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Technical Paper

Driving Behaviour Analysis Software for Data-Driven Path Planning Functionalities for Automated Vehicles

2022-03-29
2022-01-0218
Autonomous driving is currently one of the most challenging Artificial Intelligence (AI) problems as it requires combination of state-of-the-art solutions in multiple areas including computer vision, sensor fusion, control theory and software engineering. Deep learning has been pivotal to solving some of these problems, especially in computer vision. This enabled some autonomous vehicle companies started leveraging the benefits of deep learning for creating smooth, natural, human-like motion planning systems. In particular, the plethora of driving data captured from modern cars is a key enabler for training data-driven path planning systems. , Developing deep learning-powered systems relies heavily on big and high-quality data required for training of the models, in which the intrinsic statistics of the data that the model is trained on can result in different agent behavior in different scenarios.
Technical Paper

Development of Vehicle Thermal Management Model for Improving the Energy Efficiency of Electric Vehicle

2022-03-29
2022-01-0201
Recently, automobile manufacturers are interested in the development of battery electric vehicle (BEV) having a longer mileage to satisfy customer needs. The BEV with high efficiency depends on the temperature of the electric components. Hence it is important to study the effect of the cooling system in electric vehicle in order to optimize efficiency and performance. In this study, we present a 1-D vehicle thermal management (VTM) simulation model. The individual vehicle subsystems were modeled including cooling, power electric (PE), mechanical, and control components. Each component was integrated into a single VTM model and it would be used to calculate energy transfer among electrical, thermal, and mechanical energy. As a result, this simulation model predicts a plenty of information including the state of each component such as temperature, energy consumption, and operating point about electric vehicle depending on driving cycles and environmental conditions.
Technical Paper

Comparing stress gradient and other concepts for fatigue analysis of notched components

2022-03-29
2022-01-0252
Nowadays simulation of the fatigue life is an essential part of the development of components in the automotive and machinery industry. Weak points can be identified fast and reliable with respect to stiffness, strength and lightweight. A pure virtual optimization of the design can be performed without the need of prototypes. Only for the production release a final test is necessary. A lot of parameters influence the fatigue life as the local stress, material, surface roughness, size of the component, temperature etc. Notches have the strongest impact on fatigue life, depending on radius and shape. Stresses at the notch base are increased because the load flow is forced through a reduced cross section, or changes its direction around an inwardly curved edge. But notches cause not only an increase of the local stress. Also, the local fatigue strength is increased because of a support effect from the neighboring areas, where the stress is already reduced.
Technical Paper

Research on Vehicle State Segmentation and Failure Prediction Based on Big Data

2022-03-29
2022-01-0223
Vehicle failure prediction technology is an important part of PHM(Prognostic and Health Management) technology, which is of great significance to the safety of vehicles and to improve driving safety. Based on the vehicle operating data collected by the on-board terminal (T-box) of the telematics system, the research on the state of vehicle failure is conducted. First, this paper conducts statistical analysis on vehicle historical fault data. Preprocessing procedures such as cleaning, integration, and protocol are performed to group the data set. Then, three indexes including recency(R) frequency(F), and days(D) are selected to construct a vehicle security status subdivision system, and K -Means algorithm is utilized to divide different vehicle categories from the perspective of vehicle value. Labeled information of vehicles in different security status are further established.
Technical Paper

Modern Product Development Platform for Living Products in Perpetual Systems

2022-03-29
2022-01-0230
In 1930, John Maynard Keynes predicted, that due to software and automation, 15-hour work weeks would be a reality by the end of the century. While that envisioned “utopia” has not been realized, Mr. Keynes did have the radical vision to imagine a pretty radical low code highly automated future - one to which the future of software in mobility arguably depends on. So, what went wrong? Well, its not about as much about what went wrong but about how adoption is taking place and how it needs to change. In any software development, no matter where in history, as soon as software testing became a hot topic, automation tools started springing up and then "selective parts" that were iterative and time-consuming in the software were automated away. This begs several questions. The first and obvious, why automate these parts - and the second - whether software developers are making themselves obsolete by building automation tools.
Technical Paper

A study on editing method of road load spectrum of automobile rubber isolator using time-frequency domain methods

2022-03-29
2022-01-0272
In order to enhance the efficiency of durability testing of automobile parts, a time-frequency domain accelerated editing method of road load time series of rubber mount on powertrain was discussed. Based on Stockwell Transform method and Accumulative Power Spectral Density, a new time-frequency domain accelerated editing method (ST-APSD) was proposed. The accumulative power spectral density was obtained by ST of the load time series signal of automobile powertrain rubber mounting force which is acquired by the real vehicle in the test field. Based on the accumulative power spectral density, the threshold value was proposed to identify and delete the small damage load fragments, and then the acceleration spectrum was obtained.
Technical Paper

The investigation of a contact and element-based approach for Cohesive zone modelling in the simulation of Delamination propagation

2022-03-29
2022-01-0259
The CAE industry always moves towards new ways to improve the productivity, efficiency and to reduce the solution times. Conventional method of Cohesive Zone Modelling has drawback of higher computation and modelling time. Due to this problem, sometimes Engineers need to avoid simulations and rely only on some sort of approximation of crack from previous designs. This approximation can lead to either product failure or overdesign of the product. A new approach is discussed in this paper to simulate crack initiation and propagation with Cohesive Zone Modelling. Conventional method uses Cohesive zone modelling with Hex or Penta elements by assigning material with cohesive properties, which increases computation and modelling time. The new approach models Cohesive zone as contact between two bodies, thus eliminating the need to use cohesive elements which will essentially reduce the computation time as well as modelling time.
Technical Paper

Fatigue life prediction method for natural rubber material based on Extreme Learning Machine

2022-03-29
2022-01-0258
Uniaxial fatigue tests of rubber dumbbell specimens under different mean and amplitude of strain are carried out. An Extreme Learning Machine (ELM) model optimized by Dragonfly Algorithm (DA) is proposed to predict the fatigue life of rubber based on measured rubber fatigue life data. Mean and amplitude of strain and measured rubber fatigue life are taken as input variables and output variables respectively in DA-ELM model. For comparison, genetic algorithm (GA) and particle swarm optimization (PSO) are used to optimize ELM parameters, and GA-ELM and PSO-ELM models are established. The comparison results show that DA-ELM model performs better in predicting the fatigue life of rubber with least dispersion. The coefficients of determination for the training set and test set are 99.47% and 99.12%, respectively. In addition, a life prediction model equivalent strain amplitude as damage parameter is introduced to further highlight the superiority of DA-ELM model.
Technical Paper

Technical Keynote: Durability Validation for Variable Vehicle Usage

2022-03-29
2022-01-0255
Durability engineering for vehicles is about relating real operational loading to the actual strength of the product and its components. In the first part of this presentation, we show how to calculate failure probabilities and safety factors based on the load and strength distributions. We discuss the uncertainty within the estimations, which is considerably large in case of extremely small failure probabilities as required for safety critical components. In the second part, we focus on modelling and simulating the loads based on real vehicle usage, such that the resulting statistics allows to understand and quantify the usage variability. The idea is, to simulate thousands of vehicle life spans of, say, 300.000 km or 15.000 h of operation each. The input data for such simulations typically consists of a combination of geographic data (like road network, topography, road conditions, traffic data, and points of interest) and properly segmented rich data from measurement campaigns.
Technical Paper

Numerical Investigation on the Internal Flow Field of Electronic Expansion Valve as the Throttle Element

2022-03-29
2022-01-0318
As one of the key components of the heat pump system, the electronic expansion valve mainly plays the role of throttling and reducing pressure in the heat pump system. The refrigerant flowing through the orifice will produce complex phase change. It is of great significance to study the internal flow field by means of CFD calculations. Firstly, a three-dimensional fluid model is established and the mesh is divided. Secondly, the phase change model is selected, the material is defined and the boundary conditions are determined. According to the principle of the fluid passing through thin-walled small holes, the flow characteristics of electronic expansion valve are theoretically analyzed. Then the flow characteristics of expansion valve are numerically calculated, and a bench for testing mass flow rate of the expansion valve is built. Then the theoretical value, CFD value and experimental value are compared to verify the correctness of the established three-dimensional fluid model.
Technical Paper

Design and Optimization of an Electric Car Chassis and Body using Structural Analysis and CFD

2022-03-29
2022-01-0292
The transition from traditional gasoline-powered automobiles to electric vehicles (EVs) has taken time, two major challenges of engine- powered vehicles are greenhouse gas emissions and fuel economy. Electric cars require less maintenance. A lot of money can be saved while also helping the environment. In today's world, working with lightweight materials have emerged as a key area for improvement in the automotive industry. The most efficient method for increasing power output is to reduce the weight of vehicle components. Composite materials have benefited greatly from research and development because they are stronger, more recyclable, and easier to integrate into vehicles. The primary goal of this research is to design the body and chassis frame of a two-seater electric car.
Technical Paper

A New Pathway for Prediction of Gasoline Sprays using Machine-Learning Algorithms

2022-03-29
2022-01-0492
The fuel spray process is of utmost importance to internal combustion engine design as it determines engine performance and emissions characteristics. While designers rely on CFD for understanding of the air-fuel mixing process, there are recognized shortcomings in current CFD spray predictions, particularly under super-critical or flash-boiling conditions. In contrast, time-resolved optical spray experiments have now produced datasets for the three-dimensional liquid distribution for a wide range of operating conditions and fuels. Utilizing these detailed experimental results, we have explored a machine learning approach to prediction of fuel sprays. The ML approach for spray prediction is promising because (1) it does not require phenomenological spray models, (2) it can provide time-resolved spray data without time-stepping simulation, and (3) it is computationally faster than CFD. In this study, a pixel-regression model has been developed and applied for gasoline spray prediction.
Technical Paper

A Review of Current Understanding of the Underlying Physics Governing the Interaction, Ignition and Combustion Dynamics of Multiple-injections in Diesel Engines

2022-03-29
2022-01-0445
This work is intended to be a comprehensive technical review of existing literature and a synthesis of current understanding of the governing physics behind the interaction of multiple fuel injectio ns, ignition and combustion behavior of multiple-injections in diesel engines. Multiple-injection is a widely adopted operating strategy applied in modern compression-ignition engines, which involves various combinations of small pre-injections and post-injections of fuel before and after the main injection and splitting the main injection into multiple smaller injections. This strategy has been conclusively shown to improve fuel economy in diesel engines while achieving simultaneous NOx, soot, and combustion noise reduction in addition to a reduction in the emissions of unburned hydrocarbons and CO by preventing fuel wetting and flame quenching at the piston wall.
Technical Paper

Modeling the Effects of Drop Impingement Frequency on Heated Walls at Engine Conditions

2022-03-29
2022-01-0508
Understanding the fundamental details of drop/wall interactions is important to improving engine performance. Most of the drop-wall interactions studies are based on the impact of a single drop on the wall. To accurately mimic and model the real engine conditions, it is necessary to characterize spray/wall interactions with different impingement frequencies at a wide range of wall temperatures. In this study, a numerical method, based on Smoothed Particle Hydrodynamics (SPH), is used to simulate consecutive droplet impacts on a heated wall both below and above Leidenfrost temperature. Impact regimes are identified for various impact conditions by analyzing the time evolution of the post-impingement process of n-heptane drops at different impingement frequencies and wall surface temperatures. At low temperature, crown propagation and merging are dominant at low K-number whereas at high K-number there is significant splashing with the traces of liquid film on the surface.
Technical Paper

Managing Trust along the CAN Bus

2022-03-29
2022-01-0119
Multiple approaches have been created to enhance intra-vehicle communications security over the past three decades since the introduction of CAN. The twin pair differential-mode communications bus is tremendously robust in the face of interference, yet physical access to the bus offers a variety of potential attack vectors whereby false messages and/or denial of service are easy to achieve. This paper seeks to evaluate extensions of a common-mode watermark-based authentication technique recently developed to improve authentication on the CAN bus by considering the watermark as a side-channel communications means for high value information. We also describe a variety of higher layer algorithms, with benefits and pitfalls, for employing the watermark as a physical-layer firewall. All of these results are backed by a software-defined radio (SDR) based hardware testbed.
Technical Paper

Modification of the Lower Limb and the Pelvis for the Pedestrian Dummy

2022-03-29
2022-01-0851
In order to further reduce the pedestrian fatalities, the improvement of pedestrian safety performance of vehicles is needed. One of the way to further understand read-world pedestrian accidents is the evaluation by using a whole-body pedestrian dummy. In the past studies, the leg, the thigh and the pelvis of the pedestrian dummy were developed and improved. However, the requirements for the biofidelity of the pedestrian dummy have been improved in SAE J2782. Therefore, this study aimed to evaluate these responses of the past studies by using new requirements and to modify these parts that didn’t meet them. The force-defection curves from 3-point lateral bending tests for the leg and the thigh were compared with the corridors updated in SAE J2782. The biofidelity of the pelvis was evaluated in dynamic lateral compression tests of the isolated pelvis. The sacrum and the pubis force-deflection curves of the iliac or the acetabulum impact were compared with the corridors.
Technical Paper

Rollover and near-rollover kinematics during evasive steer maneuvers

2022-03-29
2022-01-0855
We present 6-degree-of-freedom (6DOF) kinematic data from two SUVs during evasive steer maneuvers that did and did not result in rollovers. The vehicles were instrumented with a GPS speed sensor, tri-axial accelerometers, tri-axial angular rate sensors, and a steering wheel angle sensor. Drone-based and land-based video cameras recorded all tests. Six degree of freedom position/orientation data were extracted from the video using match moving techniques with 3D constraints from laser scans of the test site and vehicles as described in our previous SAE paper (SAE 2020-01-0272). The initial speeds varied from 100 to 124 km/h and the steering input during the tests were similar. We examine the magnitude and timing of the vehicle pre-roll kinematics to identify differences between the roll and non-roll events. We also present the 6DOF kinematics of the rollovers themselves. This study provides valuable insight into factors that predict roll initiation during evasive steer maneuvers.
Technical Paper

Optimized Variable Gear Ratio Steering System with Reduced EPAS Motor Size achieving Performance Targets

2022-03-29
2022-01-0874
In electric power assisted steering system (EPAS), the steering assistance torque is provided by the electric motor. The motor rating is decided based on rack force requirement which depends on the vehicle weight, steering gear ratio, wheel angles & turning circle diameter etc. The load on the EPAS motor varies with respect to the steered angles of the road wheels. The motor experiences higher load towards the road wheel lock position. Most of the steering systems used on passenger cars has rack and pinion gear with constant gear ratio (C-factor). The constant gear ratio is decided to create right balance between vehicle handling behavior and steering effort. The constant gear ratio exerts higher steering load which the EPAS motor is required to support up to road wheel lock angles and hence EPAS motor size increases. This paper presents variable gear ratio (VGR) steering system in which gear ratio varies from center towards end lock stroke of rack & pinion.
Technical Paper

Development of Biomechanical Computational Models of Six-year-old Child Occupant with Different Sitting Postures and Application in the Study of Whiplash Injuries

2022-03-29
2022-01-0869
Whiplash injury is one of the main types of child occupant neck injuries in traffic accident. With the development of intelligent cockpit, child occupants will engage in traffic operation in various sitting positions. Therefore, studying the mechanism and risk of whiplash injury of child occupants with different sitting postures has important application value for the research and development of child restraint system. In this study, the 120° and 135° sitting postures of six-year-old child occupant were developed based on the validated 105° sitting posture finite element model with detailed anatomical structure. The whiplash test in Euro NCAP was reconstructed to evaluate the influence of sitting position angle on the risk of whiplash injury. In the three groups of simulation experiments, the Upper Neck Tension (Fz) was far less than the higher limit of Euro NCAP evaluation although the Fz value increased as the upper torso angle increases.
Technical Paper

Modelling of switching characteristics of hydrogen-nitrogen filled DC contactor under external magnetic field

2022-03-29
2022-01-0728
With an increasing demand for hybrid and battery electric vehicles, it has become imperative to make the electrical switching process safe. In electric vehicles, this process is carried out by compact DC contactors which are designed to withstand years of use over millions of cycles. The quick disconnection is often enabled by an external magnetic field and pressurized hydrogen-nitrogen environment in the contactor. The disconnection process of these contactors leads to the formation of an arc which results from the breakdown of the gas inside the contactor chamber. The breakdown occurs in the inter-connection gap; however, the arc starts to move across the gap between the connectors due to the self-induced magnetic field. The interaction of arcs to the connector's body could lead to undesired metal vapours which could further decrease the creepage distance.
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