C. Steele, Alissa Fitzgerald, T. Kenny, K. Lim, S. Puria
The purpose of this study is to resolve questions regarding the fundamental physical behavior of the cochlea of the inner ear. We seek a convergence of measurement and computation on physical models that capture essential features. Since there are unique features in the performance of the cochlea, the physical models could lead to device development. A much longer-term goal is a device for the assistance of hearing impaired individuals. The cochlea can be modeled as a tube of fluid divided by a partition, a portion of which is elastic and called the basilar membrane (BM). In preliminary work, the cochlear partition is constructed on a silicon wafer using current capabilities for micro-machining. The silicon nitride partition is inserted into a chamber of Plexiglas which is filled with solute and has a “stapes” for acoustic input and a “round window”. The silicon BM has the correct length, but is wider and isotropic. The measurements, supported by calculations, show that the deviation from the actual structure has a detrimental effect on the sharpness of the spatial distribution of the response for a fixed input frequency. Possibilities for improved models and for an active non-linear model with distributed sensors and actuators are discussed.
{"title":"Possibilities for a Silicon Model of the Cochlea","authors":"C. Steele, Alissa Fitzgerald, T. Kenny, K. Lim, S. Puria","doi":"10.1115/imece2000-1604","DOIUrl":"https://doi.org/10.1115/imece2000-1604","url":null,"abstract":"\u0000 The purpose of this study is to resolve questions regarding the fundamental physical behavior of the cochlea of the inner ear. We seek a convergence of measurement and computation on physical models that capture essential features. Since there are unique features in the performance of the cochlea, the physical models could lead to device development. A much longer-term goal is a device for the assistance of hearing impaired individuals. The cochlea can be modeled as a tube of fluid divided by a partition, a portion of which is elastic and called the basilar membrane (BM). In preliminary work, the cochlear partition is constructed on a silicon wafer using current capabilities for micro-machining. The silicon nitride partition is inserted into a chamber of Plexiglas which is filled with solute and has a “stapes” for acoustic input and a “round window”. The silicon BM has the correct length, but is wider and isotropic. The measurements, supported by calculations, show that the deviation from the actual structure has a detrimental effect on the sharpness of the spatial distribution of the response for a fixed input frequency. Possibilities for improved models and for an active non-linear model with distributed sensors and actuators are discussed.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123879388","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 streaming induced in a short vertical liquid column by the vibration of one of the supporting end walls has been utilized in this novel study. Vibration essentially drives a surface flow in the zone away from the vibrating wall, with the return flow in the bulk towards the wall. Preliminary measurements of the surface streaming velocity show that it increases with the frequency and amplitude of vibration and the zone length, and decreases with the viscosity of the zone liquid. This controlled surface streaming has been employed to balance a opposing, steady thermocapillary flow in model half-zones of silicone oil and Sodium Nitrate. In addition, in a float-zone solidification experiment with Sodium Nitrate - Barium Nitrate eutectic as the study material, we have demonstrated that streaming-based balancing of thermocapillary flow promotes a planar solid/liquid interface and a uniform microstructure.
{"title":"Role of Vibration-Induced Streaming in Float-Zone Crystal Growth","authors":"A. Anilkumar, R. Grugel, C. P. Lee, M. F. Rose","doi":"10.2514/6.2001-614","DOIUrl":"https://doi.org/10.2514/6.2001-614","url":null,"abstract":"\u0000 The streaming induced in a short vertical liquid column by the vibration of one of the supporting end walls has been utilized in this novel study. Vibration essentially drives a surface flow in the zone away from the vibrating wall, with the return flow in the bulk towards the wall. Preliminary measurements of the surface streaming velocity show that it increases with the frequency and amplitude of vibration and the zone length, and decreases with the viscosity of the zone liquid. This controlled surface streaming has been employed to balance a opposing, steady thermocapillary flow in model half-zones of silicone oil and Sodium Nitrate. In addition, in a float-zone solidification experiment with Sodium Nitrate - Barium Nitrate eutectic as the study material, we have demonstrated that streaming-based balancing of thermocapillary flow promotes a planar solid/liquid interface and a uniform microstructure.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115987657","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}
Algorithms for determining material properties and power flow in vibrating structures are presented. The new techniques are achieved by synthesizing wave component identification methods developed previously (Halliday and Grosh, 2000) with new methods targeted towards material property and structural intensity estimation. The effectiveness of this nonlinear least-squares approach is investigated through laboratory and numerical experiments on a non-uniform structure, yielding guidelines for spatial sampling and the effects of noise.
{"title":"Non-Linear Least-Squares Estimation of Material Properties and Structural Intensity in Non-Uniform Beams","authors":"P. J. Halliday, K. Grosh","doi":"10.1115/imece2000-1620","DOIUrl":"https://doi.org/10.1115/imece2000-1620","url":null,"abstract":"\u0000 Algorithms for determining material properties and power flow in vibrating structures are presented. The new techniques are achieved by synthesizing wave component identification methods developed previously (Halliday and Grosh, 2000) with new methods targeted towards material property and structural intensity estimation. The effectiveness of this nonlinear least-squares approach is investigated through laboratory and numerical experiments on a non-uniform structure, yielding guidelines for spatial sampling and the effects of noise.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128684177","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 emergence of acoustic compressors has been made possible by the development of a new technology called Resonant MacroSonic Synthesis (RMS). RMS allows the creation of macrosonic standing waves in acoustic resonators. The shape of the resonator controls the nonlinear fluid dynamic processes by which energy is transferred to higher harmonics. Through this process resonators have been designed that allow high-amplitude shock-free waveforms. A variable reluctance driver is used to transfer energy into the resonator. The entire resonator is oscillated along its axis at the fundamental acoustic resonance frequency. This process is called entire resonator drive. The valve technology used in these compressors is similar to that of conventional reciprocating compressors. Acoustic compressors are inherently variable capacity and oil-free. Other unique characteristics are flexible orientation and low profile packaging option. Development focuses on vapor-compression applications. The application discussed here is spot-cooling.
{"title":"Introduction to Acoustic Compressors","authors":"B. Lipkens, F. Lalande, D. Perkins","doi":"10.1115/imece2000-1599","DOIUrl":"https://doi.org/10.1115/imece2000-1599","url":null,"abstract":"\u0000 The emergence of acoustic compressors has been made possible by the development of a new technology called Resonant MacroSonic Synthesis (RMS). RMS allows the creation of macrosonic standing waves in acoustic resonators. The shape of the resonator controls the nonlinear fluid dynamic processes by which energy is transferred to higher harmonics. Through this process resonators have been designed that allow high-amplitude shock-free waveforms. A variable reluctance driver is used to transfer energy into the resonator. The entire resonator is oscillated along its axis at the fundamental acoustic resonance frequency. This process is called entire resonator drive. The valve technology used in these compressors is similar to that of conventional reciprocating compressors. Acoustic compressors are inherently variable capacity and oil-free. Other unique characteristics are flexible orientation and low profile packaging option. Development focuses on vapor-compression applications. The application discussed here is spot-cooling.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121391664","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 computation of exterior wave problems at low wave numbers can become prohibitively expensive when higher circumferential modes are significant. An analysis of the effect of wave number on scattering problems, with local absorbing boundary conditions specified on simple shapes as on-surface radiation conditions, provides guidelines for satisfactory performance. Excessive computational cost may be avoided for most practical applications.
{"title":"The Effect of Wave Number on the Performance of BGT Absorbing Boundary Conditions for Acoustic Scattering","authors":"I. Harari, R. Djellouli","doi":"10.1115/imece2000-1593","DOIUrl":"https://doi.org/10.1115/imece2000-1593","url":null,"abstract":"\u0000 The computation of exterior wave problems at low wave numbers can become prohibitively expensive when higher circumferential modes are significant. An analysis of the effect of wave number on scattering problems, with local absorbing boundary conditions specified on simple shapes as on-surface radiation conditions, provides guidelines for satisfactory performance. Excessive computational cost may be avoided for most practical applications.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132359147","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 this study the free bending vibrations of compsite base plates or panels reinforced by a non-central (or eccentric) stiffening plate strip are considered. The base plate and the stiffening plate strip are dissimilar orthotropic plates. They are connected by a very thin and flexible adhesive layer. The dynamic equations of the entire composite plate system are obtained from the “Mindlin Plate Theory” for orthotropic plates. The set of the governing partial differential equations of the composite plate or panel system are reduced to a set of first order ordinary differential equations by the elimination of the time variable and one of the space variables. This final system of the first order differential equations in one space variable is integrated by the “Modified Version of the Transfer Matrix Method”. It was shown that the natural frequencies, at any mode, of the plate or panel system gradually increase at first with the increasing “Bending Cross Stiffness Ratio”. After then, for certain values of this “Ratio”, the natural frequencies for each mode, suddenly drop to a lower value and subsequently start to go up, although slowly, regardless of the support conditions. This unusual “Sudden Drop Phenomena” is explained in detail and, also, the mode shapes corresponding to the sudden drop are presented. The effect of the “hard” and the “soft” adhesive layer on the “Phenomena” are also shown.
{"title":"Sudden Drop Phenomena in Natural Frequencies of Composite Plates or Panels With a Non-Central (or Eccentric) Stiffening Plate Strip","authors":"U. Yuceoglu, V. Özerciyes","doi":"10.1115/imece2000-1634","DOIUrl":"https://doi.org/10.1115/imece2000-1634","url":null,"abstract":"\u0000 In this study the free bending vibrations of compsite base plates or panels reinforced by a non-central (or eccentric) stiffening plate strip are considered. The base plate and the stiffening plate strip are dissimilar orthotropic plates. They are connected by a very thin and flexible adhesive layer. The dynamic equations of the entire composite plate system are obtained from the “Mindlin Plate Theory” for orthotropic plates. The set of the governing partial differential equations of the composite plate or panel system are reduced to a set of first order ordinary differential equations by the elimination of the time variable and one of the space variables. This final system of the first order differential equations in one space variable is integrated by the “Modified Version of the Transfer Matrix Method”. It was shown that the natural frequencies, at any mode, of the plate or panel system gradually increase at first with the increasing “Bending Cross Stiffness Ratio”. After then, for certain values of this “Ratio”, the natural frequencies for each mode, suddenly drop to a lower value and subsequently start to go up, although slowly, regardless of the support conditions. This unusual “Sudden Drop Phenomena” is explained in detail and, also, the mode shapes corresponding to the sudden drop are presented. The effect of the “hard” and the “soft” adhesive layer on the “Phenomena” are also shown.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123763769","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 reviews research which has demonstrated the use of nondestructive measurements of stiffness and damping to characterize some interesting aspects of both micromechanical and macromechanical behavior in materials and structures. The sensitivity of stiffness and damping to material microstructural detail, macroscopic defects and damage, degradation due to environmental conditions such as temperature and moisture, and other mechanical properties is examined. Observed changes in stiffness and damping can be particularly useful when measured by using nondestructive vibration tests, and there are potential applications of such measurements in both manufacturing quality control and in-service evaluation of materials and structures. A particularly attractive method for fast, low cost nondestructive measurement of stiffness and damping is based on the use of impulsive excitation, non-contacting response measurement, and data analysis with PC-based virtual instruments.
{"title":"Sensitivity of Stiffness and Damping to Various Aspects of Material and Structural Behavior","authors":"R. Gibson","doi":"10.1115/imece2000-1617","DOIUrl":"https://doi.org/10.1115/imece2000-1617","url":null,"abstract":"\u0000 This paper reviews research which has demonstrated the use of nondestructive measurements of stiffness and damping to characterize some interesting aspects of both micromechanical and macromechanical behavior in materials and structures. The sensitivity of stiffness and damping to material microstructural detail, macroscopic defects and damage, degradation due to environmental conditions such as temperature and moisture, and other mechanical properties is examined. Observed changes in stiffness and damping can be particularly useful when measured by using nondestructive vibration tests, and there are potential applications of such measurements in both manufacturing quality control and in-service evaluation of materials and structures. A particularly attractive method for fast, low cost nondestructive measurement of stiffness and damping is based on the use of impulsive excitation, non-contacting response measurement, and data analysis with PC-based virtual instruments.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130420923","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 U. S. Navy has a long-standing history of ship design using metals. With the improvements in weapon systems, it is becoming increasingly critical to design ship structures not only to satisfy the structural loading but also to exhibit additional multifunctional properties. This is becoming evident with structures such as the Advanced Enclosed Mast Sensor System, AEM/S, which was installed on the USS Radford. This structure was designed to house radar systems and allow the passage of certain radar frequencies through the structure while simultaneously not allowing the penetration of radar at other frequencies. In addition, the structure was designed to reduce the ship’s detectability. This paper will present a summary of the large-scale composite manufacturing that is being considered for Naval Structures. These structures are being manufactured using low-cost manufacturing techniques and are incorporating multifunctional characteristics in addition to meeting the structural requirement of the application. This paper will provide a historical discussion on the use of composite applications in the surface fleet.
{"title":"The Use of Multifunctional Composite Materials in Large Scale Naval Applications","authors":"R. Crane","doi":"10.1115/imece2000-1631","DOIUrl":"https://doi.org/10.1115/imece2000-1631","url":null,"abstract":"\u0000 The U. S. Navy has a long-standing history of ship design using metals. With the improvements in weapon systems, it is becoming increasingly critical to design ship structures not only to satisfy the structural loading but also to exhibit additional multifunctional properties. This is becoming evident with structures such as the Advanced Enclosed Mast Sensor System, AEM/S, which was installed on the USS Radford. This structure was designed to house radar systems and allow the passage of certain radar frequencies through the structure while simultaneously not allowing the penetration of radar at other frequencies. In addition, the structure was designed to reduce the ship’s detectability.\u0000 This paper will present a summary of the large-scale composite manufacturing that is being considered for Naval Structures. These structures are being manufactured using low-cost manufacturing techniques and are incorporating multifunctional characteristics in addition to meeting the structural requirement of the application. This paper will provide a historical discussion on the use of composite applications in the surface fleet.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130056748","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}
R. Crane, J. Gillespie, D. Heider, D. A. Eckel, C. Ratcliffe
This paper presents the results of an ongoing investigation into the use of broadband vibration data to monitor the structural integrity and health of an all-composite road bridge. Bridge 1-351 on Business Route 896 in Glasgow, Delaware, was replaced with one of the first state-owned all-composite bridges in the nation in the fall of 1998. The bridge consists of two E-Glass/vinyl ester sandwich core sections (13-ft × 32 ft) joined by a longitudinal joint in the traffic direction. Each sandwich core section consists of a 28-inch deep core and 0.4-0.7-inch thick facesheets. Vibration data were obtained from the upper and lower surfaces of the bridge using a mesh of 1050 test points. From the modal information and the visualization of the data, several aspects of the structural behavior of the bridge were obtained. These characteristics include the interactions between the bridge and abutments; the effectiveness of the longitudinal joint to couple the deck sections; the effectiveness of the core to couple the face sheets; and the structural integrity and dynamic consistency of the entire structure. Mode shapes and natural frequencies were determined and are correlated with theoretical calculations and vibration analyses conducted for this bridge. A novel algorithm using the vibration data is being developed that enables local perturbations sensitive to the state of the material (e.g. manufacturing defects, material degradation or service damage) to be detected and spatially located in the bridge. This technique has been successfully validated for locating damage in 1-D beam structures and is being extended to the 3-D sandwich configuration of the bridge. By coupling this damage detection algorithm with the more conventional modal technique, the quality assurance/quality control and health monitoring of large composite bridge can be obtained.
{"title":"Monitoring and Defect Detection of an All-Composite Road Bridge","authors":"R. Crane, J. Gillespie, D. Heider, D. A. Eckel, C. Ratcliffe","doi":"10.1115/imece2000-1628","DOIUrl":"https://doi.org/10.1115/imece2000-1628","url":null,"abstract":"\u0000 This paper presents the results of an ongoing investigation into the use of broadband vibration data to monitor the structural integrity and health of an all-composite road bridge. Bridge 1-351 on Business Route 896 in Glasgow, Delaware, was replaced with one of the first state-owned all-composite bridges in the nation in the fall of 1998. The bridge consists of two E-Glass/vinyl ester sandwich core sections (13-ft × 32 ft) joined by a longitudinal joint in the traffic direction. Each sandwich core section consists of a 28-inch deep core and 0.4-0.7-inch thick facesheets.\u0000 Vibration data were obtained from the upper and lower surfaces of the bridge using a mesh of 1050 test points. From the modal information and the visualization of the data, several aspects of the structural behavior of the bridge were obtained. These characteristics include the interactions between the bridge and abutments; the effectiveness of the longitudinal joint to couple the deck sections; the effectiveness of the core to couple the face sheets; and the structural integrity and dynamic consistency of the entire structure. Mode shapes and natural frequencies were determined and are correlated with theoretical calculations and vibration analyses conducted for this bridge.\u0000 A novel algorithm using the vibration data is being developed that enables local perturbations sensitive to the state of the material (e.g. manufacturing defects, material degradation or service damage) to be detected and spatially located in the bridge. This technique has been successfully validated for locating damage in 1-D beam structures and is being extended to the 3-D sandwich configuration of the bridge. By coupling this damage detection algorithm with the more conventional modal technique, the quality assurance/quality control and health monitoring of large composite bridge can be obtained.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129532872","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 key to successful multifunctional materials applications for vibration, shock and acoustic control is often the proper selection of materials, geometric design and optimum application. Much work has been done in the areas of geometric designs and optimum application of the multi-functional materials. The next step is improvements in the passive damping materials themselves. The improvement in the passive materials in the past has often focused on the areas of improved damping performance (loss factor, storage modulus), material performance (acrylics, silicones, etc.) and enhanced features (thermally conductive, electrically conductive, etc). One of the newest requirements for passive damping polymers is in the area of ultra-pure viscoelastic damping polymers. This new generation of materials is finding growing use because the sensitive environment where the passive material is used require a material that will not negatively impact the components in that environment. This new generation of passive materials needs to be ultra-pure with respect to organic material outgassing, anions, catalysts and siloxanes. In addition to the viscoelastic damping polymer requirements for high purity, the associated polymeric materials (epoxies, laminating adhesives and tapes) used in the same environment must also be of a similar low outgassing, ultra-pure, ultra-clean, electronics grade or clean room performance designation. If this is not done, the environment could become contaminated and negate a portion of the benefit of using the clean damping material. This also requires an understanding of the test method used to determine each product’s cleanliness performance, as all test methods are not equal and can give significantly different test results. An example is comparing a polymer sample tested for organic outgassing and using a static headspace gas chromatography/mass spectroscopy (GC/MS) and a dynamic headspace GC/MS.
{"title":"Ultra-Pure Viscoelastic Damping Polymers and Associated Low Outgassing Materials","authors":"Jeff W. McCutcheon","doi":"10.1115/imece2000-1636","DOIUrl":"https://doi.org/10.1115/imece2000-1636","url":null,"abstract":"\u0000 The key to successful multifunctional materials applications for vibration, shock and acoustic control is often the proper selection of materials, geometric design and optimum application. Much work has been done in the areas of geometric designs and optimum application of the multi-functional materials. The next step is improvements in the passive damping materials themselves.\u0000 The improvement in the passive materials in the past has often focused on the areas of improved damping performance (loss factor, storage modulus), material performance (acrylics, silicones, etc.) and enhanced features (thermally conductive, electrically conductive, etc). One of the newest requirements for passive damping polymers is in the area of ultra-pure viscoelastic damping polymers. This new generation of materials is finding growing use because the sensitive environment where the passive material is used require a material that will not negatively impact the components in that environment. This new generation of passive materials needs to be ultra-pure with respect to organic material outgassing, anions, catalysts and siloxanes.\u0000 In addition to the viscoelastic damping polymer requirements for high purity, the associated polymeric materials (epoxies, laminating adhesives and tapes) used in the same environment must also be of a similar low outgassing, ultra-pure, ultra-clean, electronics grade or clean room performance designation. If this is not done, the environment could become contaminated and negate a portion of the benefit of using the clean damping material. This also requires an understanding of the test method used to determine each product’s cleanliness performance, as all test methods are not equal and can give significantly different test results. An example is comparing a polymer sample tested for organic outgassing and using a static headspace gas chromatography/mass spectroscopy (GC/MS) and a dynamic headspace GC/MS.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115980353","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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