Fatigue design for plug/ring type gas welded joints of sts301l including welding residual stresses

This paper presents a fatigue design method for plug and ring type gas welded joints, which incorporates welding residual stress effects. A non-linear finite element analysis (FEA) was first performed to simulate the gas welding process. The numerically predicted residual stresses of the gas welds were then compared to experimental results measured using a hole drilling method. In order to evaluate the fatigue strength of the plug and ring type gas welded joints, a stress amplitude (σ _a ) _R taling the welding residual stress of the gas weld into account was introduced and is based on a modified Goodman equation incorporating the effect of the residual stress. Using the stress amplitude (σ _a ) _R , the ΔP-N _f relations obtained from fatigue tests for plug and ring type gas welded joints having various dimensions and shapes were systematically rearranged into (σ _a ) _R -N _f relations. It was found that the proposed stress amplitude (σ _a ) _R could provide a systematic and reasonable fatigue design criterion for the plug and ring type gas welded joints.     

Ergonomic and biomechnical analysis of automotive general assembly using XML and digital human models

Automotive general assembly requires many manual assembly operations to be carried out by human workers. Ergonomic analysis is an important part of the design and evaluation of products, jobs, tools, machines and environments for safe, comfortable and effective human functioning. Most recent researches have involved the evaluation of working conditions to prevent work-related musculoskeletal disorders. The majority of previous research on automotive companies has mainly considered the results of ergonomic analyses such as RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment) and OWAS (Ovako Working Posture Analysis System). Analysis of static posture including reachability, clearances for arm, hand and tool has also been used to evaluate working conditions. However, in addition to static posture analysis, a biomechanical analysis in dynamic conditions should also be conducted. There are no integrated frameworks or standard schema for ergonomic analysis using digital human models in digital environments. The purpose of this paper is to propose a new framework for the evaluation of working conditions by ergonomic and biomechanical analysis using digital models based on XML standard schema, including: products, processes, manufacturing resources and human workers. This paper presents the analysis results using the proposed framework for automotive general assembly operations. We propose a new framework for the evaluation of the assembly operations and their environments. Then we apply a digital human model to the dynamic simulation of general automotive assembly operations based on standard schemas in XML and PPRH (Product, Process, Resource and Human). Using PPRH information based on a standard XML schema to analyze the ergonomic and biomechanical results, the engineer can visualize, analyze and improve assembly operations and working environments in automotive general assembly shops using digital models.     

3-D numerical and experimental analysis for airflow within a passenger compartment

People use cars so frequently that they always consider the air-conditioning, and thermal comfort of the driver and passenger when buying a new car. Therefore accurate simulation of the thermal performance of automobile air conditioners to improve human comfort has become increasingly important. In order to improve the thermal comfort of passengers, 3-D flow motion and thermal behavior within vehicles must be analyzed. In this paper, a numerical simulation was used to investigate thermal behavior in a vehicle. Because air temperature at an air vent is related to the cooling capacity of the air conditioner, the cooling capacity was calculated using ɛ-NTU (effective number of transfer unit) theoretical equations. Using the air temperature relationship between inlet and outlet vents as boundary conditions, a 3-D unsteady κ-ɛ turbulent model was used to give a transient analysis simulation of the temperature field and flow conditions in a vehicle’s passenger cabin. Cooling cycle analysis and conjugate heat transfer analysis at the inside surface of the cabin’s ceiling, floor and sides were also considered. The predicted temperature distributions in the vehicles passenger cabin were in good agreement with those obtained experimentally.     

Simulation of city bus performance based on actual urban driving cycle in China

This paper establishes the simulation model of a city bus on the basis of the EQ6110 bus prototype and its experimental data. According to the actual urban driving cycle, the fuel economy and the traction performance of the EQ6110 city bus have been simulated, and factors such as the driving cycle, the loss of power to engine accessories, the gear-shifting strategy, the fuel shut-off strategy of the engine, etc., which influence on the bus’s fuel economy, are also quantitatively analyzed. Some conclusions are drawn as follows: (1) driving cycles have a great influence on the fuel economy of a city bus; (2) under the typical urban driving cycle of the public bus in China, the engine fuel shut-off strategy can save about 1 to 1.5 percent of the fuel consumption; and (3) the optimized gear-shifting rules can save 6.7 percent of the fuel consumption. Experimental results verify that the fuel economy for the EQ6110 public bus is improved by 7.2 pecent over the actual Wuhan urban driving cycle of the current public bus in China.     

Desired yaw rate and steering control method during cornering for a six-wheeled vehicle

This paper proposes a steering control method based on optimal control theory to improve the maneuverability of a six-wheeled vehicle during cornering. The six-wheeled vehicle is believed to have better performance than a four-wheeled vehicle in terms of its capability for crossing obstacles, off-road maneuvering and fail-safe handling when one or two of the tires are punctured. Although many methods to improve the four-wheeled vehicle’s lateral stability have been studied and developed, there have only been a few studies on the six-wheeled vehicle’s lateral stability. Some studies of the six-wheeled vehicle have been reported recently, but they are related to the desired yaw rate of a four-wheeled vehicle to control the six-wheeled vehicle’s maneuvering during corning. In this paper, the sideslip angle and yaw rate are controlled to improve the maneuverability during cornering by independent control of the steering angles of the six wheels. The desired yaw rate that is suitable for a six-wheeled vehicle is proposed as a control target. In addition, a scaled-down vehicle with six drive motors and six steering motors that can be controlled independently is designed. The performance of the proposed control methods is verified using a full model vehicle simulation and scaled-down vehicle experiment.     

Effect of fuel stratification on initial flame development: Part 2-low swirl condition

This paper is the second invstigation on the effect of fuel stratification on flame propagation. In the previous work, the characteristics under the no port-generated swirl condition, i.e., the conventional case was studied. In this work, the flame development under the low swirl condition was considered. For this purpose, the initial flame development and propagation were visualized under different axially stratified states in a modified optical single cylinder SI engine. The images were captured by an intensified CCD camera through the quartz window mounted in the piston. Stratification was controlled by the combination of the port swirl ratio and injection timing. These were averaged and processed to characterize the flame propagation. The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance and through the mean absolute deviation of the propagating direction. The results show that the flame-flow interaction determines the direction of flame propagation and that the governing roles of the two factors vary according to the stratified state and the location in the cylinder. In addition, the flame development and the initial flame stability are strongly dependent on the stratified conditions, and the initial flame stability is closely related to the engine stability and lean misfire limit. Lastly, there is no essential difference in gasoline and CNG flame propagation characteristics.     

Adaptive neuron control using an integrated error approach with application to active suspensions

This paper proposes a new neuron control strategy for an active vehicle suspension system, with the emphasis on the study of multivariable and uncertain suspension characteristics. The novelty of this strategy is in the use of integrated error, which consists of multiple output errors in the regulated plant. By combining the integrated error approach with the traditional neuron control (TNC), integrated error neuron control (IENC) is presented. It provides a direct control to the multiple outputs of the control plant simultaneously. Taking a quarter-car model as an example, the proposed control strategy is applied and comparative simulations are carried out with various vehicle parameters and road input conditions. Simulation results prove the effectiveness and robustness of the proposed IENC method. In addition, the newly proposed neuron scheme provides a simple yet efficient new possibility for the control of a class of uncertain multivariable systems similar to an active vehicle suspension.     

垂直及斜出水流场的二维及三维TR-PIV试验

本文对钝头回转体垂直及斜出水流场采用TR-(Time-Resolved)PIV技术进行测量,并对斜出水流场进行3D-Stereo PIV(三维体视 PIV)测量.文中介绍了测试技术及测量结果,揭示了出水过程中流动结构及其演变,展示了TR-PIV技术对具有瞬态历程特征的出水流场研究的适应性.     

HSST将于日本2005国际博览会投入商业运营

介绍名古屋东部丘陵线的概况和该线所用的磁悬浮运输系统、磁悬浮车辆的技术特点.     

A system dynamics approach to land use/transportation system performance modeling Part I: Methodology

This paper presents a system dynamics approach to simultaneous land use/transportation system performance modeling. A model is designed based on the causality functions and feedback loop structure between a large number of physical, socioeconomic, and policy variables. The model consists of 7 sub‐models: population, migration of population, household, job growth‐employment‐land availability, housing development, travel demand, and traffic congestion level. The model is formulated in DYNAMO simulation language, and tested on a data set from Montgomery County, MD. In Part I: Methodology, the overall approach and the structure of the model system is discussed and the causal‐loop diagrams and major equations are presented. In Part II: Application, the model is calibrated and tested with data from Montgomery County, MD. Least square method and overall system behavior are used to estimate the model parameters. The model is fitted with the 1970–80 data and validated with the 1980–1990 data. Robustness and sensitivities with respect to input parameters such as birth rate or regional economy growth are analyzed. The model performance as a policy analysis tool is examined by predicting the year by year impacts of highway capacity expansion on land use and transportation system performance. While this is a first attempt in using dynamic system simulation modeling in simultaneous treatment of land use and transportation system interactions, and model development and application are limited due to data availability, the results indicate that the proposed method is a promising approach in dealing with complex urban land use/transportation modeling.