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Wang T.,Nanjing University of Science and Technology | Wang L.,Nanjing University of Science and Technology | Li T.,Purdue University | Zou X.,NAVECO Ltd.
Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition) | Year: 2017

To predict fatigue failure locations of vehicle with high accuracy, a methodology integrating virtual simulation technique and road testing was proposed and demonstrated on a commercial vehicle cab. A rigid and flexible multi-body model was built and verified to simulate the dynamics of cab under fatigue road testing. Loading spectrum at cab mounts were reproduced and verified by employing the virtual iteration method. Then, fatigue failure assessment was made by adopting strain-life method, and critical regions were figured out. The results show that regions around the B pillars were vulnerable due to stress concentration, and some structural improvements are made to improve its durability performance. The conclusion is drawn that the critical regions predicted with the proposed methodology agree well with the road testing results, and the improved design proves to have a better durability performance, which indicates that the proposed methodology is feasible and effective. © 2017, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.

Teng S.,Changchun University | Shi W.K.,Changchun University | Jun K.,Changchun University | Zhang Y.J.,NAC Automotive Research Institute | Liu T.F.,Naveco Ltd
Applied Mechanics and Materials | Year: 2014

Floor vibration model was established by FEM and the modal analysis was conducted, which were based on the condition that this experiment took the automobile floor as the research object and applied the basic theory of finite element analysis. Simultaneously the results of modal analysis were compared with the results of the experiment, verifying the accuracy of the model. This can be considered as a basis of providing reference for the optimization and improvement of light bus floor. © (2014) Trans Tech Publications, Switzerland.

Wang C.,University of Pittsburgh | Liu T.,NAVECO Ltd. | Yuan L.,NAVECO Ltd. | Zhang T.,NAVECO Ltd.
SAE International Journal of Commercial Vehicles | Year: 2014

As is known to all, the modeling of vehicles and durability simulation is becoming more accurate and more compatible with physical testing, resulting in shortening of the analysis process, and a lower cost. It would be more advantageous in the future to simulate the full vehicle system before the physical testing. Thus, in the analysis of vehicle durability performance, the need for more precise rigid and flexible vehicle modeling and more precise external loadings acquisition method is increasing. In view of the typical difficulties faced in the vehicle multi-body dynamics (MBD) simulation and in the associated loading extraction, this paper proposes a method to achieve accurate external vehicle loadings by virtual simulation. This method is performed based on the physical testing and compensates for the imperfections in the MBD modeling, thus being able to improve the quality of fatigue life prediction (FLP). Key technologies to implement this approach in this study include finite element analysis (FEA), MBD simulation and virtual iteration technique (VIT). A rigid and flexible multi-body dynamics model with less modes is constructed in order to reduce the computation time and to make a better convergence in the computing of the MBD analysis simultaneously. Integrated with the statistics of physical testing, the multi-channel vehicle loadings can be achieved through virtual iteration (VI). Meanwhile, this iteration process identifies corrections to model parameters, thus helping to get a more precise MBD model. Accounting for the nonlinear effects of some of the vehicle components, by using the corresponding precise vehicle loads to excite the dynamic model, body loading spectrums of vehicle are obtained for subsequent FLP. All these measures have been demonstrated for a commercial vehicle analysis. The result showed that a better acquisition of the loading-time history has been obtained, thus reducing the time and effort used in FLP process. Copyright © 2014 SAE International.

Hao Z.,Hohai University | Ju Q.,Hohai University | Jiang W.,NAVECO Ltd. | Zhu C.,Hebei University of Engineering
The Scientific World Journal | Year: 2013

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4) presents twenty-two global climate models (GCMs). In this paper, we evaluate the ability of 22 GCMs to reproduce temperature and precipitation over the Tibetan Plateau by comparing with ground observations for 1961 1900. The results suggest that all the GCMs underestimate surface air temperature and most models overestimate precipitation in most regions on the Tibetan Plateau. Only a few models (each 5 models for precipitation and temperature) appear roughly consistent with the observations in annual temperature and precipitation variations. Comparatively, GFCM21 and CGMR are able to better reproduce the observed annual temperature and precipitation variability over the Tibetan Plateau. Although the scenarios predicted by the GCMs vary greatly, all the models predict consistently increasing trends in temperature and precipitation in most regions in the Tibetan Plateau in the next 90 years. The results suggest that the temperature and precipitation will both increase in all three periods under different scenarios, with scenario A1 increasing the most and scenario A1B increasing the least. © 2013 Zhenchun Hao et al.

Ju Q.,Hohai University | Hao Z.-C.,Hohai University | Yu Z.-B.,Hohai University | Xu H.-Q.,China Institute of Water Resources and Hydropower Research | And 2 more authors.
Shuikexue Jinzhan/Advances in Water Science | Year: 2011

The performance of twenty-two General Circulation Models (GCMs) in simulating precipitation and temperature are evaluated and validated in the Yangtze River basin. Simulations of these GCMs were used in the IPCC Fourth Assessment Report (AR4). The Bjerknes Center for Climate Research (BCCR) Bergen Climate Model (BCM) 2.0, or BCCR_BCM2.0, and other six GCMs stand out from the twenty-two evaluated GCMs. Using an artificial neural network and climate change projections from the selected seven GCMs under A1B, A2 and B1 scenarios, the hydrological response to future climate change in the Yangtze River basin is studied. The projective on the subject is presented. The result shows that there could be a decreasing trend in the mean annual streamflow in the future. At the Yichang station, a dry year condition would be likely to become more common in a warmer world. The reduction of mean annual streamflow could reach as much as 520 m 3/s for dry years, while such a reduction would be 250 m 3/s for a normal year at the Datong station. The decrease in available water could be a big challenge to the practice of water allocation and management in the western and central routes of the South-to-North Diversion project. The mean monthly streamflow would be projected to be increasing during January to June, while, the opposite should be true during the second half of the year. At Yichang and Datong, the streamflow increases would be 29.6% and 13.8% during January to June and decreases could reach as much as -18.2% and -11% during the second half of the year, respectively. The variation of streamflow could be expected to be larger at Yichang than at Datong. During flooding seasons, there would be a decrease of -8.5% in Yichang streamflow, and a slight increase for other reasons. In contrast, the Datong streamflow would have a 2.3% increase during flooding seasons, and a slight decrease in non-flooding seasons.

Hao Z.-C.,Hohai University | Ju Q.,Hohai University | Wang L.,Technical University of Delft | Wang H.-M.,Hohai University | Jiang W.-J.,NAVECO LTD
Shuikexue Jinzhan/Advances in Water Science | Year: 2011

Predictions of extreme floods from 2010-2099 are made for the Huaihe River Basin using the projected future temperature and precipitation from 22 global climate models under A1B, A2 and B1 emission scenarios in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4) and the Xin'anjiang monthly distributed hydrological model. The model is calibrated and validated with the satisfied results. The ensemble method is applied in the model prediction. The result shows that the A2 scenario would most likely result in a highest number of extreme flood events, and then followed by the A1B scenario and the B1 scenario, respectively. Under A1B, there would be an increased possibility of extreme flooding in the latter half of the 21st century; while for the A2 scenario, the extreme floods could be concentrated on the period 2035-2065 as well as after 2085. Under B1, the frequent extreme floods would most likely occur around 2070s. By integrating the diverse definitions of extreme events, we classify the extreme events into three groups based on the flood magnitudes. In the first magnitude group, the extreme flood events predicted under the A2 scenario would be the most with the largest average flood volume; while those under B1 would be the least with the minimum value of flood magnitude in the third group. There could be an increased occurrence of the extreme flood events in the first magnitude group among all three scenarios. The highest increase might be found under the A2 scenario and followed by A1B and B1. The proportion of extreme flood events in each of the three magnitude groups would also vary under different scenarios. The extreme flood events of the second magnitude group could be more frequently encountered under A1B and A2; while B1 could result in more third group extreme flooding. Nevertheless, there would only a small proportion of extreme flood events with the flood magnitude exceeding the great flood of 1954 in the first magnitude group.

Wang L.-M.,Nanjing University of Science and Technology | Chen D.-Y.,Nanjing University of Science and Technology | Zou X.-J.,NAVECO Ltd | Zhang Y.-J.,NAVECO Ltd | Zhang T.-Y.,NAVECO Ltd
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2014

In order to enhance the crashworthiness of a light truck, the light truck finite element model was built. The cab modal simulation and truck 100% frontal collision simulation were carried out. The cab modal tests and actual collision tests verified the accuracy of the finite element model. With the ECE R29-03 regulation as reference, side 20° pendulum impact simulation was carried out. Some improvement measures, such as filling structural foam in side panel top, adding a roof crossbeam and rear wall reinforcing beam, had been used to improve the original cab. The results show that the cab stiffness is improved, the energy absorptions of parts are more homogeneous, and the minimum survival space is increased from 75.3 mm to 121.9 mm, so the protection of the occupants is enhanced.

Wang T.,Nanjing University of Science and Technology | Wang L.,Nanjing University of Science and Technology | Wang Y.,Nanjing University of Science and Technology | Zou X.,NAVECO Ltd. | Guo F.,NAVECO Ltd.
SAE Technical Papers | Year: 2015

The design of aluminum foam reinforced thin-walled tubes has garnered much interest recently due to the high energy absorption capacity of these tubes. As a new kind of engineering composite material, aluminum foam can hugely increase the crashworthiness capacity without sacrificing too much weight. In this paper, axisymmetric thin-walled hollow tubes with four different kinds of cross-sections (circular, square, hexagonal and octagonal) are studied to assess their performance for crashworthiness problems. It is found that the tube with square cross-section has the best crashworthiness performance under axial impact. To seek optimal designs of square aluminum foam reinforced thin-walled tubes, a surrogate modeling technique coupled with a multi-criteria particle swarm optimization algorithm has been developed, to maximize specific energy absorption (SEA) and minimize peak crash force (PCF). To improve the accuracy of the optimization process, meta-models of SEA and PCF were constructed using the response surface method and radial basis function method, respectively. Crash simulations carried out using LS-DYNA demonstrate that the optimal design has better crashworthiness characteristics than the baseline design. These results suggest that the proposed method can be of benefit in design optimization for other crashworthiness problems. Copyright © 2015 SAE International.

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