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111.
Development of hot stamped center pillar using form die with channel type indirect blank holder 总被引:1,自引:0,他引:1
H. S. Choi B. M. Kim K. J. Nam S. Y. Ha S. H. Cha C. G. Kang 《International Journal of Automotive Technology》2011,12(6):887-894
The hot stamping process has been used in the automotive industry to reduce the weight of the body-in-white and to increase
passenger safety via improved crashworthiness. However, defects such as fracture and wrinkle occur when hot stamping is performed
using a conventional drawing or forming method. In this study, a channel-type indirect blank holder (CIBH) is proposed to
develop a high-strength center pillar in form-type hot stamping, so that the aforementioned drawbacks are overcome. This type
of blank holder plays an important role in reducing severe wrinkling at the flange; such wrinkling leads to folding after
the completion of form-type hot-stamping. First, we investigated the effect of the channel shape on the indirect blank holding
force by using a simplified two-dimensional plane-strain stamping process. Second, we selected the slope angle and corner
radius of the channel as the main shape parameters by finite element analysis and artificial neural network (ANN). It is known
that fracture at the hot formed wall and wrinkle at the flange are significantly affected by the slope angle of the channel,
and the appropriate value for eliminating fracture and wrinkle is determined to be 99°. By performing hot stamping using a
form die with the selected channel, we can manufacture a high-strength center pillar without wrinkle and fracture. 相似文献
112.
In this paper, the dynamic response of a scale model of a jacket offshore structure is investigated both theoretically and experimentally. The experiments were conducted both in air and in water. The in-water experiments were done in the towing tank of Memorial University to simulate the realistic operating conditions. The model was subjected to random wave loads. Froude's law of modeling was used to obtain the dimensions of the scale model based on the dimensions of an existing structure. The effects of varying the structure's weight, and the characteristics of the wave loading were investigated. The structure's weight was changed by adding weights to the structure's deck. A finite element model was designed to determine the dynamic response of the model. Excellent agreement between the experimental and theoretical results was obtained.The reaction force at the foundation was estimated from strain measurements and compared with the finite element calculations. Fair agreement was obtained.This work is the first stage of a project whose objective is to develop a method for structural damage detection using the free vibration response of the structure. The free vibration response will be obtained from the stationary random response of the structure using the random decrement method. Having an accurate model to describe the dynamic response of the structure is the first step in this study. 相似文献
113.
H.T. LIN 《西南交通大学学报(英文版)》2012,20(2):70-75
Vortex motion in superconductors of higb-Tc superconducting maglev system is studied by a computational simulation.The vortex system is treated in a similar fashion,as a system where defects arc arrang... 相似文献
114.
The maximum principal stresses, von Mises effective stresses and principal facet stresses at the time of creep rupture were
compared in uniaxial, biaxial, and triaxial stress states for AZ31 magnesium alloy. The creep rupture of this alloy was experimentally
controlled by cavitation, which was the result of a low damage tolerance, λ. Creep deformation could be correlated with the von Mises effective stress parameter. The failure-mechanism control parameter
governing the stress state coincided with the experimental results of the rupture of the materials under multiaxial stress
states. Finally, the theoretical prediction based on constrained cavity growth and continuous nucleation agreed with the experimental
rupture data to within a factor of three. 相似文献
115.
This paper offers novel insights to the design and implementation of an innovative state-of-charge (SOC) estimator for the lithium-ion (Li-Ion) series battery pack. The most interesting feature of this approach is that it can utilize information from each filtered terminal voltage of the Li-Ion cells connected in series for SOC estimation of the battery pack. Without actual sensing each discharging/charging current (DCC) applied to the Li-Ion cells, it is possible to extract each DCC estimation from the corresponding filtered terminal voltages with an equivalent electrical circuit model (EECM) identification of all Li-Ion cells in the battery pack. There are two advantages to SOC estimation of the battery pack with this approach. First, the proposal can be implemented simply and effectively, reducing the computational steps required for SOC estimation. By reducing computational steps, the proposal is expected to be more cost-effective. Second, the approach guarantees an improved SOC performance, even if the battery pack results in inevitable cell-to-cell variation among Li-Ion cells. Accordingly, there are fewer differences to previously estimated DCCs among Li-Ion cells. Specifically, all values from the estimated DCCs are properly compensated for by simultaneous parameter modification according to each cell’s electrochemical characteristics. Experimental results clearly demonstrate that our DCC sensorless SOC estimator provides robust SOC performance for the battery pack. This approach considered an experimental battery pack (12S1P) connected in series using 2.6 Ah LiCoO2 cells produced by Samsung SDI. 相似文献
116.
When using limited funds on bicycle facilities, it would be helpful to know the extent to which a new facility will be used. If a bicycle lane is added to a street, how many bicyclists will no longer use the adjacent sidewalk? If a separate bicycle path is constructed, how many bicyclists will move from the street or sidewalk? This study seeks to identify factors that explain a bicyclist’s choice between available facility choices—off-street (sidewalk and bicycle path) or on-street (bicycle lane and roadway). This paper investigates these issues through a survey of bicyclists headed to Purdue University in West Lafayette, IN, USA. The first data collected to address these questions were “site-based”. Bicyclists were interviewed on campus at the end of their trips and asked which part of the cross-sections along their routes they had used—on-street or off-street. The characteristics of a particular cross-section of street right-of-way were then compared against the characteristics of each bicyclist and his/her observed choice of street, sidewalk, lane, or path. Later, “route-based” serial data were also added. The study developed a mixed logit model to analyze the bicyclists’ facility preferences and capture the unobserved heterogeneity across the population. Effective sidewalk width, traffic signals, segment length, road functional class, street pavement condition, and one-way street configuration were found to be statistically significant. A bicycle path is found to be more attractive than a bicycle lane. Predictions from the model can indicate where investments in particular bicycle facilities would have the most desirable response from bicyclists. 相似文献
117.
Rodrigo Leão De Moura Carolina Viviana Minte-Vera Isabela Baleeiro Curado Ronaldo Bastos Francini-Filho Hélio De Castro Lima Rodrigues Guilherme Fraga Dutra 《Coastal management》2013,41(6):617-632
In Brazil, Marine Extractive Reserves—MERs (Reservas Extrativistas Marinhas) represent the most significant government-supported effort to protect the common property resources upon which traditional small-scale fishers depend. From an initial small-scale experience in 1992, MERs have expanded countrywide, now encompassing 30 units (9,700 km2) and nearly 60,000 fishers. Despite such escalating interest in the model, there is little research on the effectiveness of MERs. In this article, we discuss relevant parts of the history and examine the current situation of the fisheries co-management initiative in the Marine Extractive Reserve of Corumbau, which was created in 2000 as the first MER to encompass coral reefs and reef fisheries. We describe the Extractive Reserve co-management arrangement and its main policy and legislative challenges. Finally, we discuss the prospects for the use of MERs as management frameworks for traditional small-scale fisheries in Brazil. 相似文献
118.
This paper discusses the damage detection in offshore jacket platforms subjected to random loads using a combined method of random decrement signature and neural networks. The random decrement technique is used to extract the free decay of the structure from its online response while the structure is in service. The free decay and its time derivative are used as input for a neural network. The output of the neural network is used as an index for damage detection. It has been shown that function N is effective in damage detection in the members of an offshore structure. Experimental studies conducted on a reduced model for a real jacket structure with geometrical scale of 1:30 are used. The applied loads were random loads. Two different load spectra were used: White noise, and Pierson-Moskowitz. 相似文献
119.
Although there are hundreds of airports that support commercial air passenger traffic in the United States (US), not all areas are equivalently served by the commercial air transportation system. Locations in the US differ with respect to their level of access to the commercial air network and their overall accessibility within the system. Given the complexity of the domestic commercial air passenger network and supporting infrastructure, past research has only been able to provide a limited assessment of locational accessibility within the United States. To address these complexities, this paper proposes a new metric that incorporates measures of access to air transport as well as accessibility within air transportation networks. Using a comprehensive dataset on scheduled airline service, the developed approach is then applied to the US domestic commercial passenger air transportation network to explore geographic differentials in accessibility. Results suggest marked differences between core-based statistical areas throughout the US. 相似文献
120.
分析在覆盖区域大、地质复杂的条件下,中国高速铁路工务工程"高可靠性、高稳定性、高平顺性"的技术特点,针对路网规模大、运营速度高、行车密度大的特征,围绕高速铁路运营的"安全、舒适、秩序",研究提出工务设备管理维护模式,在高速铁路安全运营实践的基础上,提出适合中国高速铁路工务设备检查、监控、修理的对策。 相似文献