In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator （SRR） are investigated. We numerically demonstrate that the magnetic resonance fre...
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In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator （SRR） are investigated. We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles, and give a theoretical expression of the magnetic resonance frequency. The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials, and provide new guidance for complex metamaterials design with a tailored electromagnetic response.
Lower limb injures are frequently observed in passenger car traffic *** studies of the injuries focus on long bone fractures by using either cadaver component tests or simulations of the long bone kinematics,which lac...
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Lower limb injures are frequently observed in passenger car traffic *** studies of the injuries focus on long bone fractures by using either cadaver component tests or simulations of the long bone kinematics,which lack in-depth study on the fractures in stress *** paper aims to investigate lower limb impact biomechanics in real-world car to pedestrian accidents and to predict fractures of long bones in term of stress parameter for femur,tibia,and *** the above purposes,a 3D finite element(FE) model of human body lower limb(HBM-LL) is developed based on human *** model consists of the pelvis,femur,tibia,fibula,patella,foot bones,primary tendons,knee joint capsule,meniscus,and *** FE model is validated by comparing the results from a lateral impact between simulations and tests with cadaver lower limb *** real-world accidents are selected from an in-depth accident database with detailed information about the accident scene,car impact speed,damage to the car,and pedestrian ***-body system(MBS) models are used to reconstruct the kinematics of the pedestrians in the two accidents and the impact conditions are calculated for initial impact velocity and orientations of the car and pedestrian during the *** FE model is used to perform injury reconstructions and predict the fractures by using physical parameters,such as von Mises stress of long *** calculated failure level of the long bones is correlated with the injury outcomes observed from the two accident *** reconstruction result shows that the HBM-LL FE model has acceptable biofidelity and can be applied to predict the risk of long bone *** study provides an efficient methodology to investigate the long bone fracture suffered from vehicle traffic collisions.
This paper presents a crashworthiness design optimization method based on a metamodeling technique. The crashworthiness optimization is a highly nonlinear and large scale problem, which is composed various nonlinearit...
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A novel approach for discrete multibody system modeling is presented. The approach segments the multibody system into a series of subsystems with kinematic constraints. The equations of motion of the "unconstrain...
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ISBN:
(纸本)9780889868724
A novel approach for discrete multibody system modeling is presented. The approach segments the multibody system into a series of subsystems with kinematic constraints. The equations of motion of the "unconstrained" subsystems either are easier to obtain or already exist. The Udwadia-Kalaba equation is then introduced to calculate the constraint forces due to the presence of constraints. The approach does not require any auxiliary variables, such as Lagrange multipliers, nor does it need projection.
20 series of empirical parameters were obtained by applying optimal Latin Hypercube method in Isight, and then the external flow field around Ahmed model was simulated with these parameters in Fluent. On this basis, K...
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20 series of empirical parameters were obtained by applying optimal Latin Hypercube method in Isight, and then the external flow field around Ahmed model was simulated with these parameters in Fluent. On this basis, Kriging model was used to create approximate model. Taking the results from wind tunnel experiments as the optimization goal, the empirical parameters in the Realizable k-Ε turbulence model were optimized with the Multi-island Genetic Algorithm. Finally, these parameters were applied to the development of some real road vehicles, and were verified with the wind tunnel experiment. The results have shown that, by using the optimized empirical parameters, the contour of velocity from simulation is much closer to that of the experiment, and the drag force coefficient error also decreases by 2.8% with fast convergence velocity.
This study investigates head impact conditions for different vehicle types for both adult and child pedestrians in terms of head impact point (Wrap Around Distance: WAD), head relative velocity and impact angle. A sim...
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This study investigates head impact conditions for different vehicle types for both adult and child pedestrians in terms of head impact point (Wrap Around Distance: WAD), head relative velocity and impact angle. A simulation matrix is established using four parameters: vehicle model, pedestrian size, pedestrian gait and collision speed. A total of five vehicle types Super Mini Car (SMC), Small Family Car (SFC), Large Family Car (LFC), Multi Purpose vehicle (MPV) and Sport Utility vehicle (SUV) are selected to consider different shapes and sizes of vehicles. Two mathematical models of the pedestrian, first a 50th male pedestrian and second a 6 year old child pedestrian, are used in the MADYMO environment. Seven pedestrian gaits (0%, 20%, 40%, 60%, 80%, front and rear) are determined based on typical pedestrian accidents. In order to simulate a large range of impact conditions, four impact speeds (30km/h, 40km/h, 50km/h and 60km/h) are considered for each pedestrian position and vehicle type. The results indicate that the head impact velocity, impact angle and head impact point is influenced by vehicle front geometry. It is obvious that pedestrian position and vehicle travel speed strongly influence head impact conditions as well. The results of this study suggest that head impact conditions should be considered in regulation test procedures involving the front of different passenger vehicles.
The uncertainty optimization of vehicle occupant restraint system is studied in this paper based on interval number programming. Firstly a simulation model for occupant restraint system is set up using MADYMO software...
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The uncertainty optimization of vehicle occupant restraint system is studied in this paper based on interval number programming. Firstly a simulation model for occupant restraint system is set up using MADYMO software with the model verified by tests. Then, a weighted injury criterion is taken as objective, and the stiffness and upper anchor position of seat belt, as well as the tearing force and stretch length of force limiter etc are selected as design variables with the stiffnesses of seat and knee bolster as uncertain variables, and the uncertainty optimization is transformed into certainty optimization by using interval number programming. Next, the surrogate models for objective and constraint functions are built with Latin hypercube experiment design, and by utilizing sequential quadratic programming and genetic algorithms as the solvers for inner and outer layers respectively, an optimization is performed. Finally the approximately optimum solutions of the parameters of occupant restraint system are obtained.
The external flow field of Ahmed model is simulated by Fluent, and is verified with experiments. On that basis, The Ahmed model with different rear slant angles and ride heights are simulated. Then the reasons for the...
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