Effect of different noise reduction measures for diesel engines was evaluated based on hierarchy diagnosis. The hierarchy diagnosis chart and hierarchy judgment matrix were given. Through evaluation of noise reduction...Effect of different noise reduction measures for diesel engines was evaluated based on hierarchy diagnosis. The hierarchy diagnosis chart and hierarchy judgment matrix were given. Through evaluation of noise reduction measures, the main strategies of noise reduction were found. The result shows that the noise reduction level of different frequency belts varies from measure to measure. The reduction capacity of different measures could not add simply, which relates to the problem of parameter matching.展开更多
Based on the principle of impedance mismatching,the performance of rigid vibration isolation mass in impeding vibration wave propagation was discussed from the perspective of wave approach.Based on FEM,the influence o...Based on the principle of impedance mismatching,the performance of rigid vibration isolation mass in impeding vibration wave propagation was discussed from the perspective of wave approach.Based on FEM,the influence of its weight as well as the cross-section shape parameters on the isolation performance of rigid vibration isolation mass was studied through numerical simulation.The results show that rigid vibration isolation mass can effectively impede the propagation of the medium and high frequency vibration waves,and the heavier the vibration isolation mass,the better the isolation performance.For low frequency waves,the vibration isolation effect is not so obvious;for a rectangular vibration isolation mass,the isolation performance could be effectively improved by increasing the cross-section height and reducing the cross-section width.A useful reference was provided for the application of rigid vibration isolation masses to the vibration isolation and noise reduction of ship structure.展开更多
In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic opt...In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.展开更多
The multi-body dynamics model of the X6170ZC diesel is established to analyze vibration and acoustic noise. The high quality finite element and simulation models are developed, and nonlinear springs are used to imitat...The multi-body dynamics model of the X6170ZC diesel is established to analyze vibration and acoustic noise. The high quality finite element and simulation models are developed, and nonlinear springs are used to imitate the joints of engine components. The acoustic behavior of the structure is evaluated by the velocity of surface vibration. The noise level is reduced by improving the structure of the engine. The result shows that the surface vibration velocity level is decreased about 3.7 dB (A) at 1 600 Hz after the optimization. Based on the contrast between the two structures, it is concluded that through structure design the combined noise can be reduced, and the virtual design mode of diesel engines is feasible.展开更多
声学黑洞(Acoustic Black Hole,ABH)对弯曲波的聚集效应具有宽频、高效、实现方法简单灵活等特点,在结构减振降噪领域具有广泛的应用前景。以一维声学黑洞梁为对象,结合声学黑洞半解析建模计算方法和响应面优化方法,分析声学黑洞特征长...声学黑洞(Acoustic Black Hole,ABH)对弯曲波的聚集效应具有宽频、高效、实现方法简单灵活等特点,在结构减振降噪领域具有广泛的应用前景。以一维声学黑洞梁为对象,结合声学黑洞半解析建模计算方法和响应面优化方法,分析声学黑洞特征长度、截断厚度、幂律以及阻尼层特征长度和厚度这5个参数对一维声学黑洞梁减振效果的影响规律。以一维声学黑洞梁的减振效果为优化目标,对梁和阻尼的结构参数进行优化设计,优化后的一维声学黑洞梁结构在10~8000Hz频率范围内的平均加速度级降低19.03dB。研究对一维声学黑洞梁结构在减振领域的工程应用具有参考价值。展开更多
为实现对缸套-活塞环摩擦润滑状态的监测,基于声发射技术对某小型四缸柴油机缸套−活塞环的润滑状态进行研究。采用小波阈值降噪法抑制阀门启闭和燃烧所引起的声发射信号,分别提取每个冲程声发射信号均方根(root mean square,RMS),选择RM...为实现对缸套-活塞环摩擦润滑状态的监测,基于声发射技术对某小型四缸柴油机缸套−活塞环的润滑状态进行研究。采用小波阈值降噪法抑制阀门启闭和燃烧所引起的声发射信号,分别提取每个冲程声发射信号均方根(root mean square,RMS),选择RMS值作为评价缸内润滑状态的指标。研究结果表明:进排气冲程RMS值可以很好地表征缸内的润滑状态;受试验条件的限制,贫油状态的RMS值整体上略低于正常状态的RMS值,但差异性并不明显。展开更多
基金Supported by China Postdoctoral Science Foundation (No.20060400193)Yunnan Foundation for Science and Technology Cooperation between Government and University(No.2003HBBAA02A049) .
文摘Effect of different noise reduction measures for diesel engines was evaluated based on hierarchy diagnosis. The hierarchy diagnosis chart and hierarchy judgment matrix were given. Through evaluation of noise reduction measures, the main strategies of noise reduction were found. The result shows that the noise reduction level of different frequency belts varies from measure to measure. The reduction capacity of different measures could not add simply, which relates to the problem of parameter matching.
基金Supported by the Shipbuilding Industry of National Defense Science and Technology Research Projects in Advance under Grant No.153010110031
文摘Based on the principle of impedance mismatching,the performance of rigid vibration isolation mass in impeding vibration wave propagation was discussed from the perspective of wave approach.Based on FEM,the influence of its weight as well as the cross-section shape parameters on the isolation performance of rigid vibration isolation mass was studied through numerical simulation.The results show that rigid vibration isolation mass can effectively impede the propagation of the medium and high frequency vibration waves,and the heavier the vibration isolation mass,the better the isolation performance.For low frequency waves,the vibration isolation effect is not so obvious;for a rectangular vibration isolation mass,the isolation performance could be effectively improved by increasing the cross-section height and reducing the cross-section width.A useful reference was provided for the application of rigid vibration isolation masses to the vibration isolation and noise reduction of ship structure.
基金Supported by the Shipbuilding Industry of National Defense Science and Technology Research Projects in Advance (153010110031)
文摘In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.
文摘The multi-body dynamics model of the X6170ZC diesel is established to analyze vibration and acoustic noise. The high quality finite element and simulation models are developed, and nonlinear springs are used to imitate the joints of engine components. The acoustic behavior of the structure is evaluated by the velocity of surface vibration. The noise level is reduced by improving the structure of the engine. The result shows that the surface vibration velocity level is decreased about 3.7 dB (A) at 1 600 Hz after the optimization. Based on the contrast between the two structures, it is concluded that through structure design the combined noise can be reduced, and the virtual design mode of diesel engines is feasible.
文摘声学黑洞(Acoustic Black Hole,ABH)对弯曲波的聚集效应具有宽频、高效、实现方法简单灵活等特点,在结构减振降噪领域具有广泛的应用前景。以一维声学黑洞梁为对象,结合声学黑洞半解析建模计算方法和响应面优化方法,分析声学黑洞特征长度、截断厚度、幂律以及阻尼层特征长度和厚度这5个参数对一维声学黑洞梁减振效果的影响规律。以一维声学黑洞梁的减振效果为优化目标,对梁和阻尼的结构参数进行优化设计,优化后的一维声学黑洞梁结构在10~8000Hz频率范围内的平均加速度级降低19.03dB。研究对一维声学黑洞梁结构在减振领域的工程应用具有参考价值。
文摘为实现对缸套-活塞环摩擦润滑状态的监测,基于声发射技术对某小型四缸柴油机缸套−活塞环的润滑状态进行研究。采用小波阈值降噪法抑制阀门启闭和燃烧所引起的声发射信号,分别提取每个冲程声发射信号均方根(root mean square,RMS),选择RMS值作为评价缸内润滑状态的指标。研究结果表明:进排气冲程RMS值可以很好地表征缸内的润滑状态;受试验条件的限制,贫油状态的RMS值整体上略低于正常状态的RMS值,但差异性并不明显。
