The retraction affects the setting process and the useful life of the concrete with the appearance of fissures; in last year's studies and methods have been generated to mitigate and control it with the use of different products and applications. The development of road infrastructure with the use of concrete as a rolling folder, requires methods to guarantee the durability and reduce the effects of the efforts incorporated by the use, climatic conditions, support base and restrictions of movement of the structure. To evaluate the effects of recycled synthetic polypropylene fibers in plastic retraction tests (ASTM C 1579), 3 mix designs were prepared with different ratios 58 gr., 116 gr., and 176 gr. of recycled and virgin synthetic fibers; the most significant and positive result to reduce fissures without affecting the resistance of concrete by bending and compression, was 0.50 mm without addition fibers, 0.10 mm and 0.15 mm with 176 gr. of virgin and recycled synthetic fibers. Finally, it can be concluded that adding a ratio of 4 kg per m3 allows good workability, in addition, the costs of the fibers are not representative compared to the high costs for future repairs.

Injury, instrumentation, or surgery may change the functional biomechanics of the spine. Spinal fusion, the current surgical treatment of choice, stabilizes the spine by rigid fixation, reducing spinal mobility at the cost of increased stress at adjacent levels. Recently, alternatives to spinal fusion have been investigated. One such alternative is total disc replacements. The current generation of total disc replacements (TDRs) focuses on restoring the quantity of motion. Recent studies indicate that the moment-rotation response and axis of rotation, or quality of motion (QOM), may have important implications in the health of adjacent segments as well as the health of the surrounding tissue of the operative level. This dissertation examines the use of compliant mechanism design theory in the design and analysis of spinal arthroplasty devices. Particularly, compliant mechanism design techniques were used to develop a total disc replacement capable of replicating the normal moment-rotation response and location and path of the helical axis of motion. Closed-form solutions for the device's performance are proposed and a physical prototype was created and evaluated under a modified F1717 and a single-level cadaveric experiment. The results show that the prototype's QOMclosely matched the selected force-deflection response of the specified QOM profile. The use of pseudo-rigid-body modeling to evaluate the effects of various changes on motion at adjacent segments is also investigated. The ability to model biomechanical changes in the spine has traditionally been based on animal models, in vitro testing, and finite element analysis. These techniques, although effective, are costly. As a result, their use is often limited to late in the design process. The pseudo-rigid-body model (PRBM) developed accurately predicted the moment-rotation response of the entire specimen and the relative contribution of each level. Additionally, the PRBM was able to predict changes in relative motion patterns of the specimen due to instrumentation.

We introduce to computer graphics the Pseudo-Rigid-Body Mechanism (PRBM) and the chain algorithm from mechanical engineering, with a unified tutorial from disparate source materials. The PRBM has been used successfully to simplify the simulation of non-linearly elastic beams, using deflections of an analogous spring and rigid-body linkage. It offers computational efficiency as well as an automatic parameterization in terms of physically measurable, intuitive inputs which fit naturally into existing animation work flows for character articulation. The chain algorithm is a technique for simulating the deflection of complicated elastic bodies in terms of straight elastic elements, which has recently been extended to incorporate PRBM beam-elements in three dimensions. We present a new, mathematically equivalent optimization of the 3D PRBM chain algorithm, from its former asymptotic complexity of O(n^2) in the number of elements n, to O(n). We also extend an existing PRBM for combined moment-force loads to 3D, where the existing 3D PRBM chain algorithm was limited to 3D PRBM elements for a moment-only load. This optimization and extension are validated by duplicating prior experimental results, but substituting the new optimization and combined-load elements. Finally, a loose road-map is provided with several key considerations for future extension of the techniques to dynamic simulations.

Designers are constantly searching for new sourcing of inspiration for innovative design. Recently, origami has gained interest as one of these potential sources. Origami literally translated from Japanese means “paper folding” where “oru” means “to fold” and “kami” means “paper”. Since paper is insufficient to solve many engineering design problems, designers must turn to other materials. These materials will inevitably be thicker than paper and will often require different folding techniques and considerations. This thesis provides background information describing previous methods to accommodate thickness in origami-inspired design, presents a newly developed technique to address limitations of other methods, and explores the application of the technique. The newly developed technique allows designers to identify a desired motion behavior in an origami model and implement it into a thick mechanism. Many previous methods were incapable of preserving the kinematics and/or restricted usable range of motion. Understanding the capabilities and limitations of thickness accommodation methods empowers designers to better implement inspiration from origami into engineering design. The offset panel technique is further extended to include arbitrary thickness and arbitrary folding plane locations. The technique is verified through creation and testing of hardware, showcasing capabilities and limitations. Demonstration of these capabilities will serve as inspiration for furthering application of thick origami in engineering design. Preliminary work in thick origami led to the design of a thick origami-inspired medical gripper. These origami-inspired forceps, Oriceps, were designed by starting with an origami model exhibiting desired motion, grasping. The Oriceps show some challenges faced with accommodating thickness in adapting an origami model for application.

This work evaluates a specific origami device known as the kaleidocycle and the broad classof rigidly foldable origami. Both of these have potential for application in the design of deployableand foldable arrays of spatial mechanisms.Origami is considered a compliant mechanisms because it achieves its motion through thedeflection of paper creases. Compliant mechanisms generally do not allow for continuous rotation;however, the compliant kaleidocycle represents an exception to this generality. Along with theirability to rotate continuously, kaleidocycles may also be designed to exhibit multistable behaviorduring this rotation. These two characteristics make the kaleidocycle an interesting device withpotential for applications in engineering. This work presents the multistable characteristics ofkaleidocycles, showing that devices can be made which exhibit one, two, three, or four distinctstable equilibrium positions. Kaleiocycles may also be designed to exhibit a range over which thedevice is neutrally stable.The second type of origami presented in this work is rigidly foldable origami, a special classof origami in which all deflection occurs at the creases, allowing the panels to remain rigid. Thistype of origami is of particular interest because of its ability to be constructed from materials muchstiffer than paper while retaining its mobility. This property allows rigidly foldable origami to beapplied to fields such as architecture and deployable mechanisms. This work presents a method forevaluating rigid foldability in origami tessellations. This method is used to define seven theoremsfor the rigid foldability of origami twists and to develop new rigidly foldable origami “gadgets”and tessellations.

This research provides realistic techniques to visualize the process of damage to residential building caused by hurricane force winds. Three methods are implemented to make the visualization useful for educating the public about mitigation measures for their homes. First, the underline physics uses Quick Collision Response Calculation. This is an iterative method, which can tune the accuracy and the performance to calculate collision response between building components. Secondly, the damage process is designed as a Time-scalable Process. By attaching a damage time tag for each building component, the visualization process is treated as a geometry animation allowing users to navigate in the visualization. The detached building components move in response to the wind force that is calculated using qualitative rather than quantitative techniques. The results are acceptable for instructional systems but not for engineering analysis. Quick Damage Prediction is achieved by using a database query instead of using a Monte-Carlo simulation. The database is based on HAZUS® engineering analysis data which gives it validity. A reasoning mechanism based on the definition of the overall building damage in HAZUS® is used to determine the damage state of selected building components including roof cover, roof sheathing, wall, openings and roof-wall connections. Exposure settings of environmental aspects of the simulated environment, such as ocean, trees, cloud and rain are integrated into a scene-graph based graphics engine. Based on the graphics engine and the physics engine, a procedural modeling method is used to efficiently render residential buildings. The resulting program, Hurricane!, is an instructional program for public education useful in schools and museum exhibits.

Measurement of dynamic/transient torques is important in the dynamic analysis of rotating machinery as it provides insight into the internal state of the machine. Existing methods are difficult to implement, results are not obtained in real-time and are not very accurate. This thesis introduces a new method of determining real-time dynamic torque. An optical encoder is used to sense motion at a convenient point in the rotating system containing the rigid shaft of interest. The encoder's output is processed digitally to yield angular velocity, acceleration and dynamic torque. Two different experiments were conducted to demonstrate the advantages of this new method of determining dynamic torque over conventional methods. In one experiment, an extension spring was mounted on a crank arrangement coupled to a fractional horsepower motor to apply a periodic load to the system. A mathematical model of this dynamic system was developed to compare the results of this model with that of the instrumentation system. In another experiment, the instrumentation system was used on an existing motor-compressor system. The dynamic torque thus determined was again compared with the results of a simulation program. In both the above experiments the evaluated dynamic torque and computed dynamic torque were within 5% of each other, demonstrating accuracy and reliability of this personal computer based dynamic torque determining system. / Master of Science

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