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Viewing 1 to 30 of 2700
2017-06-05
Technical Paper
2017-01-1751
Nicolas Schaefer, Bart Bergen, Tomas Keppens, Wim Desmet
Abstract The continuous pursuit for lighter, more affordable and more silent cars, has pushed OEMs into optimizing the design of car components. The different panels surrounding the car interior cavity such as firewall, door or floor panels are of key importance to the NV performance. The design of the sound packages for high-frequency airborne input is well established. However, the design for the mid-frequency range is more difficult, because of the complex inputs involved, the lack of representative performance metrics and its high computational cost. In order to make early decisions for package design, performance maps based on the different design parameters are desired for mid-frequencies. This paper presents a framework to retrieve the response surface, from a numerical design space of finite-element frequency sweeps. This response surface describes the performance of a sound package against the different design variables.
2017-06-05
Technical Paper
2017-01-1760
Weimin Thor, J. Stuart Bolton
Abstract Due the increasing concern with the acoustic environment within automotive vehicles, there is an interest in measuring the acoustical properties of automotive door seals. These systems play an important role in blocking external noise sources, such as aerodynamic noise and tire noise, from entering the passenger compartment. Thus, it is important to be able to conveniently measure their acoustic performance. Previous methods of measuring the ability of seals to block sound required the use of either a reverberation chamber, or a wind tunnel with a special purpose chamber attached to it. That is, these methods required the use of large and expensive facilities. A simpler and more economical desktop procedure is thus needed to allow easy and fast acoustic measurement of automotive door seals.
2017-06-05
Technical Paper
2017-01-1784
Guillaume Baudet
Abstract Wind noise in automobile is becoming more and more important as customer requirements increase. On the other hand great progress has been made on engine and road noises. Thus, for many vehicles, wind noise is the major acoustic source during road and motorway driving. As for other noises, automobile manufacturers must be able for a new car project to specify, calculate and measure each step of the acoustic cascading: Source Transfers, both solid and air borne In the case of automotive wind noise, the excitation source is the dynamic pressure on the vehicle’s panels. This part of the cascading is the one influenced by the exterior design. Even if many others components (panels, seals, cabin trims) have a big influence, the exterior design is a major issue for the wind noise. The wind noise level in the cabin can sometimes change significantly with only a small modification of the exterior design.
2017-06-05
Journal Article
2017-01-1806
Laurent Gagliardini
Abstract The input mobility is a crucial structural parameter regarding vibro-acoustic design of industrial objects. Whatever the frequency range, the vibrational power input into a structure -and consequently the average structural-acoustic response- is governed by the input mobility. When packaging structure-borne noise sources, the knowledge of the input mobility at the source connection points is mandatory for noise control. The input mobility is classically computed at the required points as a specific Frequency Response Function (FRF). During an industrial design process, the choice of connection points requires an a priori knowledge of the input mobility at every possible location of the studied structure-borne source, i.e. a mapping of the input mobility. The classical FRF computation at every Degree Of Freedom (DOF) of the considered structure would lead to consider millions of load cases which is beyond current computational limits.
2017-06-05
Technical Paper
2017-01-1812
Steven Sorenson, Gordon Ebbitt, Scott Smith, Todd Remtema
Abstract In an effort to reduce mass, future automotive bodies will feature lower gage steel or lighter weight materials such as aluminum. An unfortunate side effect of lighter weight bodies is a reduction in sound transmission loss (TL). For barrier based systems, as the total system mass (including the sheet metal, decoupler, and barrier) goes down the transmission loss is reduced. If the reduced surface density from the sheet metal is added to the barrier, however, performance can be restored (though, of course, this eliminates the mass savings). In fact, if all of the saved mass from the sheet metal is added to the barrier, the TL performance may be improved over the original system. This is because the optimum performance for a barrier based system is achieved when the sheet metal and the barrier have equal surface densities. That is not the case for standard steel constructions where the surface density of the sheet metal is higher than the barrier.
2017-06-05
Journal Article
2017-01-1813
James M. Jonza, Thomas Herdtle, Jeffrey Kalish, Ronald Gerdes, Taewook Yoo, Georg Eichhorn
Abstract The aerospace industry has employed sandwich composite panels (stiff skins and lightweight cores) for over fifty years. It is a very efficient structure for rigidity per unit weight. For the automobile industry, we have developed novel thermoplastic composite panels that may be heated and shaped by compression molding or thermoforming with cycle times commensurate with automotive manufacturing line build rates. These panels are also readily recycled at the end of their service life. As vehicles become lighter to meet carbon dioxide emission targets, it becomes more challenging to maintain the same level of quietness in the vehicle interior. Panels with interconnected honeycomb cells and perforations in one skin have been developed to absorb specific noise frequencies. The absorption results from a combination and interaction of Helmholtz and quarter wave resonators.
2017-06-05
Technical Paper
2017-01-1842
Akin Oktav, Cetin Yilmaz, Gunay Anlas
Abstract To prevent trunk lid slam noise, reactive openings are used in the trunk cavities of passenger vehicles. In sedans, the trunk cavity and the cabin cavity are coupled acoustically through the discontinuities on the parcel shelf and/or the rear seat. In such a case, these openings behave as necks of a Helmholtz resonator, which in turn change the acoustic response of the system. In this study, the Helmholtz resonator effect of the trunk cavity is discussed analytically through a simplified cavity model. A case study, where the acoustic response of a sedan is analyzed through a computational model considering the resonator effect is also given. Sound pressure levels show that instant pressure drops and damping effects observed in the acoustic response can be explained with the resonator effect. Results obtained from the computational model of the sedan are verified with the track test measurements.
2017-06-05
Technical Paper
2017-01-1852
Satyajeet P. Deshpande, Pranab Saha, Kerry Cone
Abstract Most of NVH related issues start from the vibration of structures where often the vibration near resonance frequencies radiates the energy in terms of sound. This phenomenon is more problematic at lower frequencies by structureborne excitation from powertrain or related components. This paper discusses a laboratory based case study where different visco-elastic materials were evaluated on a bench study and then carried on to a system level evaluation. A body panel with a glazing system was used to study both airborne and structureborne noise radiation. System level studies were carried out using experimental modal analysis to shift and tune the mode shapes of the structure using visco-elastic materials with appropriate damping properties to increase the sound transmission loss. This paper discusses the findings of the study where the mode shapes of the panel were shifted and resulted in an increase in sound transmission loss.
2017-06-05
Technical Paper
2017-01-1855
Ramakanta Routaray
Abstract The basic function of a motorcycle frame is somewhat similar to that of the skeleton in the human body, i.e. to hold together the different parts in one rigid structure. One of the major benefits (for a motorcycle enthusiast) of using an advanced frame design lies in the sporty handling characteristics of the bike. A well designed frame can add to the joy of riding a motorcycle as the bike would feel more stable, effortless, and confident around corners, in straight lines and while braking. A well approved modeling [2] techniques or adequate guide line principles have to be followed while designing the body and chassis in order to achieve the vibration within control. This paper depicts a methodological right approach (guide lines) while designing the body and chassis of a two wheeler in order to control noise and vibration of the body and chassis.
2017-06-05
Technical Paper
2017-01-1849
Laurent Gagliardini, Romain Leneveu, Aurélien Cloix, Alexandre Durr
Abstract The door response to audio excitation contributes to the overall performance of the audio system on several items. First, acting as a cabinet, it influences the loudspeaker response. Second, due to the door trim inner panel radiation, the radiated power is disturbed. A third effect is the regular occurrence of squeak and rattle, that will not be considered at this stage. Design issues regarding these attributes are numerous, from the loudspeaker design to door structure and trim definition. Modeling then appears as an unavoidable tool to handle the acoustic response of the loudspeaker in its actual surrounding.
2017-06-05
Technical Paper
2017-01-1859
Filip Franek, Jungu Kang, Jeon Uk, Sunguk Choi
Abstract Structure-born vibrations are often required to be localized in a complex structure, but in such dispersive medium, the vibration wave propagates with speed dependent on frequency. This property of solid materials causes an adverse effect for localization of vibrational events. The cause behind such phenomenon is that the propagating wave envelope changes its phase delay and amplitude in time and space as it travels in dispersive medium. This problem was previously approached by filtering a signal to focus on frequencies of the wave propagating with a similar speed, with improved accuracy of cross-correlation results. However, application of this technique has not been researched for localization of vibrational sources. In this work we take advantage of filtering prior to cross-correlation calculation while using multiple sensors to indicate an approximate location of vibration sources.
2017-06-05
Journal Article
2017-01-1876
Weiyun Liu, David W. Herrin, Emanuele Bianchini
Abstract Microperforated panel absorbers are best considered as the combination of the perforate and the backing cavity. They are sometimes likened to Helmholtz resonators. This analogy is true in the sense that they are most effective at the resonant frequencies of the panel-cavity combination when the particle velocity is high in the perforations. However, unlike traditional Helmholtz resonators, microperforated absorbers are broader band and the attenuation mechanism is dissipative rather than reactive. It is well known that the cavity depth governs the frequency bands of high absorption. The work presented here focuses on the development, modeling and testing of novel configurations of backing constructions and materials. These configurations are aimed at both dialing in the absorption properties at specific frequencies of interest and creating broadband sound absorbers. In this work, several backing cavity strategies are considered and evaluated.
2017-06-05
Technical Paper
2017-01-1886
Siwen Zhang, Jian Pang, Jun Zhang, Zhuangzhuang Ma, Xiaoxuan Zhang, Congguang Liu, Lihui Deng
Abstract A subjective evaluation method for the air-borne sound insulation of vehicle body in reverberation room is developed and the correlation between the subjective preference and objective noise reduction level (NRL) is investigated in this paper. The stationary vehicle's interior noise is recorded by using a digital artificial head under a given white noise excitation in the reverberation room, which demonstrates more credible than those in traditional road test methods. The recorded noises of six different vehicles are replayed and evaluated subjectively by 22 appraisers in a sound quality room. The paired comparison scoring method is employed and the check and statistic methods for the subjective scores are introduced. The subjective preference is introduced and calculated by the statistics and normalization of the effective scores, which can indicate an overall preference ranking of all the six vehicles numerically.
2017-06-05
Journal Article
2017-01-1825
Takenori Miyamoto, Hiroshi Yokoyama, Akiyoshi Iida
Abstract Intense aeroacoustic feedback noises may radiate from flow around an airfoil, rearview mirror with small gaps and so on. Reductions of these noises are important issues in the development of industrial application. The intense noise from a bonnet of the automobile is one of the typical problems of acoustic feedback noise. In order to reduce this noise, plasma actuator (PA) was utilized to control flow and acoustic fields. The aim of this investigation is to clarify the effects of flow control by the PA on noise reduction and the noise reduction mechanism. Wind tunnel experiments were conducted with a half scale bonnet model and a low noise wind tunnel. Simultaneous measurements of flow and noise fields were conducted to understand the generation mechanism of the bonnet noise. Coherent output power (COP) of the velocity fluctuations with reference to far-field sound pressure was measured to visualize noise source distribution.
2017-06-05
Journal Article
2017-01-1830
Thomas Haase, Henning Bühmann, Martin Radestock, Hans Peter Monner
Abstract Due to the strengthened CO2 and NOx regulations, future vehicles have to be lightweight and efficient. But, lightweight structures are prone to vibrations and radiate sound efficiently. Therefore, many active control approaches are studied to lower noise radiation besides the passive methods. One active approach for reducing sound radiation from structures is the active structural acoustic control (ASAC). Since the early 90’s, several theoretical studies regarding ASAC systems were presented, but only very little experimental investigations can be found for this alternative to passive damping solutions. The theoretical simulations show promising results of ASAC systems compared to active vibration control approaches. So, for that reason in this paper an experiment is conducted to investigate the performance of an ASAC system in the frequency range up to 600 Hz.
2017-05-25
WIP Standard
ARP1107C
This recommended practice covers the fixed structure, or independent energy absorbing system affixed to the airframe to afford protection to the control surfaces, engine and other portions during ground handling, take-off and landing.
2017-05-09
WIP Standard
J2253
This SAE Standard is intended to serve as a guide for the collection of physical, mechanical, and thermal properties of fiber-reinforced polymer composite materials for automotive structural applications. This document attempts to utilize test methods applicable to the widest range of structural materials and processes without compromising the integrity of the data being sought. A summary of the material characterization is shown in Section 15.
2017-04-06
Event
BE & D cover several important areas that are related to vehicle body, including its components such as instrument panel, steering column and wheel, seats, hood, decklid, transmission cross-member, hard mounted chassis, CRFM, etc. Topics included are: Novel concepts, Analysis, Design, Testing, Predictions of strength, stiffness, and fatigue life, welding methods, vehicle body quality, durability, reliability, safety, ride & handling, NVH, aerodynamics, mass reduction, as well as fuel economy.
2017-04-06
Event
BE & D cover several important areas that are related to vehicle body, including its components such as instrument panel, steering column and wheel, seats, hood, decklid, transmission cross-member, hard mounted chassis, CRFM, etc. Topics included are: Novel concepts, Analysis, Design, Testing, Predictions of strength, stiffness, and fatigue life, welding methods, vehicle body quality, durability, reliability, safety, ride & handling, NVH, aerodynamics, mass reduction, as well as fuel economy.
2017-04-05
Event
The session will address multibody system modeling and simulation, rigid and flexible body modeling, loads predictions for vehicle body, frame/sub frame, exhaust system, driveline, and powertrain. Also discussed are vehicle dynamics simulation, durability loads simulation, data processing and analysis, design load minimization, prediction of loads effects, robust design methods, driver modeling, and system modeling.
2017-03-28
Technical Paper
2017-01-1300
Raj Jayachandran, Bhimaraddi Alavandi, Matt Niesluchowski, Erika Low, Yafang Miao, Yi Zhang
Abstract An engine cooling system in an automotive vehicle comprises of heat exchangers such as a radiator, charge air cooler and oil coolers along with engine cooling fan. Typical automotive engine-cooling fan assembly includes an electric motor mounted on a shroud that encloses the radiator core. One of main drivers of fan shroud design is Noise, Vibration, and Harshness (NVH) requirements without compromising the main function of airflow for cooling requirements. In addition, there is also a minimum stiffness requirement of fan shroud which is often overlooked in arriving at optimal design of it. Low Speed Damageability (LSD) assessment of an automotive vehicle is about minimizing the cost of repair of vehicle damages in low speed crashes. In low speed accidents, these fan motors are subjected to sudden decelerations which cause fan motors to swing forward thereby damaging the radiator core. So designing fan shroud for low speed damageability is of importance today.
2017-03-28
Technical Paper
2017-01-1468
Do Hoi KIm
Previous work identified a relationship between vehicle drop and dummy injury under the high-speed frontal impact condition [1]. The results showed that vehicle drop greater than 60mm made the dummy injury worse. Moreover, that work identified the front side member as the crucial part affecting the vehicle drop. In this study, the body structure mechanism was studied to reduce vehicle drop by controlling the front side member, shotgun, and A-pillar. By analyzing full vehicles, it was recognized that the arch shape of the front side member was very important. Furthermore, if the top of the arch shape of front side member, shotgun, and A-pillar were connected well, then the body deformation energy could lift the lower part of A-pillar, effectively reducing vehicle drop. This structure design concept is named “Body Lift Structure” (BLS). The BLS was applied to B and C segment platforms. Additionally, a “Ring” shape was defined by the front side member, dash panel, and A-pillar.
2017-03-28
Technical Paper
2017-01-1451
Jan Vychytil, Jan Spicka, Ludek Hyncik, Jaroslav Manas, Petr Pavlata, Radim Striegler, Tomas Moser, Radek Valasek
Abstract In this paper a novel approach in developing a simplified model of a vehicle front-end is presented. Its surface is segmented to form an MBS model with hundreds of rigid bodies connected via translational joints to a base body. Local stiffness of each joint is calibrated using a headform or a legform impactor corresponding to the EuroNCAP mapping. Hence, the distribution of stiffness of the front-end is taken into account. The model of the front-end is embedded in a whole model of a small car in a simulation of a real accident. The VIRTHUMAN model is scaled in height, weight and age to represent precisely the pedestrian involved. Injury risk predicted by simulation is in correlation with data from real accident. Namely, injuries of head, chest and lower extremities are confirmed. Finally, mechanical response of developed vehicle model is compared to an FE model of the same vehicle in a pedestrian impact scenario.
2017-03-28
Technical Paper
2017-01-1453
Sudip Sankar Bhattacharjee, Shahuraj Mane, Harsha Kusnoorkar, Sean Hwang, Matt Niesluchowski
Abstract Pedestrian protection assessment methods require multiple head impact tests on a vehicle’s hood and other front end parts. Hood surfaces are often lifted up by using pyrotechnic devices to create more deformation space prior to pedestrian head impact. Assessment methods for vehicles equipped with pyrotechnic devices must also validate that the hood deployment occurs prior to head impact event. Estimation of pedestrian head impact time, thus, becomes a critical requirement for performance validation of deployable hood systems. In absence of standardized physical pedestrian models, Euro NCAP recommends a list of virtual pedestrian models that could be used by vehicle manufacturers, with vehicle FEA (Finite Element Analysis) models, to predict the potential head impact time along the vehicle front end profile. FEA simulated contact time is used as target for performance validation of sensor and pyrotechnic deployable systems.
2017-03-28
Technical Paper
2017-01-1341
Alok Kumar, Sandeep Sharma
Abstract Public conveyance such as a bus is a major contributor to socio - economic development of any geography. The international market for passenger bus needed to be made viable in terms of passenger comfort, minimum operational costs of the fleet by reduced fuel consumption through light weighting and yet robust enough to meet stringent safety requirements. Optimized design of bus body superstructure plays vital role in overall performance and safety, which necessitates to evaluate bus structure accurately during initial phase of design. This paper presents a robust methodology in numerical simulation for enhancing the structural characteristics of a bus body with simultaneous reduction in the weight by multi-material optimization while supplemented with sensitivity and robustness analysis. This approach ensures significant reduction in vehicle curb weight with promising design stiffness.
2017-03-28
Technical Paper
2017-01-1725
Tanawat Tessathan, Chutiphon Thammasiri, Prabhath De Silva, Rehan Hussain, Nuksit Noomwongs
Abstract It is common for users of commuting passenger cars in Thailand to use the vehicle’s HVAC (Heating, Ventilating and Air Conditioning) system predominantly in recirculation (REC) mode. This minimizes the compressor work, thereby saving fuel, and reduces dust and odor infiltration into the vehicle cabin. The car windows are rarely opened for ventilation purposes, except for exchanges at service stations such as garage entrances and tollway booths. As such, there are few opportunities for fresh air to enter the cabin with the consequent accumulation of CO2 in vehicle cabins due to occupants’ exhalations being well documented. Field experiments conducted showed that the in-vehicle CO2 concentrations could reach up to 15 times that of the ambient concentration level during typical city commutes. Preliminary experiments were also conducted to quantify the air exchanges between the cabin and the ambient when the doors are opened for occupant egression.
2017-03-28
Technical Paper
2017-01-0417
Yingjun Li, Yunkai Gao, Gangan Ma, Qianqian Du, Yabin Wan
Abstract To solve the problem of serious roller wear and improve the smoothness of the sliding door motion process, the rigid-flexible coupling multi-body model of the vehicle sliding door was built in ADAMS. Force boundary conditions of the model were determined to meet the speed requirement of monitoring point and time requirement of door opening-closing process according to the bench test specification. The results of dynamic simulation agreed well with that of test so the practicability and credibility of the model was verified. In the optimization of the ride comfort of the sliding door, two different schemes were proposed. The one was to optimize the position of hinge pivots and the other was to optimize the structural parameters of the middle guide. The impact load of lead roller on middle guide, the curvature of the motion trajectory and angular acceleration of the sliding door centroid were taken as optimization objectives.
2017-03-28
Technical Paper
2017-01-0504
Anthony Berejka, Dan Montoney, Dan Dispenza, Len Poveromo, Rick Galloway, Mark Driscoll, Marshall Cleland
Abstract Having demonstrated the feasibility of using X-rays derived from high current industrial electron beam accelerators (EB) to cure the matrices of carbon fiber composites and then scaled this up to cure large sized, non-structural automobile components, performance car hoods, the New York State Vehicle Composites Program had a chassis designed, a cured epoxy mold made and then the chassis matrix cured using X-rays with a formulated radiation responsive matrix material. A feasibility study had shown how X-rays could cure through materials embedded within the composite layers, such as metal inserts that could be used for mechanical fastening without fracturing the composite. In producing X-ray cured hoods, the power consumption for X-ray curing was found to be more than 20% lower than that needed for autoclave curing the same sized hoods using conventional thermosetting pre-pregs. More significant was the time-to-cure.
2017-03-28
Technical Paper
2017-01-1298
Kamlesh Yadav, Abhishek Sinha, Rajdeep Singh Khurana
Abstract Vehicle Hood being the face of a passenger car poses the challenge to meet the regulatory and aesthetic requirements. Urge to make a saleable product makes aesthetics a primary condition. This eventually makes the role of structure optimization much more important. Pedestrian protection- a recent development in the Indian automotive industry, known for dynamics of cost competitive cars, has posed the challenge to make passenger cars meeting the regulation at minimal cost. The paper demonstrates structure optimization of hood and design of peripheral parts for meeting pedestrian protection performance keeping the focus on low cost of ownership. The paper discusses development of an in-house methodology for meeting Headform compliance of a flagship model of Maruti Suzuki India Ltd., providing detailed analysis of the procedure followed from introduction stage of regulatory requirement in the project to final validation of the engineering intent.
2017-03-28
Technical Paper
2017-01-1304
Alejandro Rosas Vazquez, Fernando Paisano, Diego Santillan Gutierrez
Abstract For many years, the use of in-mold fasteners has been avoided for various reasons including: not fully understanding the load cases in the part, the fear of quality issues occurring, the need for servicing, or the lack of understanding the complexity of all failure modes. The most common solution has been the use of secondary operations to provide attachments, such as, screws, metal clips, heat staking, sonic welding or other methods which are ultimately a waste in the process and an increase in manufacturing costs. The purpose of this paper is to take the reader through the design process followed to design an in-molded attachment clip on plastic parts. The paper explores the design process for in-molded attachment clips beginning with a design concept idea, followed by basic concept testing using a desktop 3D printer, optimizing the design with physical tests and CAE analysis, and finally producing high resolution 3D prototypes for validation and tuning.
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