Applied Mechanics and Materials Vols. 249-250

Abstract: The working condition of cylinder is different from the design which needs high frequency of 20~ 22MPa in hydraulic daughter station system. In order to evaluate the safety of cylinder, the fatigue performance of jumbo cylinder was studied by way of FEA. The results show that cylinder fatigue cycle life is less than 15000 under the pressure range 2~ 36.7MPa and it cannot be used as design working pressure 22MPa. But it can serve in 20~22MPa for infinite loop to meets the requirement of hydraulic daughter station.

Abstract: With large eddy simulation(LES) and Lighthill-Curle acoustic theory, the aerodynamic noises radiated from pantograph insulators with rectangular, circular, elliptical section were calculated, and the optimal pantograph insulator shape was obtained. The results show that in the same model, the sound pressure level (SPL) spectrum at different monitoring points are basically the same, but the amplitude is different. In different models, the SPL spectrum are different. As for rectangular, circular, elliptical section insulators, the frequency with maximum SPL reduces gradually. For reducing aerodynamic noise, the elliptical section insulator is optimal, and the long elliptical axis should be consistent with air flow. The pantograph with bigger and less components is helpful to reduce the aerodynamic noise.

Abstract: For a given matrix function, determining whether it meets the conditions of the state transition matrix by utilizing the criteria of the state transition matrix. If satisfied, three computing methods of systematic matrix is deduced through both qualities and relationship with the systematic matrix of the state transition matrix, comparing the characteristics of every method and inspecting availability of each solving method. Finally, the simple way for solving systematic matrix is obtained, which provides reference for solving systematic matrix in practice.

Abstract: A new-style pneumatic precision seed-metering device for super rice seed was proposed. This paper analyzed the working process for seed-metering device. The movement of rice seed in the “L” tube was simulated by finite element analysis software. The speed distribution, pressure distribution of air in the “L” tube and the trajectory of rice seed were solved. Results of the analyses indicated that there were partial reflux at the entrance and elbow; while the airflow moved steadily at the straight pipe. Based on the fabricated device, the motion trajectory was studied by high speed video camera. Experiment was used to analyze the effect of parameters. The results showed that the experimental trajectory was in accordance with theoretical models.

Abstract: Friction is a major factor in determining the characteristics ofmetals as they are forged.Regularand efficient lubrication is one of the best ways in controlling friction and wear in this process.One of the best ways of testing the lubricant is the ringCompression test. In this research the effect of mixed graphite in water and also the effect of the amount of graphite in the lubricant in the reduction of friction between the sample-die are calculated using the ring test. Friction behavior is changed fromsticking friction to sliding frictionby using the lubricant; but the changes in the amount of graphite in water didnot have a great effect on the reduction of the friction coefficient. Furthermore, after viewing differences in the friction coefficients calculated by the means of FE analysis and the friction calibration curves, it is concluded that the sole calibration curves could not be used for hot working conditions.

Abstract: In order to eliminate mutual negative effect of brake, steering and suspension system, a kind of layered coordinated control method based on multiple controllers is put forward. Framework of coordination control system of chassis is established, coordination strategy of upper controller and control strategy of lower controllers are designed. The upper controller is used mainly to receive operation information of driver, running state of vehicle and feedback information of lower controllers, and send coordination control strategy to lower controllers. The lower controllers include controller of electro mechanical braking system (EMB), controller of electric power steering system (EPS) and controller of active suspension system (ASS), which are used to receive decision instruction of upper controller, control actuators to accomplish control tasks and send execution situation to upper controller in time.

Abstract: A new model for elastic constraint wheelset system of rail vehicle is proposed. Assuming the stochastic excitation as Gauss white noise, a stochastic model is built for elastic constraint wheelset system. Here two kinds of stochastic excitations are considered: one is the internal multiplicative excitation inherited in the internal system such as the spring and wheelset/rail contact geometric relationship, the other is the external excitation induced by track random irregularities. The model defined here is considered as a weak damping, weak excitation quasi non-integrable Hamiltonian system. The maximal Lyapunov exponent is calculated by quasi non-integrable Hamiltonian theory and oseledec multiplicative ergodic theory, and the stochastic local stability conditions are obtained. Meanwhile, the stochastic global stability conditions are derived by considering the modality of the singular boundary condition.

Abstract: Based on many computing method of kinematic envelope, a new algorithm is established. According to the result of locomotive time domain responses of dynamic simulation and kinematic principle, various Active contours of locomotive are solved. Using the obtained active contour and the concept of union algorithm of polygon in computer graphics, the union algorithm of kinematic envelope is designed. This algorithm is to solve the minimal covering of various active contours. The kinematic envelopes solved by the union algorithm and by ‘Interim Provisions on Passenger Dedicated Lines’ (PDL) locomotive gauge temporary regulations are compared and checked with rolling stock gauge

Abstract: This paper focused on the interior boom noise of a mini-car when driving at high speeds. Vehicle interior noise rotor drum tests in semi-anechoic room showed that vehicle interior boom noise in narrow frequency band exited near 250Hz. Structural and acoustic finite element analysis certified the front roof and rear floor coupled with interior acoustic cavity around this frequency, causing acoustic cavity resonance. On the base of sensitivity analysis technology, a structural improvement schemes pasting free damping fin on the front roof and rear floor of mini-car body for vibration and noise reduction was proposed. Finite element Modal analysis of the mini-car body after improving indicated that local modal amplitude of the mini-car body at the front roof and rear floor around 250Hz was controlled effectively. Mini-car rotating drum test results after improving showed that vehicle interior boom noise was decreased obviously after pasting free damping fin at the front roof and rear floor. The improving schemes and noise reduction effects proposed in this paper were validated.

Abstract: Electronics cooling research has been largely focused on high heat flux removal from computer chips in the recent years. However, the equally important field of high-power electronic devices has been experiencing a major paradigm shift from air cooling to liquid cooling over the last decade. For example, multiple insulated-gate bipolar transistors (IGBT) used in a power drive for motor used in electric vehicle. Motor drive system plays an important impact on electric vehicle’ performance, so thermal design should be considered in the early stages during the motor controller design and layout of the devices. In this paper, a new type of water-cooled cold plate for motor controller was designed, and its cooling ability was analyzed by using different material base on Fluent. The results provide reference on the optimization design of cold plate.