Xianlong Jin

Geometry features measurement of traffic accident for reconstruction based on close-range photogrammetry

This paper studies the feasibility of investigating a traffic accident and offering initial data for traffic accident reconstruction (TAR) using a photogrammetric technique. Compared with the conventional roller tape applied by the traffic police of Shanghai Municipal Bureau of Public Security in 142 traffic cases, photogrammetry is proven to be a time saving and cost effective method for accident investigation. The 2D photogrammetry method and the trajectory analysis accident reconstruction technique are applied to actual traffic accidents. With the assistance of a Portable-Control System as the reference system, the 3D photogrammetry method can be used in a vehicle deformation survey. The measurement results obtained in accordance with the CRASH survey criteria for vehicle deformation can be adopted as initial information for the damage analysis reconstruction technique. It appears that photogrammetry has greater potential for application to traffic accident investigation and reconstruction.

Vehicle crash accident reconstruction based on the analysis 3D deformation of the auto-body

The objective of vehicle crash accident reconstruction is to investigate the pre-impact velocity. Elastic-plastic deformation of the vehicle and the collision objects are the important information produced during vehicle crash accidents, and the information can be fully utilized based on the finite element method (FEM), which has been widely used as simulation tools for crashworthiness analyses and structural optimization design. However, the FEM is not becoming popular in accident reconstruction because it needs lots of crash simulation cycles and the FE models are getting bigger, which increases the simulation time and cost. The use of neural networks as global approximation tool in accident reconstruction is here investigated. Neural networks are used to map the relation between the initial crash parameter and deformation, which can reduce the simulation cycles apparently. The inputs and outputs of the artificial neural networks (ANN) for the training process are obtained by explicit finite element analyses performed by LS-DYNA. The procedure is applied to a typical traffic accident as a validation. The deformation of the key points on the frontal longitudinal beam and the mudguard could be measured according to the simulation results. These results could be used to train the neural networks adapted back-propagation learning rule. The pre-impact velocity could be got by the trained neural networks, which can provide a scientific foundation for accident judgments and can be used for vehicle accidents without tire marks.

Architecture of collaborative design grid and its application based on LAN

Abstract To solve the resource sharing problems in collaborative design, computer supported collaborative design (CSCD) technology and grid technology are integrated. The application of grid technology in collaborative design is presented. Concept of collaborative design grid (CDG) is put forward for product design and simulation, and its corresponding architecture is set up based on grid middleware. Task management and resource management in the grid environment are discussed. Grid services are realized based on globus toolkit 3.0. Grid portal of the CDG based on web is developed, and advanced graphical interfaces are provided for potential users. A prototype test bed is established via a case study of a sightseeing lift. It validates the resource sharing and cooperative work through customizing design and parameterized analysis in the CDG. Finally, the performance of the CDG test bed is analyzed and concluded.

Data mining application on crash simulation data of occupant restraint system

This article presents an application of data mining method on finite element data and crashworthiness result data of an occupant restraint system. According to the characteristics of the CAE (Computer-Aided Engineering) data, a framework for data preparation is developed based on object-oriented programming concepts. Training sets are built from data recorded in 98 crash simulations that adhere to FMVSS208, the America occupant crash protection testing standard. Relationship between design parameters and system effectiveness is implied in these data sets. Decision tree using C4.5 algorithm and attribute selection method based on attributes estimated importance are introduced to perform data mining on the building of training sets. The result yielded by data mining endows us with a deeper insight into the interrelations between the key design parameters and the performance of the occupant restraint system in crash simulations. Finally, the learned rules are tested on the real crash simulation data sets. The result of the testing shows that these rules are proper, and can been used as a guidance for the design of the occupant restraint system.

Grid-based collaborative simulation system for vehicle crashworthiness

Globalization and increasing market competition are forcing the automotive industry to develop technology that will enable more efficient collaboration between carmakers and their suppliers. One of the options that can meet this demand is to adopt grid technology in the collaboration process. For the system to be successfully applied, the trust relationship among Virtual Organization (VO) members becomes a very important factor. Systems lacking in secure mechanisms require all the collaborating members to fully trust each other, and thus make their application quite limited. Based on grid technology, this paper proposes a collaborative simulation system for vehicle crash safety design, and discusses the trust relationship among VO members. The grid middleware VEGA and web services working for the collaboration also contribute to the simulation system. Also, a test bed is set up on the basis of the Local Area Network (LAN). At the end of this paper, a real case involving a carmaker and a door supplier is presented to demonstrate how the grid-based collaborative simulation system works.

A distributed simulation system and its application

Abstract Distributed systems offer flexible computational power, which can be applied to larger systems that need to evolve rapidly. Based on the concept of grid computing, the paper designed and developed a distributed simulation system named DSoG with the responsiveness of locally autonomous sub-systems where each participant defined behavior and their relationships with others. Based on multi-layer decomposition, the distributed simulation system introduced was generic enough to allow the description of divers applications, while different levels of detail were also supported. DSoG provided a flexible environment for defining, modifying and simulating the component-based aero gas turbine models, and enables users to customize and extend the framework to add new functionality or adapt simulation behavior as required. At last, a distributed aero engine model was constructed and simulated to illustrate the use of the system.

Numerical Simulation of High-Speed Maglev Vehicle-Guideway-Tunnel-Soil System

In order to study the dynamic problem due to the high-speed EMS maglev vehicle travelling through a tunnel, this paper presents a large-scale 3D model of the maglev vehicle-guideway-tunnel-soil coupling system. The 3D finite element is used for modeling the guideway-tunnel-soil system, and the heterogeneous soil conditions, detailed geometry features of guideway and tunnel, and soil-tunnel interaction are all considered. The high-speed EMS maglev vehicle is modeled as rigid bodies and coupled to the guideway through the equivalent spring/damping magnetic force model. The initial stress of the guideway-tunnel-soil is also considered in the model by the stress reduction method. The computing is accomplished on a Dawning 5000A supercomputer using the finite-element code LS-DYNA 971 MPP. The dynamic factor of the guideway is estimated in comparison with the German design guideline. The result provides a comprehensive insight into the tunnel and guideway, as well as the ground vibration.

Parallel Algorithm and Simulation Code for Spatial-Varying Seismic Motion Methods #

Abstract The simulation mechanism of seismic ground motion is presented in this paper, and the parallel numerical algorithm is applied as the attempt for the simulation of spatial seismic ground motion time histories on parallel computers, which is consistent with arbitrary response spectra from a specified target. The basic methods of simulation, which involve calculations of auto power spectra, phase difference spectra, cross power spectra, Fourier spectra, and response spectra, etc., are also within the discussions in this paper. According to these analyses, this paper presents a set of integrated methods for nonstationary seismic ground motion simulation with greater capacity of processing multiple spatial points. In additional, Parallel Seismic Ground Motion Simulator, the parallel program for artificial generation of seismic ground motion, has been developed, which is based on Message-Passing Interface and written in Fortran90, and also provides a user-friendly visualized interface based on a commercial finite-element-analysis preprocessor. The new interdisciplinary approach can not only improve scale and efficiency of simulation of the spatial stochastic field but also can provide a useful tool for simulation of seismic input load. Information for improving current seismic design codes is also presented.

A grid-based collaborative system for vehicle crash safety design and its application based on LAN

Car manufacturers and their suppliers are usually geographically dispersed, heterogeneous characters of various resources. To solve the resource sharing and data security problems in vehicle collaborative design environment, grid technology and Computer Supported Collaborative Work (CSCW) technology are integrated. This paper proposes a collaborative design system for vehicle crash safety design based on grid technology that is conformed to the OGSA framework, and explains how the grid middleware VEGA contributes to make collaboration more efficiently. Web services about the functions in this collaborative system are realized based on VEGA. Design principles and methods based on the FE analysis tool LS-DYNA are also presented. Finally, a test bed is built based on LAN and a case of a carmaker collaborating with a seat supplier is presented.

Structural improvement for solder joint failure in ultrasonic plastic assembly

Abstract This paper presents a method of structural dynamic analysis with finite element method to identify the cause failure of solder joint caused by the vibration of ultrasonic welding. In this method, explicit FE method and its contact algorithm are used to simulate the energy transmission from vibrational energy to internal energy under some assumptions. Therefore, firstly, its feasibility is verified by 2D coupled thermal–mechanical analysis. Then, based on a certain type of cell phone battery, a 3D FE model is established for analyzing the vibration of the solder joints during ultrasonic welding. According to the simulation, we analyze the cause of the failure from three aspects: the location of the chip, the shape of the PCB and the structure of the housing. Correspondingly, the improvements are presented and applied to trial manufacture. The result from mass production shows that the improvements can decrease the reject ratio by 90% compared with the original design.