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Viewing 151 to 180 of 8995
2015-06-15
Journal Article
2015-01-2224
Yong Xu
Abstract An adaptive feed-forward active control system for improving the sound quality of vehicle engine noise is presented in this paper. Based on the narrow-band and periodic properties of engine noise, an artificial waveform, which was synthesized with sinusoidal components at the fundamental frequency of the engine noise and its harmonics, was adopted as the reference signal. Then these primary noise components were canceled via an adaptive notch filter bank, the coefficients of which were updated using the FXLMS algorithm. The core of the designed system is a new algorithm for improving the quality characteristics of the residual noise by adjusting the gain values of the noise component at each reference frequency. The feasibility and advantages of the designed system were validated through both simulation and practical vehicle tests.
2015-06-15
Journal Article
2015-01-2270
Oliver Unruh, Christopher Blech, Hans Peter Monner
Abstract Global attenuation of structural velocities is one of the most effective approaches in order to reduce noise emitted by shell structures such as a car roof or aircraft fuselage panels. This global reduction can be achieved by the application of passive damping treatments like constraint layer damping on large fractions of the vibrating surface. The main disadvantage of this approach arises from the fact that it leads to increasing total cost and weight of the structure. To overcome this problem, acoustic black holes can be used to create locations with high vibration amplitudes and low bending waves velocity in order to dissipate the energy of structure borne sound by very limited application of damping treatments. Acoustic black holes are funnel shaped thickness reductions that attract sound radiating bending waves and allow a global vibration reduction by an acceptable use of additional damping.
2015-06-15
Technical Paper
2015-01-2266
Andrzej Pietrzyk
Abstract Several of the exterior noise sources existing around a vehicle can cause airborne noise issues at relatively low frequencies. SEA, traditionally used for airborne sound issues is not suitable for the frequency range of interest. Finite Element analysis has been used. Handling of the non-reflecting condition on the outer boundary of the exterior cavity is an issue. Recently, advances have been made in several commercially available codes, which made the analysis practical. Including the poro-elastic material model for foam-based carpets is also becoming practically possible. The purpose of the current study is to investigate the practical applications of those new developments against test data, and to estimate the feasibility of using these procedures in the vehicle development projects. Measurements were carried out in a new semi-anechoic chamber at Volvo Cars.
2015-06-15
Journal Article
2015-01-2276
Zhengyu Liu, Donald Wozniak, Manfred Koberstein, Curtis Jones, Jan Xu, Suhas Venkatappa
Abstract Refrigerant flow-induced gurgling noise is perceived in automotive refrigerant systems. In this study, the condition of the gurgling generation is investigated at the vehicle level and the fundamental root cause is identified as the two-phase refrigerant flow entering the TXV for system equipped with variable displacement compressors. By conducting literature reviews, the acoustic characteristics of the flow patterns and the parameters affecting the flow regimes in horizontal and vertical tubes are summarized. Then the gurgling mechanism is explained as the intermittent flow is developed at the evaporator inlet. In the end, the improved and feasible design for avoiding the intermittent flow (slug, plug or churn flow) or minimizing its formation is proposed and verified in refrigerant subsystem (RSS) level. Finally, the guidelines for the attenuation and suppression of the gurgle are provided.
2015-06-15
Journal Article
2015-01-2275
Manfred Koberstein, Zhengyu Liu, Curtis Jones, Suhas Venkatappa
Abstract In the thermal expansion valve (TXV) refrigerant system, transient high-pitched whistle around 6.18 kHz is often perceived following air-conditioning (A/C) compressor engagements when driving at higher vehicle speed or during vehicle acceleration, especially when system equipped with the high-efficiency compressor or variable displacement compressor. The objectives of this paper are to conduct the noise source identification, investigate the key factors affecting the whistle excitation, and understand the mechanism of the whistle generation. The mechanism is hypothesized that the whistle is generated from the flow/acoustic excitation of the turbulent flow past the shallow cavity, reinforced by the acoustic/structural coupling between the tube structural and the transverse acoustic modes, and then transmitted to evaporator. To verify the mechanism, the transverse acoustic mode frequency is calculated and it is coincided to the one from measurement.
2015-05-14
Article
The newly named Johnson Controls Vehicle Engineering Laboratory, on the Lawrence Technological University campus in Michigan, will serve the energy-storage-system supplier and benefit LTU engineering students.
2015-05-05
Article
At Intermat, LiuGong announced that it was in a 60-day countdown before its new Global Research and Development Center opens in June at Liuzhou, also home to the company's global headquarters.
2015-05-01
Journal Article
2015-01-9106
Magnus Löfdahl, Arne Nykänen, Roger Johnsson
Abstract In the automotive industry, tire noise is an important factor for the perceived quality of a product. A useful method to address such NVH problems is to combine recordings with measurements and/or simulations into auralizations. An example of a method to create structure-borne tire noise auralizations is to filter recordings of hub forces and moments through binaural transfer functions experimentally measured from the hub of the car to an artificial head in the car cabin. To create authentic auralizations of structure-borne sound, all six degrees of freedom (DOFs) of hub forces and moments and transfer functions should be included. However, rotational DOFs are often omitted due to measurement difficulty, complexity, time, and cost. The objective was to find which DOF (or DOFs) is perceived as most prominent in structure-borne tire noise. An auralization model of interior structure-borne tire noise was used.
2015-04-30
Article
New AWD systems from BorgWarner and Honda deliver significant improvements in efficiency, as well as vehicle dynamic performance.
2015-04-30
Standard
J1174_201504
This SAE Recommended Practice establishes the instrumentation and procedure to be used in measuring the operator ear sound level for engine powered equipment under 30 kW (40 bhp). The sound levels obtained by using this procedure are representative of the sound levels generated by the equipment under typical operating conditions. It is intended to include equipment such as lawn mowers, snow blowers, and tillers. It is not intended to include equipment designed primarily for operation on highways or within factories or buildings, or vehicles such as motorcycles, snowmobiles, and pleasure motorboats that are covered by other SAE Standards or Recommended Practices. This procedure does not cover handheld equipment such as chainsaws, leaf blowers, and trimmers. This SAE Recommended Practice may also be used when measuring the operator ear sound level of similar equipment powered by electricity or other power sources.
2015-04-30
Standard
J2883_201504
This SAE Recommended Practice describes a laboratory test procedure for measuring the random incidence sound absorption performance of a material or a part in a small size reverberation room by measuring decay rates. The absorption performance may include sound absorption coefficient of the test sample and or the amount of energy absorbed by the test sample. Materials for absorption treatments may include homogeneous materials, nonhomogeneous materials, or a combination of homogeneous, nonhomogeneous, and/or inelastic impervious materials. These materials are commonly installed in the mobility products and in the transportation systems such as ground vehicles, marine products, aircraft, and commercial industry (in industrial and consumer products) to reduce reverberant sound build-up and thus reduce the noise level in the environment by minimizing reflections off of hard surfaces.
2015-04-29
Article
One of the key differentiators of the EP-8100 for commercial and military simulation and training is the system’s ability to use customers’ existing databases.
2015-04-28
Article
EM Test now offers the VDS 200Q Series, a four-quadrant voltage drop simulator that can source and sink current using a programmed voltage in both positive and negative polarities.
2015-04-24
Article
Julabo introduces two additional highly dynamic temperature control systems: the process circulators Presto A45 and A45t.
2015-04-24
Article
Boeing is in the midst of several months of flights with its ecoDemonstrator 757 in a first-round effort to evaluate new technologies in 2015 that are expected to reduce environmental effects on natural laminar flow as a way to improve aerodynamic efficiency while reducing noise and carbon emissions.
2015-04-24
Article
The engine bay is an essential component of the AgustaWestland AW609 tilt rotor nacelle, since it determines the performance of the engine and assures safe maneuvers for every flight condition.
2015-04-21
Article
Schmitt Industries announces availability of the AR 2000 line, with special capabilities for distance measurement on hot surfaces—e.g., red hot, glowing steel, and for outdoor use in bright lighting conditions with high constant or stray light levels.
2015-04-15
Article
Given the pace of innovation, the goal of autonomy and automation will force more and more features into the electronics of off-highway vehicles, according to Ian Fountain, NI's Director of Application Segments.
2015-04-15
Standard
J2455_201504
The product for which data is to be available is for class 6 and larger, i.e., gross vehicle weight ≻ 9.6 kg (19500 lb). The objective is to establish a set of data requirements which powertrain component suppliers would have readily available to facilitate drivetrain system vibration compatibility and control studies.
2015-04-14
Technical Paper
2015-01-1122
Kengo Yabe, Toru Inagaki, Takashi Kondo
Abstract Seat vibration when a vehicle is idling or in motion is an issue in automobile development. In order to reduce this vibration, dynamic damper or inertia mass is widely used. These countermeasures increases vehicle's weight and causes bad fuel-efficiency. Some new ways to reduce the vibration without weight increase are needed. One of that is the floating seat. Seat vibration has been reduced by controlling seat resonance frequencies. In order to control resonance frequency, the structures of the seat-mounting unit are replaced with floating structures using rubber bushings. It was demonstrated that partially replacing the mounting unit with floating structures makes it possible to control the resonance frequencies of the entire seat. The issue of balancing vibration reduction with strength and durability and crash safety performance caused by the fitting of rubber bushings to the seat-mounting unit was addressed using stopper structures optimized for each type of input.
2015-04-14
Technical Paper
2015-01-1123
Jiangwu Zhang, Donghao Liu, Haisheng Yu
Abstract A novel single-mode compound split hybrid transmission with a compound planetary gear set and two brakes has been studied, which has more freedom of control to increase the system efficiency. System dynamics and matching performance of the driveline including a compound planetary gear set for a single-mode hybrid electric vehicle are numerically investigated. The multi-degrees of freedom torsional vibration model for the full-hybrid vehicle driveline with the power split device is established by MATLAB/Simulink. For comparison of the natural characteristic, eigenfrequencies and mode shapes are determined with the aid of a further simplified single-track mechanical model under different operation modes. Then, numerical simulations of dynamics and kinematics of the driveline and the compound planetary gear set are carried out.
2015-04-14
Technical Paper
2015-01-1195
Kiyotaka Maeda, Masashi Takahashi
Abstract To verify the appropriateness of the vibration test conditions of ISO 12405, we performed tailoring to derive power spectrum densities and test durations as vibration test conditions. Vehicles used for tailoring included two electric vehicles and one plug-in hybrid electric vehicle. Those vehicles were equipped with accelerometers and were run on seven different road types at different speeds while data on the acceleration of the battery packs were recorded. The power spectrum densities for three axes that were derived from the obtained acceleration data were similar in form to the power spectrum densities of ISO 12405, and almost the same root mean square accelerations were obtained, confirming that they are appropriate. However, both experiments and theory suggest that the test duration for the Z-axis exceeds those of the X- and Y-axes.
2015-04-14
Technical Paper
2015-01-1326
Sivanandi Rajadurai, Guru Prasad Mani, Kavin Raja, Sundaravadivelu Mohan
Abstract Generation of discretization with prescribed element sizes are adapted to the geometry. From the rules of thumb, for a complicated geometry it is important to select the reasonable element order, shapes and size for accurate results. In order to that, this paper describes the influence of elemental algorithm of the catalytic converter mounting brackets. Brackets are main source of mounting of various systems mainly intake and exhaust in the engine. In hot end exhaust system, a bracket design plays a vital role because it has to withstand heavy structural vibrations without isolation combined with thermal loads. Bracket design and stiffness determines the whole catalytic converter system's rigidity. So, here discretization of converter brackets by linear and parabolic elements is studied with different elements types and compared.
2015-04-14
Technical Paper
2015-01-1360
Sajjad Beigmoradi
Abstract Improvements of aerodynamics and wind noise are two important objectives for automotive engineers. Improvement of aerodynamics behavior and the reduction of wind noise have been always greatly concerned by automotive engineers since they negatively affect passengers comfort, fuel consumption, car performance and, stability. In this paper, optimum levels of four dominant rear shape parameters for a simplified car model are investigated considering drag coefficient and aerodynamic noise objectives. C-Pillar angle, trunk angle, boat tail angle and rear box length are considered as variable parameters. Taguchi method is used for finding aerodynamic and acoustic optimum levels. Numerical simulation for base case is compared with experimental results in the literature. Numerical results show good agreement with experimental test. Afterwards, optimum levels for parameters regarding objectives are calculated using Taguchi method.
2015-04-14
Technical Paper
2015-01-0635
Changxin Wang, Wenku Shi, Zhijun Guo, Meilan Liu
Abstract For the roll vibration problem of a Truck, a 4-DOF roll vibration model of its front suspension system was built. According to dynamics theory, the complex modal vibration modes of the model were all obtained. At the same time, the frequency response functions of frame roll angle acceleration, the relative dynamic load of wheel and the suspension dynamic deflection were respectively presented. Then their characteristics were respectively researched. In the process of characteristic analysis, a new system parameter was proposed, which is the space ratio of the space between suspensions of left and right sides and the wheel track of the front axle (space ratio in short). At last, the influence of system parameters on the vibration transmission property was also reserached, which included the natural frequency of the frame, the damping ratio, the stiffness ratio, the mass ratio, the rotational inertia ratio and the space ratio.
2015-04-14
Technical Paper
2015-01-0617
Jie Zhang, Xiao Chen, Bangji Zhang, Lifu Wang, Shengzhao Chen, Nong Zhang
Abstract This paper demonstrates time response analysis of the mining vehicle with bounce and pitch plane hydraulically interconnected suspension (HIS) system. Since the mining vehicles working in harsh conditions inducing obvious pitch motion and the hard stiffness of suspensions leading to the acute vibration, the passive hydraulically interconnected system is proposed to provide better ride comfort. Furthermore, the hydraulic system also increases the suspension stiffness in the pitch mode to prevent vehicle from large pitch motions. According to the hydraulic and mechanical coupled characteristic of the mining vehicles, a 7degrees of freedom (7-DOFS) mathematical model is employed and the state space method is used to establish the mechanical and hydraulic coupled dynamic equations. In this paper, the vehicles are subjected to straight line braking input, triangle block bump input applied to the wheels and random road tests.
2015-04-14
Technical Paper
2015-01-0618
Zhihong Dong, Ying Sun, Guitao Zhu, Shihu Wang, Jian Zeng, Yuliang Yang
Abstract Based on the modal frequency response theory and experiment, the installation layout evaluation and structural optimization method for SIS(side impact sensors) installation position is studied. Establish the finite element model including B-pillar, roof and floor with local constraint. Than study the key parameter's influence on the frequency response analysis results, and the simulation results are correlated by experiment. In view of the installation layout requirements of side impact sensors, the structure optimization method for installation position of side impact sensor is put forward. The optimal scheme is confirmed by the finite element analysis, and a final experimental verification was implemented by a real vehicle test.
2015-04-14
Technical Paper
2015-01-0613
Donghong Ning, James Coyte, Hai Huang, Haiping Du, Weihua Li
Abstract This paper presents a study on experimental vibration simulation using a multiple-DOF motion platform for heavy duty vehicle seat suspension test. The platform is designed to have 6-DOF with the advantages of high force-to-weight ratio, high dexterity and high position accuracy. It can simulate vehicle vibrations in the x, y and z translational axis and in the roll pitch and yaw axis rotation. To use this platform to emulate the real vibration measured from vehicle seat base under real operation for vehicle seat suspension test in lab, an Inertial Measurement Unit (IMU) is applied to collect the acceleration data from a real vehicle. An estimation algorithm is developed to estimate the displacement from the measured acceleration. The estimated displacement is then used to calculate the length of each leg of the platform so that the platform can generate the motion similar to the measured one.
2015-04-14
Technical Paper
2015-01-0615
Li Jie, Wang Wenzhu, Gao Xiong
Abstract In order to study the influence of body flexibility on the truck ride comfort, a 4 DOF half vibration model of truck based on the motion synthesis between rigid body and body flexibility is established using elastic beam theory of equal section with both free ends. At the same time, a corresponding 2 DOF rigid vibration model is also built. The frequency response functions of system and response variables of two models are derived based on front wheel. The power spectral densities and the root mean square values of body acceleration, dynamic deflections and relative dynamic loads are obtained. By comparing the simulation results of rigid-elastic model and rigid model, it shows that body flexibility has a great impact on truck ride comfort and it cannot be ignored.
2015-04-14
Technical Paper
2015-01-1285
Dingfeng Deng, Fanghui Shi, Louis Begin, Isaac Du
Abstract Instances have occurred where the outer surface of turbocharger fully floating journal bearing bushings have exhibited damage from oil debris resulting in constant tone noise and subsequent warranty claims. This paper studies the effect of oil debris in Turbocharger journal bearings on Subsynchronous NVH. A CFD model is built to study the behavior of oil debris particles with different sizes. It is found that the dominant centrifugal forces prevent larger particles from reaching the inner film while smaller particles travel more easily to the inner film. It is also found that the turbine side is more likely to become damaged from debris than the compressor side bearing due to higher temperatures. A tribology analysis shows that oil debris particles in the outer film will reduce the speed ratio, while oil debris particles in inner film will increase the speed ratio. The tribology analysis also predicts the effects of oil debris on bearing stiffness and damping.
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