动力装置隔振系统动态特性分析及实验研究

发布时间：2018-06-14 10:40

本文选题：柔性基础 + 传递率　；参考：《山东大学》2013年硕士论文

【摘要】：动力装置是车、船等交通运输工具的主要激振源,对其进行有效的振动隔离能够显著降低车船的振动水平。随着车船体结构轻薄化,动力装置安装基础的柔性特性越发明显,而动力装置的高速、大功率化使得隔振系统弹性耦合特性更加显著,导致隔振设计阶段的效果预测与工程实际误差偏大。本学位论文围绕动力装置与弹性基础的振动耦合特性,建立了动力装置弹性基础隔振系统动力学模型,以传递率与功率流为隔振效果评价指标,对比刚性基础结构模型,研究了隔振系统的耦合特性。针对工程中的动力装置隔振问题,首先建立了刚性基础隔振系统动力学模型,对其传递率进行了仿真计算,发现高频域的隔振效果与工程实际相差较大,即将基础作为刚性处理存在一定的缺陷。进一步将基础简化为集总参数与柔性梁模型,利用机械阻抗及四端参数法推导了系统传递特性表达式,以传递率为评价指标探讨了基础相关参数对隔振效果的影响,结果表明：基础的弹性使传递率曲线波峰数目增加,传递率有所增大；集总参数基础的等效质量与刚度及柔性梁基础的弹性模量与厚度足够大时,系统可作为刚性基础处理。建立了动力装置弹性基础隔振系统动力学模型,结合子结构导纳法推导了系统的功率流方程,以功率流为评价指标探讨了系统结构参数对隔振效果的影响。首先将弹性基础简化为集总参数模型,分析了基础弹性对系统传递功率流的影响：增大基础的质量与刚度使传递到基础的功率流减少；当基础质量与刚度足够大时弹性基础可作为刚性基础处理。进一步将弹性基础简化为柔性梁模型,探讨了不同结构参数下的功率流传递特性,结果表明：隔振器关于基础梁对称布置时,基础梁偶数阶模态没有被激发,高频域内波峰数减少；隔振器数目的增加、基础梁弹性模量的增大及阻尼因子的减小使传递到基础的功率流减少；低频域内柔性梁基础隔振系统的隔振问题可简化为集总参数基础处理。针对工程实际中动力装置往往受安装条件的限制,建立了动力装置斜置隔振系统力学模型,推导了系统传递特性矩阵及功率流传递函数,着重研究斜置隔振系统横向-横摇耦合振动特性,探讨了解耦条件下的隔振效果,分析了隔振器的驻波效应及动力装置二次谐波对传递功率流的影响。研究表明：合理配置支承结构参数可以实现横向、横摇振动解耦,显著降低系统的振动传递能量；隔振器共振形成驻波导致高频域功率流谱明显提高；动力装置二次谐波使输入基础的功率流有所增加。将动力装置安装基础简化为两端固支柔性梁,理论分析了其在Euler梁及Timoshenko梁理论下的振动特性并对其进行了弹性特性实验研究,与理论仿真结果对比分析,研究表明：Timoshenko梁理论下基础的各阶固有频率略低于Euler梁；测量振动信号时,传感器布置在被测系统的节点或节线处会导致模态丢失；加速度传感器质量的影响会使被测系统的固有频率有所降低；增加敲击点数可略微提高实验准确性,但使实验过程繁琐,工程中可根据实际情况选择适当的敲击点数。
[Abstract]:In this paper , the dynamic model of vibration isolation system of power plant is established based on the vibration coupling characteristics of power plant and elastic foundation , and the coupling characteristics of vibration isolation system are studied .

Aiming at the vibration isolation problem of power plant in engineering , the dynamic model of rigid foundation vibration isolation system is established firstly , and its transmission rate is simulated and calculated . It is found that the vibration isolation effect of high frequency domain is quite different from the actual engineering practice . The effect of the basic related parameters on the vibration isolation effect is discussed by means of mechanical impedance and four - end parameter method .
When the equivalent mass and stiffness of the lumped parameter foundation and the elastic modulus and thickness of the foundation of the flexible beam are large enough , the system can be treated as a rigid base .

The dynamic model of the elastic foundation vibration isolation system of the power plant is established , the power flow equation of the system is derived by combining the substructure admittance method , and the influence of the system structure parameters on the vibration isolation effect is discussed by using the power flow as the evaluation index . Firstly , the elastic foundation is simplified to the lumped parameter model , and the influence of the basic elasticity on the transmission power flow of the system is analyzed : the mass and rigidity of the foundation are increased so that the power flow to the foundation is reduced ;
The elastic foundation can be treated as a rigid foundation when the foundation quality and rigidity are large enough . The elastic foundation is simplified into a flexible beam model , and the power flow transmission characteristics under different structural parameters are discussed . The results show that the even - order modes of the foundation beam are not excited when the vibration isolator is symmetrically arranged about the foundation beam , and the number of peaks in the high - frequency domain is reduced ;
the increase of the number of vibration isolators , the increase of the elastic modulus of the foundation beam and the reduction of the damping factor cause the power flow to be transmitted to the foundation to be reduced ;
The vibration isolation problem of the flexible beam foundation vibration isolation system in the low frequency domain can be simplified as the lumped parameter base process .

In view of the limitation of the installation conditions of the power plant in engineering practice , the mechanical model of the oblique vibration isolation system of the power unit is established , the transfer characteristic matrix and the transfer function of the power flow are derived , the vibration isolation effect under the coupling condition is studied , the standing wave effect of the vibration isolator and the influence of the second harmonic of the power plant on the transmission power flow are discussed .
the resonance of the vibration isolator to form the standing wave causes the power flow spectrum of the high - frequency domain to be obviously improved ;
the second harmonic of the power plant increases the power flow of the input base .

By simplifying the installation foundation of the power plant into two fixed - branch flexible beams at both ends , the vibration characteristics of the two ends of the Euler beam are analyzed , and the experimental research on the elastic characteristics is carried out , and compared with the theoretical simulation results , the results show that the natural frequencies of the foundation under the theoretical foundation are slightly lower than the Euler beams .
when the vibration signal is measured , the sensor is arranged at the node or the node of the measured system to cause the mode to be lost ;
The influence of the mass of the acceleration sensor can decrease the natural frequency of the tested system ;
The accuracy of experiment can be improved slightly by increasing the number of tap points , but the experiment process is complicated , and the appropriate tap points can be selected according to the actual situation .
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TB535.1

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