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‣ The effects of deposit thermal history on microstructure produced by uniform droplet spray forming

Cherng, Jean-Pei Jeanie
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 92 leaves; 4418684 bytes; 4418490 bytes; application/pdf; application/pdf
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Uniform droplet spray forming is a process aimed at producing near-net-shape parts directly from the liquid melt by spraying micron-sized droplets onto a movable target. In spray forming, the solidification rate of the deposited material is a key parameter that influences its microstructure formation and consequently, its mechanical properties. Ideal deposit microstructure has fine grain size and minimal segregation. The purpose of this thesis is to quantify the effects of deposit thermal history on the microstructure produced by the UDS forming process. Experiments were conducted with Zn-20wt% Sn alloy droplets using different process parameters to vary the deposit solidification rate from 6⁰C/s to 27⁰C/s immediately after deposition. The temperature of the sprayed deposits was measured in situ with a fiber-optic infrared thermometer and a contact thermocouple. Furthermore, a 2-D axisymmetric finite element model was developed to predict the temperature of the deposit during and after deposition. The simulation results show that radial heat conduction cannot be neglected when the thermal diffusivity of the substrate material is comparable to the diffusivity of the deposit material. Simulation results showed good agreement with the measured temperature data. The resultant deposit microstructures were examined with scanning electron microscopy...

‣ Mechanics of abrasive wear of elastomeric materials

Qi, Hang, 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 326 p.; 19046294 bytes; 19046092 bytes; application/pdf; application/pdf
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Elastomeric materials are widely used as tire and sealing materials due to their ability to undergo large deformations and conform to the mating surface. However, their applications often result in repeated contact with abrasive particles, which act to abrasively wear the elastomers. Elastomeric materials are observed to exhibit a characteristic form of abrasive pattern on the surface after cyclic scratching. The dimension of this pattern is closely related to the wear rate, whereas the formation of this pattern is controlled by abrasive particle sizes, material mechanical properties, loading conditions, thermal conditions, and chemical degradation of materials. Much research has been conducted in the past. However, direct observations of the wear process are rare. The mechanics underlying the abrasive wear of elastomeric materials is unclear. In order to provide fundamental understanding of the abrasive wear of elastomeric materials due to abrasive particle indentation and scratching, this research studied the wear of elastomeric materials subjected to scratching by knife geometries that simulate abrasive particles and contact conditions. Efforts were focused on establishing direct observations and analysis of the deformation mechanics. An in situ micro scratching test capability operating within a scanning electron microscope (SEM) was developed and used together with image processing to reveal the local deformation fields. Surface profile analyses using both SEM and ZYGO (a non-contact interferometer) were also conducted to observe the surface change during cyclic scratching. The large strain nonlinear stress-strain behavior of thermoplastic polyurethanes (TPUs) exhibits strong hysteresis...

‣ Investigation of deformation and failure mechanisms in woven and nonwoven fabrics under quasi-static loading conditions

Jearanaisilawong, Petch, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 115 leaves; 6499414 bytes; 6513614 bytes; application/pdf; application/pdf
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The mechanical responses of high performance ballistic woven and nonwoven fabrics under in- plane quasi-static loading conditions have been investigated. The investigations focused on the responses of fabrics at the mesostructural level as well as at the macroscopic level under uniaxial tensile and in-plane shear modes of deformation. A number of experimental methods have been developed, including techniques to test individual fibers (coupon fiber test), techniques to test fabric specimens with the aid of custom-designed fixtures, and techniques relying on image analysis to capture the deformation response of the fabric. Two continuum models have been developed for each type of fabric based on the deformation and failure mechanisms observed in the experiments. The models are able to capture essential features of the in-plane deformation of the fabrics in a computationally efficient framework.; by Petch Jearanaisilawong.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.; "September 2004."; Includes bibliographical references (leaves 107-115).

‣ Vibration damping using low-wave-speed media with applications to precision machines

Varanasi, Kripa K. (Kripa Kiran), 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 182 p.; 8602563 bytes; 8625435 bytes; application/pdf; application/pdf
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Vibration and noise are an ever-present problem in the majority of mechanical systems, from consumer products to precision manufacturing systems. But most approaches for vibration suppression are expensive and invasive, so only a small subset of the techniques developed in research labs are widely used. In this thesis, we present a novel wave-based damping approach for the suppression of vibration in machines and structures. Our studies show that significant broad-band damping can be attained with little added mass via dynamic interaction between a structure and a low-density, low-wave-speed medium (such as a foam or powder). This damping phenomenon has great promise for many applications because it is robust (that is, not tuned), does not introduce significant creep into a structure, can accommodate large strains, and can be realized using materials that are light weight, low cost, durable, insensitive to temperature, and easy to package. We report on several experiments in which flexural and longitudinal vibration are attenuated using this approach. Experiments on flexural vibration of structures filled with low-density powder show that high damping is obtained (with loss factors as high as 12 percent for a powder fill whose mass is 2.3 percent of that of the beam) over a broad frequency range. Somewhat surprisingly...

‣ Numerical models for scoring failures of flexible metal to metal face seals

Hong, Jinchul, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 108 leaves; 5830586 bytes; 5843296 bytes; application/pdf; application/pdf
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The flexible metal to metal face seals (FMMFS) has unique features including much more flexibility in the circumferential direction than in the radial direction, identical rotating and stationary seals, and a loading mechanism using elastomeric rings. This thesis work is the first attempt to explain scoring failures of this unique type of mechanical face seal. Numerical models and new scoring failure criteria were developed to explain different scoring failures of the FMMFS. The numerical models consider interactions among seal surface deflections, lubrication in the sealing band and thermal effects simultaneously. The numerical models were validated from comparisons with experiments and applied to scoring failure tests. The new scoring failure criterion successfully predicted the likelihood of scoring failures for each seal pair at given loads and speeds. From in-depth analysis of the seal pairs with low and high scoring failure speeds, it has been shown that discontinuous contact patterns can increase scoring resistance of the seal pair. These discontinuous contact patterns are created by irregular surface profiles of the sealing band. Irregular surface profiles can decrease high temperature regions by reducing superposition of temperatures and thermal conduction resistance...

‣ Switchable stiffness scanning microscope probe

Mueller-Falcke, Clemens T. (Clemens Tobias)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 80 p.; 4652730 bytes; 4656198 bytes; application/pdf; application/pdf
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Atomic Force Microscopy (AFM) has rapidly gained widespread utilization as an imaging device and micro/nano-manipulator during recent years. This thesis investigates the new concept of a dual stiffness scanning probe with respect to biological applications and determines the resulting requirements for the scanning of soft bio samples, such as low-pressure contact. On this basis, an in-plane AFM probe that is specifically tailored to the needs of biological applications is developed. It features a variable stiffness, which makes the stiffness of the probe adjustable to the surface hardness of the sample, and a very low overall stiffness, which is needed in order to achieve high resolution imaging. The switchable stiffness probe allows the scanning of biological samples with varying surface hardness without changing probes during scanning, and therefore prevents a loss of positional information, as is unavoidable with conventional devices. For the integration of the components into a MEMS device, the conventional cantilever-type design of AFM probes has been abandoned in favor of an in-plane design. The new design has an advantage in that it facilitates a high-density array of AFM probes and allows for easy surface micromachining of the integrated device. It also enables the future integration of micro-fluidic channels for reagent delivery and nanopipetting. For the scanning of nano-scale trenches and grooves...

‣ Preferential nanoreinforcement of thermoplastic polyurethane elastomers with dispersed nano-clay

Liff, Shawna M. (Shawna Marie)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 110 p.; 8468803 bytes; 8473888 bytes; application/pdf; application/pdf
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It is difficult for scientists to engineer elastomeric materials that are both strong and tough like spider dragline silk. Inspired by the morphology of spider dragline silk and motivated to develop strong, tough, elastomeric polyurethanes to be used in soldier applications I have prepared polyurethane/clay nanocomposites. Polymer/clay nanocomposites have exhibited great potential for providing enhanced and possibly-tunable thermomechanical behavior. However, the biggest challenge facing advances in polymer/clay nanocomposites is the complete dispersion of nano- clay within the polymer matrix due to thermodynamic and kinetic limitations. A novel solvent exchange method to fully exfoliate and disperse discotic smectic clay, Laponite (diameter = 25 nm, thickness = 1 nm), in three thermoplastic polyurethane elastomers (TPUs) -- Elasthane 80A, HDI-PTMO PU, and PU-1-33 -- has been developed. This clay was selected because the diameter of one platelet is similar to the lateral dimension of a single hard-domain in block-polymeric TPU. WAXD, TEM, and AFM phase imaging of cast films following solvent exchange show that the nano-clay is well dispersed in the TPUs. Uniaxial mechanical testing showed that as much as a 23-fold increase in elastic modulus...

‣ Three dimensional mapping of lingual myoarchitecture; 3D mapping of lingual myoarchitecture

Magnusson, Lee (Lee H.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 82 p.; 4127292 bytes; 4131010 bytes; application/pdf; application/pdf
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The tongue is a structurally complex muscular organ, composed of a continuum of variably aligned intrinsic and extrinsic fibers. An understanding tongue structure and function, both under normal and pathological conditions, requires a complete three dimensional representation of fiber orientations present in the whole tissue. In order to investigate lingual myoarchitecture in the mammalian tongue, we employed several magnetic resonance imaging techniques generally based on direction specific differences in water diffusion. Muscle tissue in particular exhibits significant diffusion anisotropy in the direction of fibers, from which diffusion imaging is able to infer fiber direction. In this thesis research, several diffusion weighted MRI signal acquisition and post processing methods were tested, namely diffusion spectrum imaging (DSI), DSI with tractography, q-ball imaging, diffusion tensor imaging (DTI), and ADC and FA mapping. Each imaging method was evaluated in three ways: 1) finite element simulation using 2D structures to model the diffusion environment in an idealized situation, 2) MRI of microfluidic phantoms to quantify the effects of experimental conditions with a known diffusion environment, and 3) MRI of biological tissue...

‣ Mechanisms of plastic deformation in amorphous silicon by atomistic simulation using the Stillinger-Weber potential

Demkowicz, Michael J. (Michael John), 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 213 p.; 11049635 bytes; 11063137 bytes; application/pdf; application/pdf
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Molecular dynamics simulation of amorphous silicon (a-Si) using the Stillinger- Weber potential reveals the existence of two distinct atomic environments: one solidlike and the other liquidlike. The mechanical behavior of a-Si when plastically deformed to large strain can be completely described by the mass fraction [phi] of liquidlike material in it. Specifically, samples with higher [phi] are more amenable to plastic flow, indicating that liquidlike atomic environments act as plasticity "carriers" in a-Si. When deformed under constant pressure, all a-Si samples converge to a unique value of [phi] characteristic of steady state flow. Discrete stress relaxations were found to be the source of low-temperature plastic flow in a-Si in deformation simulations by potential energy minimization. These relaxations are triggered when a local yielding criterion is satisfied in a small cluster of atoms. The atomic rearrangements accompanying discrete stress relaxations are describable as autocatalytic avalanches of unit shearing events. Every such unit event centers on a clearly identifiable change in bond length between the two split peaks of the second nearest neighbor shell in the radial distribution function (RDF) of bulk a-Si in steady-state low.; by Michael J. Demkowicz.; Thesis (Ph. D.)--Massachusetts Institute of Technology...

‣ Development of silicon insert molded plastic (SIMP); Development of SIMP

Werkmeister, Jaime Brooke, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 p.; 6544804 bytes; 6550362 bytes; application/pdf; application/pdf
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As demand for smaller devices continues to increase, current manufacturing processes will find it more challenging to meet cost, quantity, and dimensional requirements. While microfabrication technology processes can create electronic devices in vast quantities with increasingly smaller dimensions, they are challenged to do so for mechanical devices at low cost and in large quantity. More traditional manufacturing processes such as machining or injection molding can more easily meet cost and quantity requirements, but are unable to currently match the dimensional abilities of microfabrication processes. By merging microfabrication and traditional injection molding techniques, the benefits of both technologies can be combined to produce parts to meet all three requirements. The objective of this research is to investigate the possibilities of injection molding polymer parts with sub-micron three-dimensional features using a process called Silicon Insert Molded Plastics (SIMP).; by Jaime Brooke Werkmeister; Thesis (Mech. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.; Includes bibliographical references (p. 85-86).

‣ A study of the motion of the three-linked swimmer in viscous fluid using computational and experimental methods

Ji, Susan YeYoung, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 50 leaves; 3204707 bytes; 3205337 bytes; application/pdf; application/pdf
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An experimental and numerical study was conducted to better understand the mechanics of motion of the three-linked swimmer in viscous fluid. Numerical studies in C++ were used to predict the velocity and motion of the swimmer using a modified analytical model that considers the dynamical and orientational effects of rods at the surface of a fluid. Computational simulations were graphically used to understand the pressure and velocity distributions of the fluid-structure interactions of the three-linked swimmer, with slightly different movement, using an immersed boundary method computer program. Experiments using a mechanical prototype of a three-linked swimmer were conducted to validate and compare the numerical predictions derived from computational studies. Experimental results indicate that a flexible armed swimmer is more than three times as fast as its rigid armed counterpart. The analytical model presented in this study and the corresponding computational numerical simulations were found to capture the trends of the motion, and the predicted horizontal velocity came within 66% in value of the recorded experimental data.; by Susan YeYoung Ji.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering...

‣ A ball-on-beam project kit

Rosales, Evencio A. (Evencio Alex), 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 40 leaves; 2141914 bytes; 2141571 bytes; application/pdf; application/pdf
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An apparatus of the classical ball-on-beam problem was designed and constructed to be used as a pedagogical instrument in feedback courses. The aesthetic and mechanical design incorporated economical materials to make kits of this apparatus attractive and cost effective. This thesis describes the design of the apparatus and the design of the two control loops to control the angle of the motor and the position of the ball along the beam. A lead compensator was used in each loop and an additional integrator was used in the motor loop to ensure the beam level when supporting the ball. The motor closed loop was designed for a bandwidth of 25 Hz and the ball loop was designed for 1 Hz. The closed loop control was implemented using a Matlab Simulink model and a dSPACE digital signal processor controller board. The feedback sensor of the motor angle was an encoder mounted to the back of the motor, and the sensor for the ball position was a linear potentiometer resistive element. After multiple iterations and debugging of the ball position sensor, the ball-on-beam system performed successfully, responding well to step commands and disturbances.; by Evencio A. Rosales.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering...

‣ The effects of membrane and cytoskeletal mechanics on cell adhesiveness

Shearer, David, 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 29 leaves; 1507256 bytes; 1505937 bytes; application/pdf; application/pdf
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The cytoskeleton, the internal network of filaments that regulates cell shape and structure, has been implicated in several critical aspects of cell adhesion. Its role, however, has primarily been demonstrated as a component of the numerous intracellular signaling events that regulate cell surface receptors. In this study we sought to gain insight into how the mechanical properties of the cytoskeleton could affect adhesion. Specifically, we addressed how membrane deformability, which we demonstrate is critically dependent upon tethering to the cytoskeleton, could impact a whole cell adhesion assay. To modify membrane deformability, we treated cells with the pharmacological agents phalloidin, Latrinculin B, Cytochalasin D, colchicine, and Paclitaxel, which have varying effects on microfilaments and microtubules, two of the main constituents of the cytoskeleton. We found that dissolution of the actin cytoskeleton could reduce the number of adherent cells to a callogen-coated substrate by over 85%. We theorize that this is due largely to the inhibition of signaling events associated with the cytoskeleton, but it may also be affected by changes in shape and deformability. To truly understand the implications of this experiment, we believe further study using high-resolution force technology such as atomic force microscopy or magnetic bead microrheometry is necessary.; by David Shearer.; Thesis (S.B.)--Massachusetts Institute of Technology...

‣ Stabilizing the ball on beam system with analog feedback

Ito, Bennett T. (Bennett Takeo), 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 45 p.; 2197041 bytes; 2197307 bytes; application/pdf; application/pdf
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A mechanical ball on beam system was stabilized to demonstrate the capabilities of control systems. This demonstration system is intended for use in control theory classes such as 6.011 Introduction to Communication, Control, and Signal Processing, 6.302 Feedback Systems, and 6.003 Signals and Systems. Control of this unstable system is achieved through classical control methods taught in 6.302. The compensators are implemented in analog circuitry. The system was successfully demonstrated in a 6.011 lecture (April 5, 2004). A lab kit system was designed for future 6.302 students.; by Bennett T. Ito.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.; Includes bibliographical references (p. 45).

‣ Design of a compact, lightweight, and low-cost solar concentrator

González, Gabriel J. (Gabriel Joe), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 51 leaves; 3832162 bytes; 3832972 bytes; application/pdf; application/pdf
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The objective of this mechanical design project was to improve the current design of large and heavy solar concentrators. The three main design goals were: making the system compact, making the system lightweight, and minimizing expenses. The main approach to achieving these design parameters was to use the plastic film Mylar in its aluminized form to create a paraboloid serving as a solar concentrator. The scope of design was limited to designing and prototyping the solar concentrator, and neglecting to design and prototype the container in which it should be kept while in its compact form. Two designs-the tube design and the rim design-are examined, although the rim design is emphasized because of its advantages over the tube design. The tube design included a bicycle tire tube serving as the structural element of the solar concentrator, while the rim design utilized a bandsaw blade (without teeth) as the structural element of the solar concentrator. The prototype of the rim design proved to work well as a mirror, although further work, such as improving the seal around the rim, must still be done due to the time frame and resources allowed for this project.; by Gabriel J González.; Thesis (S.B.)--Massachusetts Institute of Technology...

‣ Continuous production of conducting polymer

Gaige, Terry A. (Terry Alden), 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 64 p.; 3652287 bytes; 3654274 bytes; application/pdf; application/pdf
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A device to continuously produce polypyrrole was designed, manufactured, and tested. Polypyrrole is a conducting polymer which has potential artificial muscle applications. The objective of continuous production was to produce both larger films and films with more consistent properties than the films produced by the current batch-production method. The mechanical properties of polymers produced by batch synthesis are known to be highly dependent on reaction parameters such as temperature, and reactant and electrolyte concentrations. A system of peltier thermoelectric coolers and refrigerated-circulator held the deposition chamber at -10⁰C. The polypyrrole film deposited onto the surface of a rotating glassy carbon crucible was peeled off using a blade and spring force mechanism. The temperature, current, and voltage of the electrodeposition were recorded. Several successful, but short, continuous deposition trials were run at a current density of 0.5 A/m² and a film 50 mm long and 0.246 mm thick was produced and tested. High rate depositions were also attempted at 150 A/m² but failed due to over-oxidation. In this thesis, it is demonstrated that continuous production appears feasible. A second prototype of the device is proposed with several improvements...

‣ Environmental constituents of Electrical Discharge Machining; Environmental constituents of EDM

Cho, Margaret H. (Margaret Hyunjoo), 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 31 leaves; 1476560 bytes; 1475418 bytes; application/pdf; application/pdf
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Electrical Discharge Machining (EDM) is a non-traditional process that uses no mechanical forces to machine metals. It is extremely useful in machining hard materials. With the advantages EDM has to offer and its presence as a common and useable technique, along with the other machining processes available to the industrial world, there is an added strain on the environment. The scope of this thesis includes analyzing the various inputs into EDM and the resulting outputs into the environment. A simplified model is used to analyze the process. The main categories of flow scrutinized in the model are material flow and energy flow. The most hazardous effect to the environment is found in the resin interaction of the wire EDM process where depending on the type of material machined, there is a potential presence of hazardous materials. There are efforts to recycle all salvageable materials such as wire and metal wastes, but currently no accountability system exists as manufacturers are responsible for their actions.; by Margaret H. Cho.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.; Includes bibliographical references (leaves 30-31).

‣ Regenerative braking on bicycles to power LED safety flashers

Collier, Ian M
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 29 leaves; 1899839 bytes; 1898511 bytes; application/pdf; application/pdf
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This work develops a method for capturing some of the kinetic energy ordinarily lost during braking on bicycles to power LED safety flashers. The system is designed to eliminate: (a) battery changing in popular LED flashers, and (b) the "generator drag" associated with battery-less human-powered bicycle lights and flashers. System sizing, mechanical design considerations, potential end-user factors, and a model for braking frequencies in urban settings are discussed. With the urban commuter cyclist in mind as a potential user of the regenerative braking system, custom direct-pull brake calipers (or "V-Brakes") were designed and manufactured to include both conventional friction pads in addition to a DC motor to be used as a generator for kinetic energy capture. The energy captured by the DC motor during braking is passed through a full wave bridge to a bank of Nickel-Cadmium batteries at an efficiency of 79%. The output of the full wave bridge and the batteries are connected in parallel with a step-down switching voltage regulator, which insulates the LED safety flasher from voltage spikes due to braking at high cycling speeds. The performance of the final prototype was evaluated at cycling speeds ranging from 8 to 19 mph and braking frequencies ranging from 2 to 8 operations/stops per mile of travel.; (cont.) From the mean power flow (charging) into the batteries per unit distance of travel and the power required by LED safety flashers...

‣ Mechanics of Notched Izod impact testing of polycarbonate

Silberstein, Meredith N
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 67 leaves; 9989367 bytes; 9991618 bytes; application/pdf; application/pdf
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Polycarbonate is widely used as a transparent protective material because of its low density and excellent mechanical properties. However, when defects such as cracks or notches are introduced, it is subject to catastrophic brittle failure at relatively low loads. Notched Izod testing is a common qualitative measure of toughness of a material, measuring energy absorbed prior to failure under high triaxiality and high rate loading conditions. Much research has been done using Izod testing to compare the fracture energies of blends of Polycarbonate and rubbery materials; however the specific yielding and fracture mechanisms associated with each blend are rarely analyzed. This study presents detailed images, fracture energies, and time durations of the deformation and failure processes actively occurring during the Notched Izod testing of 3.23mm and 6.35mm thick Polycarbonate specimens, as well as of a quasi-static version of Notched Izod bending. The thin specimens were found to yield in a ductile manner followed by tearing across most of the ligament width, resulting in a final failure including a small plastically-deformed ligament hinging the two failure surfaces in both the Notched Izod impact and Quasi-Static tests.; (cont). The thick specimens exhibited slight yielding followed by catastrophic failure...

‣ The application of emerging technologies to sports technology : wired skin

Raghunathan, Smitha
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 35 leaves; 2132879 bytes; 2132085 bytes; application/pdf; application/pdf
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Technology is continuously being developed, processed and created into products for the consumer market; however, in the steps of this process, there is often one goal in mind, and using the technology is rare used for different and novel areas. The goal of this paper is to show how three emerging technologies can be used creatively beyond their original purposes by the sports industry. The technologies addressed in the paper are The Microsoft Full Body Network, ShapeTape and the FluidFocus Lens. These technologies address the issues of wireless data and power transmission, data acquisition, and the creation of a lens with variable focus with no mechanical or moving parts, respectively. Research was done to understand the current state of the technology or product, and what obstacles remain in the path to the creation of an actual working prototype. A merging of these three technologies resulted in a proposed product for the sports industry. The name, Wired Skin, was given to this envisioned product, and was tailored in response to a survey conducted with a pool of 200 individuals. The issues of the price range customers were willing to spend on various products, the importance of various improvements to existing technology and general questions to specify the demographic questioned were addressed fully. This paper creates a melding of the three technologies into a product that addresses the major barriers to the entrance of emerging technology to the area of athletics.; by Smitha Raghunathan.; Thesis (S.B.)--Massachusetts Institute of Technology...