Accurate Bolt Tightening using Model-Free Fuzzy Control for Wind Turbine Hub Bearing Assembly

"In the modern wind turbine industry, one of the core processes is the assembly of the bolt-nut connections of the hub, which requires tightening bolts and nuts to obtain well-distributed clamping force all over the hub. This force deals with nonlinear uncertainties due to the mechanical properties and it depends on the final torque and relative angular position of the bolt/nut connection. This paper handles the control problem of automated bolt tightening processes. To develop a controller, the process is divided into four stages, according to the mechanical characteristics of the bolt/nut connection: a Fuzzy Logic Controller (FLC) with expert knowledge of tightening process and error detection capability is proposed. For each one of the four stages, an individual FLC is designed to address the highly non-linearity of the system and the error scenarios related to that stage, to promptly prevent and avoid mechanical damage. The FLC is implemented and real time executed on an industrial PC and finally validated. Experimental results show the performance of the controller to reach precise torque and angle levels as well as desired clamping force. The capability of error detection is also validated.

A K-nearest clamping force classifier for bolt tightening of wind turbine hubs

A fuzzy-logic controller supporting the manufacturing of wind turbines and the bolt tightening of their hubs has been designed. The controller embeds assembly error recognition capability and detects tightening faults like misalignment, different threads, cross threads and wrong or small nuts. According to this capability, K-nearest classifiers have been implemented to cluster the output controllers into the diverse fault scenarios. Classifiers make use of the time of execution of the tightening process, the final angular position of and applied torque of the tightening tool, the resultant clamping force and possible combinations of those parameters. Two classes and five classes configurations are considered: classifiers are initially asked to discriminate between fault and no fault scenarios (e.g. two classes); then, five classes are considered according to five different fault situations (i.e. regular tightening, bolt misalignment, dissimilar threads of bolt and nut, missing nut and small bolt). Classifiers performances are estimated in terms of resubstitution and cross-validation loss. Confusion matrixes of actual and predicted classification are also evaluated for each classifier. The low computational cost of the proposed classifiers suggests directly implementing these algorithms on micro-controller and physical computing, which may be straight integrated within the tightening tool

Precision Machining

The work included in this book focuses on precision machining and grinding processes, including milling, laser machining and polishing on various materials for high-end applications. These processes are in the forefront of contemporary technology, with significant industrial applications. Their importance is also made clear by the important works that are included in the research that is presented in the book. Some important aspects of these processes are investigated, and process parameters are optimized. This is performed in the presented works with significant experimental and modelling work, incorporating modern tools of analysis and measurements

Análise e seleção de polímeros para substituição de suporte e tampa de aerogeradores

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico, de Ciências Exatas e Educação. Engenharia de MateriaisO presente trabalho visa estudar a viabilidade de substituição da matéria-prima de componente metálico presente em aerogeradores por material polimérico. O componente metálico em estudo é um conjunto composto por um suporte e uma tampa localizados no eixo do aerogerador. Este conjunto é utilizado como acesso para manutenção da graxa presente nos rolamentos. A aplicação do componente está submetida à temperatura máxima de 50ºC que o aerogerador pode atingir e ao contato com a graxa. A tampa e o suporte atualmente são feitos de aço carbono e são pintados. O objetivo deste trabalho é analisar a viabilidade de utilização de um material polimérico que atenda às condições de aplicação do conjunto suporte/tampa. Além disso, outra finalidade da substituição de matéria prima é reduzir o custo do componente e aumentar a lucratividade dos aerogeradores. Os polímeros selecionados para ensaio são o poli(acrilonitrilacobutadieno-co-estireno) (ABS), Polipropileno (PP) e Poliamida 6.6. Os materiais foram submetidos ao envelhecimento acelerado com e sem graxa para análise comparativa. E então, foram avaliados através de Espectroscopia no Infravermelho por Transformada de Fourier (FTIR) e ensaios de tração. Por fim, foi possível avaliar e determinar a viabilidade da substituição da matéria prima do componente. E, através das análises concluiu-se que o ABS foi a opção mais indicada visto que este não apresentou alteração em seu comportamento mecânico e estrutural através da comparação de resultados práticos e teóricos, e proporcionaria um saving de 94,6% anual à empresa em relação com o gasto do componente metálico atual.The present work aims to study the possibility of replacing the raw material of metallic component present in wind turbines by polymeric material. The metallic component under study is a set composed of a support and a cover located on the shaft of the wind turbine. This set is used as access for maintenance of the grease present in the bearings. The application of the component is subject to the maximum temperature of 50ºC that the wind turbine can reach and to contact with the grease. The cover and support are currently made of carbon steel and they are painted. The objective of this work is to analyze the possibility of using a polymeric material that meets the application conditions of the support/cover set. In addition, another purpose of raw material replacement is to reduce component cost and increase the profitability of wind turbines. The polymers selected for testing are poly(acrylonitrile-cobutadiene-costyrene) (ABS), Polypropylene (PP) and the Polyamide 6.6 (PA6.6). The materials were subjected to accelerated aging with and without grease for comparative analysis. Then, they were evaluated by Fourier Transform Infrared Spectroscopy (FTIR) and tensile tests. Finally, it was possible to evaluate and determine the possibility of replacing the raw material of the component. And, through the analysis, it was concluded that ABS was the most suitable option since It did not present any change in its mechanical and structural behavior through the comparison of practical and theoretical results, and It would also provide an annual saving of 94.6% to the company compared to the current metal component cost

NASA Tech Briefs, July 1995

Topics include: mechanical components, electronic components and circuits, electronic systems, physical sciences, materials, computer programs, mechanics, machinery, manufacturing/fabrication, mathematics and information sciences, book and reports, and a special section of Federal laboratory computing Tech Briefs

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

NASA Tech Briefs, June 1994

Topics covered include: Microelectronics; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Report

NASA Tech Briefs, October 2000

Topics include: special coverage sections on CAD, CAE, and PDM, and, Composites and Plastics, and sections on electronic components and systems, software, test and measurement, mechanics, manufacturing/fabrication, physical sciences, information sciences, book and reports, and special sections of Electronics Tech Briefs and Motion Control Tech Brief

NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 45)

A subject index is provided for over 5600 patents and patent applications for the period May 1969 through June 1994. Additional indexes list personal authors, corporate authors, contract numbers, NASA case numbers, U.S. patent class numbers, U.S. patent numbers, and NASA accession numbers