Pub Date : 2017-02-10DOI: 10.12677/OJAV.2017.51001
潘路希, 李易寒, 温凌坤, 杨为为
本研究是探讨不同孔径的分布对穿孔板吸声效果的影响。实验及理论分析表明，此时的孔径分布，确实存在一个最优化分布的问题。据此，研究组引入新的物理量吸声面积，从而简便的评定全频内吸声效果的优劣。之后，研究组利用数学统筹的方法，结合系统声阻及选择性吸声的原理，通过吸声面积大小的比较，研究了一定参数条件下，使效果最佳的孔径分布方案。通过实验及理论分析表明，该方案是由穿孔率、孔径、板厚等结构参数来共同决定的，这也是孔面积最佳分布点的物理意义。 The study is to investigate the influence of different pore size distribution on the effect of the sound absorption. Experimental and theoretical analysis shows that there is an optimal distribu-tion of the pore size distribution. Accordingly, a new physical sound absorption area is introduced by the study group, thus whether full-range sound absorption effect is good or bad will be evaluated simply. After that, the study group studied the optimum pore size distribution scheme under the condition of certain parameters by using the method of mathematical co-ordination, combining with the principle of acoustic impedance and selective sound absorption, and comparing sound-absorbing area. The results of experiment and theoretical analysis show that the scheme is determined by perforation rate, pore diameter, thickness of the plates and other structural parameters, which is also the physical meaning of the best distribution point of pore area.
本研究是探讨不同孔径的分布对穿孔板吸声效果的影响。实验及理论分析表明，此时的孔径分布，确实存在一个最优化分布的问题。据此，研究组引入新的物理量吸声面积，从而简便的评定全频内吸声效果的优劣。之后，研究组利用数学统筹的方法，结合系统声阻及选择性吸声的原理，通过吸声面积大小的比较，研究了一定参数条件下，使效果最佳的孔径分布方案。通过实验及理论分析表明，该方案是由穿孔率、孔径、板厚等结构参数来共同决定的，这也是孔面积最佳分布点的物理意义。 The study is to investigate the influence of different pore size distribution on the effect of the sound absorption. Experimental and theoretical analysis shows that there is an optimal distribu-tion of the pore size distribution. Accordingly, a new physical sound absorption area is introduced by the study group, thus whether full-range sound absorption effect is good or bad will be evaluated simply. After that, the study group studied the optimum pore size distribution scheme under the condition of certain parameters by using the method of mathematical co-ordination, combining with the principle of acoustic impedance and selective sound absorption, and comparing sound-absorbing area. The results of experiment and theoretical analysis show that the scheme is determined by perforation rate, pore diameter, thickness of the plates and other structural parameters, which is also the physical meaning of the best distribution point of pore area.
{"title":"不同孔径的分布对穿孔板吸声效果的影响 The Effect of Different Distribution and Sizes of Apertures on Sound Absorption Characteristics of Perforated Plate","authors":"潘路希, 李易寒, 温凌坤, 杨为为","doi":"10.12677/OJAV.2017.51001","DOIUrl":"https://doi.org/10.12677/OJAV.2017.51001","url":null,"abstract":"本研究是探讨不同孔径的分布对穿孔板吸声效果的影响。实验及理论分析表明，此时的孔径分布，确实存在一个最优化分布的问题。据此，研究组引入新的物理量吸声面积，从而简便的评定全频内吸声效果的优劣。之后，研究组利用数学统筹的方法，结合系统声阻及选择性吸声的原理，通过吸声面积大小的比较，研究了一定参数条件下，使效果最佳的孔径分布方案。通过实验及理论分析表明，该方案是由穿孔率、孔径、板厚等结构参数来共同决定的，这也是孔面积最佳分布点的物理意义。 The study is to investigate the influence of different pore size distribution on the effect of the sound absorption. Experimental and theoretical analysis shows that there is an optimal distribu-tion of the pore size distribution. Accordingly, a new physical sound absorption area is introduced by the study group, thus whether full-range sound absorption effect is good or bad will be evaluated simply. After that, the study group studied the optimum pore size distribution scheme under the condition of certain parameters by using the method of mathematical co-ordination, combining with the principle of acoustic impedance and selective sound absorption, and comparing sound-absorbing area. The results of experiment and theoretical analysis show that the scheme is determined by perforation rate, pore diameter, thickness of the plates and other structural parameters, which is also the physical meaning of the best distribution point of pore area.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"05 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2017-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41845204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Syed Ahmed Shah, C. Nageswaranath, M. Ramesh, M. V. Ramanamurthy
Torsional vibrations of coated hollow poroelastic spheres are studied employing Biot’s theory of wave propagation in poroelastic solid. The dilatations of solid and liquid media are zero, therefore the frequency equation of torsional vibrations is same both for a permeable and an impermeable surface. The coated poroelastic sphere consists of an inner hollow poroelastic sphere bounded by and bonded to a sphere made of distinct poroelastic material. The inner sphere is designated as core and outer sphere as casing. Core and casing are bonded at the curved surfaces. The inner and outer boundaries of the coated hollow poroelastic sphere are free from stress and at the interface of core and casing the displacement and stresses are continuous. It is assumed that the each material of coated sphere is homogeneous and isotropic. The frequency equation of torsional vibrations of a coated poroelastic hollow sphere is obtained when the material of the core vanishes. Also a coated poroelastic solid sphere is obtained as the limiting case of the frequency equation of coated hollow poroelastic sphere when the inner radius of core approaches to zero. Non-dimensional frequency as a function of ratio of thickness of core to that of inner radius of core is determined and analyzed. It is observed that the frequency and dispersion increase with the increase of the thickness of the coating.
{"title":"Torsional Vibrations of Coated Hollow Poroelastic Spheres","authors":"Syed Ahmed Shah, C. Nageswaranath, M. Ramesh, M. V. Ramanamurthy","doi":"10.4236/OJA.2017.71003","DOIUrl":"https://doi.org/10.4236/OJA.2017.71003","url":null,"abstract":"Torsional vibrations of coated hollow poroelastic spheres are studied employing Biot’s theory of wave propagation in poroelastic solid. The dilatations of solid and liquid media are zero, therefore the frequency equation of torsional vibrations is same both for a permeable and an impermeable surface. The coated poroelastic sphere consists of an inner hollow poroelastic sphere bounded by and bonded to a sphere made of distinct poroelastic material. The inner sphere is designated as core and outer sphere as casing. Core and casing are bonded at the curved surfaces. The inner and outer boundaries of the coated hollow poroelastic sphere are free from stress and at the interface of core and casing the displacement and stresses are continuous. It is assumed that the each material of coated sphere is homogeneous and isotropic. The frequency equation of torsional vibrations of a coated poroelastic hollow sphere is obtained when the material of the core vanishes. Also a coated poroelastic solid sphere is obtained as the limiting case of the frequency equation of coated hollow poroelastic sphere when the inner radius of core approaches to zero. Non-dimensional frequency as a function of ratio of thickness of core to that of inner radius of core is determined and analyzed. It is observed that the frequency and dispersion increase with the increase of the thickness of the coating.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"07 1","pages":"18-26"},"PeriodicalIF":0.0,"publicationDate":"2017-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42280685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For acoustic applications such as theaters, cinema halls, auditoriums the data on acoustic properties i.e. sound absorption coefficient and sound transmission loss are required to evaluate the acoustic behavior of panel products and to facilitate the necessary design computations. Fibre boards are widely used in private and commercial buildings, but not much data are available on acoustic efficiency of fibre boards. The study was carried using acoustic pulse tester based on standing wave method for evaluating sound absorption coefficient. Wood fibre boards of different densities ranging from 200 to 800 kg/m3 were taken and their sound absorption coefficients at frequencies ranging from 125 Hz to 4000 Hz were evaluated in third octave band. Noise reduction coefficient of the samples was also computed. From the study, it is observed that low density fibre board possess high sound absorption coefficient and noise reduction coefficient when compared with high density fibre boards. It was seen that sound absorption coefficient increases with decrease in density and vice versa.
{"title":"Influence of Density on Sound Absorption Coefficient of Fibre Board","authors":"A. Nandanwar, M. C. Kiran, K. Varadarajulu","doi":"10.4236/OJA.2017.71001","DOIUrl":"https://doi.org/10.4236/OJA.2017.71001","url":null,"abstract":"For acoustic applications such as theaters, cinema halls, auditoriums the data on acoustic properties i.e. sound absorption coefficient and sound transmission loss are required to evaluate the acoustic behavior of panel products and to facilitate the necessary design computations. Fibre boards are widely used in private and commercial buildings, but not much data are available on acoustic efficiency of fibre boards. The study was carried using acoustic pulse tester based on standing wave method for evaluating sound absorption coefficient. Wood fibre boards of different densities ranging from 200 to 800 kg/m3 were taken and their sound absorption coefficients at frequencies ranging from 125 Hz to 4000 Hz were evaluated in third octave band. Noise reduction coefficient of the samples was also computed. From the study, it is observed that low density fibre board possess high sound absorption coefficient and noise reduction coefficient when compared with high density fibre boards. It was seen that sound absorption coefficient increases with decrease in density and vice versa.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"7 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2017-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43259335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The first part of this article addresses the main premise of the Theory of Musical Equilibration. It states that in contrast to previous hypotheses, music does not directly describe emotions: instead; it evokes processes of the will which the listener identifies with. It is not until these processes are experienced that music appears to take on an emotional character. The second part of the article focuses on demonstrating the emotional nature of musical harmonies. The Basic Test and the Rocky Test are presented. These tests were designed to find correlations between chords and scenes from fairy tales as well as emotional terms. 86% of the participants correlated the musical selection to the emotion outlined by the Theory of Musical Equilibration the authors developed in this context.
{"title":"Feelings Which Strike a Chord, and Chords Which Strike a Feeling","authors":"Bernd Willimek, Daniela Willimek","doi":"10.4236/OJA.2017.71002","DOIUrl":"https://doi.org/10.4236/OJA.2017.71002","url":null,"abstract":"The first part of this article addresses the main premise of the Theory of Musical Equilibration. It states that in contrast to previous hypotheses, music does not directly describe emotions: instead; it evokes processes of the will which the listener identifies with. It is not until these processes are experienced that music appears to take on an emotional character. The second part of the article focuses on demonstrating the emotional nature of musical harmonies. The Basic Test and the Rocky Test are presented. These tests were designed to find correlations between chords and scenes from fairy tales as well as emotional terms. 86% of the participants correlated the musical selection to the emotion outlined by the Theory of Musical Equilibration the authors developed in this context.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"07 1","pages":"10-17"},"PeriodicalIF":0.0,"publicationDate":"2017-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46238779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This review analyzes following numerical methods of a solution of problems of a sound diffraction on ideal and elastic scatterers of a non-analytical form: a method of integral equations, a method of Green’s functions, a method of finite elements, a boundary elements method, a method of Kupradze, a T-matrix method and a method of a geometrical theory of a diffraction.
{"title":"Some Methods of Solution of Problems of Sound Diffraction on Bodies of Non-Analytical Form","authors":"A. Kleshchev","doi":"10.4236/OJA.2016.64005","DOIUrl":"https://doi.org/10.4236/OJA.2016.64005","url":null,"abstract":"This review analyzes following numerical methods of a solution of problems of a sound diffraction on ideal and elastic scatterers of a non-analytical form: a method of integral equations, a method of Green’s functions, a method of finite elements, a boundary elements method, a method of Kupradze, a T-matrix method and a method of a geometrical theory of a diffraction.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"6 1","pages":"45-70"},"PeriodicalIF":0.0,"publicationDate":"2016-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70558045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes an analysis of the sound pressure levels at the exterior facade and inside the Hospital de Clinicas of the Federal University of Parana. Measurements were taken at a total of 45 points, 24 at the exterior facade and 21 points inside the hospital on all the floors of the main building and in the maternity building. These 45 measurements were used to calculate the acoustic map of the hospital, which is located on General Carneiro Street, in the city of Curitiba, state of Parana, Brazil. A comparison of the measured outdoor sound pressure levels against those established by Curitiba Municipal Law No. 10625 revealed that they all exceeded the daytime limit of 55 dB(A) permitted for areas around hospitals. The indoor sound pressure measurements and the noise levels for acoustic comfort established by the Brazilian technical standard ABNT NBR 10152 were compared, indicating that all the measured points, including those in the neonatal intensive care unit, exceeded the established limit of 35 dB(A) to 45 dB(A).
{"title":"Assessment of Indoor and Outdoor Noise Pollution at a University Hospital Based on Acoustic Measurements and Noise Mapping","authors":"P. Zannin, F. Ferraz","doi":"10.4236/OJA.2016.64006","DOIUrl":"https://doi.org/10.4236/OJA.2016.64006","url":null,"abstract":"This paper describes an analysis of the sound pressure levels at the exterior facade and inside the Hospital de Clinicas of the Federal University of Parana. Measurements were taken at a total of 45 points, 24 at the exterior facade and 21 points inside the hospital on all the floors of the main building and in the maternity building. These 45 measurements were used to calculate the acoustic map of the hospital, which is located on General Carneiro Street, in the city of Curitiba, state of Parana, Brazil. A comparison of the measured outdoor sound pressure levels against those established by Curitiba Municipal Law No. 10625 revealed that they all exceeded the daytime limit of 55 dB(A) permitted for areas around hospitals. The indoor sound pressure measurements and the noise levels for acoustic comfort established by the Brazilian technical standard ABNT NBR 10152 were compared, indicating that all the measured points, including those in the neonatal intensive care unit, exceeded the established limit of 35 dB(A) to 45 dB(A).","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"6 1","pages":"71-85"},"PeriodicalIF":0.0,"publicationDate":"2016-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70558060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present paper, the governing equations of a linear transversely isotropic micropolar piezoelectric medium are specialized for x-z plane after using symmetry relations in constitutive coefficients. These equations are solved for the general surface wave solutions in the medium. Following radiation conditions in the half-space, the particular solutions are obtained, which satisfy the appropriate boundary conditions at the stress-free surface of the half-space. A secular equation for Rayleigh type surface wave is obtained. An iteration method is applied to compute the non-dimensional wave speed of the Rayleigh surface wave for specific material parameters. The effects of piezoelectricity, non-dimensional frequency and non-dimensional material constant, charge free surface and electrically shorted surface are shown graphically on the wave speed of Rayleigh wave.
{"title":"On Propagation of Rayleigh Type Surface Wave in a Micropolar Piezoelectric Medium","authors":"Baljeet Singh, R. Sindhu","doi":"10.4236/OJA.2016.64004","DOIUrl":"https://doi.org/10.4236/OJA.2016.64004","url":null,"abstract":"In the present paper, the governing equations of a linear transversely isotropic micropolar piezoelectric medium are specialized for x-z plane after using symmetry relations in constitutive coefficients. These equations are solved for the general surface wave solutions in the medium. Following radiation conditions in the half-space, the particular solutions are obtained, which satisfy the appropriate boundary conditions at the stress-free surface of the half-space. A secular equation for Rayleigh type surface wave is obtained. An iteration method is applied to compute the non-dimensional wave speed of the Rayleigh surface wave for specific material parameters. The effects of piezoelectricity, non-dimensional frequency and non-dimensional material constant, charge free surface and electrically shorted surface are shown graphically on the wave speed of Rayleigh wave.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"06 1","pages":"35-44"},"PeriodicalIF":0.0,"publicationDate":"2016-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70558009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-11-18DOI: 10.12677/OJAV.2016.43004
范晨光, 杨翊仁
为研究超声速轴向流中完全锥壳的气动弹性非线性响应，本文采用活塞理论计算超声速气动力，利用截锥壳的非线性气动弹性运动方程，在截锥壳顶角不为零，小半径无限趋近于零的特定边界条件下，采用一维微分求积法(DQM)离散，数值逼近求解了完全锥壳的颤振临界动压及气动弹性响应。结果表明，不同边界条件对完全锥壳气动颤振临界动压和极限环幅值的影响不大，最小颤振临界对应周向波数相对较小。当动压参数较大时，数值模拟结果显示，顶端自由，底端固支的锥壳还存在一种半稳定的高阶响应极限环，该极限环对应的振幅最大点更靠近锥壳底端。 A study on the nonlinear flutter of circular conical shells in axial supersonic airflow was presented. The piston theory was used to calculate aerodynamic force. Nonlinear aeroelastic equations of circular truncated conical shells were used, when the truncated conical shell angle is not zero and the smaller radius is infinitely close to zero. Under this specific boundary conditions, the flutter critical aerodynamic pressures and nonlinear response of circular conical shells were investigated with one dimensional DQM (differential quadrature method). The results show that, the influence of different boundary conditions on the critical dynamic pressure and the limit cycle amplitude of the circular conical shell is not significant.The wave number corresponding to the minimum critical flutter aerodynamic pressure is relatively small. When the dynamic pressure parameters are large, the numerical simulation results show that there is a semi stable high order limit cycle, which maximum point is closer to the bottom of the cone shell.
为研究超声速轴向流中完全锥壳的气动弹性非线性响应，本文采用活塞理论计算超声速气动力，利用截锥壳的非线性气动弹性运动方程，在截锥壳顶角不为零，小半径无限趋近于零的特定边界条件下，采用一维微分求积法(DQM)离散，数值逼近求解了完全锥壳的颤振临界动压及气动弹性响应。结果表明，不同边界条件对完全锥壳气动颤振临界动压和极限环幅值的影响不大，最小颤振临界对应周向波数相对较小。当动压参数较大时，数值模拟结果显示，顶端自由，底端固支的锥壳还存在一种半稳定的高阶响应极限环，该极限环对应的振幅最大点更靠近锥壳底端。 A study on the nonlinear flutter of circular conical shells in axial supersonic airflow was presented. The piston theory was used to calculate aerodynamic force. Nonlinear aeroelastic equations of circular truncated conical shells were used, when the truncated conical shell angle is not zero and the smaller radius is infinitely close to zero. Under this specific boundary conditions, the flutter critical aerodynamic pressures and nonlinear response of circular conical shells were investigated with one dimensional DQM (differential quadrature method). The results show that, the influence of different boundary conditions on the critical dynamic pressure and the limit cycle amplitude of the circular conical shell is not significant.The wave number corresponding to the minimum critical flutter aerodynamic pressure is relatively small. When the dynamic pressure parameters are large, the numerical simulation results show that there is a semi stable high order limit cycle, which maximum point is closer to the bottom of the cone shell.
{"title":"一类完全锥壳的超声速气动弹性响应问题 Supersonic Aeroelastic Response of Circular Conical Shells","authors":"范晨光, 杨翊仁","doi":"10.12677/OJAV.2016.43004","DOIUrl":"https://doi.org/10.12677/OJAV.2016.43004","url":null,"abstract":"为研究超声速轴向流中完全锥壳的气动弹性非线性响应，本文采用活塞理论计算超声速气动力，利用截锥壳的非线性气动弹性运动方程，在截锥壳顶角不为零，小半径无限趋近于零的特定边界条件下，采用一维微分求积法(DQM)离散，数值逼近求解了完全锥壳的颤振临界动压及气动弹性响应。结果表明，不同边界条件对完全锥壳气动颤振临界动压和极限环幅值的影响不大，最小颤振临界对应周向波数相对较小。当动压参数较大时，数值模拟结果显示，顶端自由，底端固支的锥壳还存在一种半稳定的高阶响应极限环，该极限环对应的振幅最大点更靠近锥壳底端。 A study on the nonlinear flutter of circular conical shells in axial supersonic airflow was presented. The piston theory was used to calculate aerodynamic force. Nonlinear aeroelastic equations of circular truncated conical shells were used, when the truncated conical shell angle is not zero and the smaller radius is infinitely close to zero. Under this specific boundary conditions, the flutter critical aerodynamic pressures and nonlinear response of circular conical shells were investigated with one dimensional DQM (differential quadrature method). The results show that, the influence of different boundary conditions on the critical dynamic pressure and the limit cycle amplitude of the circular conical shell is not significant.The wave number corresponding to the minimum critical flutter aerodynamic pressure is relatively small. When the dynamic pressure parameters are large, the numerical simulation results show that there is a semi stable high order limit cycle, which maximum point is closer to the bottom of the cone shell.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"04 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66177921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-11-18DOI: 10.12677/OJAV.2016.43005
张萌, 张硕韶, 孙海荣
本文采用等效刚度法，将铁道车辆车体这种复杂结构等效为等截面梁；应用弯曲变形能相等的原理，结合车体特征，并引入了相关修正系数，得到了车体的等效惯性矩Ie。以铁木辛柯梁的振动频率计算公式为依据，并在长度方向上对车体的面积及剪切形状系数进行了修正，得到了最终的计算公式。将简单车体及某型高速车体的参数代入公式，并将计算得到的结果与有限元结果进行了对比，证明了计算方法的可靠性，为车体垂弯频率的计算提供一种参考计算方法。 The railway vehicle car-body can be equivalent to the uniform beam with a method of equivalent stiffness. Equivalent inertia moment Ie can be calculated with bending strain energy equality the-ory and a related coefficient according to car-body structure. With the Timoshenko beam theory and some models, a final formula is obtained. A simple car-body model and a high-speed car-body model are calculated with above method, and there are acceptable errors between analytical and finite element results, which is a reference method for car-body design.
本文采用等效刚度法，将铁道车辆车体这种复杂结构等效为等截面梁；应用弯曲变形能相等的原理，结合车体特征，并引入了相关修正系数，得到了车体的等效惯性矩Ie。以铁木辛柯梁的振动频率计算公式为依据，并在长度方向上对车体的面积及剪切形状系数进行了修正，得到了最终的计算公式。将简单车体及某型高速车体的参数代入公式，并将计算得到的结果与有限元结果进行了对比，证明了计算方法的可靠性，为车体垂弯频率的计算提供一种参考计算方法。 The railway vehicle car-body can be equivalent to the uniform beam with a method of equivalent stiffness. Equivalent inertia moment Ie can be calculated with bending strain energy equality the-ory and a related coefficient according to car-body structure. With the Timoshenko beam theory and some models, a final formula is obtained. A simple car-body model and a high-speed car-body model are calculated with above method, and there are acceptable errors between analytical and finite element results, which is a reference method for car-body design.
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Pub Date : 2016-11-18DOI: 10.12677/OJAV.2016.43003
夏 方弈
本文在考虑了阻抗管中存在多重反射的情况下，利用传递函数法优化得出了样品的透射系数和反射系数，从而获得声学超材料有效材料参数。在比较了不同阻抗管算法实验结果之后，可以发现本文提出的新测量方法和仿真结果有着很好的吻合，可以非常准确的获得材料的有效参量。新发展的测量方法，对消声端的消声吸声要求不高，可以测量不吸声的材料，扩展了阻抗管测量的适用范围，对声学超材料的设计和相关应用都有着一定价值。 A new experimental method is developed to precisely measure the effective density and bulk modulus using impedance tube. Considering the multiple reflections on multi-surfaces, a new al-gorithm using transfer matrix method is considered to obtain the transmission and reflection coefficient through a lossless sample and the corresponding effective parameter can thus be retrieved. Good consistence can be found between simulations and experiments. Having little impact from the absorbing property of the termination, our newly developed method has advantages to traditional impedance tube methods and can benefit the development of acoustic metamaterials.
本文在考虑了阻抗管中存在多重反射的情况下，利用传递函数法优化得出了样品的透射系数和反射系数，从而获得声学超材料有效材料参数。在比较了不同阻抗管算法实验结果之后，可以发现本文提出的新测量方法和仿真结果有着很好的吻合，可以非常准确的获得材料的有效参量。新发展的测量方法，对消声端的消声吸声要求不高，可以测量不吸声的材料，扩展了阻抗管测量的适用范围，对声学超材料的设计和相关应用都有着一定价值。 A new experimental method is developed to precisely measure the effective density and bulk modulus using impedance tube. Considering the multiple reflections on multi-surfaces, a new al-gorithm using transfer matrix method is considered to obtain the transmission and reflection coefficient through a lossless sample and the corresponding effective parameter can thus be retrieved. Good consistence can be found between simulations and experiments. Having little impact from the absorbing property of the termination, our newly developed method has advantages to traditional impedance tube methods and can benefit the development of acoustic metamaterials.
{"title":"Measuring Effective Parameters of Composite Acoustic Metamaterials Using Impedance Tube","authors":"夏 方弈","doi":"10.12677/OJAV.2016.43003","DOIUrl":"https://doi.org/10.12677/OJAV.2016.43003","url":null,"abstract":"本文在考虑了阻抗管中存在多重反射的情况下，利用传递函数法优化得出了样品的透射系数和反射系数，从而获得声学超材料有效材料参数。在比较了不同阻抗管算法实验结果之后，可以发现本文提出的新测量方法和仿真结果有着很好的吻合，可以非常准确的获得材料的有效参量。新发展的测量方法，对消声端的消声吸声要求不高，可以测量不吸声的材料，扩展了阻抗管测量的适用范围，对声学超材料的设计和相关应用都有着一定价值。 A new experimental method is developed to precisely measure the effective density and bulk modulus using impedance tube. Considering the multiple reflections on multi-surfaces, a new al-gorithm using transfer matrix method is considered to obtain the transmission and reflection coefficient through a lossless sample and the corresponding effective parameter can thus be retrieved. Good consistence can be found between simulations and experiments. Having little impact from the absorbing property of the termination, our newly developed method has advantages to traditional impedance tube methods and can benefit the development of acoustic metamaterials.","PeriodicalId":63563,"journal":{"name":"声学期刊(英文)","volume":"04 1","pages":"19-26"},"PeriodicalIF":0.0,"publicationDate":"2016-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66177855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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