Abstract: The dynamic model of the cage in high-speed ball bearing was developed according to the geometry and force relationship between bearing elements. Based on this dynamic model, cage instability was researched through mass center whirl. The effect of clearance ratio, load and bearing rotation speed on cage instability were studied by taking type 7004 angular ball bearing as an example. The results shown that the increase of clearance ratio and radial load makes cage stability lowered, and the cage stability could be enhanced by increasing the axial load and bearing rotation speed.
Abstract: XY motion platform in flip chip machine plays a key module to achieve precise positioning in the process of flip chip packaging. The paper presents an XY motion platform structure. The static and modal characteristics of the XY motion platform were calculated by finite element method, and then some important conclusions were obtained. The displacement and stress distribution of XY motion platform were disclosed. The relevant change trends of displacement and stress under the different load were investigated and the first four natural vibration modes of the XY motion platform were obtained. In the experiment, the vibration behavior was measured by a non-contact laser measuring device. The experiments verify the correctness of the simulation of the XY motion platform. These results can help improve the reliability of the XY motion platform.
Abstract: For the wide use of the suspension K&C test rig, this paper presents the basic requirements of the vehicle suspension K&C test and provides a reference for unifying the test methods and the test standards. Then, it also gives the specific test specifications and requirements of the vertical wheel jump test, the roll test, the longitudinal force test, and the lateral force test. Finally, the main indicators of the suspension, the steering system and the tire can be obtained.
Abstract: The second vibration isolation support (SVIS) is very important parts of the vibration engineering equipment, and its dynamic performance will affect the operating condition of the entire device. In the design process, the sensitivity of design parameters provides a very effective way for design of SVIS. By analyzing the sensitivity of the amplitude of SVIS relative to the mass of SVIS, the spring stiffness and the operating frequency, as well as the sensitivity of the modal natural frequency relative to the plate thickness, the influence degree of these design parameters on the dynamic characteristics of SVIS were obtained and the best optimization parameters the structure of SVIS were obtained.
Abstract: A novel planetary gear hybrid powertrain is proposed. It contains mainly nine components: A planetary gear mechanism, an internal combustion engine, two motors, two invertors, a set of battery, a power control unit(PCU) and a differential. To further the verification, the feasibility has been demonstrated by system operations analysis. The proposed hybrid powertrain harmonizes the operation of two motors and an engine. It achieves pure electric driving, hybrid driving and regenerative while braking, improves the fuel economy and benefits from the simple configuration, easy assembling and the flexibility of application.
Abstract: There are two common research methods on the dynamic states model of belt conveyor in China at present. The mathematical model is built by finite element method then it is solved by numerical method. And the continuous model is built when the belt is treated as elastic body then it is solved by mathematical method. This paper puts forward the establishment of continuous model, the model is solved by FDM and the simulation results are given.
Abstract: CAAC (Civil Aviation Administration of China) set a standard on A380 wake turbulence separation right after China Southern Airlines brought in Airbus A380 in 2001.This paper considers from the possibility of the latter aircraft wake turbulence influencing the preceding one, which means the wake turbulence risk, makes safety evaluation on the wake turbulence separation standard of the preceding aircraft as A380, and the latter one as heavy type, medium type and light type, based on the safety target level that ICAO (International Civil Aviation Organization) authorized. Each type chooses a typical aircraft to calculate the possibility of influenced by the preceding wake turbulence corresponding with the standard under calm wind. The final result shows that the A380 wake turbulence separation standard setting by CAAC is safe.
Abstract: Hydrostatic Curves is widely used to calculate vessel’s displacement by ship’s officers and surveyors. However, under some specific circumstances such as light ballast arrival condition, it is difficult to obtain an accurate figure of displacement by using Hydrostatic curves. At this time, Bonjean curves as an alternative can be employed in calculating vessel’s displacement. The procedures are introduced step by step to calculate the vessel’s displacement by Bonjean’s curves. The differences of calculation by two means are demonstrated on a specific bulk carrier and therewith the reasons are analyzed. Finally, the article appeals the detailed Bonjean curves shall be provided on board by shipyard for improving the accuracy of calculation.
Abstract: Power tracking is the foundation of power allocation of hybrid vehicles, the error of prediction in power tracking is also influent a lot on the steady of battery’s state of charge (SOC ) level. In this paper, driving modes of all-terrain robot have been discussed, a new power tracking model based on Hidden Markov model (HMM) was proposed, in this model the working mode is divided into acceleration mode, deceleration mode, even pace mode, mutation acceleration mode and mutation deceleration mode due to the velocity variation, in each mode we build different control strategy for the battery management, such as regenerative braking or engine-generator power unit (IGPU) export power, and those strategy would keep the SOC in a constant interval, in which the battery has a excellent charge-discharge properties. A power prediction model based on HMM has also been set up due to the historical data. A simulation which the velocity curve was simplified as a sine-wave has been made, and the true power curve and predicted curve were compared, the error of the prediction is allowable.