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A Holistic Approach to Develop a Modern High Power Density Diesel Engine to Meet Best-in-class NVH levels.

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Rajkumar Bhagate, Madhu Chalumuru
  • Technical Paper
  • 2020-01-0406
To be published on 2020-04-14 by SAE International in United States
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration and harshness (NVH) levels. This papers presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4 cylinder diesel engine. The base engine architecture was designed with NVH reduction features such as crank-offset, cast iron crankcase, stiffened ladder frame, structural oil pan and front cover. Piston skirt profile was optimized to reduce the slapping noise by carefully studying the secondary motion and skirt contact pressure. The plastic parts such as cylinder head cover and intake manifold were designed with closely spaced ribs and high wall thickness. Natural frequency targets for different parts were set for the entire engine at component level and system level and confirmed through simulations. High frequency acoustic simulation was carried out to identify and improve the areas of high surface velocity. "Acoustic holography" technology was extensively used to identify the areas of high noise radiation in the running engine. Based on the measurements, it was identified…
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A Research on Multi-disciplinary Optimization of the Vehicle Hood at Early Design Phase

Changan Automobile Co., Ltd.-Ruyi Chen
Chongqing University-Huijie Xu, Yue Fu, Guan Lin, Zhenfei Zhan
  • Technical Paper
  • 2020-01-0625
To be published on 2020-04-14 by SAE International in United States
Vehicle hood design is a typical multi-disciplinary task. It has to meet the demands of different attributes like safety, dynamics, statics, NVH (Noise, Vibration, Harshness). Multi-disciplinary optimization (MDO) of vehicle hood at conceptual design phase is an efficient way to support right design decision and avoid late-phase design changes. However, due to lacking of CAD models, it is difficult to realize MDO at conceptual design phase. In this research, a new method of design and optimization at conceptual design phase is proposed to improve the design efficiency. Firstly, a parametric concept hood model is first built to optimize the structure size, shape and topography. Secondly, an integration automatic platform is developed to integrate CAD/CAE software to call simulation queen, undertake sensitivity analysis and find optimum result. Besides, a multi-disciplinary design example of vehicle hood is given as a test of the proposed methodology in details. The results show that this method reduce weight by 10.1%, improve pedestrian protection performance score from 7.35 to 7.65 according to the China New Car Assessment Program(C-NCAP).
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Test Bench for Static Transmission Error Evaluation in Gears

Politecnico di Torino-Carlo Rosso
Politecnico di Torino / GeDy TrAss-Tommaso Maggi, Claudio Marcellini, Fabio Bruzzone
  • Technical Paper
  • 2020-01-1324
To be published on 2020-04-14 by SAE International in United States
In this paper a test bench for measuring the Static Transmission Error of two mating gears is presented and a comparison with the results obtained with the code GeDy TrAss and a commercial Finite Element software are shown. Static Transmission Error is considered as the main source of overloads and Noise, Vibration and Harshness issues in mechanical transmissions. It is defined as the difference between the theoretical angular position of a gear under load in quasi-static conditions and the real one. This parameter strictly depends on the applied torque and the tooth macro and micro-geometry. The test bench illustrated in this work is designed to evaluate the actual Static Transmission Error of two gears under load in quasi-static conditions. In particular this testbed can be divided in two macro elements: the first one is the mechanism composed by weights and pulleys that generates a driving and a breaking torque up to 500 Nm. The second element is composed by two structures called “support”: one fixed to the floor and the other movable in order to…
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A Comprehensive Study on the Challenges of Dual Mass Flywheel in Real-World Operating Conditions of the Indian Market

Mahindra & Mahindra Ltd-Vikraman Vellandi, Suresh Kumar Somarajan, Mohan Selvakumar Ganesh
  • Technical Paper
  • 2020-01-1014
To be published on 2020-04-14 by SAE International in United States
Dual mass flywheel (DMF) is widely used to isolate the drivetrain from the high torsional vibrations induced by the engine. While DMF can significantly improve the noise, vibration and harshness (NVH) characteristics of the vehicle, there are multiple challenges experienced in the real-world operating conditions when compared with the single mass flywheel (SMF). This paper explains the challenges of using DMF in a high power-density diesel powertrain for a multi-purpose vehicle (MPV) application in the Indian market. The gradient launch performance of the vehicle is compared for different gradients (6%, 8%, 12%, 18% and 28%) and the results confirmed that the slip time and launch energy of the DMF variant is ~50% higher than the SMF. Moreover, the DMF vehicle could be launched comfortably only upto 12% gradient whereas the SMF variant could negotiate upto 18% gradient easily. Furthermore, the higher launch energy requirement of the DMF is also responsible for a higher temperature of the clutch system by 33% as confirmed by the temperature measurements inside the clutch housing. The increased temperature poses a…
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Noise Source Identification of a Gasoline Engine based on Parameters Optimized Variational Mode Decomposition and Robust Independent Component Analysis

Tianjin University-Xiao Yang, Fengrong Bi, Lipeng Zhang, Xiaobo Bi, Teng Ma, Daijie Tang
  • Technical Paper
  • 2020-01-0425
To be published on 2020-04-14 by SAE International in United States
Noise source identification and separation of internal combustion engines is an effective tool for engine NVH (noise, vibration and harshness) development. Among various experimental approaches, noise source identification using signal processing has attracted extensive attention because of that the signal can be easily acquired and the requirements for equipment is relatively low. In this paper, variational mode decomposition (VMD) combined with independent component analysis (ICA) is used for noise source identification of a turbo-charged gasoline engine. Existing algorithms have been proved to be effective to extract signal features but also have disadvantages. In this scheme, one of the key problems is that the main components of the signal, i.e. the main source of the noise, are unknown in advance. Thus the parameters selection of signal processing algorithms, which has a significance influence on the identification result, has no uniform criterion. To solve this problem, a parameter selection method is developed to optimize the decomposition level and the quadratic penalty of VMD. After the signal is decomposed into several relevant intrinsic mode functions (IMFs), ICA is…
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Engine Mount Stopper Design Techniques to Balance Vehicle Level Buzz, Squeak, Rattle and Durability.

Tata Motors, Ltd.-Sandip Hazra, Sagar Deshmukh
  • Technical Paper
  • 2020-01-0401
To be published on 2020-04-14 by SAE International in United States
In the highly competitive global automotive market and with the taste of customer becoming more refined, the need to develop high quality products and achieve product excellence in all areas to obtain market leadership is critical. Buzz, squeak and rattle (BSR) is the automotive industry term for the audible engineering challenges faced by all vehicle and component engineers. Minimizing BSR is of paramount importance when designing vehicle components and whole vehicle assemblies. Focus on BSR issues for an automobile interior component design have rapidly increased due to customer's expectation for high quality vehicles. Also, due to advances in the reduction of vehicle interior and exterior noise, engine mounts have recently been brought to the forefront to meet the vehicle interior sound level targets. Engine mounts serve two principal functions in a vehicle, vibration isolation and engine support. The objective of this paper to experimentally analyze the impact of conventional engine mount design on the rattle and whistling noise audible from the engine mounts when the vehicle is subjected to rough road conditions and pot holes…
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Noise, Vibration, and Harshness Considerations for Autonomous Vehicle Perception Equipment

Kettering University-Charlie Gates, Jennifer Bastiaan, Prashant Jadhav, Javad Baqersad, Diane Peters
  • Technical Paper
  • 2020-01-0482
To be published on 2020-04-14 by SAE International in United States
With automakers looking to remake their traditional vehicle line-up into autonomous vehicles, Noise, Vibration, and Harshness (NVH) considerations for autonomous vehicles are soon to follow. While traditional NVH considerations still must be applied to carry-over systems, additional components are required for an autonomous vehicle to operate in addition to the basic vehicle itself. These additional components needed for autonomy also require NVH analysis and optimization. Autonomous vehicles rely on a suite of sensors, including RADAR, LiDAR, and cameras, placed at optimal points on the vehicle for maximum coverage and utilization. In this study, the NVH considerations of autonomous vehicles are examined, focusing on the additional perception equipment installed in autonomous vehicles. In particular, the nature of modifications to existing vehicles to increase the level of autonomy, and the associated NVH characteristics of these alterations, are reviewed with suggestions for future application to autonomous vehicles. A case study in the design of an original autonomous vehicle based on a production all-electric car, a 2017 Chevrolet Bolt, is outlined. A detailed description of the NVH design and…
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Human Response to Vibrations and Its Contribution to The Overall Ride Comfort in Automotive Vehicles – A Literature Review

Chalmers University of Technology-Anna-Lisa Osvalder, Patrik Höstmad
China Euro Vehicle Technology AB-Xiaojuan Wang, Ingemar Johansson
  • Technical Paper
  • 2020-01-1085
To be published on 2020-04-14 by SAE International in United States
The various factors that affect ride comfort have been in focus in many research studies due to an increasing demand in ride comfort in the automotive industry. Noise, vibration and harshness (NVH) and the human response to NVH has been highlighted as an important contribution to assess and predict overall ride comfort. The purpose of this paper is to present an approach to explain ride comfort with respect to vibration for the seated occupant based on a systematic literature review of previous fundamental research and to relate these results to the application in the contemporary automotive industry. The results from the literature study show that numerous research studies have determined how vibration frequency, magnitude, direction, duration affect human response to vibration. Also, the studies have highlighted how body posture, age, gender and anthropometry affect the human perception of comfort. An analysis was made of the consistency and inconsistency of the results obtained in the different studies. The deviations of the research results from real-world ride comfort in automotive vehicles were analyzed and divided into three…
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NVH Full Vehicle Development - Virtual Simulation Process for Low Frequency Structure-Borne Regions

Tata Technologies, Ltd.-Prajith J, Vinayak Sagade
  • Technical Paper
  • 2020-01-1266
To be published on 2020-04-14 by SAE International in United States
NVH (noise, vibration and harshness) is a key attribute in Vehicle development. Refined vehicle enhances customer’s perception and also the brand image. Most of the OEMS have well-articulated NVH Development process which is integrated in to Product development Cycle (PDC). The need for such process is essential to identify the inherent weakness or threats at earlier stage. And so the mitigation process need not warrant deviation or protection of resources, which would be a bottleneck at later stage. NVH is complex phenomena which deals with structure borne and airborne sources. So a NVH compliant vehicle is the product of resources which includes the skilled manpower, process and computational infrastructure. The stress for NVH front loading has gained traction in Global OEMS, to deliver “First Time Right “NVH products. Full Vehicle NVH (VNVH) simulation is one of the complex virtual methods, done to understand and mitigate the inherent weakness of the systems and integration. Evaluations are based on load cases which are designed to simulate RWUP (Real World Usage Profiles). A systematic - “Sub System to…
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Applications of Strain Measurements to Improve Results on Transfer Path Analysis

Centro Federal de Educação Tecnológica de Minas Gerais-C. A. P. Melo
Escola de Engenharia de São Carlos, Universidade de São Paul-A. C. R. Ramos, L.P.R de Oliveira
  • Technical Paper
  • 2019-36-0323
Published 2020-01-13 by SAE International in United States
Vehicles with lower noise levels and better levels of vibratory comfort for passengers made the area of noise, vibration and harshness (NVH) one of the main areas related to the perception of vehicle quality. Several approaches on the contribution of transfer paths have been studied to define the propagation energy in vehicular structures. Transfer Path Analysis (TPA) is a tool to improve NVH performance with the primary goal of reducing and improving perceived vibrations and noise in the cabin vehicle by occupants. Indirect methods are especially important in cases where the force signals are immeasurable in practice in terms of cost and space for sensor couplings, in the measurement configuration, and particularly in the case of distributed forces. The matrix inversion method, perhaps the most popular classic TPA, identifies operational forces using passive body acceleration. However, removal of the source can change the dynamic characteristics of the assembled structure and increase the time of the experiment, which results in misleading information in the measurements. For this reason, the inversion operation of the acceleration matrix can…
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