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Technical Paper

Aeroacoustics of Heavy Duty Truck Side Mirrors –an Experimental Study

2018-06-13
2018-01-1516
Side mirrors are a known source of aerodynamically generated noise on vehicles. In this work we focus on mirrors for heavy duty trucks, they are large, often not designed with main focus on aero-acoustics and are located in a cumbersome position on the up-right A-pillar of European trucks. First the test method itself is discussed. To allow fast and cost effective design loops a bespoke vehicle, where the powertrain is separated from the cab, is developed. This vehicle can be run on a standard test track. While running the tests the wind speed is monitored, any variations are then compensated for in the post processing allowing averaging over longer time periods. For the mirror tests the door of the vehicle was especially trimmed to reduce other transmission paths into the cab than the side window. Additionally other possible aeroacoustic sources were reduced as much as practically possible.
Technical Paper

Pass-by Noise Reduction of Light Commercial Vehicle

2018-06-13
2018-01-1539
The increasing in popularity of Light Commercial Vehicles (LCV) segment is an emerging trend in the commercial vehicle industry. LCVs are very efficient and cost-effective for transportation of materials and good on short distances or loads of smaller weights. Sensing the market potential, many auto companies have launched LCVs recently. Since LCV segment is very price sensitive, low cost single cylinder air cooled diesel engine being used as prime mover. High noise & vibration is inherent feature of diesel engine & it is predominant in single cylinder diesel engine. In order to maintain low cost of product, less attention is given on overall noise of vehicle. To meeting the regulatory limits of Pass-by Noise (PBN) for this category of vehicle is also a challenge. This paper is a development work done for pass-by noise reduction of a diesel powered single cylinder SCV vehicle. A prototype vehicle needs to meet the legislative pass-by noise requirement when tested as per IS0 362.
Technical Paper

Simulations Based Approach for Powertrain Noise Reduction in Tractors

2018-06-13
2018-01-1478
Abstract Noise emanating from tractors is a potential health risk for operators, especially during prolonged working hours. As regulations governing noise radiation are made stringent, a first time right simulations based approach is needed to refine various noise sources of tractors. In present case study, powertrain noise optimization of an open station tractor has been carried out. Various noise sources of engine like; structure, intake, exhaust, timing gears and blower fan have been studied. NVH testing has been conducted for noise source ranking and establishing correlation with baseline simulations. Optimization has been performed on engine and it’s aggregates for achieving overall noise reduction of 3 dB(A) at tractor operator ear level, using; multibody dynamics, CFD simulations, linear acoustics and Rayleigh integral approach.
Technical Paper

Robust Design of Acoustic Treatments for Powertrain Noise Radiation

2018-06-13
2018-01-1486
Abstract The reduction of the emitted noise from vehicles is a primary issue for automotive OEM’s due to the constant evolution of the noise regulations. As the noise generated by the powertrain remains one of the major noise sources at low/mid vehicle velocities, focus is set on efficient methods to control this source. Acoustic treatments and covers, made of multi-layered trimmed panels, are frequently selected to control the radiated sound and its directivity. In this context, numerical acoustic simulation is an attractive approach as efficient methodologies are available to study the acoustic radiation of powertrain units in working conditions (up to 6500 RPM nd frequencies up to 4 kHz). Moreover, handling acoustically-treated covers in such simulations has a low impact on the computational cost.
Technical Paper

Seat Belt Retractor Noise Test Correlation to 2DOF Shaker Test and Real Vehicle Comfort

2018-06-13
2018-01-1507
Abstract Seatbelt retractors as important part of modern safety systems are mounted in any automotive vehicle. Their internal locking mechanism is based on mechanically sensing elements. When the vehicle is run over rough road tracks, the retractor oscillates by spatial mode shapes and its interior components are subjected to vibrations in all 6 degrees of freedoms (DOF). Functional backlash of sensing elements cause impacts with neighbouring parts and leads to weak, but persistent rattle sound, being often rated acoustically annoying in the vehicle. Current acoustic retractor bench tests use exclusively uni-directional excitations. Therefore, a silent 2 DOF test bench is developed to investigate the effect of multi-dimensional excitation on retractor acoustics, combining two slip-tables, each driven independently by a shaker.
Technical Paper

Pass by Noise Reduction on an Intermediate Commercial Vehicle

2018-06-13
2018-01-1535
Abstract A major activity of any new vehicle development program, is to meet legal requirements of local markets. Pass by noise (PBN) test is one of the standardized tests and is used to certify new vehicles/variants for their Noise emissions. Certification for noise emissions of commercial vehicles is achieved by measuring external sound levels according to procedures defined by standards such as IS: 3028 for Indian market. Before a physical proto-vehicle is assembled, various systems and subsystems are readily made available by suppliers off the shelf. During final design validation of the vehicle by mule-vehicle testing, PBN target compliance need be assured for all these systems in order to meet overall PBN target. The PBN on an Intermediate commercial vehicle (ICV) migrated to the latest Exhaust emission standard, was the subject of this study. This vehicle emitted PBN greater than accepted threshold.
Technical Paper

Robustness and Reliability Enhancement on Retractor Noise Testing, from Development Considerations to Round Robin

2018-06-13
2018-01-1533
Abstract Sensing and acting elements to guarantee the locking functions of seat belt retractors can emit noise when the retractor is subjected to externally applied vibrations. For these elements to function correctly, stiffness, inertia and friction needs to be in tune, leading to a complex motion resistance behavior, which makes it delicate to test for vibration induced noise. Requirements for a noise test are simplicity, robustness, repeatability, and independence of laboratory and test equipment. This paper reports on joint development activities for an alternative test procedure, involving three test laboratories with different equipment. In vehicle observation on parcel shelf mounted retractors, commercially available test equipment, and recent results from multi-axial component tests [1], set the frame for this work. Robustness and reliability of test results is being analyzed by means of sensitivity studies on several test parameters.
Technical Paper

Prediction of Eigenfrequencies and Eigenmodes of Seatbelt Retractors in the Vehicle Environment, Supporting an Acoustically Optimal Retractor Integration by CAE

2018-06-13
2018-01-1543
Abstract From an acoustical point of view, the integration of seatbelt retractors in a vehicle is a real challenge that has to be met early in the vehicle development process. The buzz and rattle noise of seat belt retractors is a weak yet disturbing interior noise. Street irregularities excite the wheels and this excitation is transferred via the car body to the mounting location of the retractor. Ultimately, the inertia sensor of the locking mechanism is also excited. This excitation can be amplified by structural resonances and generate a characteristic impact noise. The objective of this paper is to describe a simulation method for an early development phase that predicts the noise-relevant low frequency local modes and consequently the contact of the retractor with the mounting panel of the car body via the finite element method.
Technical Paper

Finite Element Based Active Vibration Control of Hierarchical Honeycomb Plates Integrated with Piezoelectric Actuator

2018-06-13
2018-01-1558
Abstract Hierarchical honeycomb (HH) structures with level of hierarchy more in the honeycomb construction (by replacing the vertices of a regular hexagonal lattice with smaller hexagons) are widely used in engineering applications mainly due to their superior mechanical behavior and lightweight high strength characteristic. At the same time, the role of hierarchy and control gain on the dynamic behavior of HH structures with surface-bonded actuator remains largely unexplored. In this study, we investigated the active vibration control behavior of the HH structure with surface-bonded piezoelectric actuators. The HH plate like structures was constructed with two identical face sheets and placed HH core in-between. By using ANSYS parametric design language (APDL), the proportional-integral-derivative (PID) control algorithm was incorporated into the finite element model for performing the closed-loop control simulations.
Technical Paper

Vibro-Acoustic Modeling of a Trimmed Truck Cabin in Low Frequency Range to Tackle the Challenge of Weight Reduction

2018-06-13
2018-01-1549
Abstract In the challenge of reducing the weight of the vehicle structures, a particular focus has to be done on the interior noise. Indeed, the weight reduction of the structure often implies an increase of the noise in the cabin. To maintain a constant acoustic performance, acoustic packages often have to be added, the challenge being that the weight of the acoustic materials added remains lower than the weight saved in the structure. In today’s engineering world, numerical simulation is the primary tool to assess the vibro-acoustic behavior of the vehicle during the design phase. To tackle the challenge of weight reduction, it is necessary to simulate accurately the vibro-acoustic response of the structure including the acoustic treatments. This paper presents the validation of a simulation method for the vibro-acoustic response of a truck cabin, taking into account the effect of acoustic treatments, in the frequency range [0-200 Hz].
Technical Paper

Efficient Trim Modelling Simulation Method for Vehicle Design Phase

2018-06-13
2018-01-1568
Abstract During the design phase of a vehicle, it is important to have a simulation tool, which allows to make multiple runs and check the sensitivity of the acoustic response to several trim configurations with a quick turnover time. The Statistical Energy Analysis (SEA) is widely used to investigate such problems for airborne excitation. For structure-borne excitation, classical methods based on a simplistic modeling of the trim using 1D oscillators and non-structural mass are not accurate enough to capture the actual behavior of the trim. On the other hand, a detailed Finite Element-Poroelastic Element Method (FE-PEM) modeling strategy of the trim may be time consuming. Besides the large number of degrees of freedom required to accurately model dissipative materials (e.g. poroelastic), a FE-based approach also needs a preprocessing phase where each layer of the trims must be carefully meshed.
Technical Paper

Driveline Noise Source Identification and Reduction in Commercial Vehicles

2018-06-13
2018-01-1474
Abstract Driveline (DL) is one of the major sources of noise and vibration which excites the vehicle structures across a wide band of frequencies in commercial vehicles (CV). Current work focuses on the driveline noise source identification and its reduction in a heavy commercial vehicle. An abnormal noise is perceived in a CV in high gears at high speeds. This annoying DL noise is subjectively perceived in geared and neutral coast down conditions. Objective NVH assessment including near source noise and vibration of the driveline components was performed to quantify the noise. Initial test results revealed that the DL excitations are aggravated in auxiliary gear box as broadband rattle noise. The design configuration of the DL components and related subsystems such as propeller shafts and gearbox etc. was studied to the find root cause of the excitations. The driveline configuration including the auxiliary gearbox tooth geometry is also scrutinized and modified.
Technical Paper

SmEdA Vibro-Acoustic Modeling of a Trimmed Truck Cab in the Mid-Frequency Range

2018-06-13
2018-01-1506
Abstract The City Lightweight and Innovative Cab (CLIC) project was a scientific collaboration gathering public and private organizations. The aim was to propose an innovative lighten truck cab, where a high strength steel was used. As long as it could affect directly the acoustic environment of the cab, it was necessary to be able to simulate the vibroacoustic behavior of the truck cab in the mid frequency range. The dissipative treatments used for noise and vibration control such as viscoelastic patches and acoustic absorbing materials must then be taken into account in the problem. A process based on the SmEdA (Statistical modal Energy distribution Analysis) method was developed and is presented in this paper. SmEdA allows us substructuring the global problem, to study the interaction between the floor and the interior cavity.
Journal Article

Abdominal Injury Patterns in Frontal Crashes: Analysis of Front and Rear Seat Occupants using NASS/CDS and CIREN

2018-05-11
2018-01-9751
Field accident data from the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) and the Crash Injury Research and Engineering Network (CIREN) databases were used to identify the factors affecting abdominal injury type and incidence for front and rear seat occupants in frontal collisions. The NASS/CDS analysis was conducted to identify the nature and magnitude of abdominal injuries, while a separate CIREN analysis was conducted to investigate the mechanistic differences between types of abdominal organ injuries. Abdominal injury risk was found to increase with increasing occupant age in both the front and rear seating positions. Abdominal injury risk also increased with factors associated with more severe collisions including the number of crash events, extent of frontal crush, collision type, and crash speed.
Technical Paper

Optimal Automated Calibration of Model-Based ECU-Functions in Air System of Diesel Engines

2018-05-05
2018-01-5003
Abstract The success of model-based ECU-functions relies on precise and efficient modeling of the behavior of combustion engines. Due to the limited computing power, usually a combination of physical models and calibration parameters is preferred for engine modeling in ECU. The parameters can be scalars, 1 or 2-dimensional empirical models, such as look-up table for volumetric efficiency and effective area of the exhaust gas recirculation (EGR). A novel algorithm is proposed to automatically calibrate the look-up tables characterizing stationary functional relationships in ECU-function of the air system of a diesel engine with minimum calibration cost. The algorithm runs in the framework of online design of experiment (DoE), in which Gaussian process model (GPM) is adopted to approximate the relationships of interest.
Technical Paper

Study on Predicting Bus Lateral Transfer Ratio Using a Modified Grey Model

2018-04-15
2018-01-5008
Currently, buses are equipped with anti-rollover systems to prevent vehicle rollovers that cause numerous traffic deaths each year. In order to improve the functioning of the existing anti-rollover systems, this study proposes a new method to predict the lateral transfer ratio (LTR) of a bus to achieve early detection of bus rollover risks. This early rollover detection method is a combination of the LTR, the grey model, and a buffer operator, which can predict the LTR trend, for providing a certain timing advance to the anti-rollover control system. First, an estimation equation is proposed to better estimate the LTR, and validated using Simulink and TruckSim. Then, a basic grey model is utilized with the estimated LTR to predict the future LTR.
Technical Paper

Sodium Cooling Efficiency in Hollow Valves for Heavy Duty Engines

2018-04-03
2018-01-0368
Abstract As a consequence of the ongoing evolution of engines, where performance is continuously improving and the use of alternative fuels is being adopted by many engine manufacturers, thermal working conditions of the exhaust valves are increasingly critical. In order to better resist the higher temperature levels of the exhaust gases, current development ranges from improvement of the cooling concept for the overall system, new materials for valve set components up to the upgrade of the exhaust manifold material. Change in the design of several valvetrain components due to the increased thermal loads is a logical consequence of this technical evolution process. Hollow exhaust valves filled with Sodium (Na) are a known technology that is widely used in passenger car engines to improve thermal behavior and to avoid the need to change to expensive materials (Ni-base alloys).
Technical Paper

Correlation and Verification of a Tractor Cab Model Using Statistical Energy Analysis

2018-04-03
2018-01-0142
Abstract A model of a tractor cab was built using Statistical Energy Analysis (SEA) best practices. In this paper, it is shown how this model was correlated using p/Q transfer functions measured in the lab with a volume velocity source. After correlation, the model was excited using acoustic loads measured during tractor operation. It was found that the data predicted by the model is in good agreement with the data measured inside the cabin during this test. It was concluded that SEA can be used as an engineering tool to predict the behavior under many different conditions and can be used to guide the development process.
Technical Paper

Model-Based Pneumatic Braking Force Control for the Emergency Braking System of Tractor-Semitrailer

2018-04-03
2018-01-0824
Abstract As bottom layer actuator for the AEB system, the active brake system and the brake force control of tractor-semitrailer have been the hot topics recently. In this paper, a set of active pneumatic brake system was designed based on the traditional brake system of tractor-semitrailer, which can realize the active brake of the vehicle under necessary conditions. Then, a precise mathematical model of the active pneumatic brake system was built by referring the flow characteristics of the solenoid valve, and some tests were implemented to verify the accuracy and validity of the active brake system model. Based on the model, an active pneumatic brake pressure control strategy combining the feedforward and feedback controlling modes was designed. By generating the PWM control signal, it can precisely control the desired wheel cylinder brake pressure of the active brake system. Finally, the brake pressure control strategy was validated both by simulation tests and bench tests.
Technical Paper

Influences on Energy Savings of Heavy Trucks Using Cooperative Adaptive Cruise Control

2018-04-03
2018-01-1181
Abstract An integrated adaptive cruise control (ACC) and cooperative ACC (CACC) was implemented and tested on three heavy-duty tractor-trailer trucks on a closed test track. The first truck was always in ACC mode, and the followers were in CACC mode using wireless vehicle-vehicle communication to augment their radar sensor data to enable safe and accurate vehicle following at short gaps. The fuel consumption for each truck in the CACC string was measured using the SAE J1321 procedure while travelling at 65 mph and loaded to a gross weight of 65,000 lb, demonstrating the effects of: inter-vehicle gaps (ranging from 3.0 s or 87 m to 0.14 s or 4 m, covering a much wider range than previously reported tests), cut-in and cut-out maneuvers by other vehicles, speed variations, the use of mismatched vehicles (standard trailers mixed with aerodynamic trailers with boat tails and side skirts), and the presence of a passenger vehicle ahead of the platoon.
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