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2015-06-25
Event
The Structure Borne NVH Workshop continues with the same lecture team since inception in 2003. If you are still fuzzy about the new ideas you’ve seen, or from the hospitality suites the nights before, we have our new Thursday morning opportunity to 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. Recent advances in NVH Computer Aided Testing and Simulation will be reviewed drawn from the latest research efforts.
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.
2015-06-24
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
2015-01-2228
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.
2015-06-15
Technical Paper
2015-01-2293
Manchi Venkateswara Rao, S Nataraja Moorthy, Prasath Raghavendran
Tactile vibration during vehicle key on/off is one of the critical factors contributing to the customer perceived quality of the vehicle. Minimization of the powertrain transient vibration in operating conditions such as key on/off, tip in/out and engagement/disengagement of engine in hybrid vehicles must be addressed carefully in the vehicle refinement stage. Source of start/stop vibration depends on many factors like engine cranking, engine rpm at which the combustion process starts and rate of engine rpm rise etc. The transfer path consists of elastomeric mounts of powertrain and vehicle structure from mounts to tactile response location. In this paper, the contribution of rigid body motion of powertrain of a front wheel drive vehicle during key on/off is analyzed in both frequency and time domain. The signal is analyzed in frequency domain by using Fast Fourier Transform, Short Time Fourier Transform and Wavelet Analysis. The merits and demerits of each method are illustrated.
2015-06-15
Technical Paper
2015-01-2288
Abdelkrim Zouani, Joseph Stout, Salah Hanim, Changshen Gan, Gabriela Dziubinschi, William Baldwin, Zhi fu
A new turbocharged 60◦ 2.7L V6 gasoline engine has been developed by Ford Motor Company for both the pickup truck and car applications. This engine was code named “Nano” due to its compact size and features a CGI cylinder block, an Aluminum ladder, an integrated exhaust manifold and twin turbochargers. The goal of this engine is to deliver 120HP/L, ULEV70 emission, fuel efficiency improvements and leadership level NVH. This paper describes the upfront design and optimization process used for the NVH development of this engine; it will discuss the critical NVH design features and the final results relative to the benchmarks.
2015-06-15
Technical Paper
2015-01-2287
Yaqiong Deng, Xiandi Zeng
Among the lower frequency vehicle NVH problems, booming noise is one of the most concerned issues. There are all kinds of booming noises from different driving conditions such as idling, driving away, and driving at lower speed on coarse road. In order for a vehicle to avoid those booming noises, the vehicle has to be designed to have the right structures and right counter -measures for all conditions possible for booming noise. One of the most common booming noise sources is the torsional vibration of the powertrain and driveline for rear-wheel drive and four-wheel drive vehicle. The solutions for this problem are either to use a torsional dynamic absorber or to use a lower stiffness clutch. Both solutions require the modal frequency of the torsioanal vibration of the powertrain and driveline. At early design stages, vehicle prototype is not available for measuring this frequency. Analytical method is usually used to calculate this frequency.
2015-06-15
Technical Paper
2015-01-2289
Joseph L. Stout, Vincent Solferino, Simon Antonov
Powerplant NVH decisions are sometimes made looking only at how the change impacts either the source radiated noise level or the source vibration. Depending on the Engine Configuration, those can be good approximations, but they can also be very misleading. By combining both noise sources into a Vehicle Equivalent noise level a much better analysis can be made of the impact of the design on the Customer perceived loudness. This paper will investigate several different senarios and identify how the airborne and the structureborne paths combine for I4, V6 and V8 engine configurations. Similar relationships will be shown for path as well as the source contributions.
2015-06-15
Technical Paper
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
2015-01-2229
Scott Allen Noll, Benjamin Joodi, 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
Technical Paper
2015-01-2232
Hyosig Kim, Joong Hee Kim
Multi-disciplinary design optimization (MDO) is a field of engineering that uses optimization methods to solve design problems incorporating a number of disciplines. These days, automotive engineers should consider harder trade-off configuration among the allowable design limits when they make design studies on a newly developed vehicle. In order to achieve a good lightweight structure with a reasonable compromise among the major automotive performances such as, NVH(Noise, vibration and Harshness), Crashworthiness, Durability, etc, the engineer must need a methodology based on a multidisciplinary approach efficient enough to be applied to the complex automotive performances. This paper addresses a study on the multi-disciplinary design optimization of a vehicle body structure. NVH performance was estimated with two kinds of computational model: BIW(Body in White) model and BIG(Body in Grey in other words, full vehicle) model.
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
Technical Paper
2015-01-2292
Xiaorui Lu, Junda Ma
Over recent years, NVH refinement of engine is becoming increasingly important in buying decision and can significantly give competitive edge to the vehicle in market place. This paper deals with the development phase of a prototype engine in which a specific testing activity was carried out to improve the overall NVH behavior of the powertrain. In order to explain the optimization process in detail, a case study was described in this paper. First, NVH targets of the engine were set via benchmark tests on existing competitive products. Then series of baseline tests, such as 1M sound pressure level test and noise source identification, were performed on the engine. Test results indicated that an obvious breathing vibration mode exist near the intake manifold, which radiates high level noise. In order to achieve the NVH targets, a correlation validation was performed to find out the main reason that caused the vibration of intake manifold.
2015-06-15
Technical Paper
2015-01-2127
Andrea Munzing, Franck Hervy, Stephane Catris
A helicopter blade profile was tested in the DGA Aero-engine’s S1 icing wind tunnel in Saclay, France in winter 2013/2014. The 2D airfoil was a helicopter main rotor blade profile. Ice accretion tests have been performed to assess the profile’s time dependant aerodynamic behaviour during ice accretion. Real ice shapes were collected after each icing test. Moreover, iced profile polars were realized over a large range of angle of attack until stall. This paper presents the test set up, the test model and the test results. The test results presented in this paper are dry air and iced profile polars as well as ice shapes. The complete iced profile polars and the aerodynamic behaviour in time of the iced blade profile during ice accretion will be used for adjusting and validating prediction tools like Airbus Helicopter’s analytical iced rotor performance degradation model and they will aid to appraise the rotor loads evolution in icing conditions.
2015-06-15
Technical Paper
2015-01-2079
Colin Hatch, Jason Moller, Eleftherios Kalochristianakis, Ian Roberts
Summary The size and shed time of ice shed from a propeller is predicted using a process that determines ice shape, ice growth rate and both internal and ice-structure interface stresses. A brittle failure damage model is used to predict the onset of local failure and to propagate damage in the ice until local ice shedding is obtained. Background Research into suitable ice-phobic coatings as a potential approach in an integrated aircraft ice protection system (IPS) has been ongoing for many years. Durability of these coatings has been an issue; however future research programmes such as the EU programmes AEROMUCO [1] and STORM [2] are looking to improve the Technology Readiness Level (TRL) of the application of these types of coatings. The introduction of ice-phobic coatings may make it possible to provide ice protection on rotating surfaces without the need for specialist ice protection systems.
2015-06-15
Technical Paper
2015-01-2121
Yong Chen, Liang Fu
In helicopter, the icing rotor blades will decrease the effectiveness of the helicopter and endanger the lives of the pilots. The asymmetrical ice break-up and shedding could also lead to severe vibrations of the rotor blade. Ice break-up from the main rotor may strike the fuselage and tail rotor, even worse, find its way into the engine, which may cause serious aircraft accidents. An understanding of the mechanisms responsible for ice shedding process is necessary in order to optimize the helicopter rotor blade design and de-icing system to avoid hazardous ice shedding. In previous study, the ice shedding criteria was established by comparing the centrifugal force and the adhesion force. In most cases, part of the ice will shed before the centrifugal force equals to the adhesion force, because the adhesion stress between the ice and the blade is not uniform.
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