Recursos de colección

DSpace at MIT (104.280 recursos)

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Mechanical Engineering - Engineer's degree

Mostrando recursos 1 - 20 de 136

  1. An investigation into the design of surface piercing super cavitating hydrofoils

    Dutton, Timothy Spaulding
    The fluid-dynamic design of hydrofoils to support marine crafts at high speeds has received growing interest in recent years. Physics involved in the design of high-speed surface-piercing hydrofoils is complex involving three different fluid phases (air, water and vapor) and complex fluid dynamic mechanisms like unsteady cavitation and ventilation and their interaction. For speeds considerably higher than the incipient cavitation speed, the hydrofoil sections need to be adapted and design to exploit cavitation instead of avoiding it. This is particularly true for surface piercing hydrofoils that in addition to cavitation are affected by ventilation from the free surface. This thesis...

  2. Material characterization and axial loading response of pouch lithium ion battery cells for crash safety

    Mason, Amber J
    Recent research conducted at MIT's Impact and Crashworthiness Laboratory (ICL) has focused on material characterization of lithium ion battery cell components for use in the development of an accurate and practical computational model intended to predict mechanical deformation and related short circuit behavior of Li-ion battery cells and stacks in real world impact scenarios. In an effort to continue to refine and validate this modeling tool, characterization testing was conducted on battery cell pouch material using uniaxial stress and biaxial punch tests. At the full cell level, hemispherical punch indentation validation testing and internal electric short circuit testing was conducted...

  3. Load bearing interface design for a pan-tilt mechanism for severe marine environments

    Beautyman, Michael John, Jr
    The Naval Research Laboratory (NRL) requested the design of a two-axis gimbal device for the shipboard support of a sensor payload. Previous design efforts presented a low-mass two-axis (pan and tilt) machine. Vibration and shock testing induced failure in the interface between the payload and the tilt shaft, through which the control cabling connected to the sensors, taking the system out of service and creating a hazard for Sailors. This thesis proposes a tapered, hollowed shaft and flange interface connected by an interference fit that is preloaded and retained by a single hollowed bolt for ease of maintenance at sea....

  4. Examination of hull forms for an Offshore Nuclear Plant

    Jagoe, Randall Thomas
    The Nuclear Science and Engineering Department at MIT has a concept design for an Offshore Nuclear Plant (ONP). This project highlights the advantages of the offshore location by reducing the risk of natural disasters and cost of terrestrial nuclear power facilities. The original ONP conceptual design consists of a large cylindrical floating platform similar to existing platforms in the offshore oil and natural gas industries. This study investigates the advantages and disadvantages of different hull forms that the ONP may use in an effort to identify an optimal balance between hull configuration and stability. Multiple platform designs were modeled to...

  5. Slip clutch design for position sensitive systems in marine environments

    Finley, Thomas Patrick
    The Naval Research Laboratory (NRL) requested a two-axis pan tilt mechanism be designed, built, and tested for shipboard deployment of a sensor payload. Of paramount consideration to this design was the robustness of the system in the face of wave impact loading from "green water" taken over the superstructure of naval vessels. Central to providing such a system is the prevention of drive train failures given wave or other forms of impact loading. Through the course of work completed for his Master's thesis, Nathan M. Mills brought the design effort through initial bench testing. Several failures were experienced due to...

  6. Intent-aware collision avoidance for autonomous marine vehicles

    Leavitt, Joseph William
    Applications of autonomous marine vehicles in dynamic and uncertain environments continuously grow as research unveils new enabling technology and academic, commercial, and government entities pursue new marine autonomy concepts. The safe operation of these vehicles in the marine domain, which is currently dominated by human-operated vehicles, demands compliance with collision avoidance protocol, namely the International Regulations for Preventing Collisions at Sea (COLREGS). Strict application of this protocol can lead to a highly constrained motion planning problem, in which it is difficult for a vehicle to identify a safe and efficient motion plan. This thesis proposes a multi-objective optimization-based method for...

  7. Design, evaluation, and validation of a naval ship structural health monitoring tool

    Olena, Jessica Jill
    The US Navy implements structural preventative maintenance procedures onboard its vessels using ship's personnel inspection. These procedures have been largely successful in identifying major problem areas before any interference with mission execution has occurred. However, changes in the Navy's manning philosophy to minimal manning and new ship designs focused on automation encourage a re-evaluation of these structural preventative maintenance procedures. Automation of structural inspection and damage detection would reduce associated manpower costs as well as inform better preventative maintenance schedules for US Navy vessels. This study outlines a modeling tool for structural health monitoring using nonlinear Kalman Filter methodologies such...

  8. Design and numerical analysis of an unconventional surface-piercing propeller for improved performance at low and high speeds

    Parker, Justin Richard
    Traditional propellers operate fully submerged, with cavitation limited as much as possible in order to minimize its disruptive and damaging consequences. Conversely, supercavitating propellers operate in an encompassing vapor cavity, thereby averting these negative effects while substantially reducing drag on the blades. Surface-piercing propellers, operating under a similar concept as supercavitation, often achieve even greater efficiency by drawing in an air cavity from the free surface. Existing small craft have demonstrated the ability of such propellers to yield extremely high speeds (110+ knots); nevertheless, the full potential of these propellers has yet to be explored. In particular, designs often neglect...

  9. Using the principles of set-based design to realize ship design process improvement

    Genta, John (John Anthony)
    Set-based design (SBD) is a relatively new complex product development method. Its use has been well researched in the automotive and aerospace industries and, although it requires an upfront investment in resources, it has been shown to reduce design cycle time, later stage rework, total ownership cost, and improve design knowledge capture. The current fiscal environment of the U.S. Government has obligated the Department of Defense to challenge each service to "do more, without more" by finding efficiencies. Since 2005, the U.S. Navy has self-identified ship design as a process improvement priority and embarked in design tool and policy changes...

  10. Automation as a manpower reduction strategy in navy ships

    Powers, Roxane (Roxane Bloodworth)
    Since the early 2000's, the US Navy has endeavored to decrease the Total Ownership Cost (TOC) of their ships through a decrease in Operating and Support costs. This led to a large-scale effort by ship program managers to decrease crew size on current and prospective ships. Also during this time period, the rapid-onset improvement of technology led to the increase and complexity of automated systems and equipment installed on ships. These combining trends have caused ships to evolve from a fully manually operated system into a socio-technical system. But does increasing automation to support minimally manned ships lead to the...

  11. An experimental study of the one Atmosphere Diving Suit (ADS) and data analysis of military diving

    Colgary, James J., Jr
    The Atmospheric Diving Suit (ADS) is a one-man submarine with moveable, humanlike appendages with internal pressure maintained at one atmosphere. This precludes the possibility of common diving related illnesses while giving the operator an increased depth of operation compared to traditional diving systems. The ADS provides additional capability for industries and militaries around the world, but is not without its own unique challenges and limitations. Current ADS maneuverability, specifically that associated with joint rotation, lacks natural movement and range of motion, rendering most normal underwater tasks more challenging and taxing on the operator. Concerns about the lack of maneuverability and...

  12. Design and testing of a pan-tilt mechanism for severe environments

    Mills, Nathan (Nathan Matthew)
    U.S. Navy ships have non-rotating radar and electronic warfare devices installed, which are often supported and trained by two-axis gimbals. In current shipboard solutions the payloads are often placed on a platform above the gimbal drive train, which results in high moment loads on drive components during a wave impact. As the payloads grow in size, the moment grows as well, and the current gimbal design is insufficient to support some payload geometries. This thesis presents a novel design for a low-mass two-axis machine that supports large payloads without large impact moments by locating the center of action along the...

  13. Object localization and identification for autonomous operation of surface marine vehicles

    Mentzelos, Konstantinos
    A method for autonomous navigation of surface marine vehicles is developed A camera video stream is utilized as input to achieve object localization and identification by application of state-of-the-art Machine Learning algorithms. In particular, deep Convolutional Neural Networks are first trained offline using a collection of images of possible objects to be encountered (navy ships, sail boats, power boats, buoys, bridges, etc.). The trained network applied to new images returns real-time classification predictions with more than 93% accuracy. This information, along with distance and heading relative to the objects taken from the calibrated camera, allows for the precise determination of...

  14. An experimental study of the human interface with one atmosphere diving suit by appendages

    Wilkins, Christopher Michael
    This experimental study of the human interface with an Atmospheric Diving Suit (ADS) develops a method for quantitatively evaluating how the pilot interacts with the suit's appendages to inform design improvements and to provide a baseline of joint performance for existing technologies. An Atmospheric Diving Suit is a one person anthropomorphic pressure vessel, with manually operated maneuverable appendages, capable of carrying a diver to great depths in the sea while maintaining the internal cabin pressure at one atmosphere (14.7 psi). Commercial ADS are used regularly around the world in offshore industries, and military ADS are used by a large number...

  15. Integrating Model Based Engineering and trade space exploration into naval acquisitions

    Stepanchick, Justin
    The Navy Acquisition force is faced with designing, procuring, and managing some of the most complex systems and technologies imagined. Balancing a shrinking and fickle budget environment with a program that has dynamic requirements and scheduling pressures only complicates this already difficult job. While developing these increasingly complex systems, major programs often face decisions without a sufficient analysis on a performance-versus-cost tradeoff. To surmount these challenges, the Navy must look at how industries excelled in similar environments. The concept of Model Based Engineering (MBE) is introduced as an approach that could move Navy Acquisition from document-centric to model-centric, enabling efficiency...

  16. Multi-attribute tradespace exploration for US Navy surface ship survivability: a framework for balancing capability, survivability, and affordability

    Walker, Johnathan C. (Johnathan Clyde)
    In a political environment of austerity, the importance of understanding the design tradeoffs for new naval ship concept designs cannot be understated. A combination of a tightened shipbuilding budget, large high-priority procurement programs, and an emphasis on affordability will require high level tradeoffs to be made in future ship programs. Understanding tradeoffs in naval ship capability and survivability for the sake of affordability early in concept ship design gives Navy leadership real options for affordable ships and reduces the likelihood of detailed design changes late in the acquisition process. In the naval ship design process capability and affordability are typical...

  17. Bragg reflector geometries for colorimetric orientation and deformation sensing

    Wing, Christopher (Christopher John)
    Propulsion systems of commercial and naval ships are typically large and expensive. They must be kept well-aligned and free of corrosion to efficiently and reliably transfer torque to a ship's propeller. Early identification of misalignment or surface corrosion is therefore crucial, making an easily deployable, reliable, lightweight system that visually indicates potential alignment and structural integrity issues desirable. This thesis demonstrates the design of a system for visual deformation and orientation indication based on naturally occurring micro-scale surface geometries that show a strong variation in their optical appearance as a function of illumination and observation directions. Specifically, the fabrication of...

  18. Modeling brake specific fuel consumption to support exploration of doubly fed electric machines in naval engineering applications

    Rowles, Jr., Michael R. , Jr
    The dynamic operational nature of naval power and propulsion requires Ship Design and Program Managers to design and select prime movers using a much more complex speed profile rather than typical of commercial vessels. The inherently reduces the overall efficiency of the plant as operated in comparison to its potential. The fuel consumption of prime movers is a multi-variable function of power demand and rotational speed. Mechanically coupled power and propulsion arrangements constrain this two degree of freedom relationship by removing the independence of the speed parameter. Fixed frequency power generation requires a constant prime mover speed that has a...

  19. Design and analysis of mobile sensing systems : an environmental data collection swarm

    Zoss, Brandon M
    Recent advances in small-scale portable computing have lead to an explosion in swarming as a viable method to approach large-scale data problems in the commercial, scientific, and defense sectors. This increased attention to large-scale swarm robotics has lead to an increase in swarm intelligence concepts, giving more potential to address issues more effectively and timely than any single unit. However, the majority of today's autonomous platforms are prohibitively costly and too complex for marketable research applications. This is particularly true when considering the demands required to be temporally and spatially pervasive in a marine environment. This work presents a low...

  20. Initiation of smoldering combustion in flexible polyurethane foams

    Mak, Audie Y. K
    by Audie Y.K. Mak.

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