Lorentz force actuator and carbon fiber co-winding design, construction and characterization

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 66-67).Carbon fiber composites are materials that present many benefits to engineering applications, ranging from aerospace to medicine. This thesis provides background on carbon fiber properties and manufacturing techniques, and outlines the methodology for manufacturing a co-wound carbon fiber and copper coil for use in linear Lorentz force actuators. A conventionally-wound, plastic-bobbin actuator coil and the new, co-wound coil were then tested to compare their electrical, thermal, and mechanical performance. In a needle-free injection application, the cowound coil demonstrated improved performance over the conventional coil configuration. The carbon fiber coil is lighter by 3.75 ± 0.155 grams, increases the transient heat transfer by 15.7 %, is 2.18 ± 0.13 times stiffer, and can survive a higher compressive force than the conventional plastic bobbin.by Yi Chen.S.B

An investigation of yarn spinning from electrospun nanofibres

The aim of the thesis is to investigate yarn spinning from electrospun nanofibres. The concepts of staple and core yarn spinning on electrospun nanofibres has been investigated by examining nanofibre uniformity, alignment, twist insertion and yarn take up by engining and engineering a new take up mechanism. Nylon 6 nanofibres have been fabricated and used throughout this work. The effects of varying the electrospinning parameters such as applied voltage, polymer solution concentration and electrospinning distance on fibre morphology have been established for process optimization. A novel nanofibre aligning mechanism has been devised and systematically revised to enable optimization of alignment process parameters. MWCNTs have been successfully dispersed into nylon 6 nanofibres and have been aligned along the nanofibre body by manipulating the electric and stretching forces with the aid of the alignment mechanism. Novel mechanisms for spinning continuous twisted nanofibre/composite nanofibre yarn and core electrospun yarn have been researched, developed and implemented by making samples. It has been found that defining the velocity and count of the nanofibres entering the spinning zone is important for controlling the yarn count and twist per unit length. By modelling the electrospinning jet, mathematical equations for theoretically calculating the velocity of the jet and nanofibres and their count have been established, necessary for process control. Aspects of practical measurement and comparison of jet and nanofibre velocities have been described and discussed. Tensile testing of single nanofibre and nanofibre mats has been attempted for mechanical characterization. Initial results show the range of tensile strength of nylon 6 nanofibre assemblies and indicate the effect of change of process parameters. A review of those engineering mechanisms related to various nanofibre architectures and their industrial and commercial importance has also been reviewed, described and discussed

An Investigation into Interdependencies in Electrical Machines Involving Deformable Materials: A Model-Based Multi-Objective Framework

The increasing popularity of the green industrial revolution has led to a rise, in the production and use of Electric Vehicles (EVs) and their associated parts, like motors, generators and transformers [1]. This surge was driven by a growing emphasis on sustainability and the need to shift towards alternatives especially in transportation [2]. However meeting the growing demand for these parts while maintaining production standards presents a challenge. To address this challenge it is important to improve manufacturing processes by prioritizing early detection of faults to reduce End of Line (EoL) tests and ensure efficient production. The efficiency and cost control of Electrical Machines (EM) greatly depend on the interactions, between components and subsystems. The inclusion of deformable materials such as copper wire introduces complexity owing to their nature. This study suggests various frameworks to improve efficiency by minimising the need for tests and effectively handle deformable materials during the manufacturing process. In this research, a framework that utilises Discrete Event Simulation (DES) was presented to investigate the interrelationships in EM manufacturing specifically focusing on the coil winding process. Through experiments, connections between winding speed, wire thickness, bobbin shape and variations in resistance were discovered. These findings highlight the importance of control features. Additionally, this study introduced an improved DES framework that combines the original DES model with a Supervised Machine Learning (SML) algorithm via Knowledge Distillation (KD). This integration significantly reduced simulation times while still maintaining accuracy. Lastly, a new approach was introduced with the aim to optimise the linear coil winding process by considering multiple objectives. The goal was to minimise production costs and decrease faults by examining the connections between these objectives. Advanced techniques like the NSGA-II algorithm were utilised to find a balance between faults and production costs resulting in enhancements, in operational efficiency and cost reduction

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Time domain analysis of switching transient fields in high voltage substations

Switching operations of circuit breakers and disconnect switches generate transient currents propagating along the substation busbars. At the moment of switching, the busbars temporarily acts as antennae radiating transient electromagnetic fields within the substations. The radiated fields may interfere and disrupt normal operations of electronic equipment used within the substation for measurement, control and communication purposes. Hence there is the need to fully characterise the substation electromagnetic environment as early as the design stage of substation planning and operation to ensure safe operations of the electronic equipment. This paper deals with the computation of transient electromagnetic fields due to switching within a high voltage air-insulated substation (AIS) using the finite difference time domain (FDTD) metho

Adaptive deformable mirror : based on electromagnetic actuators

Refractive index variations in the earth's atmosphere cause wavefront aberrations and limit thereby the resolution in ground-based telescopes. With Adaptive Optics (AO) the temporally and spatially varying wavefront distortions can be corrected in real time. Most implementations in a ground based telescope include a WaveFront Sensor, a Deformable Mirror and a real time wavefront control system. The largest optical telescopes built today have a ~ 1 Om primary mirror. Telescopes with more collecting area and higher resolution are desired. ELTs are currently designed with apertures up to 42m. For these telescopes serious challenges for all parts of the AO system exist. This thesis addresses the challenges for the DM. An 8m class telescope on a representative astronomical site is the starting point. The atmosphere is characterized by the spatial and temporal spectra of Kolmogorov turbulence and the frozen flow assumption. The wavefront fitting error, caused by a limited number of actuators and the temporal error, caused by a limited control bandwidth, are the most important for the DM design. It is shown that ~5000 actuators and 200Hz closed loop bandwidth form a balanced choice between the errors and correct an 8m wavefront in the visible to nearly diffraction limited. An actuator stroke of ~5.6J.!m and ~0.36J.!m inter actuator stroke is thereby needed. Together with the nm's resolution, low power dissipation, no hysteresis and drift, these form the main DM requirements. The design, realization and tests of a new DM that meets these requirements and is extendable and scalable in mechanics, electronics and control to suit further Extremely Large Telescopes (ELTs) is presented. In the DM a few layers are distinguished: a continuous mirror facesheet, the actuator grid and the base frame. In the underlying layer - the actuator grid - low voltage electromagnetic push-pull actuators are located. Identical actuator modules, each with 61 actuators, hexagonally arranged on a 6mm pitch can be placed adjacent to form large grids. The base frame provides a stable and stiff reference. A thin facesheet is needed for low actuator forces and power dissipation, whereby its lower limit is set by the facesheets inter actuator deflection determined by gravity or wind pressure. For both scaling laws for force and dissipation are derived. Minimum power dissipation is achieved when beryllium is used for the mirror facesheet. Pyrex facesheets with 100J.!m thickness are chosen as a good practical, alternative in the prototype development. Struts (00.1 x 8mm) connect the facesheet to the actuators and ensure a smooth surface over the imposed heights and allow relative lateral movement of the facesheet and the actuator grid. Measurements show 3nm RMS surface unflattness from the glued attachment. The stiffness of the actuators form the out-of-plane constraints for the mirror facesheet and determine the mirrors first resonance frequency. and is chosen such that the resonance frequency is high enough to allow the high control bandwidth but not higher that needed to avoid excessive power dissipation and fix points in the surface in case of failure. The electromagnetic variable reluctance actuators designed, are efficient, have low moving mass and have suitable stiffness. Other advantages are the low costs, low driving voltages and negligible hysteresis and drift. The actuators consist of a closed magnetic circuit in which a PM provides static magnetic force on a ferromagnetic core that is suspended in a membrane. This attraction force is increased of decreased by a current through a coil. The actuators are free from mechanical hysteresis, friction and play and therefore have a high positioning resolution with high reproducibility. The actuator modules are build in layers to reduces the number of parts and the complexity of assembly and to improve the uniformity in properties. Dedicated communication and driver electronics are designed. FPGA implemented PWM based voltage drivers are chosen because of their high efficiency and capability to be implemented in large numbers with only a few electronic components. A multidrop LVDS based serial communication is chosen for its low power consumption, high bandwidth and consequently low latency, low communication overhead and extensive possibilities for customization. A flat-cable connects up to 32 electronics modules to a custom communications bridge, which translates the ethernet packages from the control PC into LVDS. Two DMs prototypes were successfully assembled: a 050mm DM with 61 actuators and a 0l50mm DM with 427 actuators. In the second prototype modularity is shown by the assembly of seven identical grids on a common base. The dynamic performance of each actuator is measured, including its dedicated driver and communication. All actuators were found to be functional, indicating that the manufacturing and assembly process is reliable. A nonlinear mathematical model of the actuator was derived describing both its static and dynamic behavior based on equations from the magnetic, mechanic and electric domains. The actuator model was linearized, leading to expressions for the actuator transfer function and properties such as motor constant, coil inductance, actuator stiffness and resonance frequency. From frequency response function measurements these properties showed slight deviations from the values derived from the model, but the statistical spread for the properties was small, stressing the reliability of the manufacturing and assembly process. The mean actuator stiffness and resonance frequency were 0.47kN/m and 1.8kHz respectively, which is close to their design values of 500N/m and 1.9kHz. The time domain response of an actuator to a 4Hz sine voltage was used to determine hysteresis and semi-static nonlinear response of the actuator. This showed the first to be negligible and the second to remain below 5% for ±10J.!m stroke. Measurements showed that in the expected operating range, the total power dissipation is dominated by indirect losses in FPGAs. The static DM performance is validated using interferometric measurements. The measured influence matrix is used to shape the mirror facesheet into the first 28 Zernike modes, which includes the piston term that represents the best flat mirror. The total RMS error is ~25nm for all modes. The dynamic behavior of the DM is validated by measurements. A laser vibrometer is used to measure the displacement of the mirror facesheet, while the actuators are driven by zero-mean, bandlimited, white noise voltage sequence. Using the MOESP system identification algorithm, high-order black-box models are identified with VAF values around 95%. The first resonance frequency identified is 725Hz, and lower than the 974Hz expected from the analytical model. This is attributed to the variations in actuator properties, such as actuator stiffness. The power dissipation in each actuator of the 050mm mirror to correct a typical Von Karmann turbulence spectrum is ~ 1.5m W

Encapsulating soldered electronic components for electronically functional yarn

E-Textiles are fabrics with embedded electronic functions that can be used in many fields, such as clothing, medicine, furniture, safety and many others. The integration of electronics with textiles requires a flexible structure that keeps the garment flexible to ensure the textile retains its physical characteristics and feel. E-textiles in wearable applications are subject to human activities. The integrated electronic components are vulnerable to these stresses, such as bending, torsion, and tensile. These forces can potentially damage the components or their interconnection. Electronics can be integrated into textiles in one of three approaches described as generations of E-Textiles. The Thesis will introduce the three generations of E-textiles through a comprehensive literature review in chapter 2. It will then discuss developing the electronically functional yarn (EFY) as a third generation in E-textiles and garments. The production process of this yarn has three main steps: soldering the semi-conductor on the copper wire, encapsulating it within a micro pod of resin, and covering the micro pod within the filament of the yarn. A detailed study of the encapsulation process and the unit's design is then introduced in the Thesis, where a novel method for packaging electronics using a UV-curable resin was introduced. The design process for the automated encapsulation of soldered semi-conductor has been investigated in Chapter 3 of this Thesis. The novel approach has been evaluated on various electronics and then extended to thin Kapton strips with embedded electronics. The resulting EFY then can be later used in woven or knitted textile. Finite element analysis (FEA) of the soldered semi-conductor on the wire is presented in chapter 4. FEA simulations are used to evaluate the mechanical performance of different electronics and how stresses are distributed after adding the resin and creating the micro pod. This FEA investigation of the materials and micro pod dimensions will understand the packaging method's reliability. The final part of the Thesis included further development added to the design of the encapsulation unit and the electronically functional yarn manufacturing. Developing a reliable, repeatable, and automated electronic packaging method for electronics embedded in the electronically functional yarn (EFY) was achieved in this project. The results were promising for further research