Institute of Logistics Engineering of PLA

Chongqing, China

Institute of Logistics Engineering of PLA

Chongqing, China
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Li F.,Institute of Logistics Engineering of PLA | Zhao Q.,Nanjing University of Technology | Chen H.,Beijing Institute of Technology | Xu L.,First Research Division
Steel and Composite Structures | Year: 2017

A new composite tube connection method called the pre-tightened teeth connection technique is proposed to improve the composite tube connection efficiency. This paper first introduces the manufacturing process of the proposed technique. It then outlines how the mechanical properties of this technology were tested using four test groups. The factors that influence the load-bearing capacity and damage model of the connection were analyzed, and finally, the transfer load mechanism was investigated. The following conclusions can be obtained from the research results. (1) The new technique improves the compressive connection efficiency by a maximum of 79%, with the efficiency exceeding that of adhesive connections of the same thickness. (2) Changing the depth of teeth results in two types of damage: local compressive damage and shear damage. The bearing capacity can be improved by increasing the depth, length, and number of teeth as well as the pre-tightening force. (3) The capacity of the technique to transfer high loads is a result of both the relatively high interlaminar shear strength of the pultruded composite and the interlaminar shear strength increase provided by the pre-tightening force. The proposed technique shows favorable mechanical properties, and therefore, it can be extensively applied in the engineering field. Copyright © 2017 Techno-Press, Ltd.

Lei Y.B.,Institute of Logistics Engineering of PLA | Cao X.J.,Chongqing Jiaotong University | Ding Y.J.,University of Tennessee at Knoxville
Kemija u industriji/Journal of Chemists and Chemical Engineers | Year: 2015

Asphalt is considered a colloidal material and it is important to study the relationship between its colloidal structure, chemical components and performance. The aromatic nucleus content of asphalt at different depth analysed by attenuated total reflection (ATR) was taken as the index of colloid structure. The gray correlation was used to analyse the relationship between colloidal structure and chemical components of asphalt gel and performance. The results show that the correlation degree between the index of colloidal structure and saturates and resins is high, which proves that saturates and resins play an important role in asphalt colloid structure. With regard to the asphalt performance indexes, the complex modulus G∗ and the tangent of the phase angle (tan δ) have good correlation with the index of colloidal structure at the temperature of 30-70 °C but poor correlation at the temperature of 70-90 °C. Low temperature performance has a good correlation with colloid structure index, and tg can better reflect the characteristics of colloidal structure. The analysis shows that the colloidal structure of asphalt is a complex system and it is necessary to use more than one index to characterize the performance.

Zhang D.,PLA University of Science and Technology | Zhao Q.,PLA University of Science and Technology | Huang Y.,PLA University of Science and Technology | Li F.,Institute of Logistics Engineering of PLA | And 2 more authors.
Composite Structures | Year: 2014

A hybrid FRP-aluminum space truss structure system was designed as a modular emergency bridge with a span of 12. m. The bridge has a light weight of only approximately 1.2. tons and contains 8 structural units, which are composed of an aluminum bridge deck supported by FRP trussed members and connected by male jugs and female jaws based on the pre-tightened teeth connection (PTTC) technique. In the paper, the conceptual design of the bridge, assembly of structural units and bridge erection are described in detail. To understand the actual flexural behavior of the bridge, 4 prototype structural units were fabricated and mounted as a single-span simply supported structure and subjected to the four-point bending loading test. Structural computational models, including two FE models and a simplified analytical planar model, were constructed and validated by the experimental results. The results indicated that (1) the specimen displayed linear behavior under the ultimate-limit-state loading level, and both the strength and stiffness satisfied the design requirements; (2) the bridge deck exhibited an unexpected complex strain distribution, which is different from that of the analogous structure; and (3) the "beam-grillage" FE model and simplified analytical planar model provided effective calculation methods for the proposed bridge. © 2013 Elsevier Ltd.

Li F.,Institute of Logistics Engineering of PLA | Zhao Q.,PLA University of Science and Technology | Gao Y.,PLA University of Science and Technology | Xu L.,The First Research Division | Chen H.,PLA University of Science and Technology
Composite Structures | Year: 2016

In the conventional methods, the failure load and failure mode of composite pre-tightened tooth connections are determined by experiment. To determine the failure load and failure mode of the composite pre-tightened tooth connection without performing experiments, a new method based on the characteristic lengths is presented in this paper. This method involves three steps: first, based on the concept of the method to determine the shear characteristic length, the compressive characteristic length is defined and the characteristic length of composite tooth can be determined; second, the stress distribution of the composite joint is analyzed by the use of a finite element method; finally, combined with failure criterion and the stress distribution of the composite joint, the failure load and failure mode of this joint can be determined by the compression factor fc and shear factor fs. The prediction methods based on the characteristic lengths are validated by the tests for composite joints with different parameters, and the results indicate that the methodology proposed in this paper can accurately and effectively predict failure loads as well as failure modes in composite pre-tightened tooth. © 2016 Elsevier Ltd

Ding Y.,PLA University of Science and Technology | Jiang K.,PLA University of Science and Technology | Shao F.,PLA University of Science and Technology | Deng A.,Institute of Logistics Engineering of PLA
Structural Engineering and Mechanics | Year: 2013

To have a better understanding of the torsional mechanism and influencing factors of PC composite box-girder with corrugated steel webs, ultimate torsional strength of four specimens under pure torsion were analyzed with Model Test Method. Monotonic pure torsion acts on specimens by eccentric concentrated loading. The experimental results show that cracks form at an angle of 45° to the member's longitudinal axis in the top and bottom concrete slabs. Longitudinal reinforcement located in the center of cross section contributes little to torsional capacity of the specimens. Torsional rigidity is proportional to shape parameter η of corrugation and there is an increase in yielding torque and ultimate torque of specimens as the thickness of corrugated steel webs increases. Copyright © 2013 Techno-Press, Ltd.

Deng X.,PLA University of Science and Technology | Li F.,Institute of Logistics Engineering of PLA | Jiang F.,Engineering Design and Research Institute of Navy | Wang Y.,PLA University of Science and Technology
Jiefangjun Ligong Daxue Xuebao/Journal of PLA University of Science and Technology (Natural Science Edition) | Year: 2014

To study the modification effect of polypropylene superfine powder on mortar and concrete, the effects of the different admixtures as silica fume, polypropylene fiber and polypropylene superfine powder on the mechanical properties of mortar and concrete were studied comparatively through experiments. Then the modification mechanisms of different admixtures were analyzed with microscopic technical. The results show that polypropylene superfine powder has the merits of the polymer material and the active mineral joined material, and that it can improve the microstructure of cement matrix significantly, and increase the compactness of it. The addition of polypropylene superfine powder can reinforce the axial compression strength, the fexural strength, the splitting tensile strength and the toughness of the concrete, but it has an unfavorable influence on the workability of the concrete.

Deng A.Z.,Institute of Logistics Engineering of PLA | Zhao Q.L.,PLA University of Science and Technology | Li F.,Institute of Logistics Engineering of PLA | Chen H.,PLA University of Science and Technology
Journal of Reinforced Plastics and Composites | Year: 2013

As the new composite connection technology, pre-tightened teeth connection can play better mechanical performance for composite materials. To this connection technology, the ultimate bearing capacity of the first tooth is very important. In this article, the ultimate bearing capacity of the single tooth is researched by the experiment and theory. Firstly by the experiment, the optimal tooth depth and an effective teeth length are obtained. Secondly on the basis of reasonable simplified load model of a single tooth, the theoretical solution of the interlaminar stress distribution on a single tooth is worked out. And depending on the interlaminar stress distribution theory, the concepts of optimal tooth depth and tooth length are explained and their determination methods are given out. Finally combined with tests, the approach to determine the ultimate bearing capacity of the single tooth is put forward, hence offering design method for the final connection. © The Author(s) 2013 Reprints and permissions:

Chen S.,University of Sichuan | Zhu R.,University of Sichuan | Li X.,University of Sichuan | Ying D.,Institute of Logistics Engineering of PLA
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2014

According to the characteristics of randomness and intermittent of wind power, a multipoint DC voltage adaptive droop control strategy was proposed for the interconnection of wind farms by VSC-MTDC. Under this control strategy, all converters which have power regulation ability would share the task of stable dc voltage. The converter which has already operated closely to the rating would share little unbalanced wind power, meanwhile the converter which has much available headroom would share more unbalanced wind power, thus avoiding the possible overloading which may occur with fixed value of power-voltage droop. Finally, simulation was processed with PSCAD/EMTDC. The simulation results showed that the proposed control which needn't communication, is suitable for interconnection by VSC-MTDC of wind farms whose flow changes frequently.

Lei Y.,Institute of Logistics Engineering of PLA | Cao X.,Chongqing Jiaotong University
Journal of Materials in Civil Engineering | Year: 2015

Epoxy resin concrete can be used as one kind of repairing material for pavement. In this study, Bisphenol A epoxy resin (E51) and four different types of curing agents were selected. By comparing the mechanical strength of different epoxy gel systems under microwave curing conditions, a polyamide (V-125) curing agent was confirmed for its good comprehensive mechanical properties. The addition of diluents decreases the viscosity of the gel system, which is beneficial to construction. The compressive and tensile strength decrease, but the impact strength increases with increasing dosage of diluent. Ten percent diluents was recommended through comprehensive consideration. The compressive strength, tensile strength, and impact strength of E51/V-125 with 10% diluent under microwave curing conditions are slightly higher than that under thermal curing conditions. A self-made microwave radiation device was applied for curing the large size epoxy concrete specimens. The index of Marshall stability, air voids, and flow value of epoxy resin concrete were put forward. The gradation middle value of dense-graded asphalt concrete (AC-13) and 5.0% gel-stone ratio were determined using the Marshall method. The high and low temperature, and water-resistant, oil-resistant, and anti-skid properties of the microwave curing concrete were evaluated, and the results shows it has good pavement performance. © 2014 American Society of Civil Engineers.

Zhu R.,University of Sichuan | Li X.,University of Sichuan | Ying D.,Institute of Logistics Engineering of PLA
Dianwang Jishu/Power System Technology | Year: 2014

The constant active power control mode cannot offer mutual support for power grids at AC side while accident occurs in the power grid at AC side. Since the voltage sourced converter is highly controllable, flexible and efficient, a frequency stability control strategy suitable for interconnected voltage sourced converter based multi-terminal high voltage direct current (VSC-MTDC) system is proposed. Not needing communication between inverter stations, only using additional frequency control the inverter stations can respond to the frequency of power systems in AC side, and through controlling the droop of DC voltage multi inverter stations can jointly share the power unbalance in HVDC network, thus when the frequency in one of the AC systems evidently changes, the rest of AC systems can offer power support via VSC-MTDC system to mitigate the active power unbalance in the faulty AC system. The PSCAD/ EMTDC based simulation results show that the proposed strategy; can fully utilize the frequency adjustment capability of interconnected VSC-MTDC system, and the frequency fluctuation extent in the faulty AC system is reduced.

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