Deformation Regularity Of Al/Gf/PP Thermoplastic Based Fiber Metal Laminate Under Warm Condition

As a hybrid composite,fiber metal laminates combined the advantages of metal and fiber composites,but the low production efficiency and high cost limited their application.In order to solve this problem,Al/Gf/PP fiber metal laminate was prepared through substituting thermosetting resin with thermoplastic one.Firstly,the process of demolding and curing was studied,and a novel rapid curing process was designed.Secondly,the deformation regularity and coupling effect of the laminate with temperature and strain rate under simple stress state were quantitatively analysed,using polynomial equation to fit the variation process.Finally,the deformation law under complex stress in the actual forming process was studied in which forming defects were analysed for solution.The main conclusions were as follows:(1)The demolding mode and the cooling and curing process in the preparation of the laminate were optimized.Firstly,the effect of different peel ply structures on the spillage of resin curing process was investigated,which showed that the peel ply with holes could better maintain the fiber arrangement and prevent excessive resin overflow.In addition,the effect of cooling method after demolding was researched.Taking into account the preparation efficiency,mechanical properties and deformation,air cooling was the optimal curing method.Finally,a new curing curve was designed so that the tensile properties of the laminate can reach 96% of the theoretical value while maintaining high preparation efficiency.(2)The deformation law of the thermoplastic laminate under the coupling of temperature field and strain rate field was investigated.Furthermore,the sensitivity of the laminate to temperature and strain rate was studied.In order to quantitatively analyse the deformation regularity,a high-order polynomial was used to fit the deformation law.The contour map and the failure mode was adopted to analyse the sensitivity of the laminate to temperature and strain rate.The results indicated that under tensile conditions,the temperature played a dominant role;In the case of bending loading,the temperature had a significant effect on the deformation of the laminate before reaching the softening point,and the influence of the strain rate was highlighted after the temperature reached the softening point;Under interlaminar shear conditions,the temperature dominated before reaching the softening point,and the strain rate had a significant effect on laminate throughout the temperature change procedure.(3)The forming processes of U-shaped parts and cylindrical parts were adopted to study the warm forming law of laminates under complex stress conditions.When the laminate was plastically formed under warm conditions,the metal layer could be synergistically deformed well with metal layer or fiber layer,and the overall deformation law was similar to the metal plastic forming.In addition,affected by the orientation of the fibers in the cylindrical member,the strain parallelled to the fiber laying direction was smaller than strain not parallelled to the direction.Providing suitable thick compressive stress during the forming process is the key to reducing defects and improving the quality of the forming.