Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine cranks...Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine crankshaft assembly,reveals obvious simulation errors.The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness.In this paper,a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method.The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments.The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method.The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method.The simulation results are compared with a lumped mass model and a detailed model using the system matrix method.Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration,and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor.The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia.This research project is aimed at improving nonlinear dynamics theory,and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.展开更多
The failure modes and effects analysis （FMEA） is widely applied in manufacturing industries in various phases of the product life cycle to evaluate the system, its design and processes for failures that can occur. T...The failure modes and effects analysis （FMEA） is widely applied in manufacturing industries in various phases of the product life cycle to evaluate the system, its design and processes for failures that can occur. The FMEA team often demonstrates different opinions and these different types of opinions are very difficult to incorporate into the FMEA by the traditional risk priority number model. In this paper, for each of the Occurrence, Severity and Detectivity parameters a fuzzy set is defined and the opinion of each FMEA team members is considered. These opinions are considered simultaneously with weights that are given to each individual based on their skills and experience levels. In addition, the opinion of the costumer is considered for each of the FMEA parameters. Then, the Risk Priority Numbers （RPN） is calculated using a Multi Input Single Output （MISO） fuzzy expert system. The proposed model is applied for prioritizing the failures of Peugeot 206 Engine assembly line in IKCo （Iran Khodro Company）.展开更多
"Environmental protection concept" is the latest project construction concept put forward by Chinas construction industry in the market development. Reasonable, standardized and scientific use of green techn..."Environmental protection concept" is the latest project construction concept put forward by Chinas construction industry in the market development. Reasonable, standardized and scientific use of green technology in prefabricated building construction can not only bring into play the higher economic benefits of the building in the market, but also create a better social image for builders and construction units in the market. In order to implement this work, solve the extensive production problems existing in the early development of the construction industry in the market and reduce the problems of high energy consumption and heavy pollution caused by unreasonable construction technology.展开更多
Prefabricated steel structure has a high utilization rate in todays social development. This is because the building system conforms to the concept of green environmental protection, which can control the building pol...Prefabricated steel structure has a high utilization rate in todays social development. This is because the building system conforms to the concept of green environmental protection, which can control the building pollution and ensure that the building quality is not affected. Prefabricated steel structure is a common structure in building structures, which can effectively control the design points and improve the construction quality. This paper makes an all-round analysis of the technical application problems in the construction of high-rise buildings, so as to improve the application effect of science and technology in the development of the construction industry, and provide theoretical support for the steel structure construction technology of prefabricated buildings.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50975026)Ministerial Eleventh Five-Year Plan Basic Product Pre-research Project of China (Grant No. D2220062905)
文摘Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine crankshaft assembly,reveals obvious simulation errors.The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness.In this paper,a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method.The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments.The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method.The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method.The simulation results are compared with a lumped mass model and a detailed model using the system matrix method.Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration,and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor.The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia.This research project is aimed at improving nonlinear dynamics theory,and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.
文摘The failure modes and effects analysis （FMEA） is widely applied in manufacturing industries in various phases of the product life cycle to evaluate the system, its design and processes for failures that can occur. The FMEA team often demonstrates different opinions and these different types of opinions are very difficult to incorporate into the FMEA by the traditional risk priority number model. In this paper, for each of the Occurrence, Severity and Detectivity parameters a fuzzy set is defined and the opinion of each FMEA team members is considered. These opinions are considered simultaneously with weights that are given to each individual based on their skills and experience levels. In addition, the opinion of the costumer is considered for each of the FMEA parameters. Then, the Risk Priority Numbers （RPN） is calculated using a Multi Input Single Output （MISO） fuzzy expert system. The proposed model is applied for prioritizing the failures of Peugeot 206 Engine assembly line in IKCo （Iran Khodro Company）.
文摘"Environmental protection concept" is the latest project construction concept put forward by Chinas construction industry in the market development. Reasonable, standardized and scientific use of green technology in prefabricated building construction can not only bring into play the higher economic benefits of the building in the market, but also create a better social image for builders and construction units in the market. In order to implement this work, solve the extensive production problems existing in the early development of the construction industry in the market and reduce the problems of high energy consumption and heavy pollution caused by unreasonable construction technology.
文摘Prefabricated steel structure has a high utilization rate in todays social development. This is because the building system conforms to the concept of green environmental protection, which can control the building pollution and ensure that the building quality is not affected. Prefabricated steel structure is a common structure in building structures, which can effectively control the design points and improve the construction quality. This paper makes an all-round analysis of the technical application problems in the construction of high-rise buildings, so as to improve the application effect of science and technology in the development of the construction industry, and provide theoretical support for the steel structure construction technology of prefabricated buildings.
