| Because composite materials have the advantages of high specific stiffness and high specific strength,and there is a large space for optimal design of paving,they have important application prospects in high-value ships such as military ships and yachts.Compared with the traditional structural skeleton superstructure,the composite superstructure with equal stiffness and strength can reduce the weight by more than50%.However,the traditional thermosetting composites have weak impact resistance and are prone to delamination damage,which limits their application.In order to overcome the above shortcomings,a new composite toughened ply structure is designed,and the interlayer toughening and damage characteristics of thermosetting composites under low-speed impact are studied,so as to provide support for the application of thermosetting composites.In this paper,four kinds of toughened ply structures with different characteristics are designed,and the drop weight test and subsequent damage morphology observation are carried out respectively.Firstly,through the film interlayer toughening technology,using polyetherimide thermoplastic polymer film(hereinafter referred to as PEI film)as the toughening layer,the four designed toughening ply structures were prepared into Toughened Composite(HBD)laminates containing thermoplastic phase,and TSC specimens with the same number of prepreg layers were prepared as the contrast.Then,three different impact energy levels were set to observe the low-speed drop hammer impact and subsequent damage morphology of each specimen.By comparing the impact response,delamination shape,delamination size and damage degree of different structures,the differences of impact resistance of various laminated structures are analyzed.The results show that under high-energy impact,HBD laminates improve the local stiffness and damage impedance,and PEI films provide excellent toughening effect.Through the comparison of delamination damage area,the effectiveness of HBD laminate in reducing delamination damage is verified.Secondly,the multiple impact characteristics of HBD laminated structure are studied.Several impact tests were carried out on HBD laminates and TSC.According to the test results,the multi impact resistance of composite laminates and the role of Pei film in improving the properties of laminates were analyzed.The experimental results show that the multi impact resistance of HBD laminated structure is greatly improved compared with TSC,the number of multi impact resistance is increased by130%,and the delamination damage area during penetration is significantly lower than TSC.Subsequently,the vibration characteristics of HBD toughened composite laminates were studied..The vibration characteristics are studied by hammering method,and the damping value and maximum acceleration of each structural laminated plate are obtained based on the free attenuation formula.The modal shapes and natural frequencies of the laminated plates are calculated.By comparing the modal shapes and natural frequencies of each order,the effect of the toughening effect of Pei film on improving the natural frequencies of HBD laminates is analyzed.Finally,ABAQUS simulation software is used to study the low-speed impact damage characteristics of toughened laminates.Through simulation,it is determined that under the toughening effect of Pei thermoplastic film,matrix tensile damage and fiber tensile damage mainly occur on the impact back,while matrix compression damage and fiber tensile damage mainly occur on the impact surface under the axial compression and shear action of hammer head. |
