Double-swing-arm scanning angle mirrors assembly of spaceborne Michelson interferometer has many technical difficulties, such as space cantilever structure with many dimensions, high precision and difficult detection, etc. This paper proposes a method of "vector analysis + precision micro-adjustment", and the following measures are taken: 1) Establish the assembly and inspection benchmarks; 2) Simplify the installation structure model of the angle mirrors assembly, simplifying the vertex of the angle mirrors into a space point vector, converting the adjustment of the space point into the in-plane adjustment and the normal adjustment of the installation surface according to the constraint conditions of installation and adjustment, and quantifying the adjustment amount by calculating; 3) According to the vector relationship of each adjustment quantity, the adjustment sequence of "first method to back plane" is designed; 4) According to the adjustment precision and the constraint state of the angle mirrors, special precision micro-motion device and other control measures are designed, and finally the high-precision adjustment of the spatial multi-degree-of-freedom angle mirrors assembly is realized. After the adjustment, the symmetry of the vertex position of the angle mirrors reaches 0.008mm, which is better than the design precision index. The interferometer has been successfully applied to Fengyun Meteorological Satellite, which has certain significance for the development of greenhouse gas space detection technology in China.
In this paper,the simulation research about deformation after dual laser-beam bilateral synchronous welding(DLBSW)for the frame-truss tank wall structure is conducted.Firstly,the finite element model of DLBSW for the frame-truss tank wall structure is established,and verified by experimental results.Subsequently,the effect of welding sequence and direction on the deformation of frame-truss tank wall structure fabricated by DLBSW is emphatically investigated to obtain the deformation control strategy.Finally,the frame-truss tank wall structure is successfully manufactured by DLBSW with the optimized scheme.The results show that the welding deformation is greatly reduced under the welding sequence of"cross center welding".Based on the optimized welding sequence,the welding deformation can be further reduced bv changing the welding direction of the middle three welds.
In order to improve the surface quality of single crystal silicon after single-point diamond turning,this paper investigates the influence of laser-assisted turning(LAT)technology on machining quality by analyzing surface roughness,surface morphology and Raman spectroscopy of samples prepared by LAT and conventional turning(CT),respectively.Based on the orthogonal test method,the LAT process parameters of single-crystal silicon were investigated on surface roughness.The influence of each factor on surface roughness was evaluated by variance analysis and range analysis.The results show that LAT can effectively improve machined surface quality and reduce residual stress on material surface compared with CT.The contribution proportions of spindle speed,feed rate,cutting depth and pulse duty cycle to surface roughness were 17.51％,44.48％,6.69％and 14.70％,respectively.Finally,the optimal combination of machining parameters was determined to be:spindle speed of 4000 r/min,feed rate of 2 mm/min,cutting depth of 5 μm,and pulse duty cycle of 30％,with a high-quality surface with a surface roughness(Rq)of 2.4 nm was finally obtained.
In order to investigate the structural safety of composite laminates due to impact loads in practical applications,the influence of the impactor shape on the damage mechanism of composite laminate was analyzed simultaneously by experiment and simulation.Subsequently,the variation pattern of the load-bearing capacity and energy absorption of the laminate was further revealed considering different impact energy.The results show that under same impact energy,the damage range and bearing capacity of laminates present incremental change when impacted by conical,hemispherical and flat impactors.The critical penetration energy of laminates increases along using conical,hemispherical and flat impactors.The impactor shape and the impact energy have a greater influence on the energy absorption capacity of laminates.
In order to study the irradiation characteristics of SiGe heterojunction bipolar transistors with different emitter areas at extreme temperatures,characteristics of irradiated power SiGe heterojunction bipolar transistors(SiGe HBTs)were systematically analyzed at different temperatures in this paper;Correlation between emitter area and power SiGe HBTs'irradiation damage of SiGe HBTs was revealed.Modeling of power SiGe HBTs device was conducted to extract the main internal parameters of the device affected by irradiation.The variation of electron density(Δ edensity),carrier recombination(Δ SRH recombination)and carrier mobility(Δ emobility)before and after irradiation were characterized,whose affecting mechanism on power SiGe HBTs irradiation was systematically analyzed.The results show proportional proton irradiation damage of emifferarea on power SiGe HBTs.SiGe HBTs have better proton irradiation resistance at extreme temperatures.which presents great potential in the field of radiation resistance and space application.
