Time filter

Source Type

Huludao, China

Ma Y.,Tsinghua University | He M.,Tsinghua University | Shen W.,Naval Aviation Institute | Ren G.,Tsinghua University
Journal of Sound and Vibration | Year: 2015

In this paper, a simple and designable shock isolation system with ideal high-static-low-dynamic-stiffness (HSLDS) is proposed, which is intended for the horizontal plane shock isolation application. In this system, the isolated object is suspended by several bearing cables and constrained by a number of uniformly distributed pretensioned cables in the horizontal plane, where the low dynamic stiffness of the system is main controlled by the pretension of the planar cables, whilst the high static stiffness is determined by the axial stiffness of the planar cables and their geometric settings. To obtain the HSLDS characteristic of the system, a brief theoretical description of the relationship between the restoring force and displacement is derived. By obtaining the three-order Taylor expansion with sufficient accuracy of the restoring force, influence of planar cable parameters on the low dynamic and high static stiffness is thus given, therefore, the required HSLDS isolator can be easily designed by adjusting the planar cable length, pretension and tensile stiffness. Finally, the isotropy characteristic of the restoring force of the system with different numbers of planar cables is investigated. To evaluate the performance of the system, a rigid isolated object and flexible cables coupling simulation model considering the contacts of the system is established by using multibody dynamics approach. In this model, flexible cables are simulated by 3-node cable element based on the absolute nodal coordinate formulation; the contact between cable and isolated object is simulated based on Hertz contact theory. Finally, the time-domain shock excitation is converted from the design shock spectrum on the basis of BV043/85 criterion. The design procedure of this isolator and some useful guidelines for choosing cable parameters are presented. In addition, a summary about the performance of the isolators with different numbers of cables shocking in an arbitrary direction is given in the conclusion. © 2015 Elsevier Ltd. Source

Yue K.,Airborne | Yue K.,Beihang University | Cheng L.,Naval Aviation Institute | Cheng L.,Beihang University | And 3 more authors.
Aerospace Science and Technology | Year: 2016

The aerodynamic characteristics of the flow field of an embarked buddy-refueling aircraft are analyzed to technically aid the docking between the embarked buddy-refueling aircraft and the receiver. A three-surface geometric model of the embarked buddy-refueling aircraft is designed with CATIA software, and then the model is imported into Fluent Module of Workbench Software to generate an unstructured tetrahedral mesh. Based on CFD technique, the turbulence model adopts the standard k-ε equations and the control theory adopts three-dimensional N-S equations. The aerodynamic characteristics of the flow field of the embarked buddy-refueling aircraft are numerically simulated with energy conservation equations and the basic characteristics of the flow field such as the pressure, velocity, trapped vortex and the temperature of jet blast are derived through the simulation. The results indicate the efficiency of the simulation method to analyze the aerodynamic characteristics of the flow field of the embarked buddy-refueling aircraft and the consistency with the experimental results. © 2015 Elsevier Masson SAS. Source

Shen W.,Tsinghua University | Shen W.,Naval Aviation Institute | Zhao Z.,Tsinghua University | Ren G.,Tsinghua University | Liu J.,Tsinghua University
Mathematical Problems in Engineering | Year: 2013

The arresting dynamics of the aircraft on the aircraft carrier involves both a transient wave propagation process in rope and a smooth decelerating of aircraft. This brings great challenge on simulating the whole process since the former one needs small time-step to guarantee the stability, while the later needs large time-step to reduce calculation time. To solve this problem, this paper proposes a full-scale multibody dynamics model of arresting gear system making use of variable time-step integration scheme. Especially, a kind of new cable element that is capable of describing the arbitrary large displacement and rotation in three-dimensional space is adopted to mesh the wire cables, and damping force is used to model the effect of hydraulic system. Then, the stress of the wire ropes during the landing process is studied. Results show that propagation, reflection, and superposition of the stress wave between the deck sheaves contribute mainly to the peak value of stress. And the maximum stress in the case of landing deviate from the centerline is a little bit smaller than the case of landing along centerline. The multibody approach and arresting gear system model proposed here also provide an efficient way to design and optimize the whole mechanism. © 2013 Wenhou Shen et al. Source

Li S.,Southwest Jiaotong University | Li S.,Naval Aviation Institute | Li S.,Key Laboratory of Cloud Computing and Intelligent Technique | Li T.,Southwest Jiaotong University | And 3 more authors.
Knowledge-Based Systems | Year: 2015

In this paper, a new composite rough set model is proposed to process incomplete composite information with criteria and regular attributes. Following that, some strategies for incrementally updating approximations of composite rough sets when adding or removing some objects are discussed and the corresponding incremental algorithms are designed. Several numerical examples illustrate the feasibilities of the composite rough set model and the incremental strategies, respectively. Experimental evaluation shows that the incremental algorithms can effectively reduce the running time than their counterparts. © 2015 Elsevier B.V. All rights reserved. Source

Yue K.,Airborne | Yue K.,Beihang University | Cheng L.,Beihang University | Cheng L.,Naval Aviation Institute | And 2 more authors.
Aerospace Science and Technology | Year: 2015

Abstract The jet blast impact of embarked aircraft on the takeoff zone is studied to support carrier-aircraft adaptation. The geometric model of carrier-aircraft system is built in CATIA Software and an unstructured mesh of the model is generated in Workbench Software. The jet blast impact of embarked aircraft on flight deck and jet blast deflector while taking off from takeoff zone is numerically simulated with standard κ-ε and three dimensional N-S equations based on CFD theory. Thermal coupling of wind over deck and jet blast is also taken into consideration. The distribution of temperature, pressure, velocity and streamline of the coupling flow is numerically simulated through Fluent Software and the temperature characteristics distribution on axes is also obtained. The results indicate: (1) the method presented in the paper can analyze fluid mechanics problems of complicated geometric models and obtain highly reliable simulation results; (2) the safe operation region for personnel, the suitable outfitting of jet blast deflector and proper layout of takeoff zone can be obtained. © 2015 Elsevier Masson SAS. All rights reserved. Source

Discover hidden collaborations