Applied Mechanics and Materials Vol. 274

Abstract: MEMS devices commercialization is hindered by reality problems. Among them main problem is caused by dielectric charging. This paper studies charging model and charges distribution which are constructed on adhesion failure. Lifetime prediction formula is given. Simulation results show that under the condition of low driven voltage requirement, lifetime is bigger than 1000 hours when elastic coefficient (K) adopts 4-16N/m, 0.4-1μm for dielectric thickness, 2-5μm for plate distance and S3iN4 as dielectric material. At last, C-V performances inflected by dielectric charging is studied by theoretical calculations and analyzing positive or negative charging respectively.

Abstract: With the improvement of mechanical processing automatic level, the measurement of the surface roughness requires the ever-increasing demands, including the improvement of measurement methods, improve measurement accuracy and roughness parameters assessed. Around these requirements, this paper is the research to 3D surface roughness parameters, gives the method to determine the datum and 3D roughness assessment parameters.

Abstract: The super low speed performance of continuous rotary motor is the key performance, many factors influence the super low speed performance, such as friction and leakage characteristics of the motor, pressure impact, pressure fluctuation of the oil source, resolution and the dead zone of the servo valve. This paper study the low speed movement mechanism, by analyzing the friction mechanism model of motor, and analyze the low-speed process the system to explore the factors that affect the low-speed performance of system, and determine the lowest steady speed of motor.

Abstract: The research on the combination of the characteristics becomes extremely important to the success of machine tool design. This paper mainly studies the dynamic and static characteristic parameters of heavy machine tool guide-way joint. And put forward a practical machine tool combining surface analysis method according to the experimental verification. It is presented that small linear guide as a scale model based on similarity theory. And make a research on the static and dynamic characteristics of small guide joint and the conclusion extended to heavy machine set of faces. And the conclusion is extended to the heavy machine set of faces. The results can be used as reference data about structure and design of the machine tool due to the similarity principle and error range.

Abstract: A new-style high-voltage switch named trigatron with great advantage, such as simple structure and applying circuits, wide operational temperature and voltage range, short delay time, long operational life is introduced in this paper. Firstly the four operational modes which trigatrons are suitable for pulse power devices are presented. Then through experimental study and theoretical analysis, the effect factors of turn-on time of trigatrons are summed up, including anode voltage, triggering voltage and triggering-wire’s length, finally giving a conclusion that the higher anode voltage and triggering pulse voltage are, the more steady and shorter turn-on time is.

Abstract: To solve the problem of automobile rear end collision, an early warning system is designed, which is based on DSP chip control. Ultrasonic ranging is selected in the system. By providing pulse trigger signals, internal modules will send out eight periodic levels with forty kHz, and detect echoes at the same time. Once the echo signal is detected, the reverberation signal will be output. Then the reverberation signal can be changed into actual distance in real time by interrupt mode. The result stands for the distance between the car and the obstacles, then corresponding braking measures and early warning will be decided according to the minimum safety distance. When it is dangerous, the car status can be controlled according to the setting logic state.

Abstract: titanium alloy cutting force testing experiment of end-surface turning is made, and spectrum character is analyzed by obtained data of cutting force experiment, and ten the influencing rule of cutting parameter on cutting force character is discovered; using the similarity between tools vibration character and cutting force spectrum character, and based on obtained data of machined surface roughness testing experiment, the two characteristic parameters of vibration frequency and amplitude value relative to work piece is calculated, and the relationship curve between cutting parameters and tools vibration character parameter is established is this paper.

Abstract: Inlet start/unstart detection has been the focus of researching hypersonic inlet, the operation mode of the inlet detection is the prerequisite for the unstart protection control of scramjet. Actually, due to computational complexity and high dimension discrete experimental data, all of these factors are against for the classification of real-time data. To solve this problem, firstly, the 2-D wind tunnel experiment is carried out, inlet start/unstart experiment phenomenon are analyzed; Secondly, isomap algorithm is introduced to reduce high dimensional data , the optimal classification method were obtained with the weighted embedded manifold learning algorithm, At last the superiority of the classification criterion is verified by decision tree algorithm.

Abstract: An advanced structure containing cavities was adopted in distribution layers. A series of large-scale similarity-simulation tests was conducted on the defense effect of the four structures under plane impact loads. Based on the tests results and theoretical analysis conclusions, numerical simulations were developed by LS-DYNA software. The results indicate that the numerical results agree well with the test data; the stress peak was distinctively decayed below the cavities, and the defense effect of circle-section cavity is more effective than square-section cavity while the defense effect was weakened when a thin steel plate was laid above the cavities. Compared with clipping performance of it under the explosion loads of mass ammunition, which of the structure with cavities under plane impact loads is better effective. This work provides an important basis for designing the scientifically safe distribution layers.

Abstract: In order to analyze the cooling air velocity and pressure distribution characteristics in a ventilation scheme presented for the irradiation box of cable ultraviolet cross-linking, the three-dimensional solid model of the irradiation box was established, its flow field was simulated by software FLUENT according to computational fluid dynamics principle under some calculation conditions. The results show that the air velocity around the cable is higher, enhancing convective heat transfer effect, the irradiation box large space is under negative pressure condition.