Applied Mechanics and Materials Vols. 105-107

Abstract: Dynamic responses of flexi rotor-ball-bearing system under unbalance misalignment rubbing coupling faults are studied. Coupling faults dynamic control model of flexi-multi-system of rotor-ball-bearing system is established, based on finite element analysis and numerical integral combined simulate method. Then nonlinear bearing force and rub-impact force models are programmed in MATLAB. Analysis and compare vibration characteristics of system while under faults-free, unbalance and rub-impact faults. The result demonstrates that when system under unbalance faults, vibration frequency brought by eccentric mass is agreed with rotating speed frequency, its fundamental frequency wave add high frequency component, can show the characteristics of unbalance-rubbing faults efficiently; when system under misalignment faults, with frequency double vibration and high harmonics; when system under unbalance-misalignment-rubbing coupling faults, support force of shafting of rotor system appears high frequency responses like saw tooth based on sine wave, causing aggravation of rub-impact faults.

Abstract: This paper investigates the dynamics of a sinking winch mechanism in the framework of non-smooth dynamics. The previous works ignored the unilateral property of the cable (it can only pull the platform but can’t push it), which is specially taken into consideration in this paper. We propose the set-valued tension law to model the unilateral constraints of the cables. The equations of motion are derived by use of the Lagrange multiplier method. The dynamics model of the mechanism is obtained by combining the equations of motion and the set-valued tension law. Its solution is solved by the Moreau midpoint method. We present a numerical simulation study to demonstrate that the non-smooth dynamics framework is effective and suitable for the dynamic analysis of the sinking winch mechanism.

Abstract: To send the very low frequency signals, the length of antenna must attend one-half of a wavelength, maybe more than 8,000 meters sometimes. And the projection of the antenna on plumb line must exceed seventy percent of the antenna’s whole length. So the dynamic character and control of trailing antenna on a aircraft is one of most inmportant problems which need to research. The steady dynamic is the base of the dynamic character and control. The mathematics model of the trailing antenna is founded,and sloved via a shooting technique. The inflences of the angle of bank and the velocity of aircraft to the the end radius and verticality are reached. The result shows:under the low drag,for certain ranges of the angle of bank and the velocity ,the equilibruim solution is multivalued.

Abstract: To investigate the main vibration source which caused the serious vibration in passenger ride area of one type bus under its engine’s idling status, the effect of isolated vibration and energy transfer characteristics of the engine mounting block are tested and analyzed by modern signal processing technology in this paper. By the measurement of the acceleration response signals of engine’s exciting points and the fixed points of engine’s mounting on its chassis, the transfer function of engine’s mounting block under engine’s idling status was obtained. The calculation and analyzed results draw a conclusion that: the stiffness of the engine’s front mounting is too hard, and the vibration of the engine in idling status was amplified obviously. And then the harshness of the studied bus could be improved according to this conclusion.

Abstract: Aeroelastic analysis plays a vital role in the design of hypersonic wings. The thermal flutter of hypersonic tail under different materials at different temperature is analyzed by using MSC.NASTRAN, and the hypersonic piston theory is used for the modeling of supersonic aerodynamic loads. The research results showed: nature frequency is reduced as temperature increased, elevated temperature tend to reduce model stiffness due to changes in material properties and development of thermal stresses. Increased temperature will decrease the flutter velocity, flutter speed of tail is different with different material of titanium, but the trend and the value of variety of flutter speed are same as temperature increase. When material is different, the value of variety of flutter speed is also different.

Abstract: The arresting landing of carrier aircraft is especial dynamic problem. During this process,the gear would bear the very big dynamic load,which does the biggest harm to gear .In this paper,it analyzed the landing gear shock strut in carrier aircraft arresting landing,and aiming at the runout of shock strut and the flexibility of the landing gear by using the Lagrange equation.Then it concluded the chaging of landing gear shock strut with symmetrical and straight arresting,3m of off-center distance arresting and 2°of rolling angle arresting after simulating.The conclusion showed that the landing gear shock strut would be stable after a short time concussion;rolling and unsymmetrical affected the shock strutmore severe than off-center and symmetrical arresting,and the qualities of concussion also being more acute.

Abstract: Galloping of power transmission lines is a low frequency self-oscillation with large amplitude. The aerodynamic effect on each sub-conductor of 4-bundle conductor is different due to wake-flow-influence. In order to explore the reasons leading to galloping, a 3-D model for power transmission line is built. A two-node quadratic beam element in 3-D and a structure mass element are applied to establish the finite element model of iced 4-bundle conductor in ANSYS software. Then dynamic transient response calculations are made on this model. According to the results, difference in vibration of sub-conductors and frequency coupling of torsional and transverse vibration can be confirmed. The simulation results illustrate the wake-flow-influence effect and the coupled motions effect on galloping of 4-bundle conductor.

Abstract: In this paper, the hypersonic aircraft model is divided into several substructures according to its structure and shape characteristics. Furthermore, the hysteresis nonlinearity of wing-fuselage connection which is caused by relaxation and friction is within consideration. The third-order piston theory and strip theory is employed to obtain the distribution of nonlinear aerodynamic force which is applied upon the wings. By means of free interface modal synthesis of dynamic substructure method, the nonlinear dynamic model of hypersonic aircraft is obtained. Then, through numerical simulation method, this paper researches on the model’s dynamic response and bifurcation characteristics, which is influenced by different hysteresis nonlinear structure parameters. In the end, it is showed that the parameter of hysteresis nonlinearity has a great impact on response and bifurcation characteristics of the system.

Abstract: According to statistics, 70% of national highway traffic accidents are due to tire blowout, and a speed of more than 160km/h makes mortality possibility up to nearly 100%. In light of this, the Tire Pressure Monitoring Inflatable Restraint System is put forward. Sensor can send signals to the controller, and then the controller directs the gas generator to generate a lot of gas instantly, and the tire is inflated, so that the instability of the vehicle is eased. In this paper, principle and process of TPIS are illustrated in detail. The process of blowout, sensor detection, control process and the vacuum tire inflation are also scientifically analyzed.

Abstract: Fidelity of vehicle dynamics is directly affected by virtual terrain data in driving simulator, in order to satisfy both high fidelity and simulation frame rate, management of high resolution terrain data is necessary. Vehicle dynamics process and terrain data triangle grid structure are introduced firstly, then a data management algorithm is described, whole terrain data is divided into small terrain blocks identified by their row and column, according to driver’s view range, blocks around vehicle position are loaded rather than all terrain data, therefore dynamics calculation efficiency and simulation frame rate are improved. Finally, a simple driving simulator is created to test effect of this algorithm, the results show it is feasible and valid for driving simulator.