| The sandwich structure consists of two thin panels and a thick middle core.Because of its excellent comprehensive mechanical properties,it has been widely used in aerospace,ship and automotive fields.In practical engineering applications,sandwich structures are highly susceptible to low velocity impact(LVI).These low velocity impacts cause minor damage to the sandwich panel,which reduces the residual performance of the sandwich structure.At present,the research on the LVI performance and residual strength of sandwich structures has become the hot topic in the field of composite structures.Based on the finite element simulation software ABAQUS,this paper uses the nonlinear finite element method to simulate the LVI process of the aluminum honeycomb sandwich structure with carbon fiber reinforced plastic(CFRP)face sheets.The Hashin failure criterion was used to simulate the damage failure and damage evolution of carbon fiber composite panels.Johnosn-Cook material model was employed for modeling the damage behavior of aluminum honeycomb core.Cohesive elements are implemented to simulate the inter-laminar delamination induced by impact.In order to study the LVI performance and residual strength of CFRP face sheets-aluminum honeycomb core sandwich panel,the following works are mainly carried out:1.The LVI and compression after impact(CAI)of the sandwich panels were numerically simulated.The LVI performance and damage characteristics of sandwich panels with different core parameters,as well as the damage mode and compression performance of sandwich panels after impact,were analyzed.The residual compressive strengths of the sandwich plate in three damage cases: minor damage,partial penetration and complete penetration were studied.It was found that even minor damage can greatly affect the residual compressive strength of the sandwich panel.2.Three typical impact positions were selected and the LVI process of CFRP face sheets-aluminum honeycomb sandwich panel with preload(biaxial compression,biaxial tension,uniaxial compression and uniaxial tensile preload)was numerically simulated.The failure mode and damage mechanism of the sandwich panel under different preload conditions are analyzed.The impact force,displacement and energy absorption of the sandwich plate under impact are discussed.The effects of different preload and different impact positions on the LVI performance of the sandwich panel are studied.The results show that tension and compression preload have different effects on the impact performance of sandwich panels.Depending on the impact position,the preload has a different effect on the impact performance of the sandwich panel.3.The numerical simulation of LVI of the zero Poisson’s ratio core sandwich plate was carried out,and the damage mechanism of the panel and core of four different structures with zero Poisson’s ratio core layer sandwich plate(right angle type,polyline,U shape and cosine type)when subjected to LVI was analyzed.Besides,the influence of zero Poisson’s ratio core structure and the wall thickness gradient of the core on the LVI performance of the sandwich plate were analyzed.The results show that the structure of the zero Poisson’s ratio core has little effect on the damage deformation mode of the core layer,but it has a great influence on the impact performance of the sandwich panel.Under the energy impact of 5 and 10 J,the wall thickness gradient of the core layer has a great influence on the impact performance of the sandwich plate.Under the 40 J energy impact,the influence of the wall thickness gradient is small.In summary,a set of numerical models for the effective analysis of LVI performance and damage mechanism of CFRP face sheets-aluminum honeycomb core sandwich panel,as well as the residual compressive strength after impact,is established,which provides a theoretical basis and technical reference for the design and impact performance of honeycomb sandwich panel. |
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