机械振动噪声学一课件

1、机 械 振 动 噪 声 学Fundamentals of Mechanical Vibration and NoisePro. 柳贡民 办公地点: 三甲 动力装置工程技术研究所Email: Tel:82569458, 82569468,valuation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.机 械 振 动 噪 声 学Fundamentals教科书（Textbook）: 赵玫等，机械振动与噪声学， 科学

2、出版社， 2004参考书（Reference Books）: W.T. Thomson and M.D. Dahleh, Theory of Vibrations with Applications (5th ed.), Prentice Hall, 1997Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.教科书（Textbook）: 参考书（Reference B2. R.F. Barron, Industrial

3、 Noise Control and Acoustics, Marcel Dekker, 2003郑兆昌主编， 机械振动（上册），机械工业出版社，1980 商大中，动力分析基础，哈尔滨工程大学出版社，1999 季文美，机械振动，科学出版社， 1985Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.2. R.F. Barron, Industrial N1. 1 Mechanical Vibration and Con

4、trol Chapter 1 Introduction1.1.1 Summary of Mechanical VibrationVibrating Phenomena in the WorldVibration are found in many branches of science and engineering Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration

5、an1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.1 Summary of Mechanical VibrationUndesirable vibrations： Vehicle; Noise; Machines & Structures; Earthquake;Power units in every kinds of vessels may cause vibrationsEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profil

6、e .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration anUseful 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 Summary of Mechanical Vi

7、brationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Useful vibrations：1. 1 Mechan1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.2 Basic ConceptMechanical Vibration ?Research aim ?Vibration is a phenomena that a bod

8、y or structure oscillates about some specified reference point. Vibration is commonly 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 vibrationsEvaluation only.Created wi

9、th Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration an1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.3 Model of Vibration System离散系统 （集中参数系统） Discrete system (Lumped parameter system)连续系统 （分布参数系统） Continuous system (Distr

10、ibuted parameter system)Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration an1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations(1) 按自由度分(According to the deg

11、ree of freedom)The least number of mutually independent parameters (coordinates) required to uniquely define a material systems position in space, time, etc单自由度系统振动 (single degree of freedom) 多自由度系统振动 (multiple degree of freedom)连续系统振动 (continuous system)Evaluation only.Created with Aspose.Slides fo

12、r .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration anChapter 1 Introductionz单自由度系统振动 (single degree of freedom) 多自由度系统振动 (multiple degree of freedom)ABABEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspo

13、se Pty Ltd.Chapter 1 Introductionz单自由度Chapter 1 Introduction模型与自由度 (Model and degree of freedom)Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Chapter 1 Introduction模型与自由度 1. 1 Mechanical Vibration and Control Chapter 1 Introduction1

14、.1.4 Clarification of Mechanical Vibrations(2) 按激励形式分(According to the excitation)：自由振动 (free vibration) (no force) 强迫振动 (forced vibration) (external force)Free vibration the periodic motion occurring when an elastic system is displaced from its equilibrium position; Forced vibration the vibration r

15、esulting from the application of an external force； Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration an1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations(3

16、) 按系统的响应分(According to the system response)：简谐振动 (harmonic vibration) ;周期振动 (periodic vibration)瞬态振动 (transient vibration); 随机振动 (random vibration)Harmonic vibration Oscillations in which motion is periodic with time in the form of a sine curve. Periodic vibration An oscillatory motion whose amplitu

17、de 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 amplitude is not specified at any instant of time. Evaluation only.Created with Aspose.S

18、lides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration an1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.4 Clarification of Mechanical Vibrations(4) 按系统微分方程分(According to the Differential Equation )：线性振动 (linear vibration) 非线性振动 (nonlin

19、ear vibration)Linear Vibration Linear differential equation ; (superposition) Nonlinear vibration Nonlinear differential equation Bifurcation & ChaosEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration anVibration

20、 SystemExcitationResponse?Vibration analysis or Response analysisVibration SystemExcitationResponse?Vibration environment predictionVibration SystemExcitationResponse?Vibration design or System identification1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.5 Problems of Mechanical Vib

21、ration and Solving MethodsEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Vibration SystemExcitationResp1. 1 Mechanical Vibration and Control Chapter 1 IntroductionTheoretical analysis1.1.5 Problems of Mechanical Vibration and Solving

22、 MethodsReal systemMechanics principleD.E.Numerical solutionAnalytical solutionComputer simulationMathematical toolsVibration characteristicsEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration anExperimentVibrati

23、on 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 vibration engineering,1.1.5 Problems of Mechanical Vibration and Solving Meth

24、ods1. 1 Mechanical Vibration and Control Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.ExperimentVibration monitoring控制方法：新的保护罩用打孔金属薄板和金属丝网制成。消减激振源1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.6 Mechanical Vibratio

25、n 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。Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.控制方法：新的保护罩用打孔金属薄板和金属丝网制成。消减激振源1. 1 Mechanical Vibration and Control Chapter 1 Introduction1.1.6 Mechanical Vibration Control Methods其

26、它措施：避免共振；减振与隔振。Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 1 Mechanical Vibration an1. 2 Mechanical Noise and Control Chapter 1 Introduction1.2.1 Sound and NoiseSound Waveis any disturbance that is propagated in an elastic medi

27、umSound Sourceis an object that caused vibration of medium particlesSound Fieldis a space where the sound wave existsEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 2 Mechanical Noise and Co1. 2 Mechanical Noise and Control Chapter

28、 1 Introduction1.2.1 Sound and NoiseNoiseis any unwanted sound perceived by the hearing sense of a humanis a mixture of sound waves with different frequencies and strengthsEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 2 Mechanica

29、l Noise and Co1. 2 Mechanical Noise and Control Chapter 1 Introduction1.2.2 Noise EffectsHearing and HealthExcessive noise can impair hearing, may also put stress on the heart, the circulatory system, and other parts of the bodyTechnical StandardsFor example, the pass-by noise national standards for

30、 cars, 84 dB(A) (1979), 78 dB(A) (1985), 74 dB(A) (2006).Military Vehicles RequireHigh stealth capabilitiesQuiet working and living environmentEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 2 Mechanical Noise and Co1. 2 Mechanical

31、 Noise and Control Chapter 1 Introduction1.2.3 Clarifications of Mechanical Noise(1) 按声源形成机理分(According to the mechanisms of sound source generation)：结构振动辐射噪声 (Radiated noise from structure vibration) 流体动力性噪声 (Fluid dynamic noise)(2) 按声波传递的媒质分(According to the medium in which the sound wave transmis

32、sion)：空气噪声 (Air-borne noise)结构噪声 (Structure-borne noise) Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1. 2 Mechanical Noise and Co1. 2 Mechanical Noise and Control Chapter 1 Introduction1.2.4 Methods of Mechanical Noise ControlEver

33、y situation in noise control involves a system composed of three basic elements:Source, Path, and ReceiverLow Noise Design is the ideal method for the Mechanical Product Noise ControlEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.1.

34、2 Mechanical Noise and CoClass 1Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Evaluation only.Chapter 2 Vibration of Single-Degree-of-Freedom System (SDOF) 2. 1 Differential Equation of Vibration2. 2 Free Vibration2. 3 Forced Vibrat

35、ion2. 4 Vibration IsolationOutline:Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Chapter 2 Vibration of SingleMechanical model of physical system2. 1 Differential Equation of VibrationEvaluation only.Created with Aspose.Slides for .

36、NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Mechanical model of physical A shafting of diesel engine 柴油机轴系扭振模型1. piston 2. connecting rod 3. crankshaft 4. flywheel 5. intermediate shaft 6. screw propellerMechanical model of physical system2. 1 Differential Equation of Vibration

37、Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.A shafting of diesel engine 柴油 Discretization of physical systemMass elementSpring elementDamping element2.1.1 Mechanical Model of Physical System2. 1 Differential Equation of Vib

38、rationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd. Discretization of phys Elastic Mounted Diesel Generating Set Example 2- Discretization of physical system2.1.1 Mechanical Model of Physical System2. 1 Differential

39、Equation of VibrationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd. Elastic Mounted Diesel GenerExample 2-1 Elastic mounted Generating Set SDOF System Discretization of physical system2.1.1 Mechanical Model of Physical Syste

40、m2. 1 Differential Equation of VibrationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Example 2-1 Elastic mounted GMass element质量元件Inelastic, rigid body，kinetic energy storage elements是无弹性的刚体,储存动能的元件Translation平移： Force力, mass质量 & a

41、cceleration加速度 Units量纲: N、kg、m/s 2。 Rotation旋转： Moment力矩, moment of inertia转动惯量 & angular acceleration角加速度 Units量纲: Nm、kg m 2、rad / s 2 Discretized mechanical system2.1.1 Mechanical Model of Physical System2. 1 Differential Equation of VibrationEvaluation only.Created with Aspose.Slides for

42、.NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Mass elementTranslation平移： Spring (elastic) element弹性元件Potential energy storage elements是势能储存元件Force力, stiffness刚度 &displacement位移Units量纲: N, N/m & m Moment力矩, torsion stiffness扭转刚度 & angle角位移Units量纲: Nm, Nm/rad & radTranslation平移：Ro

43、tation旋转： Discretized mechanical system2.1.1 Mechanical Model of Physical System2. 1 Differential Equation of VibrationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Spring (elastic) elementForce力Damping element阻尼元件Energy diss

44、ipation elements耗能元件Force力, damping coefficient阻尼系数& velocity速度Units量纲: N, Ns/m & m/s 。 Moment力矩, torsion damping coefficient扭转阻尼系数& angular velocity角速度 Units量纲: Nm, Nms/rad & rad/sTranslation平移：Rotation旋转： Discretized mechanical system2.1.1 Mechanical Model of Physical System2. 1 Differentia

45、l Equation of VibrationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Damping elementForce力, damping(1) Force method2.1.2 Methods to Establish Differential EquationSteps： 1. Generalized coordinate 建立广义坐标2. Draw a diagram of equilibri

46、um of forces of the mass element作质量元件的隔离体受力分析图 . Normal form of the vibration equation 建立振动微分方程并整理成标准的形式2. 1 Differential Equation of VibrationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.(1) Force method2.1.2 Methods (1) Force met

47、hod Example 2-2 SDOF damping system Generalized coordinate .建立广义坐标 (direction方向,origin原点)Mechanics principle 力学定律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Evaluation only.Created with Aspose.Slides for .NET

48、3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.(1) Force method SDOF damping single pendulumGeneralized coordinate . (direction,origin) Equilibrium of moments at the jointDAlembert Principle(1) Force method Example 2-3 2. 1 Differential Equation of Vibration2.1.2 Methods to Establish

49、Differential EquationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.single pendulumGeneralized cooMultiple Mass System Generalized coordinate x1=a , x2=2a (1) Force method Example 2-4 2. 1 Differential Equation of Vibration2.1.2 Meth

50、ods to Establish Differential EquationNewton 2nd law for m1 and m2 Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Multiple Mass System Generaliz(1) Force method Example 2-4 2. 1 Differential Equation of Vibration2.1.2 Methods to Esta

51、blish Differential EquationMoment law for m3whereorEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.(1) Force method 2. 1 DifferenLinearization Vibration Differential Equation3. Using principle of conservation of energy(2) Energy metho

52、d Steps： 1. Generalized coordinate. 2. 1 Differential Equation of Vibration2.1.2 Methods to Establish Differential Equation2. Kinetic energy V, potential energy U & dissipation energy PEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.L

53、inearization Vibrati(2) Energy method Example 2-5 ： 2. 1 Differential Equation of Vibration2.1.2 Methods to Establish Differential Equation1. Generalized coordinate. Kinetic energy 动能T、potential energy 势能U3. Using principle of conservation of energyEvaluation only.Created with Aspose.Slides for .NET

54、 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.(2) Energy method 2. 1 DiffereMultiple 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 EquationEvaluation onl

55、y.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Multiple Mass System GeneralizKinetic energy V Potential energy U Dissipation energy P Using principle of conservation of energy Example 2-6 (2) Energy method 2. 1 Differential Equation of Vibration2.

56、1.2 Methods to Establish Differential EquationEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Kinetic energy V Using prMulti-mass (or spring, damping) elements General form of vibration equation for SDOF systemTranslation：Rotation：equ

57、ivalence2. 1 Differential Equation of Vibration2.1.3 Equivalent SystemSingle-mass (or spring, damping) element Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Multi-mass (or spring, dampingParallel springsEquivalent stiffnessParallel

58、springs2. 1 Differential Equation of Vibration2.1.3 Equivalent System(1) Equivalent stiffness Methods： 1 Definition of stiffness。 2 Potential energy Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Parallel springsEquivalent stiSeries

59、Springs Series SpringsEquivalent stiffness2. 1 Differential Equation of Vibration2.1.3 Equivalent SystemEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Series Springs Series SpringsEParallel systemSeries system(2) Equivalent damping2.

60、 1 Differential Equation of Vibration2.1.3 Equivalent SystemEvaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile .Copyright 2004-2011 Aspose Pty Ltd.Parallel systemSeries system2.Example 2-7 Equivalent mass to A point Spring-lever-mass system Kinetic Energy (original system)