Research On Thermoforming Process Of Complex Aircraft Skin Parts For TA32 Titanium Alloy

TA32 is a modified near-α high-temperature titanium alloy that can be used as an alternative material for the next generation of Aircraft engines.However,it is difficult to manufactures a skin part with complex shape for its excellent high temperature performance and complex forming process,which limits its application in aircraft application.In order to meet the demand of development of new aircraft,this paper takes the thermoforming manufacturing process of two complex aircraft skin parts as the object of the research and carries out the relevant thermoforming technology research.The main research contents and conclusions of this paper are carried out as follows.The high temperature rheological behavior of TA32 titanium alloy is obtained through uniaxial tensile test and the deformation behavior is studied at different temperatures and strain rates.Based on the principle of regularization,a hyperbolic sine model is established to characterize the rheological behavior of TA32 at high temperature.The accuracy of the modified model is found to be a theoretical basis for subsequent process and simulation.Through the high temperature stress relaxation experiment,the effect of different temperature and initial state on the stress relaxation behavior is study.Based on the experimental curves,the stress relaxation and creep equations of TA32 alloy are obtained through fitting calculation,which is a reference for the precision thermoforming technology of TA32 alloy.The simulated stamping formability experiments were conducted to obtain the performance of different forming process indicators to assess the adaptability to different hot forming process of TA32 high temperature alloy.Then the design experiment is carried out to determine the forming limit curve of TA32 at high temperature.This curve can be used as the judgment criterion of the tensile instability in the simulation and forming process.The simulated research on the forming process of the complex deformed curvature shaped pieces and oversized size titanium alloy skin parts in the project is carried out.Through the establishment of a scientific failure analysis parameters,the effects of technological factors such as mold structure,forming temperature and pressing speed on the final forming result are studied.According to the results of simulation and failure theory,the process is modified and the result verifies the optimization measures can reduce the forming rupture and wrinkling defects effectively.Considering the thermal expansion effect,the design and manufacture of thermoforming mold is completed.Then the process experiment is carried out,and the forming quality of the two complicated shaped parts is analyzed and discussed.The complex deformed curvature shaped pieces and the oversized size titanium alloy skin parts are obtained.Both of them satisfy the requirement of design.The experiment proves the rationality of the process plan formulated in this subject.The research overcomes the difficulties of thermoforming process of TA32 complex skin and advances the research and development of the new aircraft project.