A methodology for evaluating the performance of tow-steered composite technology over a range of planform configurations

Tow-steered composite technology allows for composite fibers to be arranged in customized curving paths rather than in conventional straight lines. This additional design freedom can provide passive load alleviation and increased load path efficiency, which can lead to reduced structural weight, higher wing aspect ratio, and ultimately better vehicle performance. To best take advantage of this technology the weight reduction should be accounted for during the conceptual design stage, when the vehicle’s configuration is still fluid. Since the technology effect could depend on the planform it must be assessed across the range of potential planforms, motivating the development of the thesis methodology. Evaluating tow steering’s technology benefit presents a challenge: due to a lack of historical data the effects must be quantified with parametric physics-based analysis, incurring both development and computational expenses. Additionally, determining the benefit requires repeatedly performing the analysis to solve a high-dimensional constrained optimization problem. In order to better leverage existing weight estimation programs and lessen the impact of computational expense the methodology pursues a surrogate modeling approach. Two main research focuses were addressed while developing the methodology. The first explored how to cope with the large number of dimensions when making the surrogate and applied an active subspace approach to attempt to reduce the dimensionality of the associated constrained optimization problem. The second focus investigated how to most efficiently collect data to build the surrogate and led to the development of an adaptive sampling technique for families of related optimization problems. The findings from these efforts were synthesized to form the thesis methodology, which was then demonstrated in an example use case. The results from this use case were examined to assess the methodology’s successes and limitations, and to provide insight into the behavior of tow-steered composites.Ph.D

Graduate Catalog/Supplement 1995-1998

Contains course descriptions, University college calendar, and college administration.https://digitalcommons.usu.edu/universitycatalogs/1040/thumbnail.jp

Conceptual modelling: A psychological perspective.

This thesis describes the formulation and experimental use of psychological principles that apply to conceptual modelling as practised during information systems development. The principles address cognition (perception, memory and mental models) and group dynamics. The aim is to determine whether application of fundamental psychological principles can help to make modellers, especially those who are relatively inexperienced, more effective. An experimental graphical modelling technique (method 'X') is presented that conforms to the psychological principles, together with a supporting software tool for visual construction of models in the design of typical business database systems. The effectiveness of both inexperienced and expert modellers using method 'X' in real business situations was compared with that of modellers using conventional object modelling. Data was gathered in a series of field experiments using participant observation, questionnaires, and interviews and by analysing the resulting models. With conventional object modelling, untrained modellers produced results that were grossly incomplete and incorrect (22-35%, on average). Using method 'X', untrained modellers produced models that were almost complete and correct (better than 82%). Significant productivity gains were observed with method 'X' (approximately 150% for expert modeller and over 450% for untrained modellers). For an expert modeller no measurable differences in quality were observed between methods, but the modeller regarded the quality of method 'X' models as better and expressed a preference method 'X' over the conventional approach. The results appear to support the idea of re-engineering conceptual modelling practice according to psychological first principles. The fact that more dramatic performance improvements were observed for inexperienced modellers suggests that modelling need not require a high degree of expertise, if methods and tools are adapted appropriately. The results could be exploited to empower untrained modellers, such as end users, who wish to develop large software systems but lack access to the skills of trained IT professionals