Air suspension is gaining more and more popularity with both the auto industry and drivers. Traditionally the height adjustability aspect of air suspension systems has been their main attracting attribute. More recently, resolving the classic conflict of combining comfortable ride with sport handling in a single suspension setup has become the main attraction of air suspension. An air suspension system has been developed which in addition to height adjustment, can adjust its damping and stiffness in real time with using neither viscous dampers nor any additional actuators. This is done by real-time adjustment air flow to and from the air springs using proportional valves. Measured relative displacement and acceleration as well as estimated velocity of the sprung mass with respect to unspring mass at each corner are fedback, thru their corresponding gains, to create the control signal that adjusts the proportional valve with the goal of controlling the height, stiffness, and damping at that corner. In a numerical study followed by laboratory testing, the effectiveness of the proposed air suspension system in terms of its ability to vary the damping and stiffness as well as the height of the suspension system is demonstrated.
{"title":"An Air Suspension System With Adjustable Height, Damping and Stiffness Using No Viscous Dampers","authors":"R. Kashani","doi":"10.1115/imece2019-10153","DOIUrl":"https://doi.org/10.1115/imece2019-10153","url":null,"abstract":"\u0000 Air suspension is gaining more and more popularity with both the auto industry and drivers. Traditionally the height adjustability aspect of air suspension systems has been their main attracting attribute. More recently, resolving the classic conflict of combining comfortable ride with sport handling in a single suspension setup has become the main attraction of air suspension.\u0000 An air suspension system has been developed which in addition to height adjustment, can adjust its damping and stiffness in real time with using neither viscous dampers nor any additional actuators. This is done by real-time adjustment air flow to and from the air springs using proportional valves. Measured relative displacement and acceleration as well as estimated velocity of the sprung mass with respect to unspring mass at each corner are fedback, thru their corresponding gains, to create the control signal that adjusts the proportional valve with the goal of controlling the height, stiffness, and damping at that corner.\u0000 In a numerical study followed by laboratory testing, the effectiveness of the proposed air suspension system in terms of its ability to vary the damping and stiffness as well as the height of the suspension system is demonstrated.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122739269","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, a kind of elastic metamaterial substructure was designed for the selective mode filtering and transmission of symmetric and antisymmetric elastic waves. It is composed of double-sided aluminum-lead composite cylinders arranged in a periodic pattern bounded on an aluminum plate. The band structure of elastic metamaterial unit cell is numerically investigated using the modal analysis of a finite element model (FEM) by treating a unit microstructural cell with the Bloch-Floquet boundary condition. Through analyzing the vibration modes of the unit cell, a complete antisymmetric wave bandgap and a complete symmetric wave bandgap can be formed in different frequency ranges. Considering the geometric complexity of the designed substructure, the dynamic effective mass density of the proposed metamaterial unit cell is calculated by considering the structure as a homogeneous medium under the sub-wavelength requirement. The negative effective mass density behavior for in-plane and out-of-plane plate modes will be presented to verify the bandgap effect of different wave modes. A FEM harmonic analysis is further conducted to obtain the spectral response of a chain model and explore the mode filtering efficiency. Finally, a coupled field transient dynamic FEM is carried out to acquire the dynamic response of the structure. The frequency-wavenumber analysis demonstrates the successful achievement of model filtering behavior. The proposed selective mode transmission control methodology possesses great potential in future SHM and NDE applications. A case study for S0 mode conversion to SH0 mode using a different metamaterial unit cell is exhibited to illustrate other wave control capabilities. The paper finishes with summary, concluding remarks, and suggestions for future work.
{"title":"Selective Lamb Mode Transmission Enabled by Local Resonance Based Ultrasonic Metamaterial","authors":"Yiran Tian, Yanfeng Shen","doi":"10.1115/imece2019-10872","DOIUrl":"https://doi.org/10.1115/imece2019-10872","url":null,"abstract":"\u0000 In this study, a kind of elastic metamaterial substructure was designed for the selective mode filtering and transmission of symmetric and antisymmetric elastic waves. It is composed of double-sided aluminum-lead composite cylinders arranged in a periodic pattern bounded on an aluminum plate. The band structure of elastic metamaterial unit cell is numerically investigated using the modal analysis of a finite element model (FEM) by treating a unit microstructural cell with the Bloch-Floquet boundary condition. Through analyzing the vibration modes of the unit cell, a complete antisymmetric wave bandgap and a complete symmetric wave bandgap can be formed in different frequency ranges. Considering the geometric complexity of the designed substructure, the dynamic effective mass density of the proposed metamaterial unit cell is calculated by considering the structure as a homogeneous medium under the sub-wavelength requirement. The negative effective mass density behavior for in-plane and out-of-plane plate modes will be presented to verify the bandgap effect of different wave modes. A FEM harmonic analysis is further conducted to obtain the spectral response of a chain model and explore the mode filtering efficiency. Finally, a coupled field transient dynamic FEM is carried out to acquire the dynamic response of the structure. The frequency-wavenumber analysis demonstrates the successful achievement of model filtering behavior. The proposed selective mode transmission control methodology possesses great potential in future SHM and NDE applications. A case study for S0 mode conversion to SH0 mode using a different metamaterial unit cell is exhibited to illustrate other wave control capabilities. The paper finishes with summary, concluding remarks, and suggestions for future work.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126170340","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}
Bearings are critical mechanical components that are used in rotary machinery. Timely detection of defects in such components can prevent catastrophic failure. Noise is generated during the rotation of bearings even without the presence of defects due to finite number of rotating elements to carry the load. Such noise is associated with the change in effective stiffness during rotation, however, a sharp spike is observed in the noise level with presence of local defects. This study uses the noise generation aspect of roller bearings to identify local defect in a single row ball bearing with outer race stationary under radial load. Experimental testing is conducted on two identical bearings. The defective bearing is selected from a diesel engine subjected to 20 years of service. Dissecting the defective bearing revealed pitting and spalling of the inner race and balls, the most two common bearing defects. Both time and frequency analysis of sound pressure generated by the bearings were performed. The results show that there is a clear distinction in the time and frequency spectra between healthy and defective bearings. Findings of this study revealed that using a simple cost efficient in-house experimental setup, local defects can be readily detected.
{"title":"An Experimental Approach in Defect Detection of a Single Row Ball Bearing Using Noise Generation Signal","authors":"A. Afsharfard, سید حمیدرضا صانعی","doi":"10.1115/imece2019-12146","DOIUrl":"https://doi.org/10.1115/imece2019-12146","url":null,"abstract":"\u0000 Bearings are critical mechanical components that are used in rotary machinery. Timely detection of defects in such components can prevent catastrophic failure. Noise is generated during the rotation of bearings even without the presence of defects due to finite number of rotating elements to carry the load. Such noise is associated with the change in effective stiffness during rotation, however, a sharp spike is observed in the noise level with presence of local defects. This study uses the noise generation aspect of roller bearings to identify local defect in a single row ball bearing with outer race stationary under radial load. Experimental testing is conducted on two identical bearings. The defective bearing is selected from a diesel engine subjected to 20 years of service. Dissecting the defective bearing revealed pitting and spalling of the inner race and balls, the most two common bearing defects. Both time and frequency analysis of sound pressure generated by the bearings were performed. The results show that there is a clear distinction in the time and frequency spectra between healthy and defective bearings. Findings of this study revealed that using a simple cost efficient in-house experimental setup, local defects can be readily detected.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122282352","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 paper, we report the experimental data of the elastic properties of the young and shear modulus based on the variation in the ultrasonic velocity parameter during the microstructural evolution in a Ti-6Al-4V alloy with two varying microstructures, bimodal and acicular respectively. The two different initial microstructures, were treated thermally by aging at 515°C, 545°C and 575°C at different times from 1 min to 576hr to induce a precipitation process. Ultrasonic measurements of shear and longitudinal wave velocities, scanning electron microscopy (SEM) image processing, optical microscopy (OM) and microhardness were performed, establishing a direct correlation with the measurements of the ultrasonic velocity and the elastic properties developed during the thermal treatment of the artificial aging. The results of the ultrasonic velocity show a very clear trend as the aging time progresses, which is affected by precipitation of Ti3Al particles inside the α phase. In this way, we can know, in a fast and efficient way, the elastic properties developed during the heat treatment of aging at long times, since the presence of these precipitates hardens the material microstructure affecting the final mechanical properties.
{"title":"Ultrasonic Characterization of the Elastic Constants in an Aging Ti-6Al-4V ELI Alloy","authors":"H. Carreón","doi":"10.1115/imece2019-10194","DOIUrl":"https://doi.org/10.1115/imece2019-10194","url":null,"abstract":"\u0000 In this paper, we report the experimental data of the elastic properties of the young and shear modulus based on the variation in the ultrasonic velocity parameter during the microstructural evolution in a Ti-6Al-4V alloy with two varying microstructures, bimodal and acicular respectively. The two different initial microstructures, were treated thermally by aging at 515°C, 545°C and 575°C at different times from 1 min to 576hr to induce a precipitation process. Ultrasonic measurements of shear and longitudinal wave velocities, scanning electron microscopy (SEM) image processing, optical microscopy (OM) and microhardness were performed, establishing a direct correlation with the measurements of the ultrasonic velocity and the elastic properties developed during the thermal treatment of the artificial aging. The results of the ultrasonic velocity show a very clear trend as the aging time progresses, which is affected by precipitation of Ti3Al particles inside the α phase. In this way, we can know, in a fast and efficient way, the elastic properties developed during the heat treatment of aging at long times, since the presence of these precipitates hardens the material microstructure affecting the final mechanical properties.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117301667","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 objective of this experimental investigation was to determine the effectiveness of different thermal insulating materials noise reduction properties when exposed to acoustic signals of varying frequencies and amplitudes. The experimental system incorporated two boxes separated by a thermal insulation wall. A speaker was used in one box with varied sound amplitude and frequency to test how effective the insulating material was at reducing sound transmission through a wall. The sound level was measured with a microphone in each box and the values were used to calculate the Sound Transmission Loss (STL) for each trial. Fiberglass insulation and cork insulation were the two insulation materials tested. The frequency levels of500 Hz, 1000 Hz, and 2000 Hz were tested. A three factor ANOVA analysis was completed and the null hypothesis was rejected with 95% confidence for each of the three factors. A Tukey test was conducted to determine which factor, if any, had a significant impact on the STL value. The Tukey test determined that frequency had the most significant impact on the STL value followed by the material choice with the average difference of means for comparison groups being 17.92 dB and 7.74 dB, respectively. The Tukey test also determined sound level did not have a significant impact on the STL value. The fiberglass insulation tested had the highest STL value of the two materials tested, with a maximum STL of 49.5 dB at 2000 Hz while the minimum STL was 26.2 dB at 500 Hz. The cork insulation had a maximum STL of 44.4 dB at 2000 Hz and a minimum STL of 10.5 dB of 500 Hz. At 1000 Hz however, the cork insulation had a higher STL than the fiberglass insulation with 32.6 dB and 31.6 dB respectively. This discrepancy might be due to a specific property of the cork dictating how it interacted within a specific frequency range. The test had an overall uncertainty of ±1.34 STL which was much smaller than the difference between sample groups. The ANOVA analysis also showed a strong interaction between the insulating material and the frequency as it had a much greater F-value of 869.56 as compared with the F-critical value of 2.42.
{"title":"The Feasibility of Noise Insulating Materials With Variability of Frequencies and Amplitudes","authors":"Zach Kitowski, Andrew Marsh, R. Graves","doi":"10.1115/imece2019-11024","DOIUrl":"https://doi.org/10.1115/imece2019-11024","url":null,"abstract":"\u0000 The objective of this experimental investigation was to determine the effectiveness of different thermal insulating materials noise reduction properties when exposed to acoustic signals of varying frequencies and amplitudes. The experimental system incorporated two boxes separated by a thermal insulation wall. A speaker was used in one box with varied sound amplitude and frequency to test how effective the insulating material was at reducing sound transmission through a wall. The sound level was measured with a microphone in each box and the values were used to calculate the Sound Transmission Loss (STL) for each trial. Fiberglass insulation and cork insulation were the two insulation materials tested. The frequency levels of500 Hz, 1000 Hz, and 2000 Hz were tested. A three factor ANOVA analysis was completed and the null hypothesis was rejected with 95% confidence for each of the three factors. A Tukey test was conducted to determine which factor, if any, had a significant impact on the STL value. The Tukey test determined that frequency had the most significant impact on the STL value followed by the material choice with the average difference of means for comparison groups being 17.92 dB and 7.74 dB, respectively. The Tukey test also determined sound level did not have a significant impact on the STL value. The fiberglass insulation tested had the highest STL value of the two materials tested, with a maximum STL of 49.5 dB at 2000 Hz while the minimum STL was 26.2 dB at 500 Hz. The cork insulation had a maximum STL of 44.4 dB at 2000 Hz and a minimum STL of 10.5 dB of 500 Hz. At 1000 Hz however, the cork insulation had a higher STL than the fiberglass insulation with 32.6 dB and 31.6 dB respectively. This discrepancy might be due to a specific property of the cork dictating how it interacted within a specific frequency range. The test had an overall uncertainty of ±1.34 STL which was much smaller than the difference between sample groups. The ANOVA analysis also showed a strong interaction between the insulating material and the frequency as it had a much greater F-value of 869.56 as compared with the F-critical value of 2.42.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131592137","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}
Sophie R. Kaye, Ethan D. Casavant, Paul E. Slaboch
Attenuating low frequencies is often problematic, due to the large space required for common absorptive materials to mitigate such noise. However, natural hollow reeds are known to effectively attenuate low frequencies while occupying relatively little space compared to traditional absorptive materials. This paper discusses the effect of varied outer diameter, and outer spacing on the 200–1600 Hz acoustic absorption of additively manufactured arrays of hollow cylinders. Samples were tested in a 10 cm diameter normal incidence impedance tube such that cylinder length was oriented perpendicular to the incoming plane wave. By varying only one geometric element of each array, the absorption due to any particular parameter can be assessed individually. The tests confirmed the hypothesis that minimizing cylinder spacing and maximizing cylinder diameter resulted in increased overall absorption and produced more focused absorption peaks at specific low frequencies. Wider cylinder spacing produced a broader absorptive frequency range, despite shifting upward in frequency. Thus, manipulating these variables can specifically target absorption for low frequency noise that would otherwise disturb listeners.
{"title":"Low Frequency Absorption of Additively Manufactured Cylinders","authors":"Sophie R. Kaye, Ethan D. Casavant, Paul E. Slaboch","doi":"10.1115/imece2019-11338","DOIUrl":"https://doi.org/10.1115/imece2019-11338","url":null,"abstract":"\u0000 Attenuating low frequencies is often problematic, due to the large space required for common absorptive materials to mitigate such noise. However, natural hollow reeds are known to effectively attenuate low frequencies while occupying relatively little space compared to traditional absorptive materials. This paper discusses the effect of varied outer diameter, and outer spacing on the 200–1600 Hz acoustic absorption of additively manufactured arrays of hollow cylinders. Samples were tested in a 10 cm diameter normal incidence impedance tube such that cylinder length was oriented perpendicular to the incoming plane wave. By varying only one geometric element of each array, the absorption due to any particular parameter can be assessed individually. The tests confirmed the hypothesis that minimizing cylinder spacing and maximizing cylinder diameter resulted in increased overall absorption and produced more focused absorption peaks at specific low frequencies. Wider cylinder spacing produced a broader absorptive frequency range, despite shifting upward in frequency. Thus, manipulating these variables can specifically target absorption for low frequency noise that would otherwise disturb listeners.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122943372","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}
Marine Hydrokinetic (MHK) cycloturbines exploit tidal currents to generate sustainable electric power. Because of the harsh marine environment, MHK cycloturbines require frequent maintenance and repair, which for current systems necessitates the use of a ship, making the process difficult and costly. A novel MHK cycloturbine system has been designed that uses pitching foils for maneuver, potentially circumventing the costs and difficulties associated with deployment and repairs. The vehicle fatigue is decreased and the vehicle’s acoustic signature underwater is reduced by design of a novel acoustic controller. This controller specifically reduces the tonal noise at blade rate frequency. Each turbine foil radiates noise equivalent to an acoustic dipole at multiples of blade rate frequency, and so the vehicle is modelled as an acoustic multipole. At blade rate frequency, the turbine size compared to its acoustic wavelength allows for the entire vehicle to be treated as a compact source. The effect of turbine clocking on directivity and sound power is shown. The effects of the designed controller to reduce tonal noise at blade rate frequency and multiples are verified experimentally through testing in ARL’s Reverberant Tank facility. Fixing a Subscale Demonstrator (SSD) to a reaction frame provides the ability to measure the integrated loads using load cells. The radiated sound pressure is computed for the load cell data obtained. Acoustic control is implemented using the turbine RPM: turbines are clocked by slowing one turbine relative to another for a short period of time.
{"title":"Acoustic Control of a Maneuverable Marine Hydrokinetic Cycloturbine","authors":"Margalit Goldschmidt, Michael L. Jonson, J. Horn","doi":"10.1115/imece2019-11381","DOIUrl":"https://doi.org/10.1115/imece2019-11381","url":null,"abstract":"\u0000 Marine Hydrokinetic (MHK) cycloturbines exploit tidal currents to generate sustainable electric power. Because of the harsh marine environment, MHK cycloturbines require frequent maintenance and repair, which for current systems necessitates the use of a ship, making the process difficult and costly. A novel MHK cycloturbine system has been designed that uses pitching foils for maneuver, potentially circumventing the costs and difficulties associated with deployment and repairs. The vehicle fatigue is decreased and the vehicle’s acoustic signature underwater is reduced by design of a novel acoustic controller. This controller specifically reduces the tonal noise at blade rate frequency.\u0000 Each turbine foil radiates noise equivalent to an acoustic dipole at multiples of blade rate frequency, and so the vehicle is modelled as an acoustic multipole. At blade rate frequency, the turbine size compared to its acoustic wavelength allows for the entire vehicle to be treated as a compact source. The effect of turbine clocking on directivity and sound power is shown. The effects of the designed controller to reduce tonal noise at blade rate frequency and multiples are verified experimentally through testing in ARL’s Reverberant Tank facility. Fixing a Subscale Demonstrator (SSD) to a reaction frame provides the ability to measure the integrated loads using load cells. The radiated sound pressure is computed for the load cell data obtained. Acoustic control is implemented using the turbine RPM: turbines are clocked by slowing one turbine relative to another for a short period of time.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128981560","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}
Douglas MacNinch, Daniel Pacheco, Arjun Tandon, C. Bancroft, Isaac Flores, Matthew Rue, Andrei N. Zagrai
This contribution reports design and development of a payload for structural health monitoring (SHM) experiments on the International Space Station (ISS). The payload was designed to operate in low earth orbit (LEO) environment and fit specifications of the Materials International Space Station Experiment (MISSE) module. In particular, LEO environmental factors such as a strong vacuum, thermal variations from −18°C to 60°C [1], and background radiation were considered. The payload is a rectangular multi-leveled structure which houses several SHM experiments, active sensors self-assessment, and electronic hardware with data storage and retrieval capabilities. SHM experiments include guided wave propagation in a metallic structure, monitoring of an imitated crack, assessment of a bolted joint, investigation of structural vibration via electromechanical impedance method, and acoustic emission monitoring. In addition, piezoelectric sensor self-assessment is realised using impedance diagnostics. It is anticipated that the payload will operate for one year in LEO and provide insights on the effect of space environment on SHM of future space vehicles during long-duration flights. This contribution focuses on mechanical design of the payload to support SHM experiment. Specific arrangement of payload elements and implementation of boundary conditions for SHM experiments are reported. Theoretical calculations and examples of SHM experimental data obtained in laboratory tests are presented and discussed in light of expected variations due to LEO environment. Measures to protect SHM hardware from harsh space environment are presented. Perspective applications of SHM as an integral component of future space systems are discussed.
{"title":"Mechanical Design and Development of a Payload for Structural Health Monitoring Experiments on the International Space Station","authors":"Douglas MacNinch, Daniel Pacheco, Arjun Tandon, C. Bancroft, Isaac Flores, Matthew Rue, Andrei N. Zagrai","doi":"10.1115/imece2019-12093","DOIUrl":"https://doi.org/10.1115/imece2019-12093","url":null,"abstract":"\u0000 This contribution reports design and development of a payload for structural health monitoring (SHM) experiments on the International Space Station (ISS). The payload was designed to operate in low earth orbit (LEO) environment and fit specifications of the Materials International Space Station Experiment (MISSE) module. In particular, LEO environmental factors such as a strong vacuum, thermal variations from −18°C to 60°C [1], and background radiation were considered. The payload is a rectangular multi-leveled structure which houses several SHM experiments, active sensors self-assessment, and electronic hardware with data storage and retrieval capabilities. SHM experiments include guided wave propagation in a metallic structure, monitoring of an imitated crack, assessment of a bolted joint, investigation of structural vibration via electromechanical impedance method, and acoustic emission monitoring. In addition, piezoelectric sensor self-assessment is realised using impedance diagnostics. It is anticipated that the payload will operate for one year in LEO and provide insights on the effect of space environment on SHM of future space vehicles during long-duration flights. This contribution focuses on mechanical design of the payload to support SHM experiment. Specific arrangement of payload elements and implementation of boundary conditions for SHM experiments are reported. Theoretical calculations and examples of SHM experimental data obtained in laboratory tests are presented and discussed in light of expected variations due to LEO environment. Measures to protect SHM hardware from harsh space environment are presented. Perspective applications of SHM as an integral component of future space systems are discussed.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116691936","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 recent years it has been discovered that besides non-uniform flow excitation such as from stator wakes; acoustic pressure pulsation can be a concern, especially for high pressure centrifugal compressor impellers. This has been termed “triple coincidence” and explains rare failures and likely a reason, at least partially, for some previous undocumented failures. Bladed disk interaction resonance discovered by the author in the mid 1970’s can be avoided such as for centrifugal impellers as needed, depending on vibratory mode involved, available damping, and potential excitation level. Especially for stages having vanes in the diffuser near impeller tips, concern for high cycle fatigue is very high as certain numbers of vanes combined with number of rotating blades can give correct phase to excite a highly responding mode. Intentional mistuning of disk-dominated modes has potential for reducing response. A similar but more complex interaction is with transverse acoustic modes having a specific number of nodal diameters. In this case acoustic gas modes in cavities at sides of impellers can match rotating acoustic pulsations at BPF (blade passing frequency) and/or harmonics, termed Tyler-Sofrin modes with increased noise. Also acoustic mode matching impeller structural mode can give the triple coincidence causing resonant response of the impeller. The concern for this coincidence is often difficult to evaluate. For some cases, calculations give enough evidence to modify number of vanes or blades to correct a possible cause of a fatigue failure. This coincidence can add to the direct response, e.g. from either upstream wakes or downstream diffuser vane interacting “potential flow” excitation, herein termed “quadruple coincidence resonance”. Dimensions of impeller side cavities are axisymmetric and are set by aerodynamics, so that outer and inner radii define transverse modes with small radial dimensional changes available. Often a minor aerodynamic performance compromise can be used to change designs to avoid serious resonances, e.g. revise numbers of vanes and/or blades, avoid the response of a matching diameter mode or have a different less responsive mode to alleviate concern. Besides turbomachinery e.g. compressors and pumps, some other methods as described could be utilized for any cavity that has diametrical mode shapes, or possibly other patterns for pressure pulsation frequencies. These modification(s), including patent-pending method, PCT/US2018/020880 described herein can alleviate if not eliminate concern for any mechanism having structural vibration excitation and/or environmental noise issues.
{"title":"Quadruple Flow and Acoustic Coincident Resonance of Rotating Bladed Disks Interacting With Stationary Elements","authors":"Frank Kushner","doi":"10.1115/IMECE2018-86303","DOIUrl":"https://doi.org/10.1115/IMECE2018-86303","url":null,"abstract":"In recent years it has been discovered that besides non-uniform flow excitation such as from stator wakes; acoustic pressure pulsation can be a concern, especially for high pressure centrifugal compressor impellers. This has been termed “triple coincidence” and explains rare failures and likely a reason, at least partially, for some previous undocumented failures. Bladed disk interaction resonance discovered by the author in the mid 1970’s can be avoided such as for centrifugal impellers as needed, depending on vibratory mode involved, available damping, and potential excitation level. Especially for stages having vanes in the diffuser near impeller tips, concern for high cycle fatigue is very high as certain numbers of vanes combined with number of rotating blades can give correct phase to excite a highly responding mode. Intentional mistuning of disk-dominated modes has potential for reducing response. A similar but more complex interaction is with transverse acoustic modes having a specific number of nodal diameters. In this case acoustic gas modes in cavities at sides of impellers can match rotating acoustic pulsations at BPF (blade passing frequency) and/or harmonics, termed Tyler-Sofrin modes with increased noise. Also acoustic mode matching impeller structural mode can give the triple coincidence causing resonant response of the impeller. The concern for this coincidence is often difficult to evaluate. For some cases, calculations give enough evidence to modify number of vanes or blades to correct a possible cause of a fatigue failure. This coincidence can add to the direct response, e.g. from either upstream wakes or downstream diffuser vane interacting “potential flow” excitation, herein termed “quadruple coincidence resonance”. Dimensions of impeller side cavities are axisymmetric and are set by aerodynamics, so that outer and inner radii define transverse modes with small radial dimensional changes available. Often a minor aerodynamic performance compromise can be used to change designs to avoid serious resonances, e.g. revise numbers of vanes and/or blades, avoid the response of a matching diameter mode or have a different less responsive mode to alleviate concern. Besides turbomachinery e.g. compressors and pumps, some other methods as described could be utilized for any cavity that has diametrical mode shapes, or possibly other patterns for pressure pulsation frequencies. These modification(s), including patent-pending method, PCT/US2018/020880 described herein can alleviate if not eliminate concern for any mechanism having structural vibration excitation and/or environmental noise issues.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129602809","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 involute spur gear system has been widely utilized in the mechanical transmission domain, and the control of the acceleration noise of the involute spur gear system has become the key technology to solve the NVH performance of the power transmission system, especially in the automobile industry. In the process of the gear meshing, the unavoidable acceleration noise of the involute spur gear system is mainly caused by the meshing stiffness and error excitation due to the structural parameters. Therefore, the investigation on the effects of structure parameters on acceleration noise of the involute spur gear system is necessary. In this paper, the numerical model for predicting the acceleration noise of the involute spur gear system has been established. The simulation results of the acceleration noise were compared with the experimental results, and the errors between these two results were only 2.9%, within permission. The effects of structure parameters including base pitch error and pressure angle on the acceleration noise of the involute spur gear system have been discussed. Results showed that increasing the base pitch error, the acceleration noise level of the involute spur gear increased, and the gap of the noise level between different base pitch errors narrowed according to the increase of gear load and rotation speed. Increasing the pressure angle also increased the acceleration noise level, however, the gap between different pressure angles remained the same regardless the variations of gear load and rotation speed, which was different than the variations of base pitch error.
{"title":"Numerical Investigation on Effects of Structure Parameters on Acceleration Noise of Involute Spur Gear System Under Different Operation Conditions","authors":"Changyin Wei, Jingang Wang, Hai Liu, Yong Chen, Kunqi Ma, Hanzhengnan Yu","doi":"10.1115/IMECE2018-86955","DOIUrl":"https://doi.org/10.1115/IMECE2018-86955","url":null,"abstract":"The involute spur gear system has been widely utilized in the mechanical transmission domain, and the control of the acceleration noise of the involute spur gear system has become the key technology to solve the NVH performance of the power transmission system, especially in the automobile industry. In the process of the gear meshing, the unavoidable acceleration noise of the involute spur gear system is mainly caused by the meshing stiffness and error excitation due to the structural parameters. Therefore, the investigation on the effects of structure parameters on acceleration noise of the involute spur gear system is necessary.\u0000 In this paper, the numerical model for predicting the acceleration noise of the involute spur gear system has been established. The simulation results of the acceleration noise were compared with the experimental results, and the errors between these two results were only 2.9%, within permission.\u0000 The effects of structure parameters including base pitch error and pressure angle on the acceleration noise of the involute spur gear system have been discussed. Results showed that increasing the base pitch error, the acceleration noise level of the involute spur gear increased, and the gap of the noise level between different base pitch errors narrowed according to the increase of gear load and rotation speed. Increasing the pressure angle also increased the acceleration noise level, however, the gap between different pressure angles remained the same regardless the variations of gear load and rotation speed, which was different than the variations of base pitch error.","PeriodicalId":197121,"journal":{"name":"Volume 11: Acoustics, Vibration, and Phononics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125200321","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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