domain of feasible combination of geometrical parameters in order to deconstruct the well-established gear design process based on rating standards and base the defined gear geometry on operational and manufacturing constraints only. From this parametric study, suitable suggestions for enhancing the load carrying capacity of the tooth flank are made by showing that the use of non-standard geometric parameters can improve the performance of gears. As this study also aims to improve the performances of epicyclic gearings specifically for low speed-high torque operating conditions, the optimum parameters found in the preliminary parametric analysis were applied to this category of systems. The design procedure based on the area of existence of gear geometry was extended to this case which required the determination of the domain of feasible combination for gears in internal mesh with the addition of constraints addressed to epicyclic configurations. Three epicyclic systems with same boundary design conditions but different combination of geometrical parameters have been modelled and analysed by means of quasi-static FEA. The results have shown that the improvements found for the case of two mating spur gears are also valid for the case of higher order systems in which multiple contacts are simultaneously occurring. Based on these results, suitable suggestions are made for the design of gears working in epicyclic systems for an enhanced torque capacity and a volume reduction for applications characterized by low speed and high loads conditions. An alternative solution to geared systems that guarantees compactness and high torque transmission capabilities has also been investigated; it consists of a cycloidal transmission system. The parametric equations for the cycloidal profile have been determined and an executive design, then manufactured, has been produced. The preliminary quasi-static Finite Element analysis has predicted the load sharing and stress distribution among multiple components confirming the mechanical advantage of this category of transmission systems

Social work with airports passengers

Social work at the airport is in to offer to passengers social services. The main methodological position is that people are under stress, which characterized by a particular set of characteristics in appearance and behavior. In such circumstances passenger attracts in his actions some attention. Only person whom he trusts can help him with the documents or psychologically

Bibliography of Lewis Research Center technical publications announced in 1993

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1993. All the publications were announced in the 1993 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses

Aeronautical engineering: A continuing bibliography with indexes (supplement 233)

This bibliography lists 637 reports, articles, and other documents introduced into the NASA scientific and technical information system in November, 1988. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion