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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

SISTEMÁTICA DE ANÁLISE DE FALHAS DE EQUIPAMENTO AGRÍCOLA SOB A ÓTICA DE PROJETO DE PRODUTO / FAILURE ANALYSIS SYSTEMATICS OF AGRICULTURAL EQUIPMENT UNDER THE PERSPECTIVE OF PRODUCT DESIGN

Franceschi, Alessandro de 20 February 2015 (has links)
Swine industry in Brazil, due to its growth in recent years, has generated a great quantity of waste, especially in the liquid form, which can be used, by means of agricultural equipment employment, in soil treatment and correction. The majority of small and medium businesses in the Brazilian industrial field of agricultural machinery adopts the trial and error system, not making use of any procedure that systematically assist the process of product design, which can cause problems in the conception generation and/or failure in the operating machinery. The present thesis questions whether the realization of field tests is sufficient to reduce fault problems in the final conception of agricultural machines. Thus, we proposed as main objective a comparative study of failure analysis of a liquid swine waste distributing and incorporating equipment (DLS), realized under two different approaches, by means of prototypes I and II. The first one involves an analysis of equipment testing and experimenting reports (dynamic approach) concerning prototypes I, and II, realized during the usage phase. The second one involves the employment of a systematics of equipment failure analysis - prototype II under the perspective of product design, by applying the FMEA - Failure Modes and Effects Analysis (static approach). In both approaches, the ways results were obtained were specifically analyzed, suggesting improving actions according to certain failure modes. The dynamic approach has aimed the verification of operational activities of the equipment in field, in real work conditions, allowing the identification of faults and problems by means of observation. a partial analysis of equipment failure with a reduced number of considerations if compared to Case II, presenting results that contemplate non-conformities, difficulties, and problems in some subsystems and equipment components during the equipment utilization. The static approach, departing from the equipment functional and structural analysis, allowed evidence in the systems, subsystems, and components on the modes, causes and effects of possible faults, totaling 108 possible modes of failure, whose 11 were considered as potentials. The use of FMEA technique justifies the importance of incorporating a way for preventing faults during every phase and stage concerning the product designing. Therefore, this study verifies that both approaches allow the establishment of a interaction of results, recommendations and suggestions which permit eliminating or minimizing failure in the final conception of agricultural machinery. However, the FMEA technique application within a systematization of fault analysis since the beginning of the equipment design allows for the suggestion of improvement actions in the prototype before it is submitted to tests and experiments. / A suinocultura no Brasil, devido ao seu crescimento nos últimos anos, tem gerado uma grande quantidade de dejetos, especialmente sob a forma líquida que pode ser aproveitada, por meio do emprego de equipamentos agrícolas, no tratamento e correção do solo. A maioria das empresas de pequeno e médio porte do setor industrial brasileiro de máquinas agrícolas adota o sistema de tentativa e erro , não fazendo uso de algum procedimento que auxilie sistematicamente no processo de desenvolvimento do produto, o que pode causar problemas na geração de concepção e/ou de falhas nas máquinas em operação. Esta tese em seu trabalho de pesquisa questiona se as realizações de testes em campo são suficientes ou não para atenuar os problemas de falhas na concepção final das máquinas agrícolas. Assim, foi proposto como objetivo geral um estudo comparativo da análise de falhas de um equipamento distribuidor e incorporador de dejetos líquidos suínos (DLS) realizado sob duas abordagens distintas, a partir dos protótipos I e II. A primeira, abrange uma análise de relatórios de testes e experimentos do equipamento (abordagem dinâmica) referente aos protótipos I e II, realizados durante a fase de uso. A segunda, compreende o emprego de uma sistemática de análise de falhas do equipamento - protótipo II sob a ótica de projeto do produto, pela aplicação da técnica FMEA - Análise dos Modos de Falhas e seus Efeitos (abordagem estática). Em ambas as abordagens foi analisada, de maneira específica, a forma de obtenção dos resultados, sendo sugeridas ações de melhoria em determinados modos de falhas. A abordagem dinâmica objetivou a verificação de atividades operacionais do equipamento em campo, em condições reais de trabalho permitindo identificar falhas e problemas por meio de observação. Já a abordagem estática, partindo da análise funcional e estrutural do equipamento, permitiu evidenciar, no sistema, subsistemas e componentes os modos, causas e efeitos das possíveis falhas, totalizando 108 possíveis modos de falhas, sendo 11 considerados como potenciais. A utilização da técnica FMEA justifica a importância de incorporar um modo de prevenção de falhas que abrange todas as fases e etapas referente a concepção do produto. Assim, constata-se que ambas as abordagens possibilitam estabelecer uma interação de resultados, recomendações e sugestões que permitem eliminar ou atenuar falhas na concepção final de máquinas agrícolas. Contudo, a aplicação da técnica FMEA dentro de uma sistematização de análise de falhas a partir do início do projeto do equipamento possibilita que sejam sugeridas ações de melhorias ao protótipo, antes de ser submetido a testes e experimentos.
2

Load allocation for optimal risk management in systems with incipient failure modes

Bole, Brian McCaslyn 13 January 2014 (has links)
The development and implementation challenges associated with a proposed load allocation paradigm for fault risk assessment and system health management based on uncertain fault diagnostic and failure prognostic information are investigated. Health management actions are formulated in terms of a value associated with improving system reliability, and a cost associated with inducing deviations from a system's nominal performance. Three simulated case study systems are considered to highlight some of the fundamental challenges of formulating and solving an optimization on the space of available supervisory control actions in the described health management architecture. Repeated simulation studies on the three case-study systems are used to illustrate an empirical approach for tuning the conservatism of health management policies by way of adjusting risk assessment metrics in the proposed health management paradigm. The implementation and testing of a real-world prognostic system is presented to illustrate model development challenges not directly addressed in the analysis of the simulated case study systems. Real-time battery charge depletion prediction for a small unmanned aerial vehicle is considered in the real-world case study. An architecture for offline testing of prognostics and decision making algorithms is explained to facilitate empirical tuning of risk assessment metrics and health management policies, as was demonstrated for the three simulated case study systems.

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