Roof strength performance improvement enablers

Before 2009, rollover in vehicle accidents had not been significantly studied not only because its rate is lower than other types of accidents but also because it had been easy to meet the rollover regulation, the FMVSS 216 Roof Crush Resistance target. The regulation only requires that the strength-to-weight ratio (SWR) be 1.5, i.e., it was acceptable when the roof could withstand a force of only 1.5 times the vehicle??s weight. In other words, rollover is not considered an important safety factor. However, presently, the situation has completely changed. Rollover is now considered a key safety factor. Recently, the number of rollover incidences has been increasing, reaching as much as the number of front, side and rear accidents. Furthermore, the IIHS has begun to require that the roof must withstand a force of 4.0 times the vehicle??s weight, a more severe restriction than FMVSS. To satisfy this requirement, many manufacturers, universities and institutes are studying the topic. This paper focuses on changing the body structure to minimize injury to the occupant when rollover occurs and help rollover safety performance become excellent. This paper draws on a simple analysis that is based on general factors: changes in the material, the addition of welds and additional reinforcements. The best result will be determined, as described by this paper.     

Technology analysis and low-cost design of automotive radar for adaptive cruise control system

Recently, the advanced driver assistance system (ADAS), which helps mitigate car accidents, has been developed using environmental detection sensors, such as long and short range radar, lidar, wide dynamic range cameras, ultrasonic sensors and laser scanners. Among these detection sensors, radars can quickly provide drivers with reliable information about the velocity, distance and direction of a target obstacle, as well as information about the vehicle in changing weather conditions. In the adaptive cruise control system (ACCS), three radar sensors are usually needed because two short range radars are used to detect objects in the adjacent lane and one long range radar is used to detect objects in-path. In this paper, low-cost radar based on a single sensor, which can detect objects in both the adjacent lane and in-path, is proposed for use in the ACCS. Before designing the proposed radar, we analyzed the world-wide radar technology and market trends for ACCS. Based on this analysis, we designed a novel radar sensor for the ACCS using radar components, such as an antenna, transceiver module, transceiver control module and signal processing algorithm. Finally, target detection experiments were conducted. In the experimental results, the proposed single radar can successfully complete the detection required for the ACCS. In the conclusion, the perspective and issues in the future development of the ACCS radar are described.     

Experimental study on the characteristics of nano-particle emissions from a heavy-duty diesel engine using a urea-SCR system

Particulate matter in diesel engine exhaust, particularly nano-particles, can cause serious human health problems including diseases such as lung cancer. Because diesel nano-particle issues are of global concern, regulations on particulate matter emissions specify that not only the weight of particulate matter emitted but also the concentration of nanoparticles must be controlled. This study aimed to determine the effects on nano-particle and PM emissions from a diesel engine when applying a urea-SCR system for NO_x reduction. We found that PM weight increases by approximately 90% when urea is injected in ND-13 mode over the emission without urea injection. Additionally, PM weight increases as the NH₃/NO_x mole ratio is increased at 250 °C. In SEM scans of the collected PM, spherical particles were observed during urea injection, with sizes of approximately 200 nm to 1 μm. This study was designed to determine the conditions under which nano-particles and PM are formed in a urea-SCR system and to relate these conditions to particle size and shape via a quantitative analysis in ND-13 mode.     

Tensile properties of different chemical compositions for TRIP-assisted multiphase steel for automobile structures

The microstructural changes and the tensile properties of TRIP-assisted steels resulting from different chemical compositions were investigated by using SEM, TEM, XRD and UTM. As a result of microscopic observation, the morphology of retained austenite could be characterized by two types: a granular type in steel containing higher Si and a film type in steel having higher C. In the case of the steel containing higher C with a tensile strength of 860 MPa and a total elongation of 38%, the film type retained austenite could be observed among the lath bainitic ferrites. Actually, the metastable retained austenite was required for good formability, which means that the chemical composition plays a significant role in the microstructure and tensile property of TRIP-assisted steel. With respect to the tensile property, each steel type that contained an suitable amount of Si and Mn demonstrated a typical TRIP effect on a stress-strain curve while steel that contained a higher Mn content exhibited similar behaviors, as demonstrated in the dual phase steels.     

Active controller design for an electromagnetic energy-regenerative suspension

In this paper, with the parameters acquired from measured and tested data, a three-phase mathematical model is applied to the motor component of the developed electromagnetic suspension actuator. A main/inner-loop structure is used for its active control, and the constraints of the control current and energy flow states of actuator are analyzed by simplifying the inner-loop control system. Two different control modes, i.e., Consumptive Full Active (CFA) and Regenerative Semi Active (RSA) modes, which emphasize vibration control of sprung mass and vibration energy regeneration caused by road roughness, respectively, are proposed. Simulations are carried out using different road conditions, and the results demonstrate that the CFA mode can improve vehicle ride comfort by more than 30 percent, despite battery energy consumption; in RSA mode, the ride comfort can be improved by up to 10 percent with the battery charged by regenerated energy.     

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行程时间的不确定性是影响货运车队路径选择的一个重要因素,特别是对于要求货物准时送达的配送任务（例如商品混凝土的配送）,提出了在车辆调度中考虑由拥挤路段交通流量波动引起的行程时间不确定性的方法,建立了考虑行程时间可靠性要求的车辆优化调度数学模型,给出了相应的启发式算法,通过算例介绍了该模型和算法的应用。结果表明配送总成本随行程时间可靠性要求的提高而增加。     

拥挤条件下公交系统的拟动态均衡配流模型

论文考虑了由于公交线路运营能力不足造成的车站排队拥挤现象,在此基础上构造了拥挤条件下公交系统的拟动态均衡配流模型.该模型可自动估计不同时段内拥挤条件下的公交流量和车站的乘客排队,特别是在非常拥挤的情况下(即乘客需求超过公交网络运营能力)也能够进行流量分配,并确定车站的乘客排队长度.因此,该模型较好地反映了公交网络的拥挤效应.所给算例说明了不同需求条件下该公交均衡配流模型的应用.     

钢-混凝土组合连续弯箱梁抗火性能与设计方法

为研究提高钢-混凝土组合连续弯箱梁抗火性能的策略,选取某三跨钢-混凝土组合连续弯箱梁为研究对象,利用通用有限元软件ANSYS建立了其在火灾下的三维非线性两阶段分析模型;基于已有热-结构耦合分析方法,模型考虑了钢箱梁内空腔辐射传热过程和其上翼缘与混凝土板的接触边界条件;将模型得到的预测结果与试验数据进行了比较,验证了模型的可靠性;采用建立的模型在不同纵向受火位置、火灾强度和荷载水平作用下对钢-混凝土组合连续弯箱梁跨中挠度进行了参数敏感性分析,研究了其极限承载能力和刚度衰变规律;以火灾下跨中挠度为评估指标,提出了针对钢-混凝土组合连续弯箱梁的抗火设计方法。研究结果表明：在对称火和结构荷载作用下,钢-混凝土组合连续弯箱梁外边缘挠度大于内边缘挠度,且荷载越大,火灾越严重,这一效应越显著;在油罐车等过火面积较大的火灾作用下,刚度较极限承载能力衰退更快,与常温下的钢-混凝土组合连续弯箱梁极限承载能力和刚度相比,边跨受火16 min时极限承载能力和刚度分别降低至29%和14%,中跨受火28 min时极限承载能力和刚度分别降低至31%和22%;在钢-混凝土组合连续弯箱梁抗火设计中,应首先提高外侧钢箱梁在火灾下的刚度,增多和加宽外侧钢箱梁底板纵向加劲肋可使边跨受火20 min后内外侧钢箱梁跨中挠度差分别减小23%和30%,中跨受火32 min后内外侧钢箱梁跨中挠度差分别减小22%和27%。     

Design optimization of an injection mold for minimizing temperature deviation

The quality of an injection molded part is largely affected by the mold cooling. Consequently, this makes it necessary to optimize the mold cooling circuit when designing the part but prior to designing the mold. Various approaches of optimizing the mold cooling circuit have been proposed previously. In this work, optimization of the mold cooling circuit was automated by a commercial process integration and design optimization tool called Process Integration, Automation and Optimization (PIAnO), which is often used for large automotive parts such as bumpers and instrument panels. The cooling channels and baffle tubes were located on the offset profile equidistant from the part surface. The locations of the cooling channels and the baffle tubes were automatically generated and input into the mold cooling computer-aided engineering program, Autodesk Moldflow Insight 2010. The objective function was the deviation of the mold surface temperature from a given design temperature. Design variables in the optimization were the depths, distances and diameters of the cooling channels and the baffle tubes. For a more practical analysis, the pressure drop and temperature drop were considered the limited values. Optimization was performed using the progressive quadratic response surface method. The optimization resulted in a more uniform temperature distribution when compared to the initial design, and utilizing the proposed optimization method, a satisfactory solution could be made at a lower cost.