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Authors
Abstract(s)
Na engenharia mecânica há cada vez mais necessidade de utilizar e de prever o
comportamento das máquinas térmicas, mais propriamente dos motores de combustão
interna, em especial na área da manutenção e da prevenção de falha num dos
componentes vitais de um motor a 4 tempos: o veio de manivelas. Esta situação já tem
sido bastante observada na indústria mecânica naval, nomeadamente na Marinha
Portuguesa e, devido ao seu elevado grau de importância no desempenho de qualquer
motor, decidiu-se focar o trabalho desta tese no estudo dos motores a diesel S.E.M.T
Pielstick das unidades navais da Marinha Portuguesa, mais especificamente das corvetas
da classe “João Coutinho” e da classe “ Baptista de Andrade”, devido ao historial de
ocorrência de falhas no veio de manivelas nesta classe de navios e em outras da
Marinha Portuguesa.
Para efetuar este estudo, utilizaram-se todos os dados relativos ao historial de
ocorrências de falhas destes motores, bem como todos os dados disponíveis do
fabricante destes motores, por forma a reproduzir da forma mais fiável possível um
modelo tridimensional do veio de manivelas no programa de modelação informática
CAD Solidworks®, e possibilitar a análise cinemática do veio de manivelas. Desta
forma, foi possível simular as condições de funcionamento do motor, assim como
analisar e determinar a causa de falha do veio de manivelas, visando prolongar a vida
útil dos veios de manivelas, contribuindo não só para menores custos de manutenção
mas também para o aumento da operacionalidade destes navios.
In mechanical engineering there is an increasingly growing need to know and predict the behaviour of thermal machines more specifically of internal combustion engines. One of these behaviours concerns about the maintenance area and is the prevention of failure in a crankshaft, one of the vital components of a 4-stroke engine. This is a situation widely observed in the marine engineering industry, particularly in the Portuguese Navy and due to it´s high degree of importance in the performance of any engine, including naval engines such as the engines of Navy ships, it was decided to focus this work in the Portuguese Navy ships. In this particular case, the aim is to study the S.E.M.T Pielstick diesel engines from the Portuguese Navy ships class “João Coutinho” and “Baptista de Andrade”, due to the crankshaft failure history in this class and other classes of Portuguese Navy ships. To perform this study, we used all the data that was related to the engines’ failure history, as well as all the available data from the engine manufacturer in order to model as accurately as possible 3D model the crankshaft in the modelling and simulation computer program CAD SOLIDWORKS® in order to analyse the crankshaft through the finite elements method. Therefore it was possible to simulate the most representative engine operation conditions obtaining in the most detailed way the operating data and internal behaviour of these engines to thereby analyse and determine the cause of failure of the crankshaft. The performed numerical simulations consisted of cinematic analysis of the crankshaft in order to characterize the quality of the manufacture and determine the failure causes, in order to promote possible changes in the crankshaft geometry to minimize the stress concentration and therefore extend the longevity of these crankshafts, contributing not only to reduce the maintenance costs of this crankshafts but also to increase the operability of the Portuguese Navy ships using them.
In mechanical engineering there is an increasingly growing need to know and predict the behaviour of thermal machines more specifically of internal combustion engines. One of these behaviours concerns about the maintenance area and is the prevention of failure in a crankshaft, one of the vital components of a 4-stroke engine. This is a situation widely observed in the marine engineering industry, particularly in the Portuguese Navy and due to it´s high degree of importance in the performance of any engine, including naval engines such as the engines of Navy ships, it was decided to focus this work in the Portuguese Navy ships. In this particular case, the aim is to study the S.E.M.T Pielstick diesel engines from the Portuguese Navy ships class “João Coutinho” and “Baptista de Andrade”, due to the crankshaft failure history in this class and other classes of Portuguese Navy ships. To perform this study, we used all the data that was related to the engines’ failure history, as well as all the available data from the engine manufacturer in order to model as accurately as possible 3D model the crankshaft in the modelling and simulation computer program CAD SOLIDWORKS® in order to analyse the crankshaft through the finite elements method. Therefore it was possible to simulate the most representative engine operation conditions obtaining in the most detailed way the operating data and internal behaviour of these engines to thereby analyse and determine the cause of failure of the crankshaft. The performed numerical simulations consisted of cinematic analysis of the crankshaft in order to characterize the quality of the manufacture and determine the failure causes, in order to promote possible changes in the crankshaft geometry to minimize the stress concentration and therefore extend the longevity of these crankshafts, contributing not only to reduce the maintenance costs of this crankshafts but also to increase the operability of the Portuguese Navy ships using them.
Description
Keywords
Veio de Manivelas, Análise Cinemática, Concentração de tensões, Método dos elementos finitos. Crankshaft, Cinematic Analysis, Stress Concentration, Finite Element Method.