NOISE-CON ... proceedings最新文献_第7页

Scattering from a partially coated shell immersed in water using a subtractive modelling technique 用减法建模技术研究浸没在水中的部分涂覆壳的散射

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0019

Florent Dumortier

{"title":"Scattering from a partially coated shell immersed in water using a subtractive modelling technique","authors":"Florent Dumortier","doi":"10.3397/no_2023_0019","DOIUrl":"https://doi.org/10.3397/no_2023_0019","url":null,"abstract":"In this study, we focus on the prediction of the pressure field scattered from an immersed cylindrical shell partially coated by a soft rubber, impacted by an acoustic plane wave. As the coating covers only a partial portion along the circumference of the shell, the considered system is not axisymmetric. As a result, a spectral (Fourier) resolution of the mathematical problem would induce the coupling of the di erent circumferential orders, which can lead to prohibitive computing times. To circumvent this issue, the reverse Condensed Transfer Function (rCTF) method has recently been developed to decouple vibroacoustic subsystems initially coupled along lines or surfaces. From an analytical model of the fully coated shell impacted by the acoustic plane wave and a finite element (FE) model of the missing coating material, the rCTF approach predicts the vibroacoustic behavior of the coated shell with a voided section instead of the removed part. This voided section can then be filled by a FE model of the water domain replacing the removed coating material, using the direct CTF approach. The principle of the rCTF approach, some numerical validations, and results for the scattering from the partially coated shell are presented in this paper.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"33 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135725642","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}

引用次数: 0

A genetic-continuation algorithm for bifurcation analysis of nonlinear rotordynamic systems 非线性旋转动力系统分岔分析的遗传-延拓算法

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0051

Sitae Kim

{"title":"A genetic-continuation algorithm for bifurcation analysis of nonlinear rotordynamic systems","authors":"Sitae Kim","doi":"10.3397/no_2023_0051","DOIUrl":"https://doi.org/10.3397/no_2023_0051","url":null,"abstract":"This study presents a combined numerical scheme with genetic algorithm and continuation method for analysing nonlinear vibrations in rotor-bearing systems. A modified genetic algorithm is developed for solving multiple coexisting roots in nonlinear rotordynamic problem. Here, the genetic objective is the completion of periodicity for the boundary values of journal/pad phase states during the consecutive generations. The arc-length continuation takes the role to extend the solutions with respect to operating parameters such as the shaft spin speed and disc mass eccentricity. The resulting bifurcation diagrams, then, can comprehensively show the emergences and disappearances of multiple response states and their stability conditions in detail, which is unlike with the commonly applied numerical integration method. A finite model of heavily loaded Jeffcott rotor supported by six-pad tilting pad journal bearing is utilized to evaluate the developed algorithm. The 150 initial states for the journal and pad are generated, and the 8 optimal results are selected and inbreeded for evolution; it repeats for 15 generations. As results, multiple coexisting responses are identified at the same condition, and various bifurcation events such as periodic doubling, saddle-node are discovered from the solution manifolds.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"33 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135725643","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}

引用次数: 0

Evaluation of virtual sensing with spherical array surrounding head for directional noise 球面阵环绕头虚拟传感的方向噪声评价

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0028

Naoki Shinobu

{"title":"Evaluation of virtual sensing with spherical array surrounding head for directional noise","authors":"Naoki Shinobu","doi":"10.3397/no_2023_0028","DOIUrl":"https://doi.org/10.3397/no_2023_0028","url":null,"abstract":"Active noise control (ANC) is expected to be applicable to public transportation modalities such as airplanes and trains. In these application systems, passengers may need to avoid wearing devices such as earphones and ear microphones. However, in conventional ANC systems, it is necessary to locate a physical microphone at the ear positions as an error sensor. To overcome this problem, virtual sensing techniques have been studied for estimating sound pressures at ear positions using remote microphones. In this study, we investigated the performance of a virtual sensing method for interpolating the sound pressures at ear positions using a spherical microphone array surrounding the head, based on a spherical harmonic expansion. The experiments were conducted using a rigid sphere instead of a head and dodecahedral spherical microphone array surrounding the sphere. The estimation errors were evaluated for various noise directions at low frequencies (100, 300, 500, and 700 Hz). The experimental results showed that the estimation errors were less than -20 dB for almost all conditions below 500 Hz. By comparison with other virtual sensing methods using a few microphones in the vicinity of the ear positions, we confirmed that our proposed method was effective for any noise direction.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"32 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135725654","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}

引用次数: 0

Variability in measured resonance frequencies and loss factors of a bolted panel structure 螺栓面板结构的测量共振频率和损耗因子的变异性

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0006

Trevor Jerome

{"title":"Variability in measured resonance frequencies and loss factors of a bolted panel structure","authors":"Trevor Jerome","doi":"10.3397/no_2023_0006","DOIUrl":"https://doi.org/10.3397/no_2023_0006","url":null,"abstract":"Structural bolted joints are not perfectly contiguous or rigid. Instead, the joint stiffness, mass, and damping depend on many parameters including the joint thickness, number and size of bolts, the bolt preload, and the motion of the jointed region. Also, damping can vary with motion type (stick-slip for friction and impact for joint opening and closing) and amplitude. Finally, all joint dynamic parameters vary from installation to installation. We measured the variability of bolted joint stiffness and damping for four low-order modes of a bolted Aluminum panel structure - two flexural modes and two twisting/torsional modes. While a large portion of the bolted joint literature features a lap joint or an assembly of two beams, there are few studies dealing with flanged connections of plates. Two flanged rectangular panels were bolted together with two cap screws threaded into one of the flanges. Modal resonance frequencies and loss factors were tracked throughout a decaying vibration response induced by hammer impacts on the structure. Measurements were made for three bolt torques and two flange thicknesses, three impact force strengths, and three repeated assemblies (the panel was unbolted and bolted together again). Relative motion at the joint with respect to mode shape determines whether the joint primarily adds stiffness or mass, as well as the amount of added damping. Not surprisingly, reducing bolt preload reduces resonance frequencies. Only minor variability in resonance frequency and loss factor were observed for most conditions, except for cases with low bolt preload. In these cases mild nonlinearity is evident in the response, where resonance frequency decreases and loss factor increases with increasing vibration amplitude. Also, variability of resonance frequencies and loss factors between installations often exceeds that due to variability in preload and vibration amplitude.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"34 S1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135726945","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}

引用次数: 0

Multi-fidelity modeling using Gaussian processes for the frequency dependent Helmholtz equation 基于高斯过程的频率相关亥姆霍兹方程多保真度建模

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0025

Caglar Gurbuz

{"title":"Multi-fidelity modeling using Gaussian processes for the frequency dependent Helmholtz equation","authors":"Caglar Gurbuz","doi":"10.3397/no_2023_0025","DOIUrl":"https://doi.org/10.3397/no_2023_0025","url":null,"abstract":"In scientific and engineering problems, accurate model predictions are generally accompanied with high resource and time expenses. In most applications, the data generation process can only be performed for a limited number of forward evaluations leading to insufficient model results. The concept of multi-fidelity modeling is to holistically evaluate data from different sources with varying complexity and costs. Ideally, the predictive quality of models with a high-fidelity can be combined with the efficiency of low-fidelity models. Usually, physical experiments and numerical simulations at large-scale are attributed to high-fidelity models, while analytical solutions or small-scale numerical models and experiments are considered as low-fidelity models. This contribution aims to develop a multi-fidelity model for an interior sound propagation problem. More specifically, a vehicle interior noise problem is investigated by using two boundary element models of different fidelity levels. The finer mesh corresponds to the high-fidelity model, whereas the coarser mesh is adopted as the low-fidelity model. As such, the multi-fidelity model is realized as a vector-valued Gaussian process.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135728283","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}

引用次数: 0

Passive and active control of radiated sound from a coated cylindrical shell 涂覆圆柱壳辐射声的被动和主动控制

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0102

Cikai Lin

引用次数: 0

Bayesian approach for acoustic boundary admittance estimation 声学边界导纳估计的贝叶斯方法

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0061

Jonas M. Schmid

{"title":"Bayesian approach for acoustic boundary admittance estimation","authors":"Jonas M. Schmid","doi":"10.3397/no_2023_0061","DOIUrl":"https://doi.org/10.3397/no_2023_0061","url":null,"abstract":"It is essential for accurate acoustic predictions to represent the boundary properties of all interacting surfaces as accurately as possible. The acoustic boundary properties can be fully characterized by the complex-valued acoustic boundary admittance. Yet, it is a challenging task to determine this quantity in-situ, without measuring in laboratory conditions. A Bayesian approach is presented to estimate the acoustic boundary admittance based on a limited number of noisy sound pressure measurements at random observation points inside an acoustic domain. The sound pressure data are obtained utilizing the finite element method, which also serves as forward model in the inference process. This enables the application of the framework to arbitrarily shaped acoustic domains such as a car cabin. It is the benefit of the Bayesian approach, that it results in a probabilistic distribution for the boundary admittance and thus allows for uncertainty quantification of the estimation. The results prove, that the combined framework consisting of a FEM forward model and a Bayesian approach to solve the inverse problem is well-suited for the inference of the acoustic boundary admittance from noisy observations. It is particularly beneficial, if information about the uncertainty is desired.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"31 S1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135728288","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}

引用次数: 0

On the effects of a nonlinear boundary with cubic stiffness on the reflection coefficients of time harmonic flexural waves in an Euler-Bernoulli beam 三次刚度非线性边界对欧拉-伯努利梁时谐弯曲波反射系数的影响

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0086

Moein Abdi

{"title":"On the effects of a nonlinear boundary with cubic stiffness on the reflection coefficients of time harmonic flexural waves in an Euler-Bernoulli beam","authors":"Moein Abdi","doi":"10.3397/no_2023_0086","DOIUrl":"https://doi.org/10.3397/no_2023_0086","url":null,"abstract":"The reflection of time-harmonic flexural waves in a thin Euler-Bernoulli beam incident on a nonlinear boundary stiffness is studied. A set of waves at frequencies an integer multiple of a fundamental frequency is incident on the boundary, giving rise to an infinite set of reflected propagating and nearfield waves whose amplitudes are defined in terms of reflection coefficients. Equations for the wave amplitudes are truncated and solved numerically using the harmonic balance method. The boundary nonlinearity is assumed to be cubic with no quadratic term. Emphasis is placed on essential nonlinearity for which the linear stiffness is zero. This case is of interest due to stronger nonlinear effects being produced. The case with one incident propagating wave and two reflected propagating and nearfield waves is considered. It is seen that vibrational energy leaks from the 1st harmonic to the 3rd harmonic. A boundary configuration comprising linear springs is suggested, and the stiffness is calculated for this case and when the maximum leakage of energy occurs from the 1st harmonic to the 3rd harmonic, i.e., for the minimum reflection coefficient of the 1st harmonic. It is seen that the reflection coefficient of the incident wave at the fundamental frequency can be significantly less than 1.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"31 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135728292","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}

引用次数: 0

Programmable sound absorption performance enabled by 3D printed fibers 可编程的吸声性能由3D打印纤维实现

NOISE-CON ... proceedings Pub Date : 2023-11-05 DOI: 10.3397/no_2023_0099

William Johnston

引用次数: 0

Noise footprint assessment at a vertiport for different approach and departure procedures of a tilt-wing air-taxi 倾翼空中滑行不同进近和离场程序在垂直机场的噪声足迹评估

NOISE-CON ... proceedings Pub Date : 2023-05-25 DOI: 10.3397/nc_2023_01_1103

Michael Bauer

{"title":"Noise footprint assessment at a vertiport for different approach and departure procedures of a tilt-wing air-taxi","authors":"Michael Bauer","doi":"10.3397/nc_2023_01_1103","DOIUrl":"https://doi.org/10.3397/nc_2023_01_1103","url":null,"abstract":"Community noise at vertiports is one of the most important questions related to upcoming urban air mobility (UAM) operations. While fixed-wing and/or fixed-rotor aircraft can mainly be treated by their changing operational parameters, such as rotor or propeller rpm, tilt-wing or tilt-engine configurations are more difficult to simulate because of their constantly changing noise emission and spatial radiation characteristics. The work presented in this paper is providing an overview of the noise situation at a virtual vertiport which is being approached and departed by a tilt-wing air-taxi in different ways. Several different departure procedures are simulated with the same generic air-taxi. For the noise emission semi-empiric methods were used. During the air-taxi's descent and climb, different tilt configurations are included, mainly defined by the time dependent engine's tilt-angle, but also related to different approach paths. Each approach or departure procedure is generating individually time dependent changing noise emission characteristics which are used for noise footprint mapping around the touch-down or lift-off point. Different noise metrics are computed, including some which are representative to indicate noise annoyance among the vertiport's neighborhood. It is expected that each procedure will generate its own specific community noise situation in the vicinity of the vertiport, and thus may provide an early recommenddation for later operations. The results are compared towards each other. Additionally, a simulated certification flyover according to ICAO Chapter 13 - which is about the noise certification of tilt-rotor aircraft - is set into relation to the vertiport's community noise.","PeriodicalId":471330,"journal":{"name":"NOISE-CON ... proceedings","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136345810","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}

引用次数: 0