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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

China Automotive Engineering Research Institute Co., Ltd.-Qingjiang Zhao, Wei Xu
Chongqing University-Huijie Xu, Xin Yang, Wenxiang Dong
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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A Maximum Incompatibility Constrained Collaborative Optimization Method for Vehicle Weight Reduction

China Automotive Engrg Rsch Inst Co Ltd-Wei Xu, Qingjiang Zhao
Chongqing University-Wenxiang Dong, Zhenfei Zhan, Chong Chen, Yudong Fang, Ling Zheng
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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Automotive Crashworthiness Design Optimization Based on Efficient Global Optimization Method

Changan Automobile Co., Ltd.-Tao Chen, Huili Yu, Hui Zhao
Chongqing University-Yudong Fang, Zhenfei Zhan
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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A Data Mining and Optimization Process with Shape and Size Design Variables Consideration for Vehicle Application

Chongqing University-Junqi Yang, Zhenfei Zhan, Yudong Fang, Gang Guo
Ford Motor Company-Ching-Hung Chuang, Hongyi Xu
Published 2018-04-03 by SAE International in United States
This paper presents a design process with data mining technique and advanced optimization strategy. The proposed design method provides insights in three aspects. First, data mining technique is employed for analysis to identify key factors of design variables. Second, relationship between multiple types of size and shape design variables and performance responses can be analyzed. Last but not least, design preference can be initialized based on data analysis to provide priori guidance for the starting design points of optimization algorithm. An exhaust system design problem which largely contributes to the improvement of vehicular Noise, Vibration and Harshness (NVH) performance is employed for the illustration of the process. Two types of design parameters, structural variable (gauge of component) and layout variable (hanger location), are considered in the studied case. The optimization results based on the proposed method are compared with baseline design to show its potential in improving optimization performance regarding both effectiveness and efficiency for real-world engineering design.
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An Integrated Deformed Surfaces Comparison Based Validation Framework for Simplified Vehicular CAE Models

Chongqing University-Xin Yang, Zhenfei Zhan, Qingmiao Wang, Ping Wang, Yudong Fang, Ling Zheng
Published 2018-04-03 by SAE International in United States
Significant progress in modeling techniques has greatly enhanced the application of computer simulations in vehicle safety. However, the fine-meshed impact models are usually complex and take lots of computational resources and time to conduct design optimization. Hence, to develop effective methods to simplify the impact models without losing necessary accuracy is of significant meaning in vehicle crashworthiness analysis. Surface deformation is frequently regarded as a critical factor to be measured for validating the accuracy of CAE models. This paper proposes an integrated validation framework to evaluate the inconsistencies between the deformed surfaces of the original model and simplified model. The geometric features and curvature information of the deformed surfaces are firstly obtained from crash simulation. Then, the magnitude and shape discrepancy information are integrated into the validation framework as the surface comparison objects. Finally, the proposed method is implemented on a crash case to verify its efficiency and feasibility in vehicle safety simulations.
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Investigation of the Samples Size Effects on Hybrid Surrogate Model Component Surrogates for Crashworthiness Design

Changan Automobile Co., Ltd.-Huili YU, Hui Zhao
Chongqing University-Chong Chen, Zhenfei Zhan, Wenxiang Dong
Published 2018-04-03 by SAE International in United States
Surrogate model based design optimization has been widely adopted in automotive industry. Hybrid surrogate model with multiple component surrogates is considered to be a better choice when simulating highly non-linear responses in vehicle crashworthiness analysis. Currently, the number of component surrogates has to be decided before-hand when constructing of a hybrid surrogate model. This paper conducts a comparative study on the performances of three popular hybrid modeling methods including heuristic computation strategy, and two kinds of optimal weighted surrogates. The effects of samples size on the number of individual surrogates that should be included into the final hybrid surrogate models for crashworthiness responses are investigated. Different hybrid modeling techniques and multiple validation criteria are evaluated. Some observations and conclusions on the selection of component surrogates in hybrid surrogate modeling are given in the end.
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An Improved K-Means Based Design Domain Recognition Method for Automotive Structural Optimization

China Automotive Engineering Research Institute Co., Ltd.-Wei Xu, Qingjiang Zhao
Chongqing University-Chen Hu, Zhenfei Zhan, Kuo Dong
Published 2018-04-03 by SAE International in United States
Design optimization methods are widely used for weight reduction subjecting to multiple constraints in automotive industry. One of the major challenges is to search for the optimal design in an efficient manner. For complex design and optimization problems such as automotive applications, optimization algorithms work better if the initial searching points are within or close to feasible domains. In this paper, the k-means clustering algorithm is exploited to identify sets of reduced feasible domains from the original design space. Within the reduced feasible domains, the optimal design can be obtained efficiently. A mathematical example and a vehicle body structure design problem are used to demonstrate the effectiveness of the proposed method.
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