Research On Low Speed Impact Damage Characteristics Of Glass Fiber Reinforced Aluminum Alloy Laminate

Fibre metal laminate(FML)is a type of laminate,in which a metal sheet and a fibre reinforced composite are stacked and then pressurized to form a hybrid composite laminated structure.Due to the combined advantages of the metal and the fibre reinforced composite,FML shows a high tolerance for fatigue,good impact resistance and erosion resistance.To date,FML has been employed in the Airbus series and Boeing series aeroplanes and has broad application prospects in aviation,aerospace,marine and transportation industries.However,the aircraft structure is susceptible to impact damage induced by hail,birds,fragments on the runway and tool stroking.This damage has a serious deleterious effect on the safe use of the aircraft structure.To meet the stability and security requirements of the structure,impact resistance is one of the important criterions to be considered d uring the design.Since the damage mode and the failure mechanism during impact are complex,comprehensive analyses of the damage evolution under impact in FML are needed.In light of the reasons mentioned above,theoretical analysis,FE simulation and experimental tests are employed to analyse the impact damage and resistance on glass fibre aluminium alloy laminates(GLARE).Content as follows:In this study,glass fibre aluminium alloy laminate(GLARE)was the focus of analysis.Commercial nonlinear finite element software LS-DYNA was used for establishing a low velocity impact finite element analytical model.In this model,a user subroutine was employed.Considering that the material properties degenerate during an impact,a gradual degradation method was adopted in this study.Damage modes of the composite,including fibre tensile failure,fibre compression failure,matrix crushing failure,matrix cracking and delamination,were incorporated in the analytical model.Low velocity impact test was employed to verify the reliability of the established model.The impact resistance of GLARE was simulated using FE simulation.The primary analysis parameters included the effect of impact resistance on impact energy and stacking sequence.The damage evolution in GLARE under impact was obtained from the simulation.Established the multiple impacts test and FE simulation method of impact sequence.A comparison of the simulation and test results validated the reliability of the FE model.The effect of single and multiple impacts was analysed using the developed FE model.The results from the finite element analysis of damage impact on GLARE was analysed based on an orthogonal experimental design involving multiple factors.The influence of the aluminium alloy sheet thickness,stacking sequences and layer number on impact resistance was determined.Our results show that a reduction in the layer orientation angle can improve the impact resistance of GLARE.