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Design & Validation of Low-Cost Sound Intensity Probe

Michigan Technological University-Karan Gundre, Andrew Barnard
  • Technical Paper
  • 2019-01-1462
To be published on 2019-06-05 by SAE International in United States
Sound intensity measurement techniques, that used a two-microphone setup, were first developed in the late 1970s. Back then, the focus was on improving precision during testing or post-processing because the equipment available was inherently inaccurate. However, with the advent of modern, sophisticated equipment, the focus has shifted to the apparatus. Availability of phase-matched microphones has made post-test correction obsolete as the microphones eliminate a majority of the errors before the data is even collected. This accuracy, however, comes at a price, as phase-matched microphones are highly priced. This paper discusses employing the method of improving post-processing precision, using inexpensive, current equipment. The phase error of the system is corrected using a simple calibration technique and a handheld phase calibrator that is similar to the one used for amplitude calibration of microphones. The intensity probe is manufactured using rapid prototyping and the executable software that goes with the probe is designed in NI LabVIEW. The entire setup uses inexpensive parts to lower the cost and modern software to compensate for the errors due to these parts.…
 

Aluminum Foil Perforation Impact on Acoustic and Thermal Performance of Automotive Sound Absorbers

General Motors-Gang Glenn Yin, Alan Parrett, Timothy J. Roggenkamp
General Motors De Mexico S de R L de CV-Felipe G. Salazar Prieto
  • Technical Paper
  • 2019-01-1580
To be published on 2019-06-05 by SAE International in United States
Adding aluminum foil on sound absorber surface has broad application in automotive industry. The foil layer offers thermal insulation for the parts close to exhaust pipes, turbo charge and other heat sources in engine compartment, it also adds physical protection in tough water-splashing/stone-impinging environment at vehicle exterior. It is known that adding impermeable plain foil will impact the sound absorption negatively, so micro perforated aluminum foil is widely used based on micro perforated absorption principle[]. Analytical results of sound absorption from micro-perforated panel or panel with fibrous substrate materials matches very well with measurement when perforation is well controlled in lab environment. However, for industry mass production perforated aluminum foil, it is found that hole size and shape, which are two important parameters of perforation pattern, are not precisely controlled as the samples for lab research, flimsy foil with thickness in between (0.02-0.25mm) is not behaving exactly like elastic panel. In addition, the adhesive film applied on foil back and hot molding process add more uncertainties to part final performance, moreover perforation pattern also might…
 

Development of an Analytical Method for Rear Differential Gear Whine Noise utilizing Principal Component Contribution by OTPA and CAE

Osaka Institute of Technology-Junji Yoshida
Toyota Motor Corporation-Miho Nakatsuka, Tetsuya Miwa
  • Technical Paper
  • 2019-01-1555
To be published on 2019-06-05 by SAE International in United States
Due to the global warming concern, CO2 emission regulations have been reinforced in most countries and electrification of automobiles has accelerated. Since the engine noise will be largely reduced, the improvements of gear whine noise becomes more important. But gear whine noise mechanism is complicated by involving many parts and transmitting paths to the cabin. Operational Transfer Path Analysis (OTPA) is one of the TPA methods to determine the main path and contributing part using only the operational data. However, in cases which many reference points are set on the same frame or body, the contribution becomes similar by high correlation among the reference data set and finding out the main transfer part becomes difficult. The contribution of principal component (PC) which is obtained from the correlated reference signals, instead of calculating the contribution from each reference point by modifying the OTPA process, has been utilized. Through this process, important vibration behavior of the target structure can be obtained as the high contributing PC mode. In this paper, this approach was applied to vehicle and…
 

Acoustic Effects of Lightweighting in a Sport Utility Vehicle

Autoneum North America Inc.-Andrea Lynne Frey
  • Technical Paper
  • 2019-01-1506
To be published on 2019-06-05 by SAE International in United States
Recently a vehicle study was performed to determine if the current production sound package in a sport utility vehicle could be improved while reducing or maintaining the weight. The study focused on sound package parts which typically utilize a heavy barrier layer to provide sound transmission loss: carpet, rear wheelhouse inner and trunk insulation, and dash inner. In addition, the heavy-weight underbody shields were replaced with lightweight compressed fiber to allow for increased coverage and to evaluate the effect on additional possible engine noise paths. Testing was performed both at the component level in the laboratory and at the vehicle level on the road. This paper presents the results of that study. It was found that the sound levels were improved slightly with the lower-weight parts, while articulation index was greatly improved. This was due to a combination of two factors. The physical properties of the new parts were better optimized to provide sound absorption in the frequency range of interest while still providing the necessary sound transmission loss along the noise paths. The new…
 

Experimental Study of Drive Rattle Noise Reduction in Passenger Car by Transmission Case Modification

Maruti Suzuki India Limited-Devendra Kumar Khare, Abhishek Lakhanlal Vaishya, Archan Sunibhai Pujara, Radhe Krishna, Kingshuk Satpathy, Ved Prakash Choudhary
  • Technical Paper
  • 2019-01-1561
To be published on 2019-06-05 by SAE International in United States
Low noise and vibration is one of the prime requirements of passenger car. Passenger car is having various noises inside passenger cabin due to various moving parts. Gear rattle noise is a very common problem of transmission. Gear rattle is generated because of impact of free gears .Impact of gear is caused by torsional vibration of engine transferred through clutch. When gear tooth impact then sound wave is generated and it is transmitted through Transmission case. Because of tooth impact, vibrations are generated and these vibrations are transferred to shaft, bearings and transmission case. Because of vibration of transmission case, noise is generated.The sound absorption and structural vibration of transmission case can be changed by changing the geometrical features of transmission case. Transmission case thickness is one of the important parameter that affects both radiation noise and structural noise.This paper describes the study of reduction of drive rattle in passenger car by transmission case modification through NVH test and experimental modal analysis of transmission case.
 

An acoustic target setting and cascading method for vehicle trim part design

ESI-Peiran Ding
ESI Group-Weiwei Wu, Xiaowu Zi, Beinan Liu
  • Technical Paper
  • 2019-01-1581
To be published on 2019-06-05 by SAE International in United States
The first concern in the vehicle trim part design may be its acoustic targets, which are generally defined by absorption area or coefficients, transmission loss (STL) or insertion loss (SIL). The acoustic target break down or cascading in vehicle design is referred to as the process to decide the trim part acoustic targets so as to guaranty the whole vehicle acoustic performance. In many cases, these targets are decided by experience or even subjective evaluation. Simulation based transfer path analysis (TPA), which trace the energy flow from source, through a set of paths, to a given receiver, provides another solution of this problem. Inspired by TPA, this paper proposes a component level target setting method based on the statistical energy analysis (SEA), which is recognized as an efficient method for vehicle NVH analysis in mid and high frequencies. By a validated SEA model for the object vehicle, the contributions of common noise sources and paths, which are generally defined as portions of sheet-metal with trim parts attached, can be calculated. The interior noise level with…
 

Accounting for Geometry and Residual Stresses in Weld Fatigue: A Strain Energy Density Approach to Total Life of Welded T-Specimens

John Deere-Peter Huffman
  • Technical Paper
  • 2019-01-0523
To be published on 2019-04-02 by SAE International in United States
Although many practical examinations of metal fatigue focus on crack initiation or crack growth, in practice many fatigue failures begin by initiating a crack which then grows until the part fractures completely or can no longer support the loads for which it was designed. This two-phase view of fatigue, called “total life”, is intended to aid engineers in designing parts that will meet design requirement while reducing unnecessary weight and cost. The challenge of using the total life to predict component life is magnified when components are welded together. This work, as a part of a larger project, examines the influence of the welding process on fatigue life predictability by predicting the life of welded specimens made from A36 steel as well as specimens machined from the same material using a geometry designed to develop a nearly identical stress distribution when loaded in the same way and comparing the predictions to measurements. Measured weld toe geometry and residual stresses were used and the results are employed in the relevant calculations. The methods used for predicting…
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Autonomous Data Cleaning by Keeping Internal Structure and Homogenous Volumes between Objects

ESS Engineering Software Steyr-Vijay Mishra, Martin Schifko, Vijai Kumar Suriyababu, Alireza Eslamian
  • Technical Paper
  • 2019-01-0808
To be published on 2019-04-02 by SAE International in United States
Autonomous cars already exist, why should anybody these days spend manual time on mesh preparation? This is a task for a machine, not for a human being. This paper shows a one-click way to prepare the mesh for multi-bodies or complex topological objects for CAX application and how to obtain autonomously suitable data cleaning and output qualities of complex multi object geometries. The underlying software is already in use for data cleaning, surface mesh generation and 3D mesh generation: here it prepares a body in white (BIW) starting from a CAD geometry to surface mesh, including data cleaning fully automatically with 5-8 hours computational time on a desktop machine, while requiring less than 15 minutes of manual work.Firstly, during the import process the object gets subdivided and differentiates each part as sheet or solid. Each of these parts are moved to the global coordinate system. The user can review if the input data is the correct one. Once this is confirmed by the user; everything else runs fully automated.In the next stage; during automated computation…
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Destructive Mechanism Solution of Aluminum Secondary Ingot

Honda R & D Co., Ltd.-Yoshiro Iwata
University Professor-Hiroyuki Toda
  • Technical Paper
  • 2019-01-1101
To be published on 2019-04-02 by SAE International in United States
Secondary ingot aluminum is used as a material for many automobile parts because it enables to simultaneously reduce weight and lower costs. However, it is unclear whether secondary ingot aluminum is used with an accurate understanding of the material characteristics. This research identified the actual factors in how parts that use secondary ingot aluminum fracture, and examined methods for enhancing the mechanical properties. The relationship between mechanical properties and part strength when secondary ingot aluminum is used in automobile parts was clarified. The fracturing factors of metal material parts were formerly evaluated by two-dimensional microstructure observation and facture surface observation. This research used high-resolution CT to evaluate the microstructure in three dimensions. In-situ observations of fracturing behavior were also made in order to clarify how the shapes of intermetallic compounds in secondary ingot aluminum influence mechanical properties, and methods for enhancing mechanical properties were examined. A study of parts shape using high pressure die-cast parts, which often use secondary ingot aluminum materials, was also carried out to accurately understand the mechanical properties. The results showed…
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A Steerable Curvature Approach for Efficient Executable Path Planning for on-Road Autonomous Vehicle

Tongji University-Dequan Zeng, Zhuoping Yu, Lu Xiong, Junqiao Zhao, Peizhi Zhang, Zhiqiang Fu
  • Technical Paper
  • 2019-01-0675
To be published on 2019-04-02 by SAE International in United States
A rapid path-planning algorithm that generates drivable paths for an autonomous vehicle operating in structural road is proposed in this paper. Cubic B-spline curve is adopted to generating smooth path for continuous curvature and, more, parametric basic points of the spline is adjusted to controlling the curvature extremum for kinematic constraints on vehicle. Other than previous approaches such as inverse kinematics, model-based prediction postprocess approach or closed-loop forward simulation, using the kinematics model in each iteration of path for smoothing and controlling curvature leading to time consumption increasing, our method characterized the vehicle curvature constraint by the minimum length of segment line, which synchronously realized constraint and smooth for generating path. And Differ from the path of robot escaping from a maze, the intelligent vehicle traveling on road in structured environments needs to meet the traffic rules. Therefore, the path could be simplified and segmented to four basic parts: go straight, lane change/merge, turn and U-turn. By given reasonable start and terminal, all the basic segments could be generated via parameterized cubic B-spline curve and…
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