加弹速度对PA6 DTY质量影响的探讨

探讨了加弹速度提高后对产量、机台生产状态、锦纶6 DTY物理性能和设备损耗等方面的影响,提出最合适锦纶6 DTY生产的加弹速度。

弹载加速度计组合连续数据采集系统设计与实现

针对捷联式惯性导航系统中,弹载加速度计动态测量范围宽、精度高、实时性好、连续性强等特点,采用了I/F转换器与高精度频率计数的数据采集方案。详细讨论了该组合高速、高精度数据采集的理论基础---多周期同步,量化时延,并设计出连续采集的实现电路。文中详细描述了数据采集系统的硬件结构和软件流程,并采用复杂可编程逻辑器件(CPLD)来实现大部分电路,增加了系统集成度,提高了系统工作可靠性,减低干扰。实践证明该数据采集系统具有很强的抗干扰能力,满足捷联式弹载加速度计组合的技术指标要求。

锦纶6弹力丝的工艺探讨

通过对热板温度、加弹速度、拉伸比、D Y比、假捻张力等工艺参数的调整 ,探讨了影响锦纶 6弹力丝生产的主要因素。

ATTITUDE MEASUREMENT ON HIGH-SPINNING PROJECTILE USING MAGNETIC SENSORS AND ACCELEROMETERS

In allusion to the limitations of the traditional attitude measurement system consisting of a three-axis magnetic sensor and two accelerometers on high-spinning projectile, a new scheme comprised of two magnetic sensors and two accelerometers installed in a particular way is given. The configuration of the sensors is described. The calculation method and the mathematical model of the projectile attitude based on the sensor configuration are discussed. The basic calculation method including the Magsonde Window, the proof of the ratios of maximums and minimums and the calculation of the attitude angles are analyzed in theory. Finally, the system is simulated under the given conditions. The simulation result indicates that the estimated attitude angles are in agreement with the true attitude angles.

Numerical simulation of projectiles with different structures penetrating multi-storey concrete target board

Because the difference between the acceleration curve of traditional projectile structure and the measured accelera- tion curve is large, refining projectile structure is proposed. After setting up multi-storey concrete target board penetrated by the projectiles with different structures, the simulations with traditional projectile structure and refining projectile structure are conducted using ANSYS/LS-DYNA, and two acceleration curves are obtained, respectively. And then the target experi- ment that the projectile penetrates eight-storey concrete board is conducted and the measured acceleration curves are ob- tained. By comparing the simulation acceleration curves with the measured acceleration curves, it can be concluded that the acceleration curve with refined projectile structure is closer to the measured curve. Therefore, the simulation curve with re- fined projectile structure is of higher reference value for simulation research.

Molecular dynamics analysis on bending mechanical behavior of alumina nanowires at different loading rates

The molecular dynamics(MD)model ofα-Al_(2)O_(3) nanowires in bending is established by using LAMMPS to calculate the atomic stress and strain at different loading rates in order to study the effect of loading rate on the bending mechanical behaviors of theα-Al_(2)O_(3) nanowires.Research results show that the maximum surface stress−rotation angle curves ofα-Al_(2)O_(3) nanowires at different loading rates are all divided into three stages of elastic deformation,plastic deformation and failure,where the elastic limit point can be determined by the curve symmetry during loading and unloading cycle.The loading rate has great influence on the plastic deformation but little on the elastic modulus ofα-Al_(2)O_(3) nanowires.When the loading rate is increased,the plastic deformation stage is shortened and the material is easier to fail in brittle fracture.Therefore,the elastic limit and the strength limit(determined by the direct and indirect MD simulation methods)are closer to each other.The MD simulation result ofα-Al_(2)O_(3) nanowires is verified to be valid by the good agreement with the improved loop test results.The direct MD method becomes an effective way to determine the elastic limit and the strength limit of nanoscale whiskers failed in brittle or ductile fracture at arbitrary loading rate.

Smart projectile acceleration testing in harsh launch environment

In order to solve the problem of parametric test of smart projectile launch,the launch environment of smart projectile was analyzed.a reasonable and feasible storage testing method was proposed,and a multi-channel test system suitable for the environment was designed.The system was successfully applied to a certain range test,and dynamic parameters such as triaxial acceleration of smart projectile launch environment were acquired.The test results play an important role in the improvements of smart projectile design process.

Design of Three-component Photoelastic Waveguide Accelerometer

In order to realize a high accuracy seismic exploration in the high electro-magnetic field and to improve oil producibility and recovery efficiency,a three-component photoelastic waveguide accelerometer is designed. Based on the photoelastic effect,the Mach-Zehnder integrated optical interferometer is designed to measure the three-orthogonal components of acceleration and the combined three-component simple harmonic vibrator is designed to reduce the cross-talk among the acceleration components. According to the variation of LiNbO3 waveguide phase under the action of the applied acceleration,the cross-axise sensitivity and transverse sensitivity ratio(TSR) were analysed. The results reveal that the accelerometer has wide band and good linearity. It can satisfy the sensor requirements of high accuracy seismic exploration. The main design parameters of the geophone system are:phase sensitivity:1.86×10-4 Rad·m-1·s-2,natural frequency:3 500 Hz,and the transverse sensitivity ratio:0.11%.

Effect of loading rates on the characteristics of thermal damage for mudstone under different temperatures

The uniaxial compression tests for mudstone specimens are carried out with four different loading rates from room temperature to 400℃ by using the Rock Mechanics Servo-controlled Testing System MTS810 and high temperature furnace MTS652.02.The mechanical properties of mudstone with various loading rates are studied under different temperature conditions.The results show that when temperature increases from room temperature to 400℃ and loading rate is less than 0.03 mm/s,the peak strength of mudstone specimen decreases as loading rate increases,while the various peak strengths show significant differences when loading rate exceeds 0.03 mm/s.At room temperature,the elastic modulus decreases at the first time and then increases with loading rate rising.When the temperature is between200 and 400℃,the elastic modulus presents a decreasing trend with increasing loading rate.With increasing the loading rate,the number of fragments in mudstone becomes larger and even the powder is observed in mudstone with higher loading rate.Under high loading rate,the failure mode of mudstone specimens under different temperatures is mainly conical damage.

Continuum description for the characteristic resistance sensed by a cylinder colliding against granular medium

In this paper, we experimentally and theoretically study the resistance force that develops when a cylinder with a flat face colliding against dry quartzite sand. Observations from experimental data clearly show that the acceleration curves are characterized by a double-peak structure. The first agitated peak can be attributed to a shock process where sand responds elastically, and the valley bottom in the double-peak structure is related to a limited plastic load when a fully plastic region is formed in the sand, while the second agitated peak corresponds to a the occurrence of the maximum of viscous force in a homogeneous developed bulk flow. We use slip line theory (SL) developed in plastic mechanics to capture the value at the valley bottom, adopt the double shearing theory (DS), together with a Local Rheological Constitutive Law (LRCL) suggested in this paper, to capture the drag force generated in a homogeneous bulk flow. Good agreements in the comparisons between numerical and experimental results support the characteristic resistance by the cylinder to predict granular states.