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The purpose of this research is to investigate the use of compliant mechanisms in space applications and design, analyze, and test a compliant space mechanism. Current space mechanisms are already highly refined and it is unclear if significant improvements in performance can be made by continuing to refine current designs. Compliant mechanisms offer a promising opportunity to change the fundamental approach to achieving controlled motion in space systems and have potential for dramatic increases in mechanism performance given the constraints of the space environment. A compliant deployment hinge was selected for development after industry input was gathered. Concepts for large-displacement compliant hinges are investigated. A design process was developed that links the performance requirements of deployment to the design parameters of a deployment hinge. A large-displacement monolithic compliant rotational hinge, the Flex-16, is designed, analyzed, and tested. It was developed for possible application as a spacecraft deployment hinge and designs were developed using three different materials (polypropylene, titanium, and carbon nanotubes) and manufacturing processes (CNC milling, electron beam manufacturing metal rapid prototyping, and a carbon nanotube framework) on two size scales (macro and micro). A parametric finite element model allowed for prediction of prototype behavior before fabrication. The Flex-16 hinge is capable of 90 degrees of deflection without failure or contact and can be designed to meet industry requirements for space.

Origami can be a powerful source of design inspiration in the creation of reconfigurable systems with unparalleled performance. This thesis provides fundamental tools for designers to employ as origami-based designs are pursued in their respective fields of expertise. The first chapter introduces origami and makes connections between origami and engineering design through a survey of engineered applications and characterizing the relationship between origami and compliant mechanisms. The second chapter evaluates the creasing of non-paper sheet materials, such as plastics and metals, to facilitate origami-based compliant mechanism design. Although it is anticipated that most origami-based design will result from surrogate folds (indirect methods of replacing the crease), it is valuable to provide information that may help in more direct approaches for origami-based design in materials other than paper. Planar sheets of homogeneous material are considered as they maintain the principles fundamental to origami (flat initial state, low cost, readily available). The reduced stiffness along the axis of the crease is an enabling characteristic of origami. Hence a metric based on the deformation of the crease compared to the deformation of the panels enables engineering materials to be evaluated based on their ability to achieve the "hinge-like" behavior observed in folded paper. Advantages of both high and low values of this metric are given. Testing results (hinge indexes, residual angles, localized hinge behavior and cyclic creasing to failure) are presented for various metals and polymers. This methodology and subsequent findings are provided to enable origami-based design of compliant mechanisms. The third chapter proposes a basic terminology for origami-based design and presents areas of considerations for cases where the final engineering design is directly related to a crease pattern. This framework for navigating from paper art to engineered products begins once the crease pattern has been selected for a given application. The four areas of consideration are discussed: 1) rigid foldability 2) crease characterization 3) material properties and dimensions and 4) manufacturing. Two examples are concurrently presented to illustrate these considerations: a backpack shell and a shroud for an adjustable C-Arm x-ray device used in hospitals. The final chapter provides concluding remarks on origami-based design.

The objective of this research project involves determining a seismic response modification factor for three-hinge glulam Tudor arches. In an attempt to meet this objective, the methods and procedures outlined in FEMA technical document P-695 were implemented on the provided arch designs. Computational models were created using finite elements within OpenSees to accurately depict the behavior of the arch. Incremental dynamic analyses were conducted on each of the provided designs and collapse margin ratios were determined allowing performance groups to be evaluated for each of seven design R-values within two gravity load cases. With the performance groups evaluated, it was determined that only groups within the low gravity load level designs were successfully able to pass, none of the groups designed for high gravity loads passed the evaluations. Within P-695, all performance groups associated with a given design R-value must pass the evaluations for that R-value to be deemed acceptable for use in designs. Because of the implications of this requirement, a seismic response modification factor could not be determined for this type of structural system within the scope of this project. / Master of Science

Pages vi, 34, 68, 158, 208 and 226 are blank and therefore omitted. / <p> To assess the ductility of shear walls under earthquake loading, more experimental evidence is strongly needed. Ductile response can be achieved through the development of a flexural plastic hinge at the base characterized by yielding of the vertical reinforcement. The length of the plastic hinge and the ultimate curvatures within this region are the essential parameters affecting the ductility and ultimate displacements of reinforced masonry shear walls. The discrepancies in existing information regarding the length of plastic hinges and ultimate curvature may be attributed to the effects of many shear wall parameters such as distribution and amount of vertical and horizontal steel, level of axial load, and wall aspect ratio. </p> <p> The focus of this study was to evaluate the effect of different parameters on plastic hinge length, energy dissipation, and on general ductility of masonry shear walls. To address the aforementioned goal, six fully grouted reinforced masonry walls were tested under fully reversed cyclic lateral loading. All walls were designed to experience ductile flexural failure. The test matrix was chosen to investigate the effects of the amount and distribution of vertical reinforcement and the level of applied axial load on the lateral loading response and ductility of reinforced masonry shear walls. To examine the effects of these parameters, measurements of the applied loads, vertical and horizontal displacements as well as strains in the reinforcing bars were used to analyze the behaviour of the walls. Also, from these measurements, other quantities used in analysis were determined, including displacement ductilities, curvature profiles, energy dissipation and equivalent plastic hinge length. </p> <p> The results show high ductile capability in the plastic hinge region and very little degradation of strength for cyclic loading. High levels of energy dissipation in the reinforced concrete masonry shear walls were achieved by flexural yielding of the vertical reinforcement. All walls showed increasing hysteretic damping ratios with increase in displacement. Results showed that displacement ductility and energy dissipation were highly sensitive to increases in amount of vertical reinforcement but were less dependent on the level of applied axial stress. The results of this study also showed that the measured plastic zone length decreases with increase of the amount of reinforcement while it is almost the same for the different levels of axial stress. Based on the test results, it was shown that reinforced concrete masonry shear walls may be utilized in high intensity seismic areas with performance meeting or exceeding current expectations. </p> / Thesis / Master of Applied Science (MASc)

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Many futuristic aircraft such as the Hybrid Wing Body have numerous control surfaces that can result in large hinge moments, high actuation power demands, and large actuator forces/moments. Also, there is no unique relationship between control inputs and the aircraft response. Distinct sets of control surface deflections may result in the same aircraft response, but with large differences in actuation power. An Artificial Neural Network and a Genetic Algorithm were used here for the control allocation optimization problem of a Hybrid Wing Body to minimize the Sum of Absolute Values of Hinge Moments for a 2.5-G pull-up maneuver. To test the versatility of the same optimization process for different aircraft configurations, the present work also investigates its application on the Forward Swept Wing aircraft. A method to improve the robustness of the process is also presented. Constraints on the load factor and longitudinal pitch rate were added to the optimization to preserve the trim constraints on the control deflections. Another method was developed using stability derivatives. This new method provided better results, and the computational time was reduced by two orders of magnitude. A hybrid scheme combining both methods was also developed to provide a real-time estimate of the optimum control deflection schedules to trim the airplane and minimize the actuation power for changing flight conditions (Mach number, altitude and load factor) in a pull-up maneuver. Finally, the stability derivatives method and the hybrid scheme were applied for an antisymmetric, steady roll maneuver. / Master of Science

This research presents a simplified framework for the analysis of deployable trusses using the concentrated strain approach and uses it to provide key insights into the many design decisions to be made in the development of concentrated strain architectures. The framework uses Euler Column Theory to derive closed form solutions to estimate truss performance. The results are compared to a classical solution and shown to give similar results. A range of strut and hinge hierarchy choices are considered. Trusses composed of solid rods with rectangular flexures are shown to have significant axial and bending stiffness reductions due to the smaller cross-sectional areas and lower modulus of the flexures. Trusses composed of tubes are less sensitive to this because the flexure cross-sectional area does not dramatically change from that of the tube. A hinge material metric that properly weights flexure strain and modulus is presented to provide a basis for the comparison and selection of proper hinge materials. However, based on this metric, new materials with higher folding failure strain and higher modulus are needed. Finally, a concentrated strain deployable truss of solid rods was designed, manufactured, and tested. A truss performance index for column loading was used to compare this system with a distributed strain ATK-ABLE GR1 coilable boom system and an articulated ATK-ABLE SRTM boom system. It was demonstrated that the concentrated strain approach has the potential to achieve a higher linear compaction ratio and truss performance index for mass efficient deployable trusses than the distributed strain approach and the articulated approach. / Ph. D.

Partitioning of finite strains in different domains within the limb and hinge regions of a fold can be used to understand the deformation processes operative during fold formation. Samples taken from the limb and hinge regions of a gently plunging, asymmetric, tight, mesoscale fold in the Erwin formation of the Blue Ridge in North Carolina were analyzed to determine the deformation mechanisms and strains associated with the folding event. Rf/phi grain shape fabric analysis was conducted for each sample and used to calculate the orientation and magnitude of the final grain shape fabric ellipsoids. Flexural folding and passive-shear folding models predict that the highest finite strains will be recorded in the hinge of a fold. The highest grain shape magnitudes recorded in the North Carolina fold, however, lie along the overturned fold limb. The final geometry of many folds indicates that hinge plane migration processes are active during compressive deformation events. Numeric, conceptual, and analogue based studies have demonstrated the migration of fold hinges during deformation. However, documentation of these processes in field based studies is rare and limited to techniques that are frequently site specific. Methods proven successful in natural studies include the analysis of superposed folding; the migration of earlier hinge-related features such as fractures, cleavage planes, and boudinaged bedding planes; and the kinematic analysis of syntectonic pressure shadows. The magnitude and orientation of the grain shape ellipsoids calculated for the North Carolina fold indicate that rocks in the overturned limb were once located in the hinge of the fold. Subsequent noncoaxial deformation processes operative during folding resulted in the migration of the hinge to its present orientation and position. This relationship indicates that it is possible to use strain/shape fabric analysis as a test for hinge migration in folds, and that this technique may be more generally applicable in natural settings than previously proposed tests. / Master of Science