分析人耳对不同频率纯音的衰减特性,提出结合人耳的衰减特性和柴油机辐射噪声的频谱特性进行响度优化的方法。运用多体动力学法和边界元法对柴油机进行声学分析,采用Moore响度模型对柴油机的辐射噪声的响度进行仿真分析。分析认为柴油机...分析人耳对不同频率纯音的衰减特性,提出结合人耳的衰减特性和柴油机辐射噪声的频谱特性进行响度优化的方法。运用多体动力学法和边界元法对柴油机进行声学分析,采用Moore响度模型对柴油机的辐射噪声的响度进行仿真分析。分析认为柴油机1 300-2 000 Hz的辐射噪声对柴油机响度贡献最大,通过声强法噪声源识别试验得出柴油机辐射噪声在该频段的主要贡献部件是油底壳、齿轮室罩、缸盖罩以及机体。对柴油机的齿轮室罩、缸盖罩以及机体进行结构改进,改进后柴油机的声功率级由76.4 d B下降至75.5 d B,降低0.9 d B;柴油机辐射噪声响度由161.5 sone下降到144.7 sone,降低10.4%,柴油机的NVH性能明显改善。展开更多
A general procedure to capture the 'dynanmic Stiffness' is presented in this paper. The governing equations of motion are formulated for an arbitrary flexible body in large overall motion based on Kane's ...A general procedure to capture the 'dynanmic Stiffness' is presented in this paper. The governing equations of motion are formulated for an arbitrary flexible body in large overall motion based on Kane's equations . The linearization is performed peroperly by means of geometrically nonlinear straindisplacement relations and the nonlinear expression of angular velocity so that the 'dynamical stiffness' terms can be captured naturally in a general tcase. The concept and formulations of partial velocity and angular velocity arrays of Huston's method are extended to the flexible body and form the basis of the analysis. The validity and generality of the procedure presented in the paper are verified by numerical results of its application in both the beam and plate models.展开更多
A forward recursive formulation based on corotational frame is proposed for flexible planar beams with large displacement.The traditional recursive formulation has been successfully used for flexible mutibody dynamics...A forward recursive formulation based on corotational frame is proposed for flexible planar beams with large displacement.The traditional recursive formulation has been successfully used for flexible mutibody dynamics to improve the computational efficiency based on floating frame,in which the assumption of small strain and deflection is adopted.The proposed recursive formulation could be used for large displacement problems based on the corotational frame.It means that the recursive scheme is used not only for adjacent bodies but also for adjacent beam elements.The nodal relative rotation coordinates of the planar beam are used to obtain equations with minimal generalized coordinates in present formulation.The proposed formulation is different from absolute nodal coordinate formulation and the geometrically exact beam formulation in which the absolute coordinates are used.The recursive scheme and minimal set of dynamic equations lead to a high computational efficiency in numerical integration.Numerical examples are carried out to demonstrate the accuracy and validity of this formulation.For all of the examples,the results of the present formulation are in good agreement with results obtained using commercial software and the published results.Moreover,it is shown that the present formulation is more efficient than the formulation in ANSYS based on GEBF.展开更多
文摘分析人耳对不同频率纯音的衰减特性,提出结合人耳的衰减特性和柴油机辐射噪声的频谱特性进行响度优化的方法。运用多体动力学法和边界元法对柴油机进行声学分析,采用Moore响度模型对柴油机的辐射噪声的响度进行仿真分析。分析认为柴油机1 300-2 000 Hz的辐射噪声对柴油机响度贡献最大,通过声强法噪声源识别试验得出柴油机辐射噪声在该频段的主要贡献部件是油底壳、齿轮室罩、缸盖罩以及机体。对柴油机的齿轮室罩、缸盖罩以及机体进行结构改进,改进后柴油机的声功率级由76.4 d B下降至75.5 d B,降低0.9 d B;柴油机辐射噪声响度由161.5 sone下降到144.7 sone,降低10.4%,柴油机的NVH性能明显改善。
文摘A general procedure to capture the 'dynanmic Stiffness' is presented in this paper. The governing equations of motion are formulated for an arbitrary flexible body in large overall motion based on Kane's equations . The linearization is performed peroperly by means of geometrically nonlinear straindisplacement relations and the nonlinear expression of angular velocity so that the 'dynamical stiffness' terms can be captured naturally in a general tcase. The concept and formulations of partial velocity and angular velocity arrays of Huston's method are extended to the flexible body and form the basis of the analysis. The validity and generality of the procedure presented in the paper are verified by numerical results of its application in both the beam and plate models.
基金Projects(11772188,11132007,11202126)supported by the National Natural Science Foundation of ChinaProject(11ZR1417000)supported by the Natural Science Foundation of Shanghai,China
文摘A forward recursive formulation based on corotational frame is proposed for flexible planar beams with large displacement.The traditional recursive formulation has been successfully used for flexible mutibody dynamics to improve the computational efficiency based on floating frame,in which the assumption of small strain and deflection is adopted.The proposed recursive formulation could be used for large displacement problems based on the corotational frame.It means that the recursive scheme is used not only for adjacent bodies but also for adjacent beam elements.The nodal relative rotation coordinates of the planar beam are used to obtain equations with minimal generalized coordinates in present formulation.The proposed formulation is different from absolute nodal coordinate formulation and the geometrically exact beam formulation in which the absolute coordinates are used.The recursive scheme and minimal set of dynamic equations lead to a high computational efficiency in numerical integration.Numerical examples are carried out to demonstrate the accuracy and validity of this formulation.For all of the examples,the results of the present formulation are in good agreement with results obtained using commercial software and the published results.Moreover,it is shown that the present formulation is more efficient than the formulation in ANSYS based on GEBF.
