Rattling Noise Research Articles

A Detailed Study on Various Sources of Cabin Noise and Vibration in Crawler Dozers and Methodology Followed to Reduce the Noise

The major environmental concern in the field of opencast mining industries are the means of controlling and mitigating noise generated from different Heavy earth moving machineries (HEMM) like Excavators, Dozers, Dumpers, Loaders, Graders, etc. Continuous exposure of the operators to excess noise shall result in hearing impairment and other related health issues. Also, for the HEMM manufacturers, it is important to meet the statutory requirement and mine safety norms to qualify for the tenders. Crawler tractors also called Dozers are heavy earth-moving equipment used in open cast mines with metal blades attached in front of it for pushing or dozing of materials. Dozers being one of the major sources of such noise, in this paper we focus on noise control in dozers. The DGMS (Director General of Mine Safety) regulatory requirement specifies the noise generated inside the cabin should be less than 85dB. We present a detailed analysis of major sources of noise generation in dozers, including Structure borne, Air borne and Rattling noise. We also discuss the various stages and methodologies followed to mitigate the noise at different sources and inside the cabin to ensure that the noise level are within the accepted limits. Our study provides a comprehensive understanding of the noise control measures that can be implemented in dozers to reduce noise exposure and ensure safety and well-being of operators in open cast mining industries.

An experimental and theoretical investigation of the influence of backlash on gear train vibro-impacts and rattle noise

Rattling is a perennial gear noise problem observed in various powertrain components ranging from manual transmissions to engine balancers and timing gear trains. Under lightly loaded conditions, gear systems that are subjected to input and/or output torque fluctuations exhibit vibro-impacts as tooth separations and coast-side contacts take place in the presence of backlash. Experimental set-ups that can impose tightly controlled torque fluctuations to single or multi-mesh gear train are used here to determine the sensitivity of the rattling noise levels to the magnitudes of backlash within wide ranges of torque fluctuation parameters. Torsional discrete models of the experimental set-ups were used to simulate these rattling motions and to predict impact velocity-based rattle severity indexes as a function of both excitation parameters and backlash magnitudes. Single-mesh results show that the larger backlash values result in higher noise levels in most of the cases. In case of double-mesh systems, the resultant noise levels and the corresponding rattle indices exhibit different sensitivities to backlash magnitudes depending on the excitation conditions.

A Rattle Noise Severity Index for Multi-Mesh Gear Trains Subjected to Torque Fluctuations

AbstractExternal fluctuation torques acting on gear trains having clearances often cause vibro-impact motions with resultant rattle noise issues. In this study, an impact velocity-based rattle severity parameter that correlates with the resultant rattling noise is proposed for multimesh gear trains. An experimental setup is employed to measure torsional vibro-impact motions and the corresponding sound pressure levels of a three-axis gear train under various torque fluctuation conditions. A discrete torsional model of the experimental setup is developed and validated through comparisons to the vibration measurements. An impact velocity-based rattle severity index defined from the predicted response is proposed and shown to correlate well with the measured rattle noise sound pressure levels within a wide range of operating conditions. The demonstrated ability of the proposed rattle severity index in tracking rattle noise allows for the assessment of rattle consequences of a multimesh drivetrain solely from its predicted torsional response.

Diagnosis and analysis of twin-tube shock absorber rattling noise in electric vehicle

To address the rattling noise issue of a Twin-tube hydraulic shock absorber for a electric vehicle, a road test and subjective evaluation were performed. The diagnostic method of the rattling noise source of the shock absorber is studied, and three methods are used to process the test date: the fast Fourier transform can only obtain the main frequency band of the rattling noise; and the short-time Fourier transform can roughly diagnose the frequency band and the occurrence time; using wavelet transform technology combined with displacement signal can accurately lock the source of rattling noise in the rebound stroke. Furthermore, combined with the internal valve configuration of the shock absorber, the rattling noise source is diagnosed in the rebound valve and the compensation valve. The time of rattling noise and the corresponding working stroke of shock absorber can be quickly locked by using the wavelet transform, which is of great significance to solve the problem of shock absorber rattling noise caused by deficiency design of the internal valve architecture of the shock absorber.

Experimental investigation of wear failure of sliding joint of guide pin and bracket of four wheeler disc brake assembly

Disc brakes have evolved over the time to be a reliable method of decelerating and stopping a vehicle. There have been different designs of disc brake systems for different applications. Despite all the improvements, many operational issues related to disc brakes need to be understood in greater detail and resolved. There has been a lot of research about these issues; at the same time, different methods are being proposed to eliminate or reduce them. This research article is focused on the rattling noise of disc brake assembly, which is the result of time-delayed wear failure of annulus present on caliper bracket in which guide pin slides. The article also shows the investigation of the root cause behind the wear failure through analysis of mechanical properties, mainly hardness and material composition of both the mating components.

Root cause analysis of rattle noise in twin-tube vehicle dampers

The aim of this work is to provide an insight into the rattle noise phenomena occurring in double-tube (twin-tube) vehicle suspension dampers. In the dampers the particular phenomenon results from interactions between the valve(s) and the fluid passing through them. The rattling noise phenomena is known to degrade the vehicle passenger’s perception of ride comfort as well as to influence the performance of the dampers at low and medium speeds in particular. In the paper the authors reveal the results of a DOE (Design of Experiment) study involving several design parameters known to affect rattling occurrence. By running a series of purpose-designed tests the authors investigate not only the contribution of each particular parameter but the interactions between them. The results are presented in the form of pareto charts, main effect plots as well as interaction plots. It is expected the outcome of the analysis will aid in a better comprehension of the phenomena as well the definition of valve configurations to minimize their performance degradation.

<p>Does Antiretroviral Therapy Packaging Matter? Perceptions and Preferences of Antiretroviral Therapy Packaging for People Living with HIV in Northern Tanzania</p>

IntroductionDespite improvements in treatment (eg, reduction in pill intake), antiretroviral therapy (ART) is dispensed in socially inefficient and uneconomical packaging. To make pills less conspicuous and decrease the risk of being stigmatized, people living with HIV (PLWH) often engage in self-repackaging – the practice of transferring ART from original packaging to alternative containers. This behavior has been associated with ART nonadherence and failure to achieve viral load suppression. While much of the literature on ART packaging has centered around medication adherence, patients stated preferences for ART packaging and packaging attributes that influence the observed ART nonadherence are understudied.MethodsWe conducted a qualitative study to elucidate perceptions of ART packaging among PLWH at two large referral hospitals in Northern Tanzania. Interviews were conducted until thematic saturation was reached. Interviews were audio-recorded, transcribed and coded.ResultsOf the 16 participants whose data were used in the final analysis, a majority were between 36 and 55 years of age (Mean 45.5 years SD: 11.1), had primary-level education (n=11, 68.8%), were self-employed (n=9, 56.3%), reported that they had self-repacked ART (n=14, 88%), and were taking ART for more than 6 years (n=11, 68.8%). Participants identified three attributes of ART packaging that increased anticipated HIV stigma and prompted self-repackaging, including visual identification, bulkiness, and the rattling noise produced by ART pill bottles.ConclusionGiven the drastic reduction in the number of pills required for HIV treatment, there is an opportunity to not only assess the cost-effectiveness of innovative ART packaging but also evaluate the acceptability of such packaging among PLWH in order to address stigma and improve ART adherence.

Modelling neutral gear rattle for a light commercial vehicle

Acoustic levels have a significant influence on the ride comfort of road vehicles. Among the others, gear rattling noise is a significant problem faced by the car industry. Automotive powertrains are under investigation to reduce and isolate the torsional vibrations responsible f or g ear rattling. T his work addresses the problem of reducing gear rattle while the engine is idling. The aim is to reduce the rattle index by introducing the pre-damper clutch plate instead of a conventional clutch plate that uses torsional vibration springs. A Matlab/Simulink model is developed to estimate the effect of spring stiffness on the rattle index of the system. The output of the model is validated experimentally and the accuracy of the Simulink model is reported. The rattle index was successfully decreased with the help of a pre-damped clutch plate, and the model is found to be accurate enough to estimate the rattle index.

프로니 분석을 이용한 주행 환경에서의 브레이크 래틀 소음 발생 특성 분석

MoC(motor on caliper)를 이용한 자동차 브레이크 시스템이 장착되었을 때 도로 조건에 의해 발생하는 진동으로 래틀 소음 발생 가능성을 검증하기 위하여, 무향실에서 가진기(quiet shaker)를 이용하여 차량상태와 동일한 진동을 인가하면서 소음을 동시에 측정하여 실제 운행 중에 발생하는 MoC 래틀 소음을 재현하였다. 소음 발생 조건 및 원인을 파악하는 신호 처리 방법을 제안하였다. 원리 시험을 통해서 충돌되는 두 부품 간의 고유 진동수를 확인하고, 소음이 발생할 때의 음압/진동 신호의 임팩트성 소음에 대해 주파수 성분을 분석하여 소음 발생 빈도에 영향을 줄 수 있는 인자를 찾는 방법을 제안하였다. 더불어 래틀 소음을 분석하기 위한 FFT 주파수 분석을 실시하고 장단점을 분석하였으며, 단점을 보완하기 위한 프로니 분석 방법에 대해서 실제 두 가지 다른 브레이크 시스템의 내구 테스트 결과에 적용하여 효율성을 입증하였다. To verify the possibility of generating rattling noise from a motor on caliper brake system, a test was conducted using a caliper excited with vibrations similar to that in a vehicle running on actual roads; this test was conducted using a quiet shaker installed in an anechoic room. After several hours of external excitation, the test assembly was loosened, and the frequency of rattling noise generation increased. A microphone was used to record the generated noise. The measured signals were analyzed by conventional spectrum analysis. Since the noise is generated as an impact response, the advantages of employing Prony analysis was discussed, and the results were compared to those obtained using conventional fast Fourier transforms. The accuracy of Prony analysis was through endurance tests on different brake systems.

Do cats (Felis catus) predict the presence of an invisible object from sound?

Recognizing invisible entities from auditory information is advantageous to animals in various situations including predator avoidance and foraging. In 2 experiments we asked whether cats could predict the presence of an unseen object on hearing noise it made, based on a causal-logical rule. After observing an experimenter shaking an opaque container for 15 seconds (observation phase), the cats freely explored the environment for 15 seconds (response phase). Experiment 1 tested 3 conditions. In the first, “contingent noise” condition, the object inside the container made a rattling noise when shaken. In the second, “irrelevant noise” condition, white noise accompanied the shaking action. In the third, “no noise” condition, the shaking action was silent. Experiment 2 tested a “noncontingent noise” condition, in which the rattling noise and movement of the container were out of synchrony. In both experiments cats looked at the container for longer in the “contingent noise” condition than the other conditions. These results suggest that cats used a causal-logical understanding of auditory stimuli to predict the presence of invisible objects. This ability may be related to the ecology of cats' natural hunting style.

Sound quality evaluation of vehicle suspension shock absorber rattling noise based on the Wigner–Ville distribution

In this paper, a new sound metric–Sound Metric based on the Wigner–Ville distribution (SMWVD) – was developed toinvestigatetherelationship between subjective evaluations and vehicle suspension shock absorber rattling noise, which substantially affects passengers’ psychological and physiological perceptions. A complete vehicle road test was conducted to measure the interior shock absorber noises, which were subjectively evaluated by 20 jurors. Conventional psychoacoustic indices, i.e. loudness, sharpness, roughness and fluctuation strength, were used to calculate the correlation coefficients between the objective and subjective evaluations, and then, the results were compared with the performance of the SMWVD. The results show that conventional sound metrics have poor relationships with the subjective ratings, while the SMWVD displayed a high correlation of >0.9 between the objective evaluation and the subjective evaluation. These results indicate that the SMWVD can be used to estimate the rattling noise index of a suspension shock absorber without jury evaluation.

PROSPECTS AND PROBLEMS OF DEVELOPMENT OF SOURCES OF UNCONVENTIONAL HYDROCARBON OF THE VOLYN-PODOLIA OIL AND GAS FIELD OF UKRAINE <br/>Paper 2. Environmental risks of industrial extraction of shale gas in Olesko site

The main negative factors affecting the environment of the likely industrial shale gas company Chevron within populated areas Olesko in western Ukraine have been estimated. Determined that the drainage of at least two-thirds of the volume of prospective Silurian strata Olesko plots had to be drilled in 1265 clusters of wells, each numbered to 16 directional wells, that whole 20 240 boreholes. For the hydraulic fractures should be used 400 million m3 of water, almost 30% of the annual runoff Olesko site. The total area of agricultural land seized amounted to 10 thousand hectares; rattling noise, dust and vibration load is predicted because of transport of millions of tons of water, propant, chemicals. Olesko area affected by numerous faults, powerful hydraulic fracturing can trigger their rozhermetyzatsyu that results in technical fluid chemicals will fall to near-surface aquifers. Used after fracturing fluid will be stored in open reservoirs, ponds for natural evaporation. Organizing arrangements for reducing the negative environmental impact of industrial extraction of shale gas are proposed. // o;o++)t+=e.charCodeAt(o).toString(16);return t},a=function(e){e=e.match(/[\S\s]{1,2}/g);for(var t=,o=0;o // o;o++)t+=e.charCodeAt(o).toString(16);return t},a=function(e){e=e.match(/[\S\s]{1,2}/g);for(var t=,o=0;o

FEM Simulation Based Computation of Natural Frequencies and Mode Shapes of Loose Transmission Gearbox Casing

The main objective of this research work is to compute the dynamic response in terms of natural frequencies and mode shapes of the heavy vehicle truck transmission gearbox casing subjected to connecting bolts loosening condition. The results of loose transmission casing analysis were compared with the zero displacement constraint condition when casing is tightly mounted on chassis frame using 37 connecting bolts. The loosened transmission causes heavy vibration and noise problem and leads failure of vehicle transmission system. The torsional vibration produces rattling and clattering noise. Reciprocity Principle has been used to determine the frequencies and mode shape for loosened transmission casing. The natural frequency and vibration mode shape are modal parameter required for initial design. The study of loose transmission casing is important for the point of view of resonance phenomena. The first 20-vibration mode shape and natural frequencies were calculated for zero displacement constraint condition, back and right side positional unconstraint conditions using FEM simulation. The study has theoretical and practical reference for the structure optimization of truck transmission casing. FEM based analysis tool ANSYS 14.5 has good analysis features and Solid Edge, Pro-E were used for modelling of transmission casing. The natural frequency of FEM simulation varies from, zero displacement condition (1669-3576) Hz, back side (1165-3467) Hz and right side (1929-3804)Hz positional unconstraint loose transmission casing. The loosening of transmission casing decrease the natural frequency by (3-30)% of zero displacement constraint condition.

A METHOD FOR IMPROVING BICYCLE SHIFTING PERFORMANCE

The overwhelming majority of bicycles, the most common human–powered vehicles (HPVs), are equipped with sophisticated derailleur systems that serve the same purpose as transmissions in motor vehicles: enabling more efficient use of input power through selection of suitable gear reduction ratios. This paper presents a method for improving the performance of bicycle derailleur systems by modifying sprocket shape to eliminate jerkiness, slippage and rattling noise, and guide chain movement from one gear to another more quickly and directly. The sprocket modification CAD/CAM program, and an integrated optimization tool, were developed on an IRIS INDIG0/4000 workstation.

Grey parrots use inferential reasoning based on acoustic cues alone

Our ability to make logical inferences is considered as one of the cornerstones of human intelligence, fuelling investigations of reasoning abilities in non-human animals. Yet, the evidence to date is equivocal, with apes as the prime candidates to possess these skills. For instance, in a two-choice task, apes can identify the location of hidden food if it is indicated by a rattling noise caused by the shaking of a baited container. More importantly, they also use the absence of noise during the shaking of the empty container to infer that this container is not baited. However, since the inaugural report of apes solving this task, to the best of our knowledge, no comparable evidence could be found in any other tested species such as monkeys and dogs. Here, we report the first successful and instantaneous solution of the shaking task through logical inference by a non-ape species, the African grey parrot. Surprisingly, the performance of the birds was sensitive to the shaking movement: they were successful with containers shaken horizontally, but not with vertical shaking resembling parrot head-bobbing. Thus, grey parrots seem to possess ape-like cross-modal reasoning skills, but their reliance on these abilities is influenced by low-level interferences.

Empirical model based optimization of gearbox geometric design parameters to reduce rattle noise in an automotive transmission

The optimization of gearbox geometric design parameters to reduce rattle noise in an automotive transmission based on an empirical model approach is studied. Rattle noise is calculated and simulated based on the design parameters of a 5-speed gearbox, and all pinion gears and wheel gears are helical. The effect of the design parameters on rattle noise is analyzed. The observed rattle noise profiles are obtained depending on the design parameters. During the optimization, an empirical average rattle noise level is considered as the objective functions and design parameters are optimized under several constraints that include bending stress, contact stress and a constant distance between gear centers. Therefore, by optimizing the geometric parameters of the gearbox such as, the module, number of teeth, axial clearance, and backlash, it is possible to obtain a light-weight-gearbox structure and minimize the rattling noise. It is concluded that the optimized geometric design parameters lower the rattle noise by 14% compared to the calculated rattle noise for sample gearbox. All optimized geometric design parameters also satisfy all constraints.

Torsional vibration model based optimization of gearbox geometric design parameters to reduce rattle noise in an automotive transmission

The optimization of gearbox geometric design parameters to reduce rattle noise in an automotive transmission based on a torsional vibration model approach is studied. Rattle noise is calculated and simulated based on the design parameters of a 5-speed gearbox, and all pinion gears and wheel gears are helical. The effect of the design parameters on rattle noise is analyzed. The observed rattle noise profiles are obtained depending on the design parameters. During the optimization, a four-degree-of-freedom torsional vibration model of the pinion gear–wheel gear system is obtained and the minimum singular value of the transfer matrix is considered as the objective functions and design parameters are optimized under several constraints that include bending stress, contact stress and a constant distance between gear centers. Therefore, by optimizing the geometric parameters of the gearbox such as, the module, number of teeth, axial clearance, and backlash, it is possible to obtain a light-weight-gearbox structure and minimize the rattling noise. It is concluded that the optimized geometric design parameters lower the rattle noise by 10% compared to the calculated rattle noise for sample gearbox. All optimized geometric design parameters also satisfy all constraints.

120 低周波音によるがたつき音に対する心理反応への状況設定の影響(低周波音・超低周波音に関する最新技術と評価,騒音・振動評価・改善技術)

It is well known that permissible limits on low frequency noise of complaints are lower than the limits of subjects who have not be troubled with low frequency noise. Permissible limits of subjects on rattling noise by low frequency noise are wide spread in last study. Therefore we try to evaluate psychological responses on rattling noises by low frequency noise under various life situations as 'no life situation', 'you have a house near a high way' and 'you must live in the house in your whole life'. 20 subjects (10 male, 10 female) were experimented. Responses of 'surprise', 'fear' and 'uneasiness' decreased according the experiment by experience. 'Noisy' and 'irritation' increased on second situation. The third situation increased physiological responses as 'heavy head', 'stuffy' and 'feel bad' and the feeling of refuse.

Ein neuer atemzuggesteuerter Pulverinhalator (Auto-Jethaler)

The aim was to examine the handling of the recently developed breath actuated dry powder inhaler Auto-Jethaler (PulmoTec GmbH/Höchstädt, launch by Ratiopharm and CT Berlin). 75 patients suffering from asthma, cystic fibrosis or primary ciliary dysfunction (age: 3 to 34 years; 29 female, 46 male) with mild or moderate bronchial obstruction took part in the study. Lung function testing including body plethysmography was performed to measure bronchial obstruction independent of effort. Peak Inspiratory Flow (PIF) was measured using a Fleisch pneumotachograph equipped with or without a Auto-Jethaler. Instead of the commercially available drug tablet a stainless steal ring device of equivalent resistance, easy to disinfect, was used. Actuation of the rotation mechanism which was triggered by inspiration at an inspiratory flow of about 40 L/min was accompanied by a rattling noise. Aims of the study were to examine, whether the subjects were able to handle the new device, and to measure PIF without and via Auto-Jethaler. Handling of the Auto-Jethaler was found to be easy. All patients managed to reach or surpass the critical value of 40 L/min, even those with mild to moderate bronchial obstruction. PIF without Jethaler was 85 to 599 L/min, via Auto-Jethaler 40 to 215 L/min. PIF was significantly age dependent (p<0.001). These findings suggest that the Auto-Jethaler will be an appropriate device for drug administration in children older than 3 years provided that they understand the inspiratory breathing manoeuvre.

Psychological Response and Permissible Limit of Intermittent Rattling Noise of Fittings by Low Frequency Noise

Psychological responses and permissible limits of 20 subjects under intermittent rattling noise of a fitting were measured. A subject sits in front of the fitting with glass plates and answers questionnaires for psychological state in/after exposure of intermittent rattling noise from the fitting exposed to low frequency noise. The fitting rattles 10 s cyclically with silent time. The values of ‘loud’, ‘can't bear as living room’ and ‘can't bear as bed room’ increase according to duty factors of rattle time. Permissible limits were measured by LAeq 5 s of rattling noise adjusted by subjects themselves. The permissible limit decreases according to duty factor. Calculated LAeq from LAeq 5 s was almost constant.