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Technical Paper

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

2019-06-05
2019-01-1581
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.
Technical Paper

Simulation and Its Contribution to Evaluate Highly Automated Driving Functions

2019-04-02
2019-01-0140
A key criterion for launching autonomous vehicles on real roads is the knowledge of their capability to ensure traffic safety. In contrast to ADAS, deriving this measure of safety is difficult to achieve as the functional scope of an autonomous driving function exceeds by far the one of ADAS. As a consequence, real-world testing solely is not sufficient enough to cover the required test volume. This assessment problem imposes new requirements on a valid test concept for automated driving. A possible solution represents simulation by enabling it to generate reliable test kilometers. As a first step, we discuss in this paper the feasibility of simulation frameworks to re-simulate a real-world test in certain scenarios. We will demonstrate that even with ground truth information of the vehicle odometry and corresponding environment model an acceptable accordance of functional behavior is not guaranteed.
Technical Paper

Student Concept Vehicle: Development and Usability of an Innovative Holographic User Interface Concept and a Novel Parking Assistance System Concept

2019-04-02
2019-01-0396
The Deep Orange program is a concept vehicle development program focused on providing hands-on experience in design, engineering, prototyping and production planning as part of students’ two-year MS graduate education. Throughout this project, the team was challenged to create innovative concepts during the ideation phase as part of building the running vehicle. This paper describes the usability studies performed on two of the vehicle concepts that require driver interaction. One concept is a human machine interface (HMI) that uses a holographic companion that can act as a concierge for all functions of the vehicle. After creating a prototype using existing technologies and developing a user interface controlled by hand gestures, a usability study was completed with older adults. The results suggest the input method was not intuitive. Participants demonstrated better performance with tasks using discrete hand motions in comparison to those that required continuous motions.
Technical Paper

Distortion Optimization through Welding Simulation in Electric Vehicle Aluminum Assemblies

2019-04-02
2019-01-0818
Electric vehicle makers have largely relied on aluminum to make their cars lighter in hopes of offsetting the weight of the battery pack and reducing overall weight. Distortion of Aluminum welding is a big issue due to Aluminum’s high coefficient of expansion ratios. This paper presents an effective numerical approach to minimize weld-induced distortion in Electrical Vehicle Aluminum assembly structures using welding sequence optimization. A numerical optimization framework based on genetic algorithms and Finite Element Analysis (FEA) is developed and implemented. The shrinkage method calibrated using transient approach, is used for the weld sequence optimization to reduce the computation time. The optimization results show that the proposed calibration approach can contribute substantially to reduce distortion by optimizing weld sequences. It enhances final aluminum assembly quality while facilitating and accelerating design and development.
Technical Paper

Crash and Statics Simulation of Short Fiber Reinforced Polymers in ESI Virtual Performance Solution Taking into Account Manufacturing Effects

2019-04-02
2019-01-0715
The present contribution will present how local micromechanical properties can be used in an industrial way to assess the crash performance of parts made of short fiber reinforced polymers. To this end, local information about the material structure, predicted by a Manufacturing Process Simulation (MPS), is transferred and mapped automatically on the performance composite part model. The homogenization and mapping techniques will be presented for elastic and nonlinear application fields. Short fiber reinforced injected thermoplastics are widely used in the automotive industry in mass production. Reliable prediction of the performance of short fiber reinforced thermoplastics by simulation for statics and crash simulation can be achieved only by accounting for the full manufacturing process coming from process simulation software.
Technical Paper

Aero-Vibro-Acoustic Simulation Methodologies for Vehicle Wind Noise Reduction

2019-01-09
2019-26-0202
Wind noise is a major contributor to vehicle noise and a very common consumer complaint for overall vehicle quality [1]. The reduction of wind noise is becoming even more important as powertrain noise is reduced or eliminated (by conversion to hybrid and electric vehicles) and as the importance of quiet interior environment for hands-free device use and voice activation systems becomes more pronounced. In contrast to other noise sources such as tires, engine, intake, exhaust or other component noise whose acoustic loads may be measured in a direct and standardized way with the proper equipment, wind noise is very difficult to predict because the acoustic part of wind noise is a small component of overall fluctuating pressures. It is very challenging to either directly measure or to simulate the acoustic component of fluctuating exterior pressures using CFD (Computational Fluid Dynamics) without a great deal of specialized experience in this area.
Technical Paper

A Pass-By Noise Prediction Method Based on Source-Path-Receiver Approach Combining Simulation and Test Data

2019-01-09
2019-26-0188
Optimizing noise control treatments in the early design phase is crucial to meet new strict regulations for exterior vehicle noise. Contribution analysis of the different sources to the exterior acoustic performance plays an important role in prioritizing design changes. A method to predict Pass-by noise performance of a car, based on source-path-receiver approach, combining data coming from simulation and experimental campaigns, is presented along with its validation. With this method the effect of trim and sound package on exterior noise can be predicted and optimized.
Technical Paper

From Theory to Three-Dimensional Finite Element Models: An Innovative Method for Validation

2018-06-13
2018-01-1536
As a key part of numerical analysis, the modeling process has a tremendous influence on the quality of the results. While there is general awareness concerning uncertainties that arise during modeling, their quantity and sensitivity rarely are known. Hence, modeling quickly can become inaccurate and inefficient. The scope of the present paper is to innovate predictive modeling processes concerning the dynamics of real complex structures by means of linear modal analysis with the finite element method (FEM). The aim is to offer a transparent design catalog relating specific uncertainties to each model component in order to achieve error prevention for engineers dealing with comparable systems. A complex system is simplified and investigated for different levels of detail. Only after the model uncertainties for one level of detail are obtained, the next level of complexity is approached.
Technical Paper

Frequency and Temperature Dependent Stiffness and Damping Properties of Reduced Viscoelastic Structures Using Component Mode Synthesis (CMS)

2018-06-13
2018-01-1498
Model Order Reduction (MOR) methods such as Component Mode Synthesis (CMS) have been used in order to simulate large linear dynamic systems for many years and have reached a considerable level of saturation. These reduction methods have many advantages such as minimizing computational costs but also have restrictions. One of their disadvantages is that material damping characteristics can only be defined in form of Rayleigh damping. Another disadvantage is that the reduced order model can only represent one state of the structure determined in the generation process of the reduced matrices. In this paper we present a way to consider material damping in reduced matrices that contain one or more materials having different damping characteristics without the disadvantages of using Rayleigh damping.
Technical Paper

A Fluid-Structure Interaction Scheme for Prediction of Flow-Induced Low Frequency Booming Noise

2018-06-13
2018-01-1521
The analysis of the acoustic behavior of flow fields has gained importance in recent years, especially in the automotive industry. The comfort of the driver is heavily influenced by the noise levels and characteristics, especially during long distance drives. Simulation tools can help to analyze the acoustic properties of a car at an early stage of the development process. This work focuses on the low-frequency sound effects, which can be a significant noise component under certain operating conditions. As a first step in the fluid-structure interaction workflow, the flow around a series-production vehicle is simulated, including passenger cabin and underhood flow. The complexity of this model poses extensive demands on the simulation software, concerning meshing, turbulence modeling and level of parallelism. We conducted a transient simulation of the compressible fluid flow, using a hybrid RANS/LES approach.
Technical Paper

Virtual Car Prototyping in Realistic Driving Environment: Examples of Deep Water Crossing and Heavy Rain Management

2018-04-03
2018-01-1065
To develop future electrical and autonomous cars, it is important to virtually test the car in real driving circumstances, including on wet road or under heavy rain conditions. It is especially critical to check that no water prevents the sensors of the driving assistance systems or autonomous cars from working properly, that water intrusion does not disturb electrical equipment, and that the driver’s visibility remains good under rain condition. ESI Group has introduced the Finite Point Method (FPM) in Virtual Performance Solution (VPS) as a CFD mesh free module in order to simulate the interaction of water with the car structure. It was initially specialized for tank sloshing and water drain applications for car closures and is now extended to other application fields. The objective is to enable a holistic prediction of the car behavior under realistic driving conditions, using a virtual car prototype.
Technical Paper

Motion Cueing Algorithm for a 9 DoF Driving Simulator: MPC with Linearized Actuator Constraints

2018-04-03
2018-01-0570
In times when automated driving is becoming increasingly relevant, dynamic simulators present an appropriate simulation environment to faithfully reproduce driving scenarios. A realistic replication of driving dynamics is an important criterion to immerse persons in the virtual environments provided by the simulator. Motion Cueing Algorithms (MCAs) compute the simulator’s control input, based on the motions of the simulated vehicle. The technical restrictions of the simulator’s actuators form the main limitation in the execution of these input commands. Typical dynamic simulators consist of a hexapod with six degrees of freedom (DoF) to reproduce the vehicle motion in all dimensions. Since its workspace dimensions are limited, significant improvements in motion capabilities can be achieved by expanding the simulator with redundant DoF by means of additional actuators.
Technical Paper

Conceptualization and Implementation of a Scalable Powertrain, Modular Energy Storage and an Alternative Cooling System on a Student Concept Vehicle

2018-04-03
2018-01-1185
The Deep Orange program immerses automotive engineering students into the world of an OEM as part of their 2-year graduate education. In support of developing the program’s seventh vehicle concept, the students studied the sponsoring brand essence, conducted market research, and made a heuristic assessment of competitor vehicles. The upfront research lead to the definition of target customers and setting vehicle level targets that were broken down into requirements to develop various vehicle sub-systems. The powertrain team was challenged to develop a scalable propulsion concept enabled by a common vehicle architecture that allowed future customers to select (at the point of purchase) among various levels of electrification best suiting their needs and personal desires. Four different configurations were identified and developed: all-electric, two plug-in hybrid electric configurations, and an internal combustion engine only.
Technical Paper

A Novel Approach for High Frequency Interior Noise Prediction

2018-04-03
2018-01-0148
Since Statistical Energy Analysis (SEA) is based on lumped parameters, acoustic responses predicted by SEA are spatially discontinuous. However, in many practical applications, the ability to predict spatially continuous energy flow is useful for guiding the design of systems with improved acoustical characteristics. A new approach, utilizing integral equations derived from energy flow concepts, is developed to predict the continuous variation of acoustic field such as sound pressure level in the interior of acoustic domains using structural response predicted by SEA. The computer code developed based on energy flow boundary integral equations is initially validated by analyzing sound propagation in a duct.
Technical Paper

Technology from Highly Automated Driving to Improve Active Pedestrian Protection Systems

2017-03-28
2017-01-1409
Highly Automated Driving (HAD) opens up new middle-term perspectives in mobility and is currently one of the main goals in the development of future vehicles. The focus is the implementation of automated driving functions for structured environments, such as on the motorway. To achieve this goal, vehicles are equipped with additional technology. This technology should not only be used for a limited number of use cases. It should also be used to improve Active Safety Systems during normal non-automated driving. In the first approach we investigate the usage of machine learning for an autonomous emergency braking system (AEB) for the active pedestrian protection safety. The idea is to use knowledge of accidents directly for the function design. Future vehicles could be able to record detailed information about an accident. If enough data from critical situations recorded by vehicles is available, it is conceivable to use it to learn the function design.
Technical Paper

Numerical Aeroacoustics Prediction of a Ducted Diaphragm Chaining RANS-LES and DES Results to a Parallel Boundary Element Method

2016-06-15
2016-01-1810
In the framework of noise reduction of HVAC (Heating, Ventilating and Air Conditioning) systems designed for cars, the present study deals with the numerical prediction of aeroacoustics phenomena encountered inside such devices for industrial purposes, i.e. with a reasonable CPU time. It is then proposed in this paper to assess the validity of the chaining, via Lighthill-Curle analogy, of a DES (Detached Eddy Simulation) resulting from the CFD code OpenFOAM (ESI Group) versus a RANS-LES (Large Eddy Simulation) and a BEM calculation resulting from the Vibro/Aeroacoustics software VA One (ESI Group) on an academic case of air passing through a rectangular diaphragm at a low Mach number. The BEM code being parallelized, the performances of DMP (Distributed Memory Processing) solution will also be assessed.
Technical Paper

Designing Sound for Quiet Cars

2016-06-15
2016-01-1839
The quiet nature of hybrid and electric vehicles has triggered developments in research, vehicle manufacturing and legal requirements. Currently, three countries require fitting an Approaching Vehicle Alerting System (AVAS) to every new car capable of driving without a combustion engine. Various other geographical areas and groups are in the process of specifying new legal requirements. In this paper, the design challenges in the on-going process of designing the sound for quiet cars are discussed. A proposal is issued on how to achieve the optimum combination of safety, environmental noise, subjective sound character and technical realisation in an iterative sound design process. The proposed sound consists of two layers: the first layer contains tonal components with their pitch rising along with vehicle speed in order to ensure recognisability and an indication of speed.
Technical Paper

Combining Modeling Methods to Accurately Predict Wind Noise Contribution

2015-06-15
2015-01-2326
Recent developments in the prediction of the contribution of wind noise to the interior SPL have opened a realm of new possibilities. The main physical mechanisms related to noise generation within a turbulent flow and the vibro-acoustic transmission through the vehicle greenhouse is nowadays better understood. Several simulation methods such as CFD, FEM, BEM, FE/SEA Coupled and SEA can be coupled together to represent the physical phenomena involved. The main objective being to properly represent the convective and acoustic component within the turbulent flow to ensure proper computation of the wind noise contribution to the interior SPL of a vehicle.
Journal Article

Further Investigations on the Flow Around a Rotating, Isolated Wheel with Detailed Tread Pattern

2015-04-14
2015-01-1554
Efforts in aerodynamic optimization of road vehicles have been steadily increasing in recent years, mainly focusing on the reduction of aerodynamic drag. Of a car's total drag, wheels and wheel houses account for approx. 25 percent. Consequently, the flow around automotive wheels has lately been investigated intensively. Previously, the authors studied a treaded, deformable, isolated full-scale tire rotating in contact with the ground in the wind tunnel and using the Lattice-Boltzmann solver Exa PowerFLOW. It was shown that applying a common numerical setup, with velocity boundary condition prescribed on the tread, significant errors were introduced in the simulation. The contact patch separation was exaggerated and the flow field from wind tunnel measurements could not be reproduced. This investigation carries on the work by examining sensitivities and new approaches in the setup.
Journal Article

Maneuver-Based Analysis of Starting-Systems and Starting-Strategies for the Internal Combustion Engine in Full Hybrid Electric Vehicles

2014-10-13
2014-01-2901
The requirement of the start of the internal combustion engine (ICE) not only at vehicle standstill is new for full hybrid electric vehicles in comparison to conventional vehicles. However, the customer will not accept any deterioration with respect to dynamics and comfort. ICE-starting-systems and -strategies have to be designed to meet those demands. Within this research, a method was developed which allows a reproducible maneuver-based analysis of ICE-starts. In the first step, a maneuver catalogue including a customer-oriented maneuver program with appropriate analysis criteria was defined. Afterwards, the maneuvers were implemented and verified in a special test bench environment. Based on the method, two sample hybrid vehicles were benchmarked according to the maneuver catalogue. The benchmarking results demonstrate important dependencies between the criteria-based assessment of ICE-starts and the embedded ICE-starting-system and -strategy.
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