机械振动噪声学一课件.ppt

1、pagepage 1授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering机机 械械 振振 动动 噪噪 声声 学学pagepage 2授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering教科书（教科书（Textbook）:赵玫等，机械振动与噪声学，科学出版社，2004参考书（参考书（Referen

2、ce Books）:1.W.T.Thomson and M.D.Dahleh,Theory of Vibrations with Applications (5th ed.),Prentice Hall,1997pagepage 3授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering2.R.F.Barron,Industrial Noise Control and Acoustics,Marcel Dekker,20033.郑兆昌主编，机械振动

3、（上册），机械工业出版社，1980 4.商大中，动力分析基础，哈尔滨工程大学出版社，1999 5.季文美，机械振动，科学出版社，1985pagepage 4授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.1 Summary of Mechanical Vibration1.1.1 Summary of Mechani

4、cal VibrationVibrating Phenomena in the WorldVibration are found in many b r a n c h e s o f s c i e n c e a n d engineering pagepage 5授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.

5、1 Summary of Mechanical Vibration1.1.1 Summary of Mechanical VibrationUndesirable vibrations：Vehicle;Noise;Machines&Structures;Earthquake;Power units in every kinds of vessels may cause vibrationspagepage 6授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Eng

6、ineeringUseful vibrations：String vibration;harmonic oscillator,resonator;Vibrating road roller;Vibrating feeder;Vibrating forming machine.1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.1 1.1.1 Summary of Mechanical Vibrationpagepage 7授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Powe

7、r and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.2 Basic Concept1.1.2 Basic ConceptMechanical Vibration?Research aim?Vibration is a phenomena that a body or structure oscillates about some specified reference point.Vibration is common

8、ly expressed in terms of frequency,amplitude and Phase angle.1.Elimination or suppression of undesirable vibrations 2.Generation of the necessary forms and quantities of useful vibrationspagepage 8授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1

9、.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.3 Model of Vibration System1.1.3 Model of Vibration System （集中参数系统）（集中参数系统）（分布参数系统）（分布参数系统）pagepage 9授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Contro

10、l Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechanical VibrationsThe least number of mutually independent parameters(coordinates)required to uniquely define a material systems position in space,time,etc 多自由度系统振动多自由度系统振动(multiple degree of freedom)振动振动 p

11、agepage 10授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringChapter 1 Introductionz 多自由度系统振动多自由度系统振动(multiple degree of freedom)ABABpagepage 11授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringCha

12、pter 1 Introduction模型与自由度模型与自由度(Model and degree of freedom)pagepage 12授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of M

13、echanical Vibrations(no force)强迫振动强迫振动(forced vibration)(external force)the periodic motion occurring when an elastic system is displaced from its equilibrium position;the vibration resulting from the application of an external force；pagepage 13授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and

14、 Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechanical Vibrations;周期振动周期振动(periodic vibration)振动振动 振动振动 Harmonic vibration Oscillations in which motion is periodic with ti

15、me in the form of a sine curve.Periodic vibration An oscillatory motion whose amplitude pattern repeats after fixed increments of time.Transient vibration Temporarily sustained vibration of a mechanical system.It may consist of forced vibration.Random vibration A vibration whose instantaneous amplit

16、ude is not specified at any instant of time.pagepage 14授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechanical Vibrat

17、ionsDifferential Equation 非线性振动非线性振动(nonlinear vibration)Linear Vibration Linear differential equation;(superposition)Nonlinear vibration Nonlinear differential equation Bifurcation&Chaospagepage 15授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering

18、Vibration SystemExcitationResponseVibration analysis or Response analysisVibration SystemExcitationResponseVibration environment predictionVibration SystemExcitationResponseVibration design or System identification1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.5 Problems of Mechanica

19、l Vibration and 1.1.5 Problems of Mechanical Vibration and Solving Methods Solving Methodspagepage 16授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.1 Mechanical Vibration and Control Chapter 1 IntroductionvTheoretical analysis1.1.5 Problems of

20、 Mechanical Vibration and 1.1.5 Problems of Mechanical Vibration and Solving Methods Solving MethodsR e a l systemMechanics principleD.E.Numerical solutionAnalytical solutionC o m p u t e r simulationMathematical toolsV i b r a t i o n characteristicspagepage 17授课人柳贡民11/26/2022动力与能源工程学院College ofCol

21、lege of Power and Energy EngineeringPower and Energy EngineeringvExperimentVibration monitoring,testing,and experimentation are important as well in the design,implementation,maintenance,and repair of engineering systems.Chapter 1 IntroductionAll these are important topics of study in the field of v

22、ibration engineering,1.1.5 Problems of Mechanical Vibration and 1.1.5 Problems of Mechanical Vibration and Solving Methods Solving Methods1.1 Mechanical Vibration and Control pagepage 18授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering控制方法：新的保护罩用打

23、孔金属薄板和金属丝网制成。1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.6 Mechanical Vibration Control Methods1.1.6 Mechanical Vibration Control Methods 压榨机的飞轮和传动带的保护罩是主要的噪声源。保护罩用实体金属薄片制成。pagepage 19授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engine

24、ering1.1 Mechanical Vibration and Control Chapter 1 Introduction1.1.6 Mechanical Vibration Control Methods1.1.6 Mechanical Vibration Control Methods避免共振；减振与隔振。避免共振；减振与隔振。pagepage 20授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.2 Mechanical No

25、ise and Control Chapter 1 Introduction1.2.1 Sound and Noise1.2.1 Sound and NoiseSound Waveis any disturbance that is propagated in an elastic mediumSound Sourceis an object that caused vibration of medium particlesSound Fieldis a space where the sound wave existspagepage 21授课人柳贡民11/26/2022动力与能源工程学院C

26、ollege ofCollege of Power and Energy EngineeringPower and Energy Engineering1.2 Mechanical Noise and Control Chapter 1 Introduction1.2.1 Sound and Noise1.2.1 Sound and NoiseNoiseis any unwanted sound perceived by the hearing sense of a humanis a mixture of sound waves with different frequencies and

27、strengthspagepage 22授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.2 Mechanical Noise and Control Chapter 1 Introduction1.2.2 Noise Effects1.2.2 Noise EffectsHearing and HealthExcessive noise can impair hearing,may also put stress on the heart

28、,the circulatory system,and other parts of the bodyTechnical StandardsFor example,the pass-by noise national standards for cars,84 dB(A)(1979),78 dB(A)(1985),74 dB(A)(2006).Military Vehicles RequireHigh stealth capabilitiesQuiet working and living environmentpagepage 23授课人柳贡民11/26/2022动力与能源工程学院Colle

29、ge ofCollege of Power and Energy EngineeringPower and Energy Engineering1.2 Mechanical Noise and Control Chapter 1 Introduction1.2.3 Clarifications of Mechanical Noise1.2.3 Clarifications of Mechanical Noise 流体动力性噪声流体动力性噪声(Fluid dynamic noise)空气噪声空气噪声(Air-borne noise)pagepage 24授课人柳贡民11/26/2022动力与能源

30、工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.2 Mechanical Noise and Control Chapter 1 Introduction1.2.4 Methods of Mechanical Noise Control1.2.4 Methods of Mechanical Noise ControlEvery situation in noise control involves a system composed of three basic element

31、s:Source,Path,and ReceiverLow Noise Design is the ideal method for the Mechanical Product Noise Controlpagepage 25授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringClass 1pagepage 26授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy Eng

32、ineeringPower and Energy EngineeringChapter 2 Vibration of Single-Degree-of-Freedom System(SDOF)2.1 Differential Equation of Vibration2.2 Free Vibration2.3 Forced Vibration2.4 Vibration IsolationOutline:pagepage 27授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and En

33、ergy Engineering2.1 Differential Equation of Vibrationpagepage 28授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering1.piston 2.connecting rod 3.crankshaft 4.flywheel 5.intermediate shaft 6.screw propeller2.1 Differential Equation of Vibrationpagepag

34、e 29授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering2.1.1.1 2.1.1.1 Discretization of physical systemMass elementSpring elementDamping element2.1.1 Mechanical Model of Physical System2.1 Differential Equation of Vibrationpagepage 30授课人柳贡民11/26/20

35、22动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering2.1.1.1 2.1.1.1 Discretization of physical system2.1.1 Mechanical Model of Physical System2.1 Differential Equation of Vibrationpagepage 31授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy Engineerin

36、gPower and Energy Engineering2.1.1.1 2.1.1.1 Discretization of physical system2.1.1 Mechanical Model of Physical System2.1 Differential Equation of Vibrationpagepage 32授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringMass element质量元件质量元件xmFm Trans

37、lation平移平移：Force力力,mass质量质量&acceleration加速度加速度 Units量纲量纲:N、kg、m/s 2。JTmRotation旋转旋转：Moment力矩力矩,moment of inertia转转动惯量动惯量&angular acceleration角加速度角加速度 Units量纲量纲:Nm、kg m 2、rad/s 2 2.1.1.2 2.1.1.2 Discretized mechanical system2.1.1 Mechanical Model of Physical System2.1 Differential Equation of Vibrati

38、onpagepage 33授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringxkFstskT Spring(elastic)element弹性元件弹性元件Force力力,stiffness刚度刚度&displacement位移位移Units量纲量纲:N,N/m&m Moment力矩力矩,torsion stiffness扭转刚度扭转刚度&angle角位移角位移Units量纲量纲:Nm,Nm/rad&radTranslation平移平移：Rot

39、ation旋转旋转：2.1.1.2 2.1.1.2 Discretized mechanical system2.1.1 Mechanical Model of Physical System2.1 Differential Equation of Vibrationpagepage 34授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringxcFdtdcT Damping element阻尼元件阻尼元件Force力力,damping coeff

40、icient阻尼系数阻尼系数&velocity速度速度Units量纲量纲:N,Ns/m&m/s。Moment力矩力矩,torsion damping coefficient扭转阻尼系数扭转阻尼系数&angular velocity角速度角速度 Units量纲量纲:Nm,Nms/rad&rad/sTranslation平移平移：Rotation旋转旋转：2.1.1.2 2.1.1.2 Discretized mechanical system2.1.1 Mechanical Model of Physical System2.1 Differential Equation of Vibratio

41、npagepage 35授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering(1)Force method2.1.2 Methods to Establish Differential EquationSteps：1.Generalized coordinate 建立广义坐标建立广义坐标2.Draw a diagram of equilibrium of forces of the mass element作质量元件的隔离体受力分析图作质量元件

42、的隔离体受力分析图 3.Normal form of the vibration equation 建立振动微分方程并建立振动微分方程并整理成标准的形式整理成标准的形式2.1 Differential Equation of Vibrationpagepage 36授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering(1)Force method Example 2-2 SDOF damping system Generalized coord

43、inate.建立广义建立广义坐标坐标(direction方向方向,origin原点原点)Mechanics principle 力学定律力学定律xmtFmgxcxk)()()(tFkxxcxm 2.1 Differential Equation of Vibration2.1.2 Methods to Establish Differential EquationEquilibrium of forces at the mass element质量受力的平衡质量受力的平衡pagepage 37授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power

44、 and Energy EngineeringPower and Energy Engineeringsingle pendulumGeneralized coordinate.(direction,origin)Equilibrium of moments at the jointDAlembert Principle0sin2lgmlm sin0）（lg(1)Force method Example 2-3 2.1 Differential Equation of Vibration2.1.2 Methods to Establish Differential Equationpagepa

45、ge 38授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringMultiple Mass System Generalized coordinate x1=a ,x2=2a (1)Force method Example 2-4 2.1 Differential Equation of Vibration2.1.2 Methods to Establish Differential EquationNewton 2nd law for m1 a

46、nd m2 111m aRk a22222m aRk apagepage 39授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering(1)Force method Example 2-4 2.1 Differential Equation of Vibration2.1.2 Methods to Establish Differential EquationMoment law for m3 02233212JakaRaRwhere230amJ

47、222222112312344420m am am ak ak ak a0teekJ orpagepage 40授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering0d/dtPUV）（3.Using principle of conservation of energy(2)Energy method Steps：1.Generalized coordinate.2.1 Differential Equation of Vibration2.1

48、.2 Methods to Establish Differential Equation221xmT20011112nnnxxiiiiiiiiUF dxk x dxk x2.Kinetic energy V,potential energy U&dissipation energy P20011nnxtiiiiiiPC x dxC x dtpagepage 41授课人柳贡民11/26/2022动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy Engineering(2)Energy metho

49、d Example 2-5：2.1 Differential Equation of Vibration2.1.2 Methods to Establish Differential Equation1.Generalized coordinate.2.Kinetic energy 动能动能T、potential energy 势能势能U3.Using principle of conservation of energy20021kxkxdxFdxUxx0 kxxmUT 代入上式，得、将0)(,UTdtdUT所以有常数xxFmo221xmTpagepage 42授课人柳贡民11/26/202

50、2动力与能源工程学院College ofCollege of Power and Energy EngineeringPower and Energy EngineeringMultiple Mass System Generalized coordinate (direction,origin)x1=a ,x2=2a Example 2-6 (2)Energy method 2.1 Differential Equation of Vibration2.1.2 Methods to Establish Differential Equationpagepage 43授课人柳贡民11/26/2