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Development of Subject-Specific Elderly Female Finite Element Models for Vehicle Safety

Chongqing University-Yunlei Yin, Junming Li, Qingmiao Wang
State Key Lab of Veh NVH & Safety Technology/Chongqing Univ-Wenxiang Dong, Zhenfei Zhan
Published 2019-04-02 by SAE International in United States
Previous study suggested that female, thin, obese, and older occupants had a higher risk of death and serious injury in motor vehicle crashes. Human body finite element models were a valuable tool in the study of injury biomechanics. The mesh deformation method based on radial basis function(RBF) was an attractive alternative for morphing baseline model to target models. Generally, when a complex model contained many elements and nodes, it was impossible to use all surface nodes as landmarks in RBF interpolation process, due to its prohibitive computational cost. To improve the efficiency, the current technique was to averagely select a set of nodes as landmarks from all surface nodes. In fact, the location and the number of selected landmarks had an important effect on the accuracy of mesh deformation. Hence, how to select important nodes as landmarks was a significant issue. In the paper, an efficient peak point-selection RBF mesh deformation method was used to select landmarks. The multiple peak points were selected to expand landmarks set, so as to improve the morphing quality compared…
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A Dynamic Local Trajectory Planning and Tracking Method for UGV Based on Optimal Algorithm

Chongqing University-Yangxin Sun, Zhenfei Zhan, Yudong Fang, Ling Zheng, Liuhui Wang, Gang Guo
Published 2019-04-02 by SAE International in United States
UGV (Unmanned Ground Vehicle) is gaining increasing amounts of attention from both industry and academic communities in recent years. Local trajectory planning is one of the most important parts of designing a UGV. However, there has been little research into local trajectory planning and tracking, and current research has not considered the dynamic of the surrounding environment. Therefore, we propose a dynamic local trajectory planning and tracking method for UGV driving on the highway in this paper. The method proposed in this paper can make the UGV travel from the navigation starting point to the navigation end point without collision on both straight and curve road. The key technology for this method is trajectory planning, trajectory tracking and trajectory update signal generation. Trajectory planning algorithm calculates a reference trajectory satisfying the demands of safety, comfort and traffic efficiency. A trajectory tracking controller based on model predictive control is used to calculate the control inputs to make the UGV travel along the reference trajectory. The trajectory update signal is generated when needed (e.g. there has a…
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A Feature-Based Responses Prediction Method for Simplified CAE Models

Chongqing University-Huijie Xu, Xin Yang, Wenxiang Dong
China Automotive Engineering Research Institute Co., Ltd.-Qingjiang Zhao, Wei Xu
Published 2019-04-02 by SAE International in United States
In real-world engineering problems, the method of model simplification is usually adopted to increase the simulation efficiency. Nevertheless, the obtained simulation results are commonly with low accuracy. To research the impact from model simplification on simulation results, a feature-based predictive method for simplified CAE model analysis is proposed in this paper. First, the point clouds are used to represent the features of simplified model. Then the features are quantified according to the factors of position for further analysis. A formulated predictive model is then established to evaluate the responses of interest for different models, which are specified by the employed simplification methods. The proposed method is demonstrated through an engineering case. The results suggest that the predictive model can facilitate the analysis procedure to reduce the cost in CAE analysis.
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Numerical Study of Intake Manifold Water Injection on Characteristics of Combustion and Emissions in a Heavy-Duty Natural Gas Engine

Chongqing University-Zhe Kang
Tongji University-Jingtao Wu, Jun Deng, Zhijun Wu, Liguang Li, Zhilong Li
Published 2019-04-02 by SAE International in United States
The performances of heavy-duty natural gas engines have been limited by combustion temperature and NOx emissions for a long time. Recently, water injection technology has been widely considered as a technical solution in reducing fuel consumption and emissions simultaneously in both gasoline and diesel engines. This paper focuses on the impacts of intake manifold water injection on characteristics of combustion and emissions in a natural gas heavy-duty engine through numerical methods. A computational model was setup and validated with experimental data of pressure traces in a CFD software coupled with detailed chemical kinetics. The simulation was mainly carried out in low-speed and full-load conditions, and knock level was also measured and calculated by maximum amplitude of pressure oscillations (MAPO). The results show that the quantity of injected water does not have a negative effect on water spray and film at an appropriate position, but an increase in the quantity of injected water leads to a negative effect on charging efficiency and a decrease in IMEP. However, the knock in natural gas engines can be suppressed…
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Study on the Controlled Field Test Scenarios of Automated Vehicles

Chongqing University-Li Huang, Hong Shu
China Automotive Eng Res Inst Co Ltd-Fei Xie, Tao Chen, Qin Xia
Published 2018-08-07 by SAE International in United States
Function and performance test of automated vehicles in the closed field is a necessary way to verify their safety, intelligence and comfort. The design and number of test scenarios will influence if the automated vehicles can be tested and evaluated effectively and fast. Based on the interrelationship among the vehicle, driver’s (or control system) driving strategy and road, we use the permutation and combination method to compare the relative position and movement relations between an automated vehicle (vehicle under test) and the surrounding vehicles to generate a total possible test scenarios group. According to the main functions features of L2 and L3 class automated vehicle, for each specified road traffic scenario, we proposed to generate a simple primary test scenario with test value firstly, then to increase the number of obstacle vehicles step by step, and to screen out the test scenarios of various levels with test value by analyzing the scenario importance and the impact analysis of the detection and response of the ego-vehicle, and finally obtain an overall test scenarios group with test…
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A Comparative Study of Two ASTM Shear Test Standards for Chopped Carbon Fiber SMC

SAE International Journal of Materials and Manufacturing

Chongqing University-Zhangxing Chen, Yimin Shao
Ford Motor Company-Hongyi Xu, Katherine Avery, Danielle Zeng, Xuming Su
  • Journal Article
  • 2018-01-0098
Published 2018-04-03 by SAE International in United States
Chopped carbon fiber sheet molding compound (SMC) material is a promising material for mass-production lightweight vehicle components. However, the experimental characterization of SMC material property is a challenging task and needs to be further investigated. There now exist two ASTM standards (ASTM D7078/D7078M and ASTM D5379/D5379M) for characterizing the shear properties of composite materials. However, it is still not clear which standard is more suitable for SMC material characterization. In this work, a comparative study is conducted by performing two independent Digital Image Correlation (DIC) shear tests following the two standards, respectively. The results show that ASTM D5379/D5379M is not appropriate for testing SMC materials. Moreover, the failure mode of these samples indicates that the failure is caused by the additional moment raised by the improper design of the fixture. Tests following ASTM D7078/D7078M can generate sound results in most cases, and therefore the ASTM D7078/D7078M seems to be a more suitable standard for characterizing chopped carbon fiber SMC material.
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A Maximum Incompatibility Constrained Collaborative Optimization Method for Vehicle Weight Reduction

Chongqing University-Wenxiang Dong, Zhenfei Zhan, Chong Chen, Yudong Fang, Ling Zheng
China Automotive Engrg Rsch Inst Co Ltd-Wei Xu, Qingjiang Zhao
Published 2018-04-03 by SAE International in United States
Collaborative optimization is an important design tool in complex vehicle system engineering. However, there are many problems yet to be resolved when applying the conventional collaborative optimization method in vehicle body weight reduction, such as convergence difficulties and low optimization efficiency. To solve these problems, a maximum incompatibility constrained collaborative optimization method is proposed in the paper. First, the 1-norm equality constraints expression of the system level is used to replace the traditional 2-norm inequality constraints. Then, a maximum incompatibility is selected from modified inequality constraints to improve optimization efficiency. Finally, an overall compatibility constraint is introduced to decrease the influence caused by the initial point. A mathematical example is used to verify the effectiveness and stability of the proposed method. The proposed collaborative optimization method is further demonstrated through a vehicle body weight reduction problem concerning vehicle safety and NVH performances.
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Driver Identification Using Multivariate In-vehicle Time Series Data

Chongqing University-Dawei Luo, Gang Guo
Ford Motor Company-Jianbo Lu
Published 2018-04-03 by SAE International in United States
All drivers come with a driving signature during a driving. By aggregating adequate driving data of a driver via multiple driving sessions, which is already embedded with driving behaviors of a driver, driver identification task could be treated as a supervised machine learning classification problem. In this paper, we use a random forest classifier to implement the classification task. Therefore, we collected many time series signals from 60 driving sessions (4 sessions per driver and 15 drivers totally) via the Controller Area Network. To reduce the redundancy of information, we proposed a method for signal pre-selection. Besides, we proposed a strategy for parameters tuning, which includes signal refinement, interval feature extraction and selection, and the segmentation of a signal. We also explored the performance of different types of arrangement of features and samples. By following the proposed tuning strategy, the prediction performance of the random forest classifier achieved an accuracy of 89.14% for an identification task of four drivers, and 60.36% for fifteen drivers.
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Automotive Crashworthiness Design Optimization Based on Efficient Global Optimization Method

Chongqing University-Yudong Fang, Zhenfei Zhan
Changan Automobile Co., Ltd.-Tao Chen, Huili Yu, Hui Zhao
Published 2018-04-03 by SAE International in United States
Finite element (FE) models are commonly used for automotive crashworthiness design. However, even with increasing speed of computers, the FE-based simulation is still too time-consuming when simulating the complex dynamic process such as vehicle crashworthiness. To improve the computational efficiency, the response surface model, as the surrogate of FE model, has been widely used for crashworthiness optimization design. Before introducing the surrogate model into the design optimization, the surrogate should satisfy the accuracy requirements. However, the bias of surrogate model is introduced inevitably. Meanwhile, it is also very difficult to decide how many samples are needed when building the high fidelity surrogate model for the system with strong nonlinearity. In order to solve the aforementioned problems, the application of a kind of surrogate optimization method called Efficient Global Optimization (EGO) is proposed to conduct the crashworthiness design optimization. Based on few samples, the initial Kriging models are constructed. Then the new sample found by the expected improvement criterion (EI) is employed to update the Kriging models in each subsequent loop iteration. Since the expected improvement…
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Research on the FE Modeling and Impact Injury of Obese 10-YO Children Based on Mesh Morphing Methodology

Chongqing University-Junming Li, Zhenfei Zhan, Yajing Shu, Gang Guo
Wayne State University-Ming Shen, Xin Jin
Published 2018-04-03 by SAE International in United States
In order to improve the comprehensive protection for children with variable shapes and sizes, this paper conducted studies on the impact injury for obese children based on a 10-YO finite element model. Some specific geometrics on the body surface were firstly acquired by the combination of pediatric anthropometric database and generator of body (GEBOD). A Radial Basis Function (RBF) based mesh morphing technique was then used to modify the original standard size FE model using the obtained geometrics. The morphed FE model was validated based on the experimental data of frontal sled test and chest-abdomen impact test. The effects of obesity on injury performances were analyzed through simplified high-speed and low-speed crash simulations.
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