• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Parameters Optimization of the Dynamic Absorber to Control the Axial Vibration of Marine Shafting System

    2012-09-22 07:15:50LILiangweiZHAOYaoLITianyunLUPo
    船舶力學 2012年3期

    LI Liang-wei,ZHAO Yao,LI Tian-yun,LU Po

    (School of Naval Architecture&Ocean Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)

    1 Introduction

    Periodical force and torque due to the propeller in non-uniform flow field will cause shaft torsional vibration,axial vibration,lateral vibration and the coupling vibration.Oscillation caused by a small variation of thrust when the blades rotate through the non-uniform wake results in axial resonance at blade frequency[1].Many researchers have explored the axial vibrations of the marine shafting system,which are directly related to the quietness and comfort for passengers.A series of methods has been used for axial shaft vibration reduction,for example,by changing the stiffness of the marine thrust bearing,increasing damping in shafting foundation with the materials that have high damping properties,or using vibration control.One of the effective and feasible ways for vibration control is to install dynamic absorbers to marine shafting system.

    The dynamic absorber attached to the primary system as a subsystem reduces vibration by introducing opposite force and also by dissipating energy through damping.The key to control the main system vibration is to clarify the parameters of dynamic absorber and locations.With the development of the different structural forms and the increasing needs of vibration control,the theory of parameters optimization has been improved.

    The theory of dynamic vibration employed to one degree of freedom system without damping was first systematically investigated by Ding[2].Then,Randall et al[3]determined the optimal linear dynamic absorber for linear damping system based on minimum-maximum amplitudes criteria to find the optimal parameters.Because of popular application of the dynamic absorber in the field of machine engine,marine,automobiles,buildings,and so on,several researchers started to pay more attention to the methods of oversimplification to represent the original system.Ram and Elhay[4]studied the behavior of multi-degree-of-freedom vibration system with a simple dynamic absorber,and they proposed the recoverage of the physical parameters of a subsystem from the frequency response function measurements.Later on,a closed-form vibration transmissibility of a general unidirectional multi-degree-of-freedom system with multiple dynamic absorbers was discussed by Hsueh[5].Based on the graph model,the force and displacement transmissibility were derived by using the topology scheme.Two examples were shown for the implementation of this method.

    Optimization and numerical algorithms were also presented in several literatures.Kitis[6]published a paper on the design of two dynamic absorbers simultaneously applied to an undamped cantilever beam with the re-analysis technique,and the design parameters were optimized by the method of feasible direction.However,in such parameters optimization of the dynamic absorber,only the optimal damping and stiffness were obtained except mass.A new geometrical design method used to simplify the stiffness matrix of dynamic absorbers for the multi-degree-of-freedom system was presented by Jang and Choi[7].Moreover,the performances of different frequency-tuning methods were examined by Sun et al[8].It was shown that the oneone method almost had the same characteristics as the optimization method,and it did not need time-consuming optimization process.

    Dylejko et al[9]analyzed the propeller-shafting system with the four-pole parameter method and used the genetic algorithm to optimize the virtual resonance changer parameters.However,the transmission matrix parameters of the RC are not derived in detail and also the influence on different locations of the RC to decrease the axial vibration was not concerned.Viana et al[10]reported an analytical solution for the parameters optimization of two different dynamic absorbers by ant colony optimization and defined an objective function used to minimize the vibration amplitude of the primary structure.Furthermore,a comprehensive review of dynamic absorber including configurations developments and applications could be found in the papers by Kela et al[11].

    After reviewing the literatures listed above,one should notice that most articles dealt with the theoretical models to optimize the parameters of dynamic absorber,while the practical en-gineering problems are less discussed.For example,little attention has been devoted to use dynamic absorber for specific resonance attenuation and solve the parameter optimization problems with the finite element method.Such problems do have considerable practical significance and therefore will be discussed in the following.

    In this paper,the marine shafting system is modeled as multiple degree-of-freedom system based on the finite element method.The dynamic absorber is used to control the axial vibration of marine shafting system.It is essential to mention that the marine shafting system simply includes propeller,shafting,coupling,journal bearing and thrust bearing.The dynamic response of axial vibration is obtained by the re-analysis technique,which reduces the calculation time.The force transmissibility and the power transmissibility at the thrust bearing are derived to examine the performance of dynamic vibration.With the methods of the genetic algorithm and the multi-objective optimization algorithms,the dynamic absorber parameters are optimized over a certain response frequency range and the problem of specific resonance attenuation is also solved by adding equality constraint in the optimization process.Dynamic vibration is applied to three different locations at marine shafting system to investigate the influence on the axial vibration with different objective functions.The results here validate the feasibility of the optimization algorithm presented,and show that the vibration transmissibility is able to serve as a good criterion for the marine shafting system design as well as vibration control.

    2 Finite element model

    2.1 The axial vibration model of marine shafting system

    The marine shafting system mainly consists of propeller,shafting,coupling,journal bearing,thrust bearing and their foundation.The components of simplified mathematical model are the lumped mass and axial stiffness,which make an impact on the behaviors of the shafting axial vibration.The axial vibration model of marine shafting system is shown in Fig.1.

    Fig.1 The sketch of axial vibration of the marine shafting system

    In order to get the motion equation of the axial vibration based on the finite element method,the marine shafting system is discretized into several elements.The position of the thrust bearing and the coupling should generate nodes according to the simplified criterion of the finite element model.The transmission shaft is generally simulated as beam element in numerical analysis.The mass of the propeller,the couplings and the thrust bearing are modeled as lump masses averagely assigned to their left and right element mass matrices.Similarly,the stiffness of thrust bearing is equivalent as axial stiffness averagely assigned to its left and right stiffness matrix.

    The analytical expression of the beam element axial displacement is solved by using the appropriate displacement interpolation function combined with the boundary conditions.By assembling the matrix of the element,the motion expression of shaft axial vibration is obtained[12].

    2.2 Model of dynamic vibration

    Suppose a single dynamic absorber attached to the marine shaft system along the axial direction at node i and the schematic is given in Fig.2,here miis the mass of marine shafting in the finite element model at node i.The dynamic absorber is composed of a virtual mass m1,a virtual stiffness k1and a virtual damping c1.The displacement of the masses at node i and the displacement of dynamic absorber are shown as ui(t)and u1(t),respectively.According to the D’Alembert principle,the dynamic absorber equation of motion is established as follows:

    Fig.2 Dynamic absorber system

    Substituting the Eq.(1)into the matrix forms:

    After installing the dynamic absorber to the marine shafting system,Fig.3 shows the finite element model of axial vibration of marine shafting system,which has n nodes.Kthis the axial stiffness of thrust bearing and the hull is equivalent as rigid boundary.

    Fig.3 The finite element model of axial vibration of marine shafting system

    The motion equations of axial vibration of marine shafting system could be written as follows based on the performance of typical vibration system.

    where[M],[K ]and[C ]are the mass,stiffness and damping matrices of this system.{F(t)}is the axial excitation force vectors.{u},{u˙}and{u¨}are the axial displacement,velocity and acceleration vectors,respectively.

    3 Parameters optimization of the dynamic absorber

    3.1 Solution of the vibration transmissibility

    As an objective function to evaluate the performance of dynamic absorber,the force transmissibility and the power transmissibility are widely used.The marine structural vibration through the thrust bearing induced by shafting system is the main reason to analyze the axial vibration.This paper will discuss the effect of a dynamic absorber to reduce the axial vibration,using the force transmissibility and the power transmissibility at the thrust bearing as a criterion.

    Suppose that the marine shafting system is excited by a periodically varying force with amplitude vector {F0},{F(t)}in Eq.(3)will be the form:

    Correspondingly,the axial displacement vector of the shafting system is also written as:

    where {u0}is the amplitude of the axial displacement vector.Substitution of Eq.(4)and Eq.(5)into Eq.(3),then takes the form:

    When the dynamic absorber parameters change in the calculation procedures,the mass matrix,stiffness matrix and damping matrix in Eq.(6)will also regenerate.Define the parameter vector x as follows:

    where q is the number of dynamic absorbers attached to the shafting system.

    This paper will use the re-analysis technology to solve the equation of motion in Eq.(3),which could reduce the structure analysis time[6].When the dynamic absorber parameters change,the new mass matrice[M′],stiffness matrice[K′]and damping matrice[C′]of the vibration system in Eq.(6)could be expressed as follows:

    where the Δ [M(x)],Δ[K(x)]and Δ[C(x)]are the variable quantity of each matrix and they are the function of the vector x.

    In order to analyze the dynamic response described as Eq.(6),the initial values of dynamic absorber are required to start the numerical computation.Then,the matrices of the system are updated according to the Eqs.(8-10).Based on the solution technology dealing with the vibration problems of multiple degree-of-freedom system[13],e.g.,the substructure mode synthesis or model reduction,the displacement,velocity and acceleration from Eq.(6)can be finally obtained.

    In the situation of the axial vibration of the marine shafting system,one can assume that the original system is excited a unit harmonically load at the propeller.With the Eqs.(6-10),the axial displacement as well as the axial velocity at each node could be solved.The force transmissibility and the power transmissibility at the thrust bearing are expressed as:

    As shown in the above equations,T(x,ω)and W(x,ω)are the functions of three main variables at thrust bearing,the force FT,the axial displacement un-2and axial velocity vn-2.The interval ω?[ωmin,ωmax]is the response frequency range of the marine shafting axial vibration.

    3.2 Objective function

    Aiming to attenuate the axial vibration of the marine shafting system over the concerned response frequency range,appropriate algorithms should be explored to solve the design variables x of the dynamic absorber.It should be noted that the marine structure vibration through the thrust bearing is the main vibration transmission path.As a result,the response at thrust bearing is to be minimized over a frequency range ωmin≤ω≤ωmaxby attaching the dynamic absorber.Correspondingly,the objective function based on the force transmissibility and the power transmissibility is given by:

    The physical meaning of Eq.(12)could be expressed as:the issue of dynamic absorber parameters optimization is to minimize the maximum value of the force transmissibility and the power transmissibility at the thrust bearing over the frequency range,and finally achieve the purposes of controlling the axial vibration of the marine shafting system.

    3.3 Constraints

    When the dynamic absorber is used to control the marine shafting system,the variables of dynamic absorber should satisfy the design requirements for parameters optimization.Define the xminand xmaxas the lower and upper limits of the design variables x,respectively,and the range of variables can be written as inequality constraints:

    For the non-linear optimization problem in this paper,by combining the objective function in Eq.(12)with the constraints in Eq.(13)and choosing the external point penalty function method,one can express the regenerate objective function as objk′(x,ω,)R :

    where R is the weight factor between the objective functions and the constraints.I is the number of inequality constraints.

    3.4 Optimization algorithm description

    The objective function described in Eq.(14) could be solved with different optimization algorithm techniques.Genetic algorithm is one of the most suitable methodologies,which is a search technique used to find the global approximate solutions to optimization.The significant advantage of the techniques for design values optimization is that there are no strict analytic objective requirements,and it is also suitable for a variety of variables,especially the discrete ones.The details of procedures for solving the Eq.(14)coupled with the genetic algorithm and multi-objective optimization algorithm are described in the following.

    The response frequency band is first discretized.The vibration transmissibility described in Eq.(11)at the ith discrete frequency is written as Yk(x,ωi),where the ωiis the discrete frequency.Using the objective functions in Eq.(14)as the fitness functions,the maximum valuecan be obtained if the parameters of the genetic algorithm are defined,such as individual numbers,generation numbers,and variable precision.All the maximum values at discrete frequencies will constitute a vector,where the s is the number of discrete frequency point.Then,the maximum value of the vibration transmissibility is minimized with the linear weighting method to solve the multi-objective optimization problem.Finally,by transforming Yk(x,ωi)to the dimensionless form at every discrete frequency,the evaluation function is obtained to solve the objective function Eq.(14)based on the linear weighting sum[14].

    where αiis the weighting coefficient which assigns the relative importance of the criterion and.Optimization problem described as Eq.(11)will change the analysis of the objective function(x,ω,R).Eq.(15)will be used to optimize the dynamic absorber parameters over the frequency range with the genetic algorithm and the multi-objective optimization algorithm.

    4 Numerical example

    4.1 Parameters optimization over 0-300 Hz

    To illustrate the numerical method described above,an example of a marine shafting system is presented and a single dynamic absorber is used to control the axial vibration of the original system.The finite element model is established based on the sketch of the marine shaft system shown in Fig.4.

    Fig.4 The finite element model of the marine shafting system

    This sketch contains 19 nodes,17 beam elements,six lump masses and one axial spring.The three natural frequencies of the axial vibration in this example over 0-300 Hz frequency range are 51 Hz,122 Hz and 256 Hz.

    The force transmissibility and the power transmissibility versus frequency of the original marine shafting system are shown in Fig.5.The following force transmissibility and the power transmissibility are calculated with base-10 logarithm.

    Fig.5 The vibration transmissibility curve of the original marine shafting system

    The paper is to study the characteristics of dynamic absorber at different positions in the marine shafting system.Since the transmission shaft mainly consists of the stern shaft,the intermediate shaft and the thrust shaft,the dynamic absorbers are applied to the three locations of the shaft segments shown in Fig.4,which are the location A,location B and location C.

    The optimization parameters of dynamic absorber are solved with objective functions(x,ω,R)given in Eq.(15)based on the optimization algorithm shown above.In addition,the effect of different locations to control the axial vibration is explored.The lower limit and the upper limit of the dynamic absorber within the optimization process are shown in Tab.1.

    Tab.1 The limits values of the dynamic absorber

    Using the force transmissibility at the thrust bearing as the criterion to solve the objective function in Eq.(15),the optimal values of the dynamic absorber are given in Tab.2,as well as the natural frequency f1.Fig.6(1)shows the force transmissibility versus frequency for the cases with dynamic absorber at three different locations.The resonance frequencies of shafting system and the amplitude of resonance peaks are different for the dynamic absorber at different positions.

    Tab.2 Optimal values of dynamic absorber with the force transmissibility

    Fig.6 The vibration transmissibility of different dynamic absorbers locations(over 0-300 Hz)

    A comparison of the resonance frequencies of shafting system is shown in Fig.6(1).The first natural frequency becomes smaller than that of the shafting system without adding dynamic absorber.It is also clear from the figure that all the other resonance peaks,except the first peak,become lower than the corresponding resonance peaks without the dynamic absorber.As a result,after applying a single dynamic absorber to the original system,the second and third resonance peaks are suppressed when the optimal parameters of dynamic absorber are set.However,the first resonance peak attenuation is not obvious.

    Simultaneously,the influence on the dynamic absorber located at three different positions in the first resonance peak attenuation is almost the same.The amplitude of second resonance peak is decreased obviously when the dynamic absorber is fixed on the intermediate shaft,and the amplitude of third resonance peak reduces more when the dynamic absorber is located at the stern shaft.

    With the power transmissibility at the thrust bearing as the criterion to solve the objective function in Eq.(15),the optimal values of the dynamic absorber parameters are also given in Tab.3.A plot of the power transmissibility versus frequency curve with the dynamic absorber at three different locations is shown in Fig.6(2).

    Tab.3 Optimal values of dynamic absorber with the power transmissibility

    Comparing Fig.6(1)and Fig.6(2),the phenomenon of dynamic absorber on axial vibration absorption based on the two objective functions is almost the same.For example,the amplitude of the second and third resonance peaks become smaller when the dynamic absorber is applied to the three different locations.However,it is observed from the Fig.6(2)that there is an anti-resonance peak at the resonance frequency 122 Hz when a single dynamic absorber is attached at the stern shaft and the intermediate shaft.This value is equal to the second resonance frequency of the original system.It is demonstrated that the resonance peaks could be suppressed when the natural frequency of dynamic absorber is equal to that of the primary system.Therefore,parameter optimization of dynamic absorber is also the process of finding the appropriate parameters to solve the system oscillation at certain frequency.

    4.2 Specific resonance frequency attenuation

    The numerical example discussed above cares about the parameters optimization of the dynamic absorber over the entire frequency range.Providing that the problem of reducing the first resonance frequency has been increasingly a major concern,the method to suppress the first resonance frequency to control the axial vibration of original system will be presented as follows.

    Based on the performance of the dynamic absorber to suppress the original system oscillation,an equality constraint will be added to the objective functions in Eq.(15).The method could enable the natural frequency of the dynamic absorber equal to the first resonant frequency.The equality constraint is expressed as follows:

    where f1is the first resonance frequency of the original marine shafting system.

    Substituting Eq.(16)into Eq.(15)to optimize the parameters of dynamic absorber,the new objective functions(x,ω,R,S)is given in Eq.(17)

    where S is the weight factor of the equality constraints.The optimal values are obtained with the objective functions in Eq.(17),as shown in Tab.4 and Tab.5.

    Tab.4 Optimal values for specific resonance attenuation with the force transmissibility

    As can be seen from Tab.4 and Tab.5,for the dynamic absorbers at the three different locations,the natural frequencies of the dynamic absorber based on the two objective functions are close to the first resonance frequency of the original marine shafting system.It is demonstrated that the specific resonance could be attenuated by adding the equality constraint to the objective functions.However,the natural frequencies of the dynamic absorber are not exactly the same regardless of the different objective functions or different locations are chosen.It is the reason why the penalty factor and the number of genetic generation are used in the genetic algorithm process.With the force transmissibility and the power transmissibility to analyze the effect of specific resonance attenuation,the different curves are shown in Fig.7(1)and Fig.7(2).

    Tab.5 Optimal values for specific resonance attenuation with the power transmissibility

    Fig.7 The vibration transmissibility for specific resonance attenuation

    The amplitude of the first resonance peak shown in the two figures is significantly suppressed.With the method of adding the equality constraint to optimize the parameters,the purpose of reducing the specific peaks could be achieveed.A comparison of the three different locations for the first resonance attenuation is presented.It is shown that the efficiency of attaching dynamic absorber to the stern shaft is better than that to the intermediate shaft.The amplitude reduction of the second and third resonance peaks is almost the same based on the two objective functions in Eq.(17),while the dynamic absorber installed to the stern shaft could be the best third resonance peak suppression.

    5 Conclusions and discussion

    Based on the previous results,we could draw the following comments and conclusions:

    1)With the method of the genetic algorithm and multi-objective optimization algorithm,the problem of parameters optimization to control the axial vibration of the marine shafting system could be solved.Over the 0-300 Hz frequency range,the phenomenon of three resonance frequency reduction is similar with the two objective functions.

    2)Comparing to the optimal results with the two objective functions over the 0-300 Hz frequency range,it is obviously proposed in this paper that the second and three resonance frequencies of the marine shafting system could be better attenuated with the optimization algorithm.However,it is shown that less effect is made to control the first resonance peak.

    3)In order to suppress the first resonance peak,the equality constraint is introduced based on the characteristic of the dynamic absorber.Optimization results show that the method presented here could control the first resonance response.Comparison of the attenuation effect of different locations shows that,the three resonance peaks could be controlled better when dynamic absorber is added to the stern shaft.

    [1]Xu Yunxiu,Zhong Xuetian,He Xuanxuan.Axial vibration of the ship shafting system[M].Beijing:China Communications Press,1985.

    [2]Ding Wenjing.Theory of vibration absorption[M].Beijing:Tsinghua University Press,1988.

    [3]Randall S E,Halsted D M,Taulor D L.Optimum vibration absorbers for linear damped systems[J].Journal of Mechanical Design,1981,103:908-913.

    [4]Ram Y M,Elhay S.The theory of a multi-degree-of-freedom dynamic absorber[J].Journal of Sound and Vibration,1996,195(4):607-615.

    [5]Hsueh W J.Vibration transmissibility of a unidirectional multi-degree-of-freedom system with multiple dynamic absorbers[J].Journal of Sound and Vibration,2000,229(4):793-805.

    [6]Kitis L.Vibration reduction over a frequency range[J].Journal of Sound and Vibration,1983,89(4):559-569.

    [7]Jang S J,Choi Y J.Geometrical design method of multi-degree-of-freedom dynamic vibration absorbers[J].Journal of Sound and Vibration,2007,303(2):343-356.

    [8]Sun H L,Zhang P Q,Chen H B,Zhang K,Gong X L.Application of dynamic vibration absorbers in structural vibration control under multi-frequency harmonic excitations[J].Applied Acoustics,2008,69:1361-1367.

    [9]Dylejko P G,Kessissoglou N J,Tso Y,Norwood C J.Optimization of a resonance changer to minimise the vibration transmission in marine vessels[J].Journal of Sound and Vibration,2007,300:101-116.

    [10]Viana F A C,Kotinda G I,Rade D A,Steffen V.Tuning dynamic vibration absorbers by using ant colony optimization[J].Computers and Structures,2008,86(14):1539-1549.

    [11]Kela L,V?h?oja P.Recent studies of adaptive tuned vibration absorbers/neutralizers[J].Applied Mechanics Reviews,2009,62(6):1-9.

    [12]Zhang Zhihua.Numerical calculation of power equipment vibration[M].Harbin:Harbin Engineering University Press,1994.

    [13]Clough R W,Penzien J.Dynamics of structures[M].New York:McGraw-Hill,1993.

    [14]Zeng Guangwu.Optimization design of ship structure[M].Wuhan:Huazhong University of Science and Technology Press,2004.

    国产精品一国产av| 夜夜骑夜夜射夜夜干| 国产日韩欧美视频二区| 在线观看免费视频网站a站| 中文字幕人妻丝袜制服| 桃花免费在线播放| 2021少妇久久久久久久久久久| 美女视频免费永久观看网站| 91精品三级在线观看| 日韩av不卡免费在线播放| 在线av久久热| 国产xxxxx性猛交| 精品少妇黑人巨大在线播放| 69精品国产乱码久久久| 亚洲精品av麻豆狂野| 亚洲av综合色区一区| 精品人妻在线不人妻| 国产免费福利视频在线观看| 2018国产大陆天天弄谢| 亚洲欧美精品综合一区二区三区| 两个人免费观看高清视频| 男女免费视频国产| 国产精品人妻久久久影院| 美国免费a级毛片| 亚洲精品一区蜜桃| 免费女性裸体啪啪无遮挡网站| 精品久久久久久电影网| 一本久久精品| 国产xxxxx性猛交| 成年美女黄网站色视频大全免费| av网站在线播放免费| 最近手机中文字幕大全| 青春草视频在线免费观看| 免费在线观看完整版高清| 人人妻人人澡人人爽人人夜夜| 男女边摸边吃奶| 亚洲国产av新网站| 国产成人欧美在线观看 | 91麻豆av在线| 国产亚洲午夜精品一区二区久久| 国产精品99久久99久久久不卡| 日本欧美视频一区| 1024视频免费在线观看| svipshipincom国产片| a 毛片基地| h视频一区二区三区| 亚洲黑人精品在线| 中国国产av一级| 侵犯人妻中文字幕一二三四区| h视频一区二区三区| 交换朋友夫妻互换小说| 国产高清videossex| 亚洲欧美日韩另类电影网站| 亚洲,欧美,日韩| 久久九九热精品免费| 精品第一国产精品| 亚洲专区中文字幕在线| 最近中文字幕2019免费版| 操美女的视频在线观看| a级毛片黄视频| 日本欧美视频一区| 天天躁夜夜躁狠狠久久av| 国产成人啪精品午夜网站| 欧美日韩av久久| 久热这里只有精品99| 1024视频免费在线观看| 啦啦啦中文免费视频观看日本| 免费在线观看影片大全网站 | 多毛熟女@视频| 777久久人妻少妇嫩草av网站| 80岁老熟妇乱子伦牲交| 婷婷色综合大香蕉| 亚洲 欧美一区二区三区| 久久久久久久大尺度免费视频| 日韩,欧美,国产一区二区三区| 欧美日韩一级在线毛片| av不卡在线播放| 天天影视国产精品| 国产精品国产三级专区第一集| 黑人欧美特级aaaaaa片| 丝瓜视频免费看黄片| 久久女婷五月综合色啪小说| 免费不卡黄色视频| 精品福利观看| 欧美人与善性xxx| 欧美少妇被猛烈插入视频| 99久久综合免费| 欧美日韩精品网址| h视频一区二区三区| 免费看十八禁软件| 啦啦啦视频在线资源免费观看| 国产欧美日韩一区二区三区在线| 大陆偷拍与自拍| 亚洲免费av在线视频| 亚洲精品国产av成人精品| 欧美精品高潮呻吟av久久| 男女免费视频国产| av一本久久久久| 天堂俺去俺来也www色官网| 亚洲男人天堂网一区| 最黄视频免费看| 亚洲中文日韩欧美视频| 久热这里只有精品99| 一区二区三区精品91| 国产99久久九九免费精品| 久久人人97超碰香蕉20202| 在线亚洲精品国产二区图片欧美| 欧美日本中文国产一区发布| 日本一区二区免费在线视频| 国产免费一区二区三区四区乱码| 精品人妻在线不人妻| 大香蕉久久成人网| 91九色精品人成在线观看| 久久国产精品男人的天堂亚洲| 国产福利在线免费观看视频| 一级毛片女人18水好多 | 七月丁香在线播放| 精品少妇一区二区三区视频日本电影| 亚洲中文av在线| 日韩大片免费观看网站| 韩国高清视频一区二区三区| 欧美日韩亚洲综合一区二区三区_| 日韩中文字幕视频在线看片| 免费看av在线观看网站| 免费观看人在逋| 欧美中文综合在线视频| 18禁观看日本| cao死你这个sao货| 日日爽夜夜爽网站| avwww免费| 一区二区三区精品91| 国产成人免费无遮挡视频| 久久精品国产a三级三级三级| 一级毛片黄色毛片免费观看视频| 搡老乐熟女国产| 每晚都被弄得嗷嗷叫到高潮| 成人免费观看视频高清| 黑人猛操日本美女一级片| 久久久久久免费高清国产稀缺| 日韩熟女老妇一区二区性免费视频| 成人国语在线视频| 在线观看www视频免费| 岛国毛片在线播放| 欧美中文综合在线视频| 国产无遮挡羞羞视频在线观看| 亚洲av日韩精品久久久久久密 | 亚洲精品国产av蜜桃| 精品国产一区二区三区久久久樱花| 大片电影免费在线观看免费| 欧美成人精品欧美一级黄| 黑丝袜美女国产一区| 国产男女内射视频| 丝瓜视频免费看黄片| 99国产精品一区二区蜜桃av | 午夜福利在线免费观看网站| 2018国产大陆天天弄谢| 亚洲国产成人一精品久久久| av网站免费在线观看视频| 青青草视频在线视频观看| 久久精品国产a三级三级三级| 亚洲av日韩在线播放| 中国国产av一级| 嫩草影视91久久| 精品免费久久久久久久清纯 | 亚洲精品中文字幕在线视频| 女人高潮潮喷娇喘18禁视频| 国产免费又黄又爽又色| 免费看不卡的av| 国产黄色免费在线视频| 久久久久视频综合| 男人操女人黄网站| 日韩伦理黄色片| 少妇的丰满在线观看| 中文字幕最新亚洲高清| 国产精品一区二区精品视频观看| kizo精华| 成人黄色视频免费在线看| 中文字幕av电影在线播放| 日本五十路高清| 91精品三级在线观看| 久久这里只有精品19| 一边亲一边摸免费视频| 九色亚洲精品在线播放| 久久亚洲国产成人精品v| 成年美女黄网站色视频大全免费| 99久久精品国产亚洲精品| 热99国产精品久久久久久7| 一区福利在线观看| 免费高清在线观看日韩| 99热网站在线观看| 99国产精品一区二区三区| 亚洲av成人不卡在线观看播放网 | videos熟女内射| 成年美女黄网站色视频大全免费| 日韩av免费高清视频| 精品少妇一区二区三区视频日本电影| 国产在线视频一区二区| 久久精品亚洲av国产电影网| 国产高清videossex| 欧美成人精品欧美一级黄| 午夜福利免费观看在线| a级毛片在线看网站| 看免费av毛片| 亚洲欧洲日产国产| av不卡在线播放| 日韩精品免费视频一区二区三区| 一级毛片黄色毛片免费观看视频| 一边亲一边摸免费视频| 久久精品久久久久久久性| 精品一区二区三卡| 天天操日日干夜夜撸| svipshipincom国产片| 婷婷色av中文字幕| 夫妻性生交免费视频一级片| 国产一区亚洲一区在线观看| 久久人人爽人人片av| 免费在线观看完整版高清| 免费看十八禁软件| 看免费av毛片| 97在线人人人人妻| 欧美日本中文国产一区发布| 国产精品秋霞免费鲁丝片| 欧美性长视频在线观看| 亚洲精品久久成人aⅴ小说| 亚洲熟女精品中文字幕| 久久 成人 亚洲| 亚洲精品第二区| 巨乳人妻的诱惑在线观看| 欧美精品一区二区免费开放| 水蜜桃什么品种好| 性色av乱码一区二区三区2| 黄片播放在线免费| 国产精品久久久av美女十八| 国产一区二区在线观看av| 国产亚洲av高清不卡| 精品国产一区二区三区久久久樱花| 亚洲国产精品一区三区| 午夜免费观看性视频| 日本wwww免费看| 黄网站色视频无遮挡免费观看| 久久人妻熟女aⅴ| 亚洲色图综合在线观看| a级片在线免费高清观看视频| 十分钟在线观看高清视频www| 婷婷成人精品国产| 日韩av在线免费看完整版不卡| av国产久精品久网站免费入址| 国产91精品成人一区二区三区 | 欧美日韩一级在线毛片| 妹子高潮喷水视频| 又大又爽又粗| 丝袜脚勾引网站| 色网站视频免费| xxxhd国产人妻xxx| 亚洲男人天堂网一区| 一级片'在线观看视频| 91字幕亚洲| 十八禁人妻一区二区| 日本欧美国产在线视频| 一级毛片黄色毛片免费观看视频| 亚洲国产欧美网| 免费在线观看完整版高清| 大片电影免费在线观看免费| 国产在线观看jvid| 欧美黄色淫秽网站| 亚洲国产精品国产精品| 又大又黄又爽视频免费| 老司机靠b影院| 免费看十八禁软件| 国产黄色视频一区二区在线观看| 国产成人精品无人区| 丝袜美足系列| 久久精品国产亚洲av涩爱| 国产男女内射视频| 丝袜喷水一区| 桃花免费在线播放| 精品人妻1区二区| 亚洲熟女精品中文字幕| 热re99久久精品国产66热6| 久久久久久久久久久久大奶| 热99国产精品久久久久久7| 亚洲av日韩精品久久久久久密 | 在线观看免费视频网站a站| 婷婷色麻豆天堂久久| 国产99久久九九免费精品| 国产免费福利视频在线观看| 伦理电影免费视频| 日韩中文字幕欧美一区二区 | 欧美日韩视频精品一区| 午夜91福利影院| www.自偷自拍.com| 成年人免费黄色播放视频| 国产成人91sexporn| 91精品伊人久久大香线蕉| 老司机靠b影院| 色94色欧美一区二区| 91麻豆av在线| 久久久久网色| 国产淫语在线视频| 一级片免费观看大全| 91麻豆av在线| 国产精品免费视频内射| 久久av网站| 人人妻人人澡人人看| 国产av国产精品国产| 在线观看人妻少妇| 国产在线免费精品| 国产精品亚洲av一区麻豆| 97人妻天天添夜夜摸| 日韩视频在线欧美| 欧美亚洲 丝袜 人妻 在线| 啦啦啦中文免费视频观看日本| 国产成人系列免费观看| 可以免费在线观看a视频的电影网站| 好男人电影高清在线观看| 国产精品一国产av| 美女视频免费永久观看网站| 免费观看a级毛片全部| 天堂俺去俺来也www色官网| a级毛片在线看网站| 国产老妇伦熟女老妇高清| 叶爱在线成人免费视频播放| netflix在线观看网站| 成年人免费黄色播放视频| 人人澡人人妻人| 热99久久久久精品小说推荐| 欧美大码av| 久久精品aⅴ一区二区三区四区| 可以免费在线观看a视频的电影网站| 97在线人人人人妻| 七月丁香在线播放| tube8黄色片| 国产一区二区在线观看av| 中文字幕亚洲精品专区| 日韩伦理黄色片| 欧美成人精品欧美一级黄| 国产精品一国产av| 女人被躁到高潮嗷嗷叫费观| 99精品久久久久人妻精品| 蜜桃国产av成人99| av福利片在线| 伊人久久大香线蕉亚洲五| 别揉我奶头~嗯~啊~动态视频 | 亚洲,欧美精品.| 国产视频首页在线观看| 欧美变态另类bdsm刘玥| 制服人妻中文乱码| 亚洲,欧美精品.| av天堂久久9| 国产不卡av网站在线观看| 欧美另类一区| 尾随美女入室| 黄色a级毛片大全视频| 午夜福利,免费看| 欧美久久黑人一区二区| 欧美黑人欧美精品刺激| av在线播放精品| 日韩,欧美,国产一区二区三区| 黄色怎么调成土黄色| 欧美黄色片欧美黄色片| 脱女人内裤的视频| 久久久国产精品麻豆| 老司机在亚洲福利影院| 国产亚洲精品久久久久5区| 一本久久精品| 高清黄色对白视频在线免费看| 色婷婷久久久亚洲欧美| 最近最新中文字幕大全免费视频 | 一区二区三区精品91| 亚洲成人免费电影在线观看 | 午夜免费成人在线视频| 久久久久视频综合| 精品一品国产午夜福利视频| 国产精品一区二区在线不卡| 国产成人一区二区在线| 亚洲精品av麻豆狂野| 国产三级黄色录像| 午夜日韩欧美国产| 狠狠婷婷综合久久久久久88av| 婷婷色综合www| 免费观看av网站的网址| 中文乱码字字幕精品一区二区三区| 亚洲九九香蕉| 免费日韩欧美在线观看| av网站免费在线观看视频| 国产精品99久久99久久久不卡| 亚洲国产欧美一区二区综合| 国产亚洲av高清不卡| 嫁个100分男人电影在线观看 | 操美女的视频在线观看| 国产免费又黄又爽又色| www.熟女人妻精品国产| 亚洲视频免费观看视频| 日本av手机在线免费观看| 黄色视频不卡| 久久精品国产综合久久久| 色网站视频免费| 亚洲欧美清纯卡通| 国产女主播在线喷水免费视频网站| 丝袜脚勾引网站| 麻豆av在线久日| 日韩中文字幕欧美一区二区 | tube8黄色片| 午夜激情久久久久久久| 久久久欧美国产精品| 9色porny在线观看| 日韩熟女老妇一区二区性免费视频| 亚洲国产欧美网| 免费观看人在逋| 美女国产高潮福利片在线看| 欧美日韩成人在线一区二区| 晚上一个人看的免费电影| 日本一区二区免费在线视频| 丝袜喷水一区| 久久久精品94久久精品| 亚洲成av片中文字幕在线观看| 免费在线观看日本一区| 天天添夜夜摸| 五月天丁香电影| 麻豆av在线久日| 免费看av在线观看网站| 亚洲国产av影院在线观看| 91成人精品电影| 国产精品人妻久久久影院| 一区福利在线观看| 黄片播放在线免费| 国产成人精品在线电影| www日本在线高清视频| 男的添女的下面高潮视频| 国产日韩欧美视频二区| 99热国产这里只有精品6| 极品少妇高潮喷水抽搐| 亚洲精品国产一区二区精华液| 久久天堂一区二区三区四区| 日日爽夜夜爽网站| 免费女性裸体啪啪无遮挡网站| 亚洲欧美中文字幕日韩二区| 只有这里有精品99| 日韩制服丝袜自拍偷拍| 成年女人毛片免费观看观看9 | 国产精品人妻久久久影院| 人妻 亚洲 视频| 人人澡人人妻人| 成人免费观看视频高清| 色婷婷久久久亚洲欧美| 大香蕉久久成人网| 老熟女久久久| 免费久久久久久久精品成人欧美视频| 久久亚洲国产成人精品v| 丁香六月欧美| 亚洲七黄色美女视频| 日韩 亚洲 欧美在线| 日本av免费视频播放| 国产深夜福利视频在线观看| 大片电影免费在线观看免费| 一本一本久久a久久精品综合妖精| 高清不卡的av网站| 性色av乱码一区二区三区2| 久久久久国产精品人妻一区二区| 观看av在线不卡| 国产亚洲精品第一综合不卡| www.熟女人妻精品国产| 19禁男女啪啪无遮挡网站| 国语对白做爰xxxⅹ性视频网站| 精品福利永久在线观看| 性色av一级| 女警被强在线播放| 久久国产精品男人的天堂亚洲| av天堂久久9| 美女高潮到喷水免费观看| 一本久久精品| 中文字幕人妻熟女乱码| 精品人妻一区二区三区麻豆| 国产精品三级大全| 老汉色av国产亚洲站长工具| 一级毛片我不卡| av网站免费在线观看视频| 婷婷色av中文字幕| 首页视频小说图片口味搜索 | 国产1区2区3区精品| 黄频高清免费视频| 欧美成人午夜精品| 久久这里只有精品19| 国产精品香港三级国产av潘金莲 | 亚洲九九香蕉| 一级黄片播放器| 国产精品一国产av| tube8黄色片| 在线观看国产h片| 国产一区二区激情短视频 | 欧美97在线视频| 久久人人爽av亚洲精品天堂| 人体艺术视频欧美日本| 少妇 在线观看| 亚洲人成电影免费在线| 青春草视频在线免费观看| 91老司机精品| 欧美激情高清一区二区三区| 亚洲中文字幕日韩| 国产成人免费观看mmmm| 18禁国产床啪视频网站| 亚洲欧美一区二区三区久久| 久久精品成人免费网站| 乱人伦中国视频| 欧美国产精品一级二级三级| 国产一区二区激情短视频 | 久热这里只有精品99| 久久精品久久精品一区二区三区| 男女之事视频高清在线观看 | 亚洲av欧美aⅴ国产| 黄色 视频免费看| 日韩中文字幕视频在线看片| 亚洲久久久国产精品| 王馨瑶露胸无遮挡在线观看| 免费看十八禁软件| 精品亚洲乱码少妇综合久久| www.熟女人妻精品国产| 亚洲av电影在线进入| 欧美精品亚洲一区二区| 国产成人一区二区三区免费视频网站 | 丝瓜视频免费看黄片| 日本猛色少妇xxxxx猛交久久| 国产欧美亚洲国产| av电影中文网址| 免费高清在线观看视频在线观看| 涩涩av久久男人的天堂| 青春草亚洲视频在线观看| 精品久久久久久久毛片微露脸 | 中文字幕亚洲精品专区| 国产精品免费大片| 视频区欧美日本亚洲| 水蜜桃什么品种好| 久久久精品国产亚洲av高清涩受| 国产午夜精品一二区理论片| 好男人视频免费观看在线| 色精品久久人妻99蜜桃| 亚洲伊人色综图| 久久久久精品国产欧美久久久 | 日韩一本色道免费dvd| 伊人久久大香线蕉亚洲五| 国产精品欧美亚洲77777| 欧美激情极品国产一区二区三区| 欧美日韩精品网址| 久久久精品国产亚洲av高清涩受| 天天躁狠狠躁夜夜躁狠狠躁| 国产亚洲午夜精品一区二区久久| 国产91精品成人一区二区三区 | 亚洲熟女精品中文字幕| 嫩草影视91久久| 日韩中文字幕视频在线看片| 精品一品国产午夜福利视频| 国产片内射在线| av有码第一页| 欧美精品亚洲一区二区| 精品久久久久久电影网| 黄片小视频在线播放| 国产精品久久久久成人av| 国产精品成人在线| 国产又爽黄色视频| 日日摸夜夜添夜夜爱| av网站免费在线观看视频| www.自偷自拍.com| 99国产精品99久久久久| 一级,二级,三级黄色视频| 一本—道久久a久久精品蜜桃钙片| 18禁国产床啪视频网站| 夜夜骑夜夜射夜夜干| 午夜av观看不卡| 男女无遮挡免费网站观看| 国产成人a∨麻豆精品| 1024视频免费在线观看| 国产日韩欧美亚洲二区| 人人澡人人妻人| 最近最新中文字幕大全免费视频 | 菩萨蛮人人尽说江南好唐韦庄| 久久久精品免费免费高清| 亚洲欧美一区二区三区久久| 两性夫妻黄色片| 男女无遮挡免费网站观看| 中文字幕高清在线视频| 这个男人来自地球电影免费观看| 无遮挡黄片免费观看| 久久久久久久精品精品| 久久99一区二区三区| 韩国精品一区二区三区| 欧美精品av麻豆av| 免费女性裸体啪啪无遮挡网站| 欧美日韩亚洲高清精品| www.熟女人妻精品国产| 中文字幕人妻丝袜制服| 国产欧美日韩一区二区三区在线| 午夜久久久在线观看| 欧美日韩综合久久久久久| 韩国高清视频一区二区三区| 一级片'在线观看视频| 亚洲av电影在线进入| 丰满饥渴人妻一区二区三| 一级片'在线观看视频| 国产成人精品在线电影| 热re99久久精品国产66热6| 国产精品免费大片| 最近中文字幕2019免费版| 黄色 视频免费看| 激情五月婷婷亚洲| 男女之事视频高清在线观看 | 欧美精品一区二区免费开放| 成年动漫av网址| 亚洲国产最新在线播放| 国产熟女午夜一区二区三区| 考比视频在线观看| 一本大道久久a久久精品| 在线观看免费午夜福利视频| 亚洲成人国产一区在线观看 | 日本色播在线视频| 国产av一区二区精品久久|