Research On Rolling Blinds Sealed Window Of Large Aperture Laser Emission System Considering Environmental Adaptability

According to GJB 4239 General Requirements for Equipment Environmental Engineering,environmental adaptability refers to the ability of equipment(product)to achieve all its intended functions and performance and/or not to be destroyed under various environments that it may encounter during its life expectancy.It is one of the important quality characteristics of equipment(product).The environmental adaptability of the product is mainly related to the structural design of the product,the material selected,the processing technology of the material and the anti-environmental measures taken in manufacturing.Generally speaking,when the product is manufactured,its environmental adaptability is basically determined.Because the environmental adaptability indicators of different products vary greatly,it is almost impossible to achieve very good results in every aspect.Therefore,in the process of product design,some environmental adaptability requirements that need to be quantitatively met are generally determined according to the product design indicators,while the other indicators only need to meet the requirements qualitatively.With the development of manufacturing technology and adaptive optics,laser weapons commonly used in military confrontation have made great progress.Because of the incomparable speed,collimation and adjustable energy of laser,the development of laser weapon has been paid more and more attention by governments.High power laser weapon systems emerge in endlessly,which leads to the increasing caliber of laser emission system.Because only when the laser emission system is kept clean and the laser beam has good focusing effect,can the laser weapon cause enough damage to the target,so it is necessary to seal the laser emission system.The lens inside the chamber is insulated from external contaminants.Therefore,it is of great significance to research the sealing structure of laser emission system and its environmental adaptability for improving the operational efficiency of laser emission system.In this paper,a vehicle-borne high-power multi-band laser emission system is taken as the research carrier,and the sealing problem of the emission system is studied.The main research contents include determining the corresponding environmental adaptability index according to the performance requirements of the equipment,determining the structure form of the sealing window through analysis and comparison,analyzing the stress and deformation of the window according to the structure form,finding out the key factors affecting the sealing performance,and controlling the sealing performance.Variable control method was used to analyze the influence of different parameters on sealing effect,integrated optimization method was used to determine the optimum size of window structure,and finally the designed window was checked according to environmental adaptability index.The contents of each part are elaborated as follows:1.Window type analysis:There are two main ways to seal the end window of laser emission system:crystal window and pneumatic window.Crystal window sealing performance is good,but the preparation of crystal materials is complex,the price is high and the laser power is too high,the crystal will be distorted due to the uneven heating,which will lead to the decrease of laser focusing ability and affect its combat effectiveness;the aerodynamic window sealing performance is slightly poor and special gas needs to be prepared,large-caliber seal will inevitably need to increase the gas outflow velocity,gas turbulence effect will cause beam distortion.Considering the intermittent working characteristics of the emission system,this paper presents a moving sealing structure using the covering pressure sealing method.2.Analysis of influencing factors of window sealing performance:Vehicle-mounted equipment is highly integrated and space size is very limited,so the window can only use Rolling Blinds sealing structure.The stress and deformation of this type of window is similar to that of thin plate with large deflection.The central deflection of the Rolling Blinds is less than a certain value,which is the key to ensure the sealing ability of the window.Through theoretical analysis,the factors affecting the central deflection of the Rolling Blinds are the elastic modulus of the Rolling Blinds material,the thickness of the Rolling Blinds material and the pre-tightening force of the Rolling Blinds material.3.Analysis of simulation results:The control variable method was used to research the influence of different variables on the central deflection of the rolling blinds.The following conclusions are drawn.The deformation cloud chart of different materials have similar changing rules:the central deflection of the rolling blinds is the largest and decreases in turn;the deformation is negatively correlated with the elastic modulus;when the thickness of the rolling blinds is small,increasing the thickness of the rolling blinds can significantly improve the sealing ability;but when the thickness of the rolling blinds is too large,the self-weight of the rolling blinds can not be neglected,and the increase of the thickness leads to the increase of the central deflection instead.Horizontal force F_x and central deflection of the rolling blinds are basically proportional changes;under different rolling blinds thicknesses,the change form of the curve is basically the same,indicating that the change relationship is not related to the thickness of the rolling blinds;when the thickness is larger,the deflection caused by the external force of the same proportion changes is smaller.Therefore,in addition to meeting the basic requirements of the system,the designed structure can consider providing a larger preload,while making the chamfer?as small as possible.4.Optimum design of window size:Using ANSYS workbench platform,multi-objective genetic algorithm(MOGA)is used to optimize the window structure size,and the related window design parameters which have an impact on the central deflection are used to optimize the variables.Finally,the window structure size that meets the design requirements is obtained.Combining with environmental adaptability index,structural dynamic and static analysis of the window are carried out.The simulation results show that all the indexes of the window meet the design requirements.5.Window experiment validation:According to the design index,the processing window is validated by experiment.Vibration experiment results show that the first-order frequency of the window is 216 Hz,which is in good agreement with the finite element simulation.The window will not resonate in the frequency range required by the index,and the structure design is reasonable.The high and low temperature test results of the rolling blinds material show that the force of the rolling blinds material to tighten the roll at different temperatures does not change much.Because there is enough design margin when the motor is selected,the rolling blinds can run normally and ensure the sealing ability.