Call number: LD2668 .T4 1986 H44 / Master of Arts / History

Bolted joints are often the most critical parts with respect to fatigue life of structures. Therefore, it is important to analyze these components and the forces they are subjected to. A one-dimensional nite element model of a bolted joint is created and implemented as a program module in the Saab software `DIM', together with a complete graphical user interface allowing the user to generate the structure freely, and to apply both mechanical and thermal loads. Available methods for calculating fastener exibility are reviewed. The ones derived by Grumman, Huth and Barrois are implemented in the module, and can thus be used when dening a geometry representing a bolted joint assembly. Investigations have shown that it cannot be said that either method is generally better than the other. Calculated properties of interest include the fastener forces, plate bearing and bypass loads, and - for simpler geometries without thermal loads - the load distribution between rows of fasteners. The program is fully functional and yields numerically accurate results for the most commonly used joints where fasteners connect two or three plates each. It has limited functionality on geometries with fasteners connecting four or more plates and for a certain loading combination also for three plates, due to the tilting of the fasteners not being accounted for in the model for these cases. Also, there is no explicit method available for nding an accurate value for the fastener exibility for these, less common, joint structures.

Inducement prizes-where cash rewards are given to motivate the attainment of targets--have been long used to encourage scientific research, develop technological innovations, or stimulate individuals, groups, and communities to accomplish diverse goals. Lately, prizes have increasingly attracted the attention of policy-makers, among others, due to their potential to induce path-breaking innovations and accomplish related goals. Academic research, however, has barely investigated these prizes in spite of their long history, recent popularity, and notable potential. This research investigates prizes and the means by which they induce innovation. It uses an empirical, multiple case-study methodology, a new model of innovation applied to prizes, and multiple data sources to investigate three cases of recent aerospace technology prizes: a main case study, the Google Lunar X Prize (GLXP) for robotic Moon exploration; and two pilot cases, the Ansari X Prize (AXP) for the first private reusable manned spacecraft and the Northrop Grumman Lunar Lander Challenge (NGLLC) for flights of reusable rocket-powered vehicles. The investigation unveils the dynamics of prizes and contributes a better understanding of their potential and disadvantages in a context in which more traditional mechanisms are used to induce innovation. This research shows that prizes are a more complex mechanism and their investigation requires analyzing entrant- and context-level factors generally not considered by the literature. Prizes complement and not replace patents and other incentive mechanisms. The incentives offered by prizes attract entrants with diverse characteristics, including unconventional entrants--individuals and organizations generally not involved with the prize technologies. Entrants are generally attracted by the non-monetary benefits of participation and the potential market value of the technologies involved in competitions. Many more volunteers, collaborators, and partners also participate indirectly and support official entries as they also perceive opportunities to accomplish their personal and organizational goals. The monetary reward is important to position the competition in the media and disseminate the idea of the prize. Prizes can induce increasing R&D activities and re-direct industry projects to target diverse technological goals, yet the evolution of prize competitions and quality of the technological outputs is generally difficult to anticipate. The overall organization of prize R&D activities and their outputs depend on entrant-level factors and can only be indirectly influenced by setting specific competition rules. The most remarkable characteristic of prize R&D activities is their interaction with fundraising efforts which, in some circumstances, may constrain the activities of entrants. Prizes can also induce innovation over and above what would have occurred anyway, yet their overall effect depends significantly on the characteristics of the prize entrants and the evolution of the context of the competition. The ability of prizes to induce innovation is larger when there are larger prize incentives, more significant technology gaps implicit in the prize challenge, and open-ended challenge definitions. To successfully induce technological breakthroughs, prizes may require complementary incentives (e.g. commitments to purchase technology) or support (e.g. seed funding.) Prizes are particularly appropriate to, for example, explore new, experimental methods and technologies that imply high-risk R&D; induce technological development to break critical technological barriers; accelerate technological development to achieve higher performance standards; and, accelerate diffusion, adoption, and/or commercialization of technologies. They involve, however, higher programmatic risks than other more traditional mechanisms and their routine use, and/or challenge definitions that overlap, can weaken the incentive power of the mechanism. Successful implementation of competitions requires many parameters to be properly set.