Research On Scanning Strategy Of Laser Induced Thermoforming Of Aluminum Alloy Cross-stiffened Integral Panel

Integrally stiffened module structure is the best choice of spacecraft,due to its high structure efficiency and good sealing performance.Bending of stiffened integral panel is a key process in the manufacture of spacecraft m odule.Commonly used forming methods such as press bending and creep age forming,need moulds and external forces,which lead to long forming time and large springback.Laser induced thermoforming is a kind of rapid forming technique without a die.The deformation of plate is caused by internal thermal stress and does not need external forces.Therefore,using laser induced thermoforming technique to bending integral panel can shorten forming time and reduce springback.In this paper,cross-stiffened integral panel(CSIP)of 5A06 aluminum alloy is investigated numerically and experimentally.The objective of this research is to realize cylinder surface forming of CSIP.Single-path scanning and multi-path scanning of CSIP are studied successively.And effective scanning strategies are proposed,which are validated by simulations and experiments.Firstly,a finite element model of laser induced thermoforming is established.By sequential coupling method,a comprehensive thermal and structural finite element model is created based on ABAQUS.The effectiveness of model is validated by temperature field and displacement field,which lays a foundation for quantitative study of deformation of CSIP.Secondly,single-path scanning of grid region on CSIP is studied.Temperature field and stress-strain field are analyzed to reveal the reasons of undesirable deformation of CSIP.The effects of laser power,scanning speed,spot diameter,number of scans and the distance from scanning line to free end on deformation are investigated by simulation,which provide a basis for choosing proper scanning parameters.Varying power scanning,partial multi-scanning,external force assisted scanning and combined scanning are proposed to improve the forming precision of grid region and the effects of these strategies are compared numerically.The best strategy are validated experimentally.Finally,multi-path scanning of CSIP and relative problems are studied.Deformation characteristics of margin scanning and stiffener scanning are analyzed by simulation and the effects of scanning way on deformation is discussed.Aiming at the accumulation of undesirable deformation in multi-path scanning,a solution by scanning stiffener is proposed.Scanning process and strategies are planned for cylinder surface forming of CSIP and the forming experiment is carried out.The results show that the strategies are effective and the c ylinder surface of CSIP is achieved successfully.