基于AutoCAD的线切割自动编程接口软件设计

在分析DXF文件格式、3B指令代码的基础上,提出了基于AutoCAD的线切割自动编程流程,并重点讨论了自动编程过程中的基本加工路线生成、间隙补偿、计数长度计算等关键技术。     

GRB 980425, SN1998BW and the EMBH model

The EMBH model, previously developed using GRB 991216 as a prototype, is here applied to GRB 980425. We fit the luminosity observed in the 40–700 keV, 2–26 keV and 2–10 keV bands by the BeppoSAX satellite. In addition we present a novel scenario in which the supernova SN1998bw is the outcome of an “induced gravitational collapse” triggered by GRB 980425, in agreement with the GRB-Supernova Time Sequence (GSTS) paradigm [Ruffini, R., Bianco, C.L., Chardonnet, P., Fraschetti, F., Xue, S.-S. On a possible GRB-supernova time sequence. Astrophys. J. 555, L117–L120, 2001c]. A further outcome of this astrophysically exceptional sequence of events is the formation of a young neutron star generated by the SN1998bw event. A coordinated observational activity is recommended to further enlighten the underlying scenario of this most unique astrophysical system.     

基于理想与实物模型的航空发动机优化装配技术研究与探讨

发动机装配是发动机制造的最终阶段。提升产品装配工艺技术,改进产品装配规划,是提升产品质量、生产效率、降低成本的关键环节。利用数字化技术,通过对航空发动机理论三维模型虚拟装配技术研究,并与实体装配技术相结合,研究了实体装配优化技术,以达到对航空发动机装配工艺优化和实体装配优化的目的。     

Design and implementation of five-axis transformation function in CNC system

To implement five-axis functions in CNC system, based on domestic system Lan Tian series, an improved design method for the system software structure is proposed in this paper. The numerical control kernel of CNC system is divided into the task layer and the motion layer. A five-axis transformation unit is integrated into the motion layer. After classifying five-axis machines into different types and analyzing their geometry information, the five-axis kinematic library is designed according to the abstract factory pattern. Furthermore, by taking CA spindle- tilting machine as an example, the forward and the inverse kinematic transformations are deduced. Based on the new software architecture and the five-axis kinematic library, algorithms of RTCP （rotation tool center point control） and 3D radius compensation for end-milling are designed and realized. The milling results show that, with five-axis functions based on such software struc- ture, the instructions with respect to the cutter＇s position and orientation can be directly carried out in the CNC system.     

基于差动气动增压装置的多次启动一体化动力系统特性

高性能、轻质量、小尺寸的上面级动力系统可以为整个任务节省更多的质量和空间,从而增加有效载荷的质量。提出了一种基于差动气动增压装置的多次启动姿轨控一体化动力系统,动力系统由主发动机系统、姿控发动机系统、一体化供应系统等组成。该动力系统的系统级试验验证结果表明:姿控发动机与主发动机可通过共用贮箱实现推进剂的一体化供应; 主...     

3D针刺C/SiC断裂韧性缺口敏感性及破坏研究

碳化硅陶瓷基复合材料是高超声速飞行器及高推重比发动机等发展所需的关键材料之一,对冲击断裂韧性、缺陷及裂纹的敏感性有较高要求。采用夏比冲击试验测定3D 针刺C/SiC 复合材料的断裂韧性,研究其处于U 型、V 型缺口分别在与针刺平行、垂直的不同分布方向时对冲击断裂韧性的影响,并通过扫描式电子显微镜及光学显微镜等手段详细分...     

固液捆绑火箭星箭耦合分析技术研究

新一代中型固液捆绑火箭频率低、模态密、全箭动力学特性复杂,助推与芯级之间的力的传递特性在纵横扭方向存在耦合,传统纵横向分离的星箭耦合分析方法无法准确预示星箭界面力学环境。本文针对固液捆绑火箭的特点,建立了星箭耦合系统纵横扭一体化有限元模型;根据火箭飞行特定设计工况建立具有时变飞行特征的外力函数,对火箭特征工况进行了瞬态响应分析;通过子结构内力恢复对固液捆绑火箭的星箭界面力学环境进行了准确预示,具有较高的工程应用价值。     

二元非对称喷管可调方案试验研究

 针对某二元非对称喷管提出了两种可调方式(方案A和方案B),开展了不同落压比(NPR)的喷管风洞试验,获得了喷管壁面压力分布和流场纹影。根据风洞试验条件,进行了详细的三维数值模拟研究,并与试验结果进行对比,两者吻合良好,验证了本文所采用的数值模拟方法的可靠性。根据数值模拟与试验结果,得出了两种方案推力性能的差异。其中,方案B(喉道和出口面积均可调节)较方案A(仅喉道面积可调节)面积膨胀比更接近喷管理想膨胀比,因此方案B推力性能较好。在落压比为3.8时,方案B较方案A推力系数提高了8%。     

Yield anisotropy and tension/compression asymmetry of a Ni3Al based intermetallic alloy

In order to investigate the yielding behavior of the newly developed Ni 3 Al-based intermetallic alloy IC10, yield stresses have been measured in tension and compression with different orientations. The specimens were cut from a sheet with different angles inclined from the solidification direction. The inclined angles were taken to be 0 , 22.5 , 45 , 67.5 and 90 . All experiments were conducted at room temperature except for orientation 0 , whose deformation temperatures ranged from 298 to 1273 K. Experimental results show that the yield strength of alloy IC10 has the anomalous behavior which has been observed for other Ll 2 -long-range ordered intermetallic alloys, but it is less pronounced. The abnormalities show the following characteristics: (i) the yield strength increases as the temperature is raised below the peak temperature, (ii) yield strength anisotropy, (iii) tension/compression asymmetry. Compared to Ni 3 Al single crystals, the polycrystalline exhibits some different yielding behaviors which may be due to the high volume fraction of c phase.     

飞机重量平衡手册的编制探究

初步研究了飞机重量平衡手册的编制规章依据、编写规范和编写方法,通过对ATA2200及S1000D相关标准的研究,为我国民机重量平衡手册的编制提出建议。