Milling Defects Of Aluminum Honeycomb Core And Its Influence On The Mechanical Properties Of Sandwich Structure

Compared with traditional metal materials,aluminum honeycomb material has excellent properties,such as light weight,high specific strength,good heat insulation and heat dissipation performance.However,honeycomb is typical thin-walled porous structure,whose in-plane stiffness is low,and it is easy to produce various defects during processing,which will affect the service performance and life of the parts.In this paper,the typical defects in aluminum honeycomb core milling were obtained by experiments,the planar compression and low-speed impact finite element models of honeycomb sandwich structure with machining defects were established by ABAQUS simulation software,the model was verified by compression test and low-speed impact test with drop weight.,milling aluminum honeycomb core was analyzed the influence law of defects on the mechanical properties,Optimized the milling processing parameters in order to control the main defects that affect the mechanical properties of honeycomb sandwich structure.The main research contents are as follows:(1)Through the milling experiments of aluminum honeycomb core,the surface morphology of aluminum honeycomb core was obtained,and the influence of different machining parameters on defects was studied.The results show that the honeycomb milling process is prone to obvious processing defects,the main defects are: tearing,folding and crushing,cracking and degumming.At the same time,there are certain tiny burrs on the aluminum honeycomb core milling surface.(2)Through the compression test and finite element simulation of aluminum honeycomb sandwich structure,the deformation process of the honeycomb core under the out-of-plane compression load was studied,and the influence of different processing defects on the flat compression performance of the sandwich structure was analyzed.The results show that the tearing of the aluminum honeycomb core processing defects has the greatest impact on the flat compression performance of the sandwich structure;the folding of the honeycomb wall has less impact;after the cracking and degumming defects reach a certain level,the bearing capacity of the aluminum honeycomb will decrease to a certain extent.(3)Through low-speed impact test and finite element simulation of aluminum honeycomb sandwich structure,the influence of machining defects on the impact performance of honeycomb core under different impact conditions was compared and analyzed.It is found that the energy absorption of the sandwich structure is slightly reduced due to the machining defect of aluminum honeycomb core under different impact energy.The impact performance of honeycomb sandwich structure is greatly affected by the thickness of panels.The specific energy absorption of honeycomb sandwich structure will be reduced by the existence of machining defects,and the influence of machining defects can be reduced by increasing the thickness of skin panels.Different punch types have great influence on the ultimate load of sandwich structure in the impact process.Under the same punch type,the sandwich structure with different processing defects has little change in energy absorption,and the energy absorption is basically the same.(4)Through the honeycomb core milling experiments under different milling speed and feed rate ratios,the milling process of aluminum honeycomb core and the influence of milling parameters on the milling force were analyzed,and the relationship between the surface quality and the processing parameters was obtained.The results show that the milling force first decreases and then increases with the increase of the spindle speed,and increases with the increase of the milling depth and the feed speed;the quantitative mathematical model of the honeycomb wall tearing defect is fitted,and the machined surface tearing defect increases with the milling speed The increase in the ratio of the feed rate to the feed rate decreases exponentially;to reduce the surface tearing defects of the machined surface as the optimization goal,the aluminum honeycomb core milling processing parameters are optimized.