基于Monte Carlo的聚焦型X射线脉冲星望远镜多物理场耦合分析方法

Monte Carlo-based multiphysics coupling analysis method for focusing X-ray pulsar telescope

聚焦型X射线脉冲星望远镜(XPT)是涉及光学、机械学、热学等多学科的复杂航天载荷,多物理场耦合分析对提高其在轨性能和可靠性至关重要。传统的光机热多场耦合分析(MCA)方法并不能考虑X射线能量及其反射率信息,而且存在学科间数据传递困难的问题。为此,首先基于Monte Carlo和X射线全反射理论提出了一种高效的多物理场耦合分析方法。该方法同时考虑X射线能量和反射率两大特征信息,基于有限元分析(FEA)法建立了XPT热-结构物理场耦合方程和有限元分析模型,针对不同工况进行热分析、结构分析以及热-结构物理场耦合分析。其次,采用Construction Geometry函数分别提取不同工况下光学镜头面形的形变量,并基于多项式函数对变形后的镜头面形进行拟合和误差分析。然后,基于所提方法对变形后的光学系统聚焦性能进行分析与评价,得到镜头形变对XPT光学聚焦性能的影响规律。最后,以多层嵌套的XPT为例,对不同视场角和形变的X射线光学系统聚焦性能进行了仿真分析。结果表明,在全视场时热-结构耦合形变、热形变及结构形变导致XPT聚焦性能分别下降30.01%,14.35%和7.85%,弥散斑均方根依次为2.914 3mm,2.603 8mm,2.531 1 mm。通过与试验结果对比分析,验证了所提方法的有效性,可用于XPT的可靠性设计。

Focusing X-ray pulsar telescope（XPT）is a typical complex space optical payload,which involves optical,mechanical,electrical and thermal disciplines.The multiphysics coupling analysis plays an important role in improving the in-orbit performance of XPT.However,the conventional multiphysics coupling analysis（MCA）methods encounter two serious problems in dealing with the XTP.One is that the energy and reflectivity information of X-ray cannot be taken into consideration,which always misunderstands the essence of XPT.The other is that the coupling data cannot be transferred automatically among different disciplines,leading to computational inefficiency and thus increase the design cost.Therefore,a new multiphysics coupling analysis method for X-ray pulsar telescope is proposed based on the Monte Carlo and the full reflective theory.The main idea,procedures and operational steps of the proposed method are addressed in detail.Firstly,this method takes both the energy and reflectivity information of X-ray into consideration simultaneously and formulate the thermalstructural coupling equation and multiphysics coupling analysis model based on the finite element analysis（FEA）method.Then,all the thermal-structural,thermal and structural analysis under different working conditions have been implemented.Secondly,the mirror deformation can be obtained using construction geometry function.Meanwhile,the polynomial function is adopted to fit the deformed mirror and meanwhile evaluate the fitting error.Thirdly,the focusing performance analysis of XPT can be evaluated by the root mean square and maximum radius of dispersion spot employing the proposed method.Finally,a six-layer nested XPT is taken as an example to verify the proposed multiphysics coupling analysis method.The simulation results show that the thermal-structural coupling deformation is bigger than others;the influencing law of deformation effect on the focusing performance has been obtained.The focusing performances of thermal-structural,thermal,structural deformations have degraded by 30.01%,14.35% and 7.85%respectively.The RMSs of dispersion spot are 2.914 3mm,2.603 8mm and 2.531 1mm.As a result,the validity of the proposed method is verified through comparing the simulation results and experiments,which can be employed in the reliability-based design of XPT.