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2015-06-25
Event
The focus of the Structural Analysis session is to share experiences on analyzing, testing, and developing solutions to structural noise and vibration problems from powertrain sources. Analytical modeling, experimental testing and predictive correlation are just a few of the tools used in this endeavor.
2015-06-25
Event
The Structure Borne NVH Workshop will root you in the fundamentals of Source-Path-Receiver Principles. A refined theoretical foundation covers the basics of low-frequency NVH, below 100 Hz, and mid-frequency, up to 500 Hz with guidelines for performance achievement. The New Tech section will overview the motivations and approaches for stochastic simulation, and its implications to NVH performance and efforts for test/CAE validation.
2015-06-24
Event
This session covers static and dynamic issues in the body and chassis that contribute to noise and vibration problems in vehicles. Included in this session are modal studies, measurement and analysis methods, transfer path analysis, design guidelines, and recommended practices for noise and vibration control of the body and chassis.
2015-06-24
Event
This session covers static and dynamic issues in the body and chassis that contribute to noise and vibration problems in vehicles. Included in this session are modal studies, measurement and analysis methods, transfer path analysis, design guidelines, and recommended practices for noise and vibration control of the body and chassis.
2015-06-23
Event
This session focuses on the development and application of analytical methods for characterizing the dynamic behavior of structural systems. Analysis methods for all structural components, subsystems and complete systems found in automotive vehicles will be considered, except for powertrain and driveline which are covered in Powertrain Structural Analysis session. Examples include (but are not limited to) body structure, chassis structure, seats and interior structures.
2015-06-15
Technical Paper
2015-01-2262
Tom Knechten, Marius-Cristian Morariu, PJG van der Linden
Structural and vibro-acoustic transfer functions still form an essential part of NVH data in vehicle development programs. Excitation in the three DOFs at all body interface connection locations to target responses gives information on local dynamics stiffness and the body sensitivity for that specific path in an efficient manner. However, vehicles become more compact for fuel efficiency and production costs and to meet the market demand for urban vehicles. Alternative driveline concepts increase the electronic content and new mount locations. To achieve the optimum on road noise NVH, handling performance while conserving interior space and trunk volume requires a complex suspension layout. On top of that, customers put weight on safety and comfort systems which result to a higher packaging density. These trends imply ever limiting accessibility of the interface connections on the body structure.
2015-06-15
Technical Paper
2015-01-2242
Ling Zheng, Zhanpeng Fang
The design optimization of interior noise in vehicle is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is established and the response of sound pressure in frequency domain is predicted by using finite element method. The minimization of sound pressure inside cabins depends on body structure and the thickness for each panel. The panel participation analysis is carried out to find out the key panels as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is proposed and utilized to optimize the vibro-acoustic properties of body structure instead of complex structural-acoustic coupling finite element model. The accuracy of the proposed RSM is evaluated and discussed. Structural-acoustic problem is approximated by a series of quadratic polynomial using RSM. Geometric optimization problem of panels is described and solved to minimize the interior noise in vehicle.
2015-06-15
Technical Paper
2015-01-2257
Ki-Chang Kim, Sang-Woo Lee, Seok-Gil Hong, Jay Kim, Gil-Jun Lee, Jae Min Choi, Yong-Jin Kim
Recently, in automobile industry, squeak and rattle (S&R) in body structure and trim parts has become a very significant issue in Initial Quality Study (IQS). In this study, a new CAE process developed by the authors to reduce S&R noises in the door system is reported. Friction-induced vibration and noise generation mechanism of a door system are studied numerically. The effect of degradation of plastics used in door trims is studied by using a model obtained from experiments. Effects of changes of material properties such as Young's modulus and loss factor, due to the material degradation as well as statistical variations are predicted using, several cases of door systems. As a new concept, the rattle and squeak index is proposed, which can be used to guide design of the body structure and trim parts. The predicted of S&R in the door system, from the proposed CAE process were compared to those obtained from the experiment.
2015-06-15
Technical Paper
2015-01-2267
Youngha Kim, Choonhyu Kim, Jaewoong Lee, Sunggi Kim
This paper describes structure borne noise reduction process that was using a combination of experimental and analytical methods. First, Major noise paths was identified using experimental Transfer Path Analysis (TPA). Next, FEA-Experimental modeling and forced response simulation were conducted using the Hybrid FEA-Experimental FRF method. Hybrid FEA-Experimental FRF-Based Substructuring (FBS) model was used along with Operational Deflection Shape (ODS) and Modal Analysis. The Hybrid FEA-Experimental model consisted of an experimental FRF representation of the body and a finite element model of sub-frame. The finite element of sub-frame is created by using Altair HyperMesh from CATIA images and dynamic analysis is carried out by using MSC Nastran. The natural frequency and frequency response function of finite element sub-frame model are compared with them of real sub-frame for the validity of applying Hybrid FBS method.
2015-06-15
Technical Paper
2015-01-2208
David Stotera, Scott Bombard
Both vehicle roof systems and vehicle door systems typically have viscoelastic material between the beams and the outer panel. These materials have the propensity to affect the vibration decay time and the vibration level of the panel with their damping and stiffening properties. Decay time relates to how pleasant a vehicle door sounds upon closing, and vibration level relates to how loud a roof boom noise may be perceived to be by vehicle occupants. If a surrogate panel could be used to evaluate decay time and vibration level, then a design of experiments could be used to compare the effects of different factors on the system. The factors were varied in laboratory tests, and the results were calculated using design of experiments software. In this paper the results of a study of the varying factors tested with respect to their effects on decay time and vibration level are presented, as well as the effect the results had on potential optimization of the systems.
2015-06-15
Journal Article
2015-01-2229
Benjamin Joodi, Scott Allen Noll, Jason Dreyer, Rajendra Singh
Elastomeric bushings exhibit frequency dependent properties that can significantly alter the performance of a system. Current methods to identify joint properties typically require direct uniaxial excitation at stepped single frequencies. This process is often time consuming and restricted to low frequencies due to test frame and fixture dynamic interference. This paper focuses on creating a benchmark experiment to identify frequency dependent stiffness matrices including rotational and coupling terms using an inverse methods for a frequency range up to 1000 Hz. For comparison, direct measurements are completed using a commercial elastomer test system. The inverse experiment consists of an elastic beam attached to ground through the elastomeric joint of interest. The translational dynamic stiffness terms show good agreement between the two approaches; whereas, the rotational and coupling terms exhibit greater sensitivity to modeling errors and are thus more challenging to identify.
2015-06-15
Journal Article
2015-01-2227
Scott Allen Noll, Benjamin Joodi, Jason Dreyer, Rajendra Singh
Shaped elastomeric joints such as engine mounts or suspension bushings undergo broadband excitation and are often characterized through a cross-point dynamic stiffness measurement; yet, at frequencies above 100 Hz in many elastomeric components, the cross- and driving-point dynamic stiffness results tend to significantly deviate. An illustrative example is developed where two different sized bushings, constructed of the same material and were shaped to achieve the same static stiffness behavior, exhibit drastically different dynamic behavior. Physical insight is provided through the development of a reduced order single-degree-of-freedom model. A method to extract the parameters for the reduced order from a detailed finite element bushing model is provided. Finally, a new controlled benchmark experiment is used to validate the simulated behavior.
2015-06-15
Technical Paper
2015-01-2206
Glenn Yin, Alan Parrett, Nitish Wagh, Dennis Kinchen
In automotive noise control, the hood liner is an important acoustic part for mitigating engine noise. The random incidence absorption coefficient is used to quantify the component level acoustic performance. Generally, air gaps, type of substrate materials, density of the substrate materials and Air Flow Resistivity of the material or cover scrim are the dominant control factors in the sound absorption performance. This paper describes a systematic experimental investigation of how these control factors affect the part performance. The first stage of this study is based on current available solutions from sound absorber suppliers, the acoustic absorption of different hood liner constructions, with variations in materials, density, air gaps, and scrims were measured. Next, hood liners with these different constructions were installed in a vehicle, and Sound Power Based Noise Reduction (PBNR) from the engine compartment to the interior was measured to quantify in-vehicle effects.
2015-06-15
Journal Article
2015-01-2222
Nikos Zafeiropoulos, Marco Ballatore, Andy Moorhouse, Andy Mackay
Road noise forces can excite different structural resonances of the vehicle hence a high number of sensors required for observing and separating all the vibrations that are coherent with the cabin noise. Current reference sensor selection methods for feedforward road noise control result to high number of sensors. Therefore there is a necessity for reducing the number of sensors without degrading the performance of an ANC system. In the past coherence function analysis has been found to be useful for optimising the sensor location. Thus, in this case coherence function mapping was performed between an array of vibration sensors and a microphone in order to identify the locations on the structure with highly correlated with road bands in the compartment. A vehicle with an advanced suspension system was used for applying the method and defining some locations as reference signals for feedforward active road noise control.
2015-06-15
Journal Article
2015-01-2263
Saeed J. Siavoshani, Prasad Vesikar
The intent of this paper is to summarize a comprehensive test-based approach developed at Siemens to analyze the door closing sound using structural and acoustic loads developed during the event. This study looks into the door closing phenomena from the structural interaction point of view between the door and the body of the vehicle. This method provides the design modification direction to improve the door closing sound and its quality. The study also quantifies the structural and acoustic loads developed at the interface mechanisms at the door-to-body frame interface during the impact event. Considering the transient nature of the door-closing event, a time domain transfer path analysis methodology is used to indirectly quantify the loads being developed between the latch and striker and different faces of door frames and body interfaces. The paper also predicts the equivalent acoustic loads developed at the interfaces between the door frame and the body.
2015-06-15
Technical Paper
2015-01-2302
Yuksel Gur, Jian Pan, David Wagner
Light weighting of vehicle panels enclosing vehicle cabin causes NVH degradation since engine, road, and wind noise acoustic sources propagate to the vehicle interior through these panels. In order to reduce this NVH degradation, there is a need to develop new sound package materials and designs for use in lightweight vehicles. In this paper, we will focus on the use of SEA (Statistical Energy Analysis Tool) as a CAE design tool to develop sound packages for use in lightweight vehicle design to recover NVH deficiencies due to sheet metal light weighting actions. Statistical Energy Analysis results for vehicle level as well as dash and floor subsystem levels will be presented and SEA prediction capability for the sound package development for vehicle design will be discussed.
2015-06-15
Journal Article
2015-01-2321
Nicholas Oettle, Andrew Bissell, Sivapalan Senthooran, Mohammed Meskine
Car manufacturers put large efforts into reducing wind noise to improve the comfort level of their cars. Each component of the vehicle is designed to meet its individual noise target to ensure the wind noise passenger comfort level inside the vehicle is met. Sunroof designs are tested to meet low-frequency buffeting targets as well as broadband noise targets for the sunroof in vent position and any noise generated by deflectors. Experimentally testing designs and making changes to meet these design targets typically involves high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the use of a reliable numerical prediction capability early in the vehicle design process.
2015-06-15
Technical Paper
2015-01-2324
Hangsheng Hou, Guiping Yue
When a sunroof opens to let the fresh air in during driving, there might be several noise issues associated with it. The most common and important one is the wind throb issue, which is normally resolved by installing a wind deflector with sufficient height. However with the wind throb issue gone, other sound quality problems may surface. The most obvious one is the hissing noise, which occurs often in higher speed range. This work investigates a sunroof deflector deployment strategy considering wind throb, hissing noise and other psychoacoustic attributes that could be felt subjectively by a customer. The goal is to optimize sound quality associated with an open sunroof, potentially targeting the most NVH demanding customers in the premium vehicle segment.
2015-06-15
Technical Paper
2015-01-2322
Bastien Ganty, Jonathan Jacqmot, Ze Zhou, ChanHee Jeong
At high cruising speed, the car A-pillars generate turbulent air flow. The resulting aerodynamic pressure applied on the windows significantly contributes to the total cabin noise. In order to predict this particular noise contribution, the physic of both the flow and the cabin needs to be accurately modeled. This paper presents an efficient methodology to predict the turbulent noise transmission through the car windows. The method relies on a two-step approach: the first step is the computation of the exterior turbulent field using an unsteady CFD solver (EXA PowerFlow); the second step consists in the computation of the acoustic propagation inside the cabin using a finite element vibro-acoustic solver (Actran). The simplified car cabin of Hyundai Motor Company, studied in this paper, involves aluminum skin, windows, sealant, inner air cavity and acoustic treatment (porous material, damping layer). A pure vibro-acoustic model with hammer shock excitation on a window is first built.
2015-06-15
Technical Paper
2015-01-2352
Chaitanya Krishna Balla, Sudhakara Naidu, Milind Narayan Ambardekar
Noise Vibration and Harshness (NVH) refinement is one of the important parameter in modern vehicle development. In city traffic conditions, idle is the engine operating condition where the driver focuses his attention more to his vehicle. Idle vibration levels at driver seat play an important role in any vehicle, as they lead to driver fatigue. Idle NVH levels should be made better to ensure the customer satisfaction and to reduce the driver’s fatigue. Vehicle idle NVH influenced mainly by power-train (PT) mount design i.e. mount location and stiffness, modal decoupling of vehicle flexible modes, PT rigid body modes with engine idle excitation. This paper documents/ describes the steps taken to improve the idle vibrations at driver seat of an existing design through multiple options which includes the changes in the mount location, mount stiffness , engine idle speed and the combination.
2015-06-15
Journal Article
2015-01-2265
Murali Balasubramanian, Ahmed Shaik
Abstract Automotive manufacturers are being challenged to come up with radical solutions to achieve substantial (30-35%) vehicle weight reductions without compromising Safety, Durability, Handling, Aero-thermal or Noise, Vibration and Harshness (NVH) performance. Developing light weight vehicle enablers have assumed foremost priority amongst vehicle engineering teams in order to address the stringent Fuel Economy Performance (FEP) targets while facilitating lower CO2 emissions, downsizing of engines, lower battery capacities etc. Body sheet metal panels have become prime targets for weight reductions via gage reduction, high strength steel replacement, lighter material applications, lightening holes etc. Many of these panel weight reduction solutions are in sharp conflict with NVH performance requirements.
2015-06-15
Technical Paper
2015-01-2290
Sivanandi Rajadurai, Guru Prasad Mani, Kavin Raja, Sundaravadivelu Mohan
Bending moment is one of the strong pursuits in resonator's structural validation. Eigen problems play a key role in the stability and forced vibration analysis of structures. This paper explains the methodlogy to determine the weak points in the resonator assembly considering the additional effects of the installation forces and temperature impacts. Using strain eenergy plots, weakest part of the product is modified in the initial stage. The solution comes in a unique way of utilizing the worse case scenarios possible. As a consequence, the stress generated by these analyses will prove to be critical in concerning the durability issue of the system. These conditions are evaluated by a finite element model through linear and non- linear approaches and results summarized.
2015-06-15
Technical Paper
2015-01-2228
Kalyan Chakravarthy Addepalli, Natalie Remisoski, Anthony Sleath, Shyiping Liu
Drivelines used in modern pickup trucks commonly employ universal joints. This type of joint is responsible for second driveshaft order vibrations in the vehicle. Large displacements of the joint connecting the driveline and the rear axle have a detrimental effect on vehicle NVH. As leaf springs are critical energy absorbing elements that connect to the powertrain, they are used to restrain large axle windup angles. One of the most common types of leaf springs in use today is the multi-stage parabolic leaf spring. A simple SAE 3-link approximation is adequate for preliminary studies but it has been found to be inadequate to study axle windup. A vast body of literature exists on modeling leaf springs using nonlinear FEA and multibody simulations. However, these methods require significant amount of component level detail and measured data. As such, these techniques are not applicable for quick sensitivity studies at design conception stage.
2015-05-04
Video
Watch how Dow Automotive teamed up with Schucker to show how structural bonding in modern car body design provides safety and weight benefits. BETAMATE™ structural adhesives help improve vehicle strength while helping to reduce weight and manufacturing costs.
2015-04-28
Standard
J2575_201504
These test procedures were developed based upon the knowledge that steel panel dent resistance characteristics are strain rate dependent. The "quasi-static" section of the procedure simulates real world dent phenomena that occur at low indenter velocities such as palm-printing, elbow marks, plant handling, etc. The indenter velocity specified in this section of the procedure is set to minimize material strain rate effects. The dynamic section of the procedure simulates loading conditions that occur at higher indenter velocities, such as hail impact, shopping carts, and door-to-door parking lot impact. Three dent test schedules are addressed in this procedure. Schedule A is for use with a specified laboratory prepared (generic) panel, Schedule B is for use with a formed automotive outer body panel or assembly, and Schedule C addresses end product or full vehicle testing.
2015-04-23
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.
2015-04-23
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
2015-04-22
Event
This symposium provides a forum for researchers and application engineers to disseminate the knowledge and information gained in the area of advanced high-strength and press-hardening steel development and applications in automotive structures, enabling light-weight and durable vehicles with improved safety.
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