The concept of segmented wind turbine blades : a review

There is a trend to increase the length of wind turbine blades in an effort to reduce the cost of energy (COE). This causes manufacturing and transportation issues, which have given rise to the concept of segmented wind turbine blades. In this concept, multiple segments can be transported separately. While this idea is not new, it has recently gained renewed interest. In this review paper, the concept of wind turbine blade segmentation and related literature is discussed. The motivation for dividing blades into segments is explained, and the cost of energy is considered to obtain requirements for such blades. An overview of possible implementations is provided, considering the split location and orientation, as well as the type of joint to be used. Many implementations draw from experience with similar joints such as the joint at the blade root, hub and root extenders and joints used in rotor tips and glider wings. Adhesive bonds are expected to provide structural and economic efficiency, but in-field assembly poses a big issue. Prototype segmented blades using T-bolt joints, studs and spar bridge concepts have proven successful, as well as aerodynamically-shaped root and hub extenders

Process planning for an Additive/Subtractive Rapid Pattern Manufacturing system

This dissertation presents a rapid manufacturing process for sand casting patterns using a hybrid additive/subtractive approach. This includes three major areas of research that will enable highly automated process planning; a critical need for a rapid methodology. The first research area yields a model for automatically determining the locations of layers, given the slab height, material types and part geometry. Layers are chosen such that it will avoid catastrophic failures and poor machining conditions in general. First, features that are possible thin material machining positions are defined, and methods for detecting these feature positions from an STL model are studied. Next, a layer thickness calculation model is presented according to positions of these features. The second area focuses on tools and parameters for the subtractive side of processing each layer. A tool size and machining parameter selection model is presented that can automatically select tool sizes and machining parameters, given layer thickness, part geometry, and material types. Machining strategies and related machining parameters are studied first. Then the method for Stepdown parameter calculation is presented. Finally, an algorithm based on both accessibility and machining efficiency is proposed for the selection of tool sizes for the rough cutting operation, finish cutting operation and optional semi-rough cutting operation. The final research area focuses on a cutting force analysis for thin material machining with additional layer thickness & tool size interaction. Popular cutting force models are reviewed, and a suitable model for cutting force calculation in this process is evaluated. Then, a cantilever beam model is used to analyze the thin material machining failure problem, and a minimum layer thickness model is presented. Third, a combined layer thickness & tool size model is constructed based on the machining tool deflection under cutting forces. This rapid pattern manufacturing process and related software has been implemented, and experimental data is presented to illustrate the efficacy of this system and its process planning methods

Design and Evaluation of High Power, High Efficiency and High Power Density Motor Drives for More Electric Aircrafts

More-electric aircraft (MEA) is an attractive concept as it can reduce carbon dioxide emission, relieve fossil-fuel consumption, improve the overall efficiency of aircraft, and reduce the operational costs. However, it poses substantial challenges in designing a high-performance motor drive system for such applications. In the report of Aircraft Technology Roadmap to 2050, the propulsion converter is required to be ultra-high efficiency, high power density, and high reliability. Though the wide band-gap devices, such as the Silicon-carbide based Metal Oxide Silicon Field Effect (SiC-MOSFET), shows better switching performance and improved high-temperature performance compared to the silicon counterparts, applying it to the MEA-related application is still challenging. The high switching speed of SiC-MOSFET reduces switching loss and enables the design of high-density converters. However, it poses intense challenges in limiting the stray inductance in the power stage. The fast switching behavior of SiC-MOSFET also challenges the design scalability by multi-chip parallel, which is essential in high-power-rating converters. Moreover, the partial discharge can happen at the lower voltage when the converter is operated at high altitude, low air-pressure conditions, which threatens the converter lifetime by the accelerated aging of the insulation system. This dissertation addresses these issues at the paper-design level, power-module level, and converter level, respectively. At the paper-design level, the proposed model-based design and optimization enables shoulder-by-shoulder performance comparison between different candidate topology and then generates optimal semiconductor design space for the selected topology. At the power-module level, this dissertation focuses on the development of an ultra-low inductance module by using a novel packaging structure that integrates the printed circuit board (PCB) with direct-bounding copper (DBC). The detailed power-loop optimization, thermal analysis, and fabrication guidance are discussed to demonstrate its performance and manufacturability. At the converter level, this dissertation provides a comprehensive design strategy to improve the performance of the laminated busbar. In the design of the busbar conduction layer, this work analyzed the impacts of each stray inductance item and then proposed a novel double-side decoupled conduction-layer structure with minimized stray inductance and improved dynamic current sharing. In the design of the insulation system of the busbar, this dissertation investigates the design strategy to ensure the busbar is free of partial discharge without sacrificing the parasitic control. Through the dissertation, a single-phase 150 kVA converter, a three-phase 450 kVA converter, and a 1.2 kV, 300 A power module are designed, fabricated, and tested to demonstrate the proposed design strategies

Master of Science

thesisThis work discusses several ways to grab and refill an intraocular drug device targeting age-related macular degeneration (AMD). The capsule drug ring (CDR) is an implantable device that stores and releases drug inside the lens capsule. Since an intraocular lens (IOL) is placed in the lens capsule during cataract surgery, a CDR can be put on the unused periphery between the IOL and the lens capsule. The objective of the refilling mechanism is to stabilize a free-floating CDR to allow penetration through the refilling ports. Two ports at each end of the CDR allow the reservoir to be refilled with bevacizumab (Avastin) every six months to one year. Some mechanisms are added on the CDR to achieve a refillable CDR. Several grabbing mechanisms are discussed and tested in this work. The 23-gauge refilling device includes a 30-gauge needle, used to penetrate the ports and inject Avastin into the CDR reservoir. Grasping, vacuum tubing, and lasso devices have been tested to stabilize and refill the CDR: These three concepts were compared and chosen to explore the possibilities of the superior lasso device. Therefore several lasso devices were tested and simplified for use. Finally, possible future modifications to the refilling devices are discussed

Tactile force-sensing for dynamic gripping using piezoelectric force- sensors

Thesis (M. Tech.) -- Central University of Technology, Free State, 200

Composite structural materials

The use of filamentary composite materials in the design and construction of primary aircraft structures is considered with emphasis on efforts to develop advanced technology in the areas of physical properties, structural concepts and analysis, manufacturing, and reliability and life prediction. The redesign of a main spar/rib region on the Boeing 727 elevator near its actuator attachment point is discussed. A composite fabrication and test facility is described as well as the use of minicomputers for computer aided design. Other topics covered include (1) advanced structural analysis methids for composites; (2) ultrasonic nondestructive testing of composite structures; (3) optimum combination of hardeners in the cure of epoxy; (4) fatigue in composite materials; (5) resin matrix characterization and properties; (6) postbuckling analysis of curved laminate composite panels; and (7) acoustic emission testing of composite tensile specimens

AN INFORMATION MODEL IN THE DOMAIN OF DISASSEMBLY PLANNING FOR SUSTAINABLE MANUFACTURING

Disassembly, a process of separating the End of Life (EOL) product into discrete components for re-utilizing their associated residual values, is an important part for the sustainable manufacturing. This work focuses on the modeling of the disassembly planning related information, and develops a Disassembly Information Model (DIM) based on an extensive investigation of various informational aspects of the disassembly planning. The developed Disassembly Information Model, which represents an appropriate systematization and classification of the products, processes, uncertainties and degradations related information, follows a layered modeling methodology. In this layered configuration, the DIM is subdivided into three distinct layers with an intent to separate general knowledge into different levels of abstractions, and to reach a balance between information reusability and information usability. The performance evaluation of the DIM (usability and reusability) is accessed by successful implementations of the DIM model into two prototype software applications in the domain of disassembly planning. The first application, called the Disassembly Sequence Generator (DSG), identifies the optimal disassembly sequence using a CAD based searching algorithm and a disassembly Linear Programming (LP) model. The searching process results in an AND/OR graph, which represents all the feasible disassembly sequences of a specific EOL product; whereas the LP model takes the AND/OR graph as an input and determines the economically optimal process sequence among all the possibilities. The second application is called the Adaptive Disassembly Planning (ADP), which further takes the EOL product uncertainty and degradation issues into consideration. In order to address these issues, fuzzy logic and Bayesian Network methodologies are used to develop a Disassembly Decision Network (DDN), which adaptively generates the optimal disassembly sequence based on the current available information. This research work is the first attempt to develop a comprehensive Information Model in the domain of disassembly planning. The associated modeling methodology that has been developed in this research is generic and scalable, and it could be widely adopted in other engineering domains, like product assembly, production planning, etc. The ultimate objective of this work is to standardize the DIM into a reference model that will be acknowledged and agreed upon by the sustainable manufacturing community

ne–xt facades: Proceedings of the COST Action TU1403 Adaptive Facades Network Mid-term Conference

The ne-xt facades conference is the official International Mid-term Conference of the European COST Action TU1403 ‘Adaptive Facades Network’, an international scientific cooperation with the aim to harmonise, share and disseminate technological knowledge on adaptive facades on the European level. During the mid-term conference first results are presented to stakeholders from industry and design and to the public. The goal is to share knowledge and discuss novel facade concepts, effective evaluation tools and design methods for adaptive facades. Alongside the contributions from members of the COST Action, the conference received many contributions from external researchers and the industry. This added to the interesting debate about adaptive facades we believe it was an excellent stage to test the first results of the COST Action