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941.
942.
Quasistatic fractures at high joint angles constitute a chronic quality problem in CV joints. This type of fracture occurs
when a driver unintentionally depresses the brake and accelerator simultaneously under a full-turn retreat condition. In general,
the cage in a ball joint can be broken only at these high joint angles. Here we present a flexible quasistatic simulation
model developed to simulate fracture in a CV joint. The cause and process of the quasistatic fracture were analyzed using
simulations and physical tests. Static fracture simulations and tests at high joint angles showed that, initially, only one
of the six cage posts was damaged. In a simulation of one revolution at constant torque, we found that an imbalance in ball
loads generated an excessive cage load. Moreover, if this high cage load was applied when the cage protruded outward, the
cage post was subjected to severe shear loading. The cage post was damaged in this specific rotational range. Quasistatic
fracture simulations and tests at high joint angles showed that all six cage posts were damaged sequentially. Because entire
cage posts were damaged, the quasistatic fracture torque was approximately half of the static torque. The plastic strain in
each cage post displayed one step-like jump per revolution in the quasistatic simulations. The ball indentation created by
a high ball load was interrupted by the cage-window edges as the ball joint rotated. This hindrance by ball indentation triggered
the final breakage of the cage, although it was not the major cause of cage fractures. 相似文献
943.
S. J. Kang M. F. Kader Y. D. Jun K. B. Lee 《International Journal of Automotive Technology》2011,12(1):39-44
Adequate visibility through the automobile windshield is of paramount practical significance, most often at very low temperatures
when ice tends to form on the windshield screen. But the numerical simulation of the defrost process is a challenging task
because phase change is involved. In this study numerical solution was computed by a finite volume computational fluid dynamics
(CFD) program and experimental investigations were performed to validate the numerical results. It was found that the airflow
produced by the defrost nozzle is highly nonuniform in nature and does not cover the whole windshield area. The nonuniformity
also severely affected the heating temperature pattern on the windshield. The windshield temperature reached a maximum in
the vicinity of the defroster nozzle in the lower part of the windshield and ranged from 9∼31°C over a period of 30 min, which
caused the frost to melt on the windshield. The melting time was under 10 minutes, which satisfied the NHTSA standard. The
numerical predictions were in close agreement with the experimental results. Thus, CFD can be a very useful design tool for
an automobile HVAC system. 相似文献
944.
J. K. Kim Y. J. Kim W. H. Yang Y. C. Park K.-H. Lee 《International Journal of Automotive Technology》2011,12(3):375-381
This study proposes a structural design method for an outer tie rod installed in a passenger car. The weight of the outer
tie rod is optimized by using the aluminum alloy Al6082M, which is developed as a steel-substitute material, and applying
structural optimization techniques. The high strength aluminum with improved mechanical properties was developed to reduce
the weight of the outer tie rod. The newly developed aluminum alloy Al6082M is applied as the material of the outer tie rod.
The static strength due to inertia force, durability and buckling performances are considered in the structural design of
the outer tie rod. At the proto design stage of a new outer tie rod, it is cost-effective to utilize FE (finite element) analysis
to predict each of these performances. In addition, the current trend in the structural design of automobile parts is to use
optimization techniques to reduce the weights of the parts. First, for an arbitrary base design, the static strength, the
life cycle and the buckling load are calculated to check whether the design satisfies its criteria. Then, the critical performance
is selected so as to include its loading condition only in the optimization process. In this study, the metamodel based optimization
process using kriging is adopted to obtain the minimum weight satisfying the critical design requirement. Then, the feasibility
of the determined optimum shape is investigated against the other performances. Finally, the optimum design of outer tie rod
is modified by considering forging efficiency. The performances of the final design are investigated through simulation and
experiment. 相似文献
945.
M. J. L. Boada B. L. Boada D. Garcia-Pozuelo V. Diaz 《International Journal of Automotive Technology》2011,12(6):821-829
The behaviour of the tyre plays an important role in the vehicle handling. An accurate tyre model that estimates these forces
and moments it is highly essential for the studies of vehicle behaviour. For the last ten years neural networks have attracted
a great deal of attention in vehicle dynamics and control. Neural networks have been effectively applied to model complex
systems due to their good learning capability. In this paper a recursive lazy learning method based on neural networks is
considered to model the tyre characteristics under combined braking and cornering. The proposed method is validated by comparison
with experimental obtained responses. Results show the estimated model correlates very well with the data obtained experimentally.
Moreover, the neural model proposed allows to include the asymetric tyre behaviour in the tyre model without difficulty. 相似文献
946.
为综合开发利用低价值贝类中的功能保健品成分,利用索氏/超声提取、尿素包合法提取了紫贻贝中的多烯脂肪酸乙酯,对提油后的残渣利用热水提取、离子交换层析富集的方法提取了其中的牛磺酸,利用高效液相色谱-二极管阵列检测器(HPLC-DAD)分析测定了产品中二十碳五烯酸乙酯(EPA-E)、二十二碳六烯酸乙酯(DHA-E)的含量,利用薄层色谱法、吸光光度法定性定量测定了产品中的牛磺酸,结果显示紫贻贝中含有相当量的多烯脂肪酸乙酯及牛磺酸成分,有望作为高价值功能保健食品的来源. 相似文献
947.
运用产业关联的基本理论,通过投入产出表的计算,对TOD模式下轨道交通产业与其他产业的直接关联系数、影响力系数及感应度系数进行分析,得出轨道交通产业的特点,同时对轨道交通产业与其他产业的技术经济联系进行分析,具有一定的参考价值。 相似文献
948.
山区高速公路地形地质复杂,构造物多,桥梁隧道占路线总长的比例大,有的桥隧比例甚至高达70%~80%。所以要设计成功一条山区高速公路,设计好其中的桥梁部分就显得十分重要。 相似文献
949.
“Big data” which admittedly means many things to many people is no longer confined to the realm of technology. Today it is a business imperative and is providing solutions to long-standing business challenges for banking and financial markets companies around the world. Financial services firms are leveraging big data to transform their processes, their organizations and the entire industry. Since 2012, the term “big data” has frequently been mentioned and used to describe and define the huge amount of data in the information explosive era and to name related technological development and innovation. As to the police work, the coming of big data era is not only a challenge but also an opportunity. Police agencies should go with the tide of development to start with such aspects as work thinking, top design, public information sharing and application and talent provision so as to promote the new development and progress of police work. This paper expounds the practical effect and significance of police big data application by cases happened in some areas. 相似文献
950.
Variable valve timing (VVT) and cylinder deactivation (CDA) are promising methods in reducing fuel consumption and emission at part load in SI engines. An SI engine which uses electromagnetic valvetrain (EMV) will eliminate flow restriction from the throttle valve and produce higher indicated mean efficiency pressure (IMEP) due to the disabling of some of the working cylinders at part load. Therefore, pumping loss can be significantly reduced at part-load conditions. In addition, duration and timing of valve events are variably controlled at different operating conditions. This contributes to the improvement of engine efficiency. In this study, a dynamic model of an unthrottled SI engine has been developed to simulate the engine cycle. The model uses an EMV system that allows valvetrain control and cylinder deactivation techniques to be carried out in simulation flexibly. The simulated results find the optimal valve timing for different engine speeds. The optimal timing of intake valve closing depends on engine speed linearly, while the intake valve opening insignificantly influences engine performance. Additionally, this study also shows that cylinder deactivation modes can be successfully applied in improving engine efficiency at different engine loads. Different cylinder deactivation strategies have been applied for the full range of engine loads. It is concluded that the two-cylinder deactivation mode (50% CDA) considerably improves fuel consumption at low engine load. Meanwhile, one-cylinder deactivation (25% CDA) is an optimal fuel economy mode at medium engine load. With proper uses of VVT and CDA strategies, the efficiency of an SI engine can be increased more than 30% at low engine load and 11.7 % at medium engine load. 相似文献