机械振动噪声学一讲解

1、pagepage 1 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering pagepage 2 授课人柳贡 民 2021-6-28 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（Reference Boo

2、ks）: 1. W.T. Thomson and M.D. Dahleh, Theory of Vibrations with Applications (5th ed.), Prentice Hall, 1997 pagepage 3 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 2. R.F. Barron, Industrial Noise Control and Acoustics, Marcel Dekker, 2003

3、 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 3. 季文美，机械振动，科学出版社， 1985 pagepage 4 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.1 Summary of Mechanical Vibration1.1

4、.1 Summary of Mechanical Vibration Vibrating Phenomena in the World Vibration 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 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Contr

5、ol Chapter 1 Introduction 1.1.1 Summary of Mechanical Vibration1.1.1 Summary of Mechanical Vibration Undesirable vibrations： Vehicle; Noise; Machines Earthquake; Power units in every kinds of vessels may cause vibrations pagepage 6 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy En

6、gineeringPower and Energy Engineering Useful vibrations： String vibration; harmonic oscillator, resonator; Vibrating road roller; Vibrating feeder; Vibrating forming machine. 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.1 1.1.1 Summary of Mechanical Vibration pagepage 7 授课人柳贡 民 2

7、021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.2 Basic Concept1.1.2 Basic Concept Mechanical Vibration ? Research aim ? Vibration is a phenomena that a body or structure oscillates abou

8、t 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 vibrations pagepage 8 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofColle

9、ge of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.3 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 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy En

10、gineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechanical Vibrations The least number of mutually independent parameters (coordinates) required to uniquely define a material systems

11、 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 pagepage 10 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Chapter 1 Introduction z 多自由度系统振动多自由度系统振动 (multiple degree of freedom) ABAB pagepage 11 授课人柳贡 民 2021-

12、6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Chapter 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 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibrati

13、on and Control Chapter 1 Introduction 1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechanical 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 result

14、ing from the application of an external force； pagepage 13 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechani

15、cal 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 time in the form of a sine curve. Periodic vibration An oscillatory motion whose amplitude pattern repeats after fixed increments of time. Transient vibration Temporarily sustaine

16、d 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. pagepage 14 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mecha

17、nical Vibration and Control Chapter 1 Introduction 1.1.4 Clarification of Mechanical Vibrations1.1.4 Clarification of Mechanical Vibrations Differential Equation 非线性振动非线性振动 (nonlinear vibration) Linear Vibration Linear differential equation ; (superposition) Nonlinear vibration Nonlinear differentia

18、l equation Bifurcation & Chaos pagepage 15 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Vibration System ExcitationResponse Vibration analysis or Response analysis Vibration System ExcitationResponse Vibration environment prediction Vibrat

19、ion System ExcitationResponse Vibration design or System identification 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.5 Problems of Mechanical Vibration and 1.1.5 Problems of Mechanical Vibration and Solving Methods Solving Methods pagepage 16 授课人柳贡 民 2021-6-28 动力与能源工程学院 College o

20、fCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction vTheoretical analysis 1.1.5 Problems of Mechanical Vibration and 1.1.5 Problems of Mechanical Vibration and Solving Methods Solving Methods R e a l system Mechanics princ

21、iple D.E. Numerical solution Analytical solution C o m p u t e r simulation Mathematical tools V i b r a t i o n characteristics pagepage 17 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering vExperiment Vibration monitoring, testing, and experi

22、mentation are important as well in the design, implementation, maintenance, and repair of engineering systems. Chapter 1 Introduction All these are important topics of study in the field of vibration engineering, 1.1.5 Problems of Mechanical Vibration and 1.1.5 Problems of Mechanical Vibration and S

23、olving Methods Solving Methods 1. 1 Mechanical Vibration and Control pagepage 18 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 控制方法：新的保护罩用打孔金属薄板和金属丝网制成。 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.6 Mechanical Vibration

24、 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 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 1 Mechanical Vibration and Control Chapter 1 Introduction 1.1.6 Mechanical Vibrat

25、ion 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 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. 2 Mechanical Noise and Control Chapter 1 Introduction 1.2.1 Sound and Noise1.2.1 Sound and Noi

26、se Sound Wave is any disturbance that is propagated in an elastic medium Sound Source is an object that caused vibration of medium particles Sound Field is a space where the sound wave exists pagepage 21 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy En

27、gineering 1. 2 Mechanical Noise and Control Chapter 1 Introduction 1.2.1 Sound and Noise1.2.1 Sound and Noise Noise is any unwanted sound perceived by the hearing sense of a human is a mixture of sound waves with different frequencies and strengths pagepage 22 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofC

28、ollege of Power and Energy EngineeringPower and Energy Engineering 1. 2 Mechanical Noise and Control Chapter 1 Introduction 1.2.2 Noise Effects1.2.2 Noise Effects Hearing and Health Excessive noise can impair hearing, may also put stress on the heart, the circulatory system, and other parts of the b

29、ody Technical Standards For example, the pass-by noise national standards for cars, 84 dB(A) (1979), 78 dB(A) (1985), 74 dB(A) (2006). Military Vehicles Require High stealth capabilities Quiet working and living environment pagepage 23 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energ

30、y EngineeringPower and Energy Engineering 1. 2 Mechanical Noise and Control Chapter 1 Introduction 1.2.3 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 2021-6-28 动力与能源工程学院 College ofColleg

31、e of Power and Energy EngineeringPower and Energy Engineering 1. 2 Mechanical Noise and Control Chapter 1 Introduction 1.2.4 Methods of Mechanical Noise Control1.2.4 Methods of Mechanical Noise Control Every situation in noise control involves a system composed of three basic elements: Source, Path,

32、 and Receiver Low Noise Design is the ideal method for the Mechanical Product Noise Control pagepage 25 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Class 1 pagepage 26 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy Engi

33、neeringPower and Energy Engineering Chapter 2 Vibration of Single-Degree-of-Freedom System (SDOF) 2. 1 Differential Equation of Vibration 2. 2 Free Vibration 2. 3 Forced Vibration 2. 4 Vibration Isolation Outline: pagepage 27 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy Engineer

34、ingPower and Energy Engineering 2. 1 Differential Equation of Vibration pagepage 28 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 1. piston 2. connecting rod 3. crankshaft 4. flywheel 5. intermediate shaft 6. screw propeller 2. 1 Differenti

35、al Equation of Vibration pagepage 29 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 2.1.1.1 2.1.1.1 Discretization of physical system Mass element Spring elementDamping element 2.1.1 Mechanical Model of Physical System 2. 1 Differential Equa

36、tion of Vibration pagepage 30 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 2.1.1.1 2.1.1.1 Discretization of physical system 2.1.1 Mechanical Model of Physical System 2. 1 Differential Equation of Vibration pagepage 31 授课人柳贡 民 2021-6-28 动力

37、与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 2.1.1.1 2.1.1.1 Discretization of physical system 2.1.1 Mechanical Model of Physical System 2. 1 Differential Equation of Vibration pagepage 32 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy Engi

38、neeringPower and Energy Engineering Mass element 质量元件质量元件 xmF m Translation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。 JTm Rotation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 mechanica

39、l system 2.1.1 Mechanical Model of Physical System 2. 1 Differential Equation of Vibration pagepage 33 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering xkF s ts kT Spring (elastic) element 弹性元件弹性元件 Force力力, stiffness刚度刚度 &displacement位移位移 Unit

40、s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 & rad Translation平移平移： Rotation旋转旋转： 2.1.1.2 2.1.1.2 Discretized mechanical system 2.1.1 Mechanical Model of Physical System 2. 1 Differential Equation of Vibration pagepage 34 授课人柳贡 民 2021-6-28 动力与能源工程学院 Coll

41、ege ofCollege of Power and Energy EngineeringPower and Energy Engineering xcF d td cT Damping element 阻尼元件阻尼元件 Force力力, damping coefficient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/s Trans

42、lation平移平移： Rotation旋转旋转： 2.1.1.2 2.1.1.2 Discretized mechanical system 2.1.1 Mechanical Model of Physical System 2. 1 Differential Equation of Vibration pagepage 35 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering (1) Force method 2.1.2 Metho

43、ds to Establish Differential Equation Steps： 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 Vibration pagepag

44、e 36 授课人柳贡 民 2021-6-28 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 coordinate .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 E

45、quation of Vibration 2.1.2 Methods to Establish Differential Equation Equilibrium 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 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering single pendulum Generalized coordinate . (direction,orig

46、in) Equilibrium of moments at the joint DAlembert Principle 0sin 2 lgmlm sin 0）（lg (1) Force method Example 2-3 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differential Equation pagepage 38 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and

47、Energy Engineering Multiple Mass System Generalized coordinate x1=a , x2=2a (1) Force method Example 2-4 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differential Equation Newton 2nd law for m1 and m2 111 m aRk a 222 22m aRk a pagepage 39 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofC

48、ollege of Power and Energy EngineeringPower and Energy Engineering (1) Force method Example 2-4 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differential Equation Moment law for m3 0 2 2 3 321 2JakaRaR where 2 30 amJ 222222 1 1231234 4420m am am ak ak ak a 0 tee kJ or pagepage

49、40 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering 0d/dtPUV）（ 3. Using principle of conservation of energy (2) Energy method Steps： 1. Generalized coordinate. 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differential Equ

50、ation 2 2 1 xmT 2 00 111 1 2 nnn xx iiiii iii UF dxk x dxk x 2. Kinetic energy V, potential energy U & dissipation energy P 2 00 11 nn xt iiii ii PC x dxC x dt pagepage 41 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering (2) Energy method Exam

51、ple 2-5 ： 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differential Equation 1. Generalized coordinate. 2. Kinetic energy 动能动能T、potential energy 势能势能U 3. Using principle of conservation of energy 2 00 2 1 kxkxdxFdxU xx 0 kxxmUT 代入上式，得、将 0)(,UT dt d UT所以有常数 x x F m o 2 2 1 xmT p

52、agepage 42 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Multiple Mass System Generalized coordinate (direction,origin) x1=a , x2=2a Example 2-6 (2) Energy method 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differenti

53、al Equation pagepage 43 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Kinetic energy V Potential energy U Dissipation energy P Using principle of conservation of energy 22 3 22 2 22 1 2 1 2 2 1 amamamV 22 3 22 2 22 1 4 9 2 1 4 2 1 2 1 akaka

54、kU 0P 0) 4 1 24( 4 2 3 2 2 2 1 2 3 2 2 2 1 akakak amamam）（ Example 2-6 (2) Energy method 2. 1 Differential Equation of Vibration 2.1.2 Methods to Establish Differential Equation pagepage 44 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Mult

55、i-mass (or spring, damping) elements General form of vibration equation for SDOF system )( eee tFxkxcxm )( e t e te tTkcJ Translation： Rotation： 2. 1 Differential Equation of Vibration 2.1.3 Equivalent System Single-mass (or spring, damping) element pagepage 45 授课人柳贡 民 2021-6-28 动力与能源工程学院 College of

56、College of Power and Energy EngineeringPower and Energy Engineering Equivalent stiffness x F k x e xkF n i ix )( 1 n i i k 1 2. 1 Differential Equation of Vibration 2.1.3 Equivalent System (1) Equivalent stiffness Methods： 1 Definition of stiffness。 2 Potential energy pagepage 46 授课人柳贡 民 2021-6-28 动

57、力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Series Springs Series Springs Equivalent stiffness x F k x e n i i x n i i x n i i k F k F xx 111 1 n i i k 1 1 1 2. 1 Differential Equation of Vibration 2.1.3 Equivalent System pagepage 47 授课人柳贡 民 2021-6-28 动力与能源

58、工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering n i i cc 1 e n ii cc 1e 11 Parallel systemSeries system (2) Equivalent damping 2. 1 Differential Equation of Vibration 2.1.3 Equivalent System pagepage 48 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Ene

59、rgy EngineeringPower and Energy Engineering Example 2-7 Equivalent mass to A point Spring-lever-mass system Kinetic Energy (original system) 2 2 2 4 2 1 2 2 1 2 1 xmml l x mxmV baba Kinetic Energy (equivalent system) 2 ee 2 1 xmV VV eba mmm4 e (3) Equivalent mass (kinetic energy equivalence) 2. 1 Di

60、fferential Equation of Vibration 2.1.3 Equivalent System pagepage 49 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege of Power and Energy EngineeringPower and Energy Engineering Problems 2-2, 2-3, 2-4, 2-5, 2-6, 2-9, 2-12 Home Works Pages 41&42 pagepage 50 授课人柳贡 民 2021-6-28 动力与能源工程学院 College ofCollege